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Viagra action description. Viagra tablets for men: instructions, description and benefits

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Viagra is pharmaceutical drug designed to correct erectile dysfunction. An interesting fact is that this remedy was developed by Pfizer specialists as a cardiological medicine, but as it was later noticed, the effect on the cardiovascular system was minimal, and further use was dictated by an exceptionally unusual side effect.

By the way, the developers of this tool, later, were awarded Nobel Prize, and this discovery fell on the same rank with such accidental inventions as x-rays and penicillin. That is why it is important for us to talk with you today about the drug Viagra, the method of using this medication.

Viagra - instructions for use:

Composition and form of release

The only active ingredient in this drug is sildenafil. This chemical compound blocks the uptake and utilization of nitric oxide by inhibiting the activity of the enzyme phosphodiesterase-5.

In addition to the main active substance, each tablet contains other components needed for shaping and so on. The list of additional chemical elements: microcrystalline cellulose, croscarmellose sodium, magnesium stearate, calcium hydrogen phosphate, titanium dioxide, lactose, and some others.

The drug is produced in tablet form, in the form of bluish tablets, slightly elongated with rounded edges. Pfizer is engraved on one side and VGR 50 on the other.

Supplied in blister packs containing 1 to 4 tablets containing 25 or 50 mg active ingredient. It is sold in pharmacies, and a prescription is not required for the purchase.

pharmachologic effect

Viagra is a selective inhibitor of an enzyme called phosphodiesterase-5. This substance is responsible for the processes of nitric oxide metabolism in the human body, which has a vasodilating effect. It is on this property that the developers of the drug were counting.

Viagra affects the smooth muscle tissue corpora cavernosa, contributing to its relaxation. As a result, much more blood enters the penis through the vessels that supply blood to the genitals of a man, contributing to the appearance of a pronounced erection.

It is believed, at least as stated by the manufacturer, that an erection will occur only in the case of sexual stimulation. In all other cases, the desired effect will not be achieved. So such scenes in comedy films are nothing more than a fiction of screenwriters.

The duration of erection can vary over a fairly wide range, from 30 minutes to several hours, and is determined by the dosage of the drug, as well as the residual ability to physiological function.

Indications for use

The use of Viagra is indicated only in one case - the correction of erectile dysfunction, in order to obtain a stable erection sufficient for a satisfactory sexual intercourse. Once again, I draw your attention to the fact that sexual stimulation is necessary to achieve the desired effect, in all other cases there will be no effect from the use of the drug.

Contraindications for use

Of course, Viagra is not indicated in all cases. There are diseases in the presence of which its use is undesirable, and perhaps even unacceptable. True, there are not so many such states. Below I will list the most common of them.

Individual intolerance to any of the components of Viagra;
The use of nitric oxide donators (organic nitrates);
The use of other erection stimulants;
In the presence of severe deformation of the penis, it is prescribed with caution;
In diseases accompanied by increased bleeding, caution should be exercised;
When transferred in the recent past (no more than 6 months) myocardial infarction and decompensated ischemic disease. Here the problem is not even in Viagra itself, but in the load that it implies.

Although Viagra is sold without a doctor's prescription, it is strongly recommended that you visit your doctor before using it. Perhaps he will help you choose the right, and therefore safe dosage, or prescribe a number of necessary examinations.

Application and dosage

Tablets should be taken one hour before the intended sexual intercourse. Reception begins with 50 mg, in the absence or insufficiency of the desired effect, the dosage can be increased to 100 mg per dose.

With poor tolerance, the dosage should be reduced to 25 mg, while monitoring the performance of the cardiovascular system. The maximum daily dose should not exceed 100 mg. In the elderly, in the absence of restrictions, as a rule, correction of the amount of the drug used is not required.

In case of pathology of the liver and kidneys, occurring against the background of a decrease in the function of these organs, the dosage of the drug is reduced to 25 mg.

Side effects

As always, unwanted effects should be considered depending on the organ system involved. From the organs of the central nervous system, headache, dizziness can sometimes occur, in some cases convulsions are possible.

From the side of the cardiovascular system: a drop in blood pressure, palpitations, fainting.

From the side digestive system: nausea, vomiting, stool changes. Other side effects also occur: allergic reactions, blurred vision and others.

Analogues

Viagra can be substituted with the following medicines: Levitra, Cialis,

Conclusion

Of course, Viagra allows you to prolong sexual activity even at a very advanced age. But when taking it, you should follow certain rules regarding the dosage and method of use, as well as periodically visit your doctor.

Pharmacology

Sildenafil is a potent selective inhibitor of cGMP-specific phosphodiesterase type 5 (PDE5).

The implementation of the physiological mechanism of erection is associated with the release of nitric oxide (NO) in the cavernous body during sexual stimulation. This, in turn, leads to an increase in the level of cGMP, subsequent relaxation of the smooth muscle tissue of the cavernous body and an increase in blood flow.

Sildenafil does not have a direct relaxing effect on the isolated human corpus cavernosum, but enhances the effect of NO through inhibition of PDE5, which is responsible for the breakdown of cGMP.

Sildenafil is selective for PDE5 in vitro, its activity against PDE5 exceeds activity against other known phosphodiesterase isoenzymes: PDE6 - 10 times; PDE1 - more than 80 times; PDE2, PDE4, PDE7-PDE11 - more than 700 times. Sildenafil is 4,000 times more selective for PDE5 than PDE3, which is of paramount importance, since PDE3 is one of the key enzymes in the regulation of myocardial contractility.

A prerequisite for the effectiveness of sildenafil is sexual stimulation.

Clinical Data

Cardiac research

The use of sildenafil in doses up to 100 mg did not lead to clinically significant ECG changes in healthy volunteers. The maximum decrease in systolic blood pressure in the supine position after taking sildenafil at a dose of 100 mg was 8.3 mm Hg, and diastolic blood pressure - 5.3 mm Hg. A more pronounced, but also transient effect on blood pressure was noted in patients taking nitrates.

In a study of the hemodynamic effect of sildenafil at a single dose of 100 mg in 14 patients with severe CAD (more than 70% of patients had stenosis of at least one coronary artery), resting systolic and diastolic BP decreased by 7% and 6%, respectively. , and pulmonary systolic pressure decreased by 9%. Sildenafil did not affect cardiac output and did not impair blood flow in stenotic patients. coronary arteries, and also led to an increase (by about 13%) of adenosine-induced coronary blood flow in both stenotic and intact coronary arteries.

In a double-blind, placebo-controlled study, 144 patients with erectile dysfunction and stable angina who were taking antianginal drugs (except nitrates) performed physical exercise until the severity of angina symptoms improved. The duration of the exercise was significantly longer (19.9 sec; 0.9-38.9 sec) in patients taking sildenafil at a single dose of 100 mg compared with patients receiving placebo.

In a randomized, double-blind, placebo-controlled study, the effect of changing the dose of sildenafil (up to 100 mg) was studied in men (n=568) with erectile dysfunction and arterial hypertension taking more than two antihypertensive drugs. Sildenafil improved erections in 71% of men compared to 18% in the placebo group. The frequency of adverse effects was comparable to that in other groups of patients, as well as in individuals taking more than three antihypertensive drugs.

Research on visual impairment

In some patients, 1 hour after taking sildenafil at a dose of 100 mg using the Farnsworth-Munsel 100 test, a mild and transient impairment in the ability to distinguish shades of color (blue / green) was detected. 2 hours after taking the drug, these changes were absent. It is believed that the violation of color vision is caused by inhibition of PDE6, which is involved in the process of light transmission in the retina. Sildenafil had no effect on visual acuity, contrast perception, electroretinogram, intraocular pressure or pupil diameter.

In a placebo-controlled crossover study of patients with proven early age-related macular degeneration (n=9), sildenafil at a single dose of 100 mg was well tolerated. No clinical significant changes vision, assessed by special visual tests (visual acuity, Amsler grating, color perception, color passage simulation, Humphrey perimeter and photostress).

Efficiency

The efficacy and safety of sildenafil was evaluated in 21 randomized, double-blind, placebo-controlled trials lasting up to 6 months in 3000 patients aged 19 to 87 with erectile dysfunction of various etiologies (organic, psychogenic or mixed). The effectiveness of the drug was assessed globally using an erection diary, an international index of erectile function (a validated questionnaire on the state of sexual function) and a partner survey. The effectiveness of sildenafil, defined as the ability to achieve and maintain an erection sufficient for satisfactory intercourse, has been demonstrated in all studies conducted and has been confirmed in long-term studies lasting 1 year. In fixed dose studies, the ratio of patients reporting that the therapy improved their erections was: 62% (sildenafil 25 mg dose), 74% (sildenafil 50 mg dose) and 82% (sildenafil 100 mg dose), compared with 25 % in the placebo group. An analysis of the international index of erectile function showed that, in addition to improving erection, treatment with sildenafil also increased the quality of orgasm, made it possible to achieve satisfaction from sexual intercourse and overall satisfaction.

According to the pooled data, 59% of patients with diabetes, 43% of patients undergoing radical prostatectomy and 83% of patients with injuries reported improvement in erection with sildenafil treatment. spinal cord(compared to 16%, 15% and 12% in the placebo group, respectively).

Pharmacokinetics

Suction

Sildenafil is rapidly absorbed after oral administration. Absolute bioavailability averages 40% (25-63%). In vitro, sildenafil at a concentration of approximately 1.7 ng / ml (3.5 nM) inhibits human PDE5 by 50%. After a single dose of 100 mg of the drug inside, the average Cmax of free sildenafil is 18 ng / ml (38 nM) and is achieved when taken on an empty stomach for an average of 60 minutes (30-120 minutes).

When taken in combination with fatty foods, the rate of absorption is reduced; T max increases by 60 minutes, and C max decreases by an average of 29%. However, the degree of absorption does not change significantly (AUC decreases by 11%).

Distribution

V d of sildenafil in the equilibrium state averages 105 liters.

The binding of sildenafil and its main circulating N-desmethyl metabolite to plasma proteins is about 96% and does not depend on the total concentration of sildenafil. Less than 0.0002% of the dose (mean 188 ng) was found in semen 90 minutes after taking the drug.

Metabolism

Sildenafil is metabolized mainly in the liver by the action of CYP3A4 isoenzymes (major pathway) and CYP2C9 (minor pathway).

The main circulating active metabolite, which is formed as a result of N-demethylation of sildenafil, undergoes further metabolism.

In terms of selectivity of action on PDE, the metabolite is comparable to sildenafil, and its activity against PDE5 in vitro is approximately 50% of the activity of sildenafil.

The plasma concentration of the metabolite is approximately 40% of that of sildenafil.

The N-demethyl metabolite undergoes further metabolism; its T 1/2 is about 4 hours.

breeding

The total clearance of sildenafil from the body is 41 l / h, and the final T 1/2 is 3-5 hours. After oral administration, sildenafil is excreted as metabolites, mainly with feces (approximately 80% of the dose) and, to a lesser extent, with urine (approximately 13% of the dose).

Pharmacokinetics in special clinical situations

At healthy people in the elderly (over 65 years), the clearance of sildenafil is reduced, and the concentration of the free active substance in plasma is approximately 40% higher than its concentration in young (18-45 years) patients. Age does not have a clinically significant effect on the incidence of side effects.

With mild renal failure (CC 50-80 ml / min) and moderate (CC 30-49 ml / min) severity, the pharmacokinetic parameters of sildenafil after a single oral dose of 50 mg do not change.

In severe renal insufficiency (CC ≤30 ml / min), the clearance of sildenafil is reduced, which leads to an approximately twofold increase in AUC (100%) and C max (88%) compared with those with normal renal function in patients of the same age group .

In patients with cirrhosis of the liver (class A and B on the Child-Pugh scale), the clearance of sildenafil is reduced, which leads to an increase in AUC (84%) and C max (47%) compared with those with normal liver function in patients of the same age. groups. The pharmacokinetics of sildenafil in patients with severely impaired liver function (Child-Pugh class C) has not been studied.

Release form

Blue film-coated tablets, diamond-shaped, slightly biconvex, with cut and rounded edges, debossed "Pfizer" on one side and "VGR 25" on the other.

Excipients: microcrystalline cellulose - 78.291 mg, calcium hydrogen phosphate - 26.097 mg, croscarmellose sodium - 7.5 mg, magnesium stearate - 3 mg.

Composition of the film shell*: Opadry blue OY-LS-20921 (hypromellose, lactose, triacetin, titanium dioxide (E171), aluminum varnish based on indigo carmine (E132)) - 3.75 mg and Opadry transparent YS-2-19114-A (hypromellose, triacetin) - 1.125 mg.

1 PC. - blisters (1) - packs of cardboard with the control of the first opening.

* up to 30 µg/g of vanillin and/or biotin can be added to the film coating; the content of one or both components in the film coating will be up to 0.75 μg for a dosage of 25 mg.

Dosage

The drug is taken orally.

In elderly patients, dose adjustment is not required.

With mild to moderate renal failure (CC 30-80 ml / min), dose adjustment is not required, with severe renal failure (CC<30 мл/мин) дозу силденафила следует снизить до 25 мг.

Combined use with other drugs

When combined with ritonavir, the maximum single dose of Viagra ® should not exceed 25 mg, the frequency of use should be 1 time in 48 hours.

When combined with inhibitors of the CYP3A4 isoenzyme (erythromycin, saquinavir, ketoconazole, itraconazole), the initial dose of Viagra ® should be 25 mg.

To minimize the risk of postural hypotension in patients taking alpha-blockers, you should start taking Viagra ® only after hemodynamic stabilization has been achieved in these patients. The feasibility of reducing the initial dose of sildenafil should be considered.

Overdose

With a single dose of the drug at a dose of up to 800 mg, adverse events were comparable to those when taking sildenafil at lower doses, but were more common.

Treatment: symptomatic therapy. Hemodialysis does not accelerate the clearance of sildenafil, because the latter actively binds to plasma proteins and is not excreted in the urine.

Interaction

Effect of other drugs on the metabolism of sildenafil

The metabolism of sildenafil occurs mainly in the liver under the action of CYP3A4 (the main route) and CYP2C9 isoenzymes, therefore inhibitors of these isoenzymes can reduce the clearance of sildenafil, and inducers, respectively, increase the clearance of sildenafil.

With the simultaneous use of CYP3A4 inhibitors (such as ketoconazole, erythromycin, cimetidine), a decrease in the clearance of sildenafil was noted.

Cimetidine (at a dose of 800 mg), which is a non-specific inhibitor of CYP3A4, with simultaneous reception with sildenafil (at a dose of 50 mg) causes an increase in plasma concentration of sildenafil by 56%.

A single dose of sildenafil at a dose of 100 mg simultaneously with erythromycin, a specific inhibitor of CYP3A4 (when taking erythromycin 500 mg 2 times / day for 5 days) against the background of achieving a constant concentration of erythromycin in the blood, leads to an increase in AUC of sildenafil by 182%.

With the simultaneous use of sildenafil (once at a dose of 100 mg) and saquinavir (at a dose of 1200 mg 3 times / day), which is both an inhibitor of HIV protease and an inhibitor of CYP3A4, while achieving a constant concentration of saquinavir in the blood, Cmax of sildenafil in the blood increased by 140% and AUC increased by 210%. Sildenafil did not affect the pharmacokinetic parameters of saquinavir.

Stronger inhibitors of the CYP3A4 isoenzyme, such as ketoconazole or itraconazole, can cause more pronounced changes in the pharmacokinetics of sildenafil.

The simultaneous use of sildenafil (once at a dose of 100 mg) and ritonavir (500 mg 2 times / day), which is an inhibitor of HIV protease and a strong inhibitor of cytochrome P450 isoenzymes, against the background of achieving a constant concentration of ritonavir in the blood, leads to an increase in Cmax of sildenafil by 300% (4 times), and AUC by 1000% (11 times). After 24 hours, the concentration of sildenafil in plasma was approximately 200 ng / ml (with a single application of one sildenafil - 5 ng / ml).

A single dose of an antacid (magnesium hydroxide / aluminum hydroxide) does not affect the bioavailability of sildenafil.

In studies involving healthy volunteers, the simultaneous use of an endothelin receptor antagonist, bosentan (an inducer of the CYP3A4 isoenzyme (moderate), CYP2C9 and possibly CYP2C19) at an equilibrium concentration (125 mg 2 times / day) and sildenafil at an equilibrium concentration (80 mg 3 times a day) /day) there was a decrease in AUC and Cmax of sildenafil by 62.6% and 52.4%, respectively. Sildenafil increased the AUC and Cmax of bosentan by 49.8% and 42%, respectively. It is assumed that the simultaneous use of sildenafil with potent inducers of the CYP3A4 isoenzyme, such as rifampicin, may lead to a greater decrease in the concentration of sildenafil in the blood plasma.

CYP2C9 isoenzyme inhibitors (such as tolbutamide, warfarin), CYP2D6 isoenzyme inhibitors (such as selective serotonin reuptake inhibitors, tricyclic antidepressants), thiazides and thiazide-like diuretics, ACE inhibitors and calcium antagonists do not affect the pharmacokinetics of sildenafil.

Simultaneous administration of azithromycin (500 mg / day for 3 days) does not affect AUC, C max , T max , excretion rate constant and T 1/2 of sildenafil or its main circulating metabolite.

Effect of sildenafil on other medicinal products

Sildenafil is a weak inhibitor of isoenzymes of the cytochrome P450 system - 1A2, 2C9, 2C19, 2D6, 2E1 and 3A4 (IK 50 > 150 μmol). When using sildenafil at recommended doses, its C max is about 1 μmol, so it is unlikely that sildenafil can affect the clearance of substrates of these isoenzymes.

Sildenafil enhances the hypotensive effect of nitrates both with long-term use and with acute indications. In this regard, the use of sildenafil in combination with nitrates or nitric oxide donators is contraindicated.

With the simultaneous administration of the alpha-blocker doxazosin (4 mg and 8 mg) and sildenafil (25 mg, 50 mg and 100 mg) in patients with benign prostatic hyperplasia with stable hemodynamics, the average additional reduction in systolic / diastolic blood pressure in the supine position was 7 /7 mm Hg, 9/5 mm Hg and 8/4 mm Hg. respectively, and in the standing position - 6/6 mm Hg, 11/4 mm Hg. and 4/5 mm Hg. respectively. Rare cases have been reported in these patients of symptomatic postural hypotension, manifested in the form of dizziness (without syncope). In selected sensitive patients receiving alpha-blockers, the simultaneous use of sildenafil may lead to symptomatic hypotension.

Signs of a significant interaction of sildenafil with tolbutamide (250 mg) or warfarin (40 mg), which are metabolized by CYP2C9, have not been identified.

Sildenafil at a dose of 100 mg does not affect the pharmacokinetic parameters of HIV protease inhibitors at a constant concentration in the blood, such as saquinavir and ritonavir, which are both CYP3A4 substrates.

Simultaneous use of sildenafil in an equilibrium state (80 mg 3 times / day) leads to an increase in AUC and Cmax of bosentan (125 mg 2 times / day) by 49.8% and 42%, respectively.

Sildenafil at a dose of 50 mg does not cause an additional increase in bleeding time when taking acetylsalicylic acid at a dose of 150 mg.

Sildenafil at a dose of 50 mg does not enhance the hypotensive effect of ethanol in healthy volunteers with a maximum blood ethanol level of 0.08% (80 mg/dL) on average.

In patients with arterial hypertension, there were no signs of the interaction of sildenafil (at a dose of 100 mg) with amlodipine. The average additional decrease in blood pressure in the prone position is 8 mm Hg. (systolic) and 7 mm Hg. (diastolic).

The use of sildenafil in combination with antihypertensive agents does not lead to additional side effects.

Side effects

The most common side effects were headache and "hot flashes".

Side effects are usually mild or moderate and transient.

In studies using a fixed dose, it was found that the frequency of some adverse events increases with increasing dose.

The frequency of adverse reactions is determined as follows:

From the immune system: infrequently - hypersensitivity reactions (including skin rash), allergic reactions.

On the part of the organ of vision: often - blurred vision, blurred vision, cyanopsia; infrequently - eye pain, photophobia, photopsia, chromatopsia, redness of the eyes / scleral injections, changes in the brightness of light perception, mydriasis, conjunctivitis, hemorrhage in the eye tissue, cataracts, disruption of the lacrimal apparatus; rarely - swelling of the eyelids and adjacent tissues, a feeling of dryness in the eyes, the presence of iridescent circles in the field of view around the light source, increased eye fatigue, vision of objects in yellow(xanthopsia), vision of objects in red (erythropsia), conjunctival hyperemia, irritation of the mucous membrane of the eyes, discomfort in the eyes; frequency unknown - non-arteritic anterior ischemic optic neuropathy (NPINZN), retinal vein occlusion, visual field defect, diplopia *, temporary loss of vision or decreased visual acuity, increased intraocular pressure, retinal edema, retinal vascular disease, vitreous detachment / vitreal traction.

On the part of the organ of hearing: infrequently - a sudden decrease or loss of hearing, tinnitus, pain in the ears.

From the side of the cardiovascular system: often - "tides"; infrequently - tachycardia, palpitations, decreased blood pressure, increased heart rate, unstable angina pectoris, AV blockade, myocardial ischemia, cerebral thrombosis, cardiac arrest, heart failure, deviations in ECG readings, cardiomyopathy; rarely - atrial fibrillation.

From the hemopoietic system: infrequently - anemia, leukopenia.

From the side of metabolism and nutrition: infrequently - a feeling of thirst, swelling, gout, uncompensated diabetes, hyperglycemia, peripheral edema, hyperuricemia, hypoglycemia, hypernatremia.

From the side respiratory system: often - nasal congestion; infrequently - nose bleed, rhinitis, asthma, dyspnea, laryngitis, pharyngitis, sinusitis, bronchitis, increased sputum volume, increased cough; rarely - a feeling of tightness in the throat, dryness of the nasal mucosa, swelling of the nasal mucosa.

From the digestive system: often - nausea, dyspepsia; infrequently - gastroesophageal reflux disease, vomiting, abdominal pain, dry mouth, glossitis, gingivitis, colitis, dysphagia, gastritis, gastroenteritis, esophagitis, stomatitis, abnormal liver function tests, rectal bleeding; rarely - hypoesthesia of the oral mucosa.

From the musculoskeletal system: often - back pain; infrequently - myalgia, pain in the extremities, arthritis, arthrosis, tendon rupture, tenosynovitis, bone pain, myasthenia gravis, synovitis.

From the side genitourinary system: infrequently - cystitis, nocturia, breast enlargement, urinary incontinence, hematuria, ejaculation disorder, genital edema, anorgasmia, hematospermia, damage to the tissues of the penis; rarely - prolonged erection and / or priapism.

From the side of the central and peripheral nervous system: very often - headache; often - dizziness; infrequently - drowsiness, migraine, ataxia, hypertonicity, neuralgia, neuropathy, paresthesia, tremor, vertigo, symptoms of depression, insomnia, unusual dreams, increased reflexes, hypoesthesia; rarely - convulsions *, repeated convulsions *, fainting.

From the side of the skin and subcutaneous tissues: infrequently - skin rash, urticaria, herpes simplex, pruritus, increased sweating, skin ulceration, contact dermatitis, exfoliative dermatitis; frequency unknown - Stevens-Johnson syndrome, toxic epidermal necrolysis.

Other: infrequently - a feeling of heat, swelling of the face, photosensitivity reactions, shock, asthenia, fatigue, pain of various localization, chills, accidental falls, pain in the area chest, accidental injury; rarely - irritability.

* Side effects identified during post-marketing studies.

During the post-marketing use of sildenafil for the treatment of erectile dysfunction, adverse events such as severe cardiovascular complications (including myocardial infarction, unstable angina, sudden cardiac death, ventricular arrhythmia, hemorrhagic stroke, transient ischemic attack, hypertension and hypotension) have been reported. ), which had a temporal relationship with the use of sildenafil. Most of these patients, but not all of them, had risk factors for cardiovascular events. Many of these adverse events were observed shortly after sexual activity, and some of them were noted after taking sildenafil without subsequent sexual activity. It is not possible to establish the existence of a direct relationship between the observed adverse events and these or other factors.

Visual disturbances

In rare cases, during post-registration use of all PDE5 inhibitors, incl. sildenafil, reported non-arteritic anterior ischemic optic neuropathy (NPINZN) - a rare disease and the cause of reduced or loss of vision. Most of these patients had risk factors, in particular, a reduced cup-to-optic disc diameter ratio ("congestive disc"), age over 50 years, diabetes mellitus, hypertension, CAD, hyperlipidemia, and smoking. An observational study assessed whether recent use of drugs of the PDE5 inhibitor class is associated with acute onset of NPINZN. The results indicate an approximately 2-fold increase in the risk of NPINZN within 5 half-lives after the use of a PDE5 inhibitor. According to published literature data, the annual incidence of NPINZN is 2.5-11.8 cases per 100,000 men aged >50 years in the general population. Should be advised to patients with sudden loss vision, discontinue sildenafil therapy and consult a physician immediately. Individuals who have already had a case of NPNDI have an increased risk of recurrent NINZN. Therefore, the physician should discuss this risk with these patients and also discuss with them the potential for adverse effects of PDE5 inhibitors. PDE5 inhibitors, incl. Sildenafil should be used with caution in such patients and only in situations where the expected benefit outweighs the risk.

When using the drug Viagra ® in doses exceeding the recommended, adverse events were similar to those noted above, but usually occurred more often.

Indications

treatment of erectile dysfunction characterized by an inability to achieve or maintain an erection of the penis sufficient for satisfactory intercourse.

Sildenafil is only effective with sexual stimulation.

Contraindications

use in patients receiving constantly or intermittently nitric oxide donators, organic nitrates or nitrites in any form, since sildenafil enhances the hypotensive effect of nitrates;
simultaneous use of the drug with other drugs for the treatment of erectile dysfunction (safety and efficacy combination therapy not studied);
children and adolescents up to 18 years of age;
women;
hypersensitivity to sildenafil or to any component of the drug.

With caution, the drug should be used for anatomical deformation of the penis (including with angulation, cavernous fibrosis or Peyronie's disease); in diseases predisposing to the development of priapism (such as sickle cell anemia, multiple myeloma, leukemia, thrombocytopenia); in diseases accompanied by bleeding; during exacerbation peptic ulcer stomach and duodenum; hereditary retinitis pigmentosa; heart failure, unstable angina, past 6 months of myocardial infarction, stroke, severe, life-threatening arrhythmias, hypertension (BP over 170/100 mm Hg) or hypotension (BP less than 90/50 mm Hg) .

Application features

Use during pregnancy and lactation

According to the registered indication, the drug is not intended for use in women.

Application for violations of liver function

Since the excretion of sildenafil is impaired in patients with liver damage (for example, with cirrhosis), the dose of the drug should be reduced to 25 mg.

Application for violations of kidney function

Use in children

The drug is not intended for use in children and adolescents under the age of 18 years.

special instructions

For the diagnosis of erectile dysfunction, determining their possible causes and the choice of adequate treatment, it is necessary to take a complete medical history and conduct a thorough physical examination. Treatments for erectile dysfunction should be used with caution in patients with anatomical deformity of the penis (angulation, cavernous fibrosis, Peyronie's disease), or in patients with risk factors for developing priapism (sickle cell anemia, multiple myeloma, leukemia).

During post-marketing studies, cases of the development of prolonged erection and priapism have been reported. If an erection persists for more than 4 hours, the patient should immediately seek medical attention. If priapism therapy is not carried out immediately, this can lead to damage to the tissues of the penis and irreversible loss of potency.

Drugs intended for the treatment of erectile dysfunction should not be prescribed to men for whom sexual activity is undesirable.

Sexual activity poses a certain risk in the presence of heart disease, therefore, before starting any therapy for erectile dysfunction, the doctor should refer the patient to a cardiovascular examination. Sexual activity is undesirable in patients with heart failure, unstable angina, myocardial infarction or stroke in the last 6 months, life-threatening arrhythmias, arterial hypertension (BP > 170/100 mmHg), or hypotension (BP<90/50 мм рт.ст.). В clinical research showed no difference in the incidence of myocardial infarction (1.1 per 100 people per year) or the incidence of death from cardiovascular diseases(0.3 per 100 people per year) in patients treated with Viagra ®, compared with patients treated with placebo.

Cardiovascular Complications

During the post-marketing use of sildenafil for the treatment of erectile dysfunction, adverse events such as serious cardiovascular complications (including myocardial infarction, unstable angina, sudden cardiac death, ventricular arrhythmia, hemorrhagic stroke, transient ischemic attack, arterial hypertension and hypotension) that had a temporal association with the use of sildenafil. Most of these patients, but not all of them, had risk factors for cardiovascular complications. Many of these adverse events were observed shortly after sexual activity, and some of them were noted after taking sildenafil without subsequent sexual activity. It is not possible to establish the existence of a direct relationship between the observed adverse events and these or other factors.

hypotension

Sildenafil has a systemic vasodilatory effect, leading to a transient decrease in blood pressure, which is not a clinically significant effect and does not lead to any consequences in most patients. However, before prescribing Viagra ®, the doctor must carefully assess the risk of possible adverse manifestations of the vasodilating effect in patients with relevant diseases, especially against the background of sexual activity. Increased susceptibility to vasodilators is observed in patients with left ventricular outflow tract obstruction (aortic stenosis, hypertrophic obstructive cardiomyopathy), as well as in rare multiple system atrophy syndrome, manifested by severe dysregulation of blood pressure from the autonomic nervous system.

Because the joint application sildenafil and alpha-blockers can lead to symptomatic hypotension in some susceptible patients, Viagra should be used with caution in patients taking alpha-blockers. To minimize the risk of developing postural hypotension in patients taking alpha-blockers, taking Viagra ® should be started only after achieving stabilization of hemodynamic parameters in these patients. You should also consider the feasibility of reducing the initial dose of the drug Viagra ® . Patients should be informed about what actions to take if symptoms of postural hypotension appear.

Visual disturbances

In rare cases, during post-registration use of all PDE5 inhibitors, incl. sildenafil, reported non-arteritic anterior ischemic optic neuropathy (NPINZN) - a rare disease and the cause of reduced or loss of vision. Most of these patients had risk factors, in particular, a reduced cup-to-optic disc diameter ratio ("congestive disc"), age over 50 years, diabetes mellitus, hypertension, CAD, hyperlipidemia, and smoking. An observational study assessed whether recent use of drugs of the PDE5 inhibitor class is associated with acute onset of NPINZN. The results indicate an approximately 2-fold increase in the risk of NPINZN within 5 half-lives after the use of a PDE5 inhibitor. According to published literature data, the annual incidence of NPINZN is 2.5-11.8 cases per 100,000 men aged >50 years in the general population. Patients should be advised in the event of sudden loss of vision to discontinue sildenafil therapy and consult a physician immediately. Individuals who have already had a case of NPNDI have an increased risk of recurrent NINZN. Therefore, the physician should discuss this risk with these patients and also discuss with them the potential for adverse effects of PDE5 inhibitors. PDE5 inhibitors, incl. Sildenafil should be used with caution in such patients and only in situations where the expected benefit outweighs the risk.

A small number of patients with hereditary retinitis pigmentosa have genetically determined disorders of the functions of retinal phosphodiesterases. There is no information on the safety of using Viagra in patients with retinitis pigmentosa, so sildenafil should be used with caution.

Hearing disorders

Some post-marketing and clinical studies report cases of sudden worsening or loss of hearing associated with the use of all PDE5 inhibitors, including sildenafil. Most of these patients had risk factors for sudden worsening or loss of hearing. A causal relationship between the use of PDE5 inhibitors and sudden hearing impairment or hearing loss has not been established. In the event of a sudden deterioration in hearing or hearing loss while taking sildenafil, the patient should immediately consult a doctor.

Bleeding

Sildenafil enhances the antiplatelet effect of sodium nitroprusside, a nitric oxide donor, on human platelets in vitro. Data on the safety of the use of sildenafil in patients with a tendency to bleeding or exacerbation of gastric and duodenal ulcers are not available, so the drug Viagra ® in these patients should be used with caution. Frequency of epistaxis in patients with pulmonary hypertension associated with diffuse disease connective tissue, was higher (sildenafil 12.9%, placebo 0%) than in patients with primary pulmonary hypertension (sildenafil 3%, placebo 2.4%). Patients receiving sildenafil in combination with a vitamin K antagonist had a higher incidence of epistaxis (8.8%) than patients not taking a vitamin K antagonist (1.7%).

Use in conjunction with other treatments for erectile dysfunction

The safety and efficacy of Viagra® in conjunction with other PDE5 inhibitors or other drugs for the treatment of pulmonary hypertension containing sildenafil (for example, Revacio®) or other treatments for erectile dysfunction have not been studied, so the use of such combinations is not recommended.

Influence on the ability to drive vehicles and control mechanisms

While taking the drug Viagra ® any negative impact on the ability to drive a car or other technical means was not observed. However, since when taking the drug, a decrease in blood pressure, the development of chromatopsia, blurred vision, one should carefully consider the individual effect of the drug in these situations, especially at the beginning of treatment and when changing the dosing regimen.

The drug Viagra is used to correct the sexual functions of men. The remedy is used for various psychogenic or physiological sexual disorders. If you want to try using Viagra in the treatment, the indications are clearly indicated in the instructions for use. Pills are prescribed if a man is concerned about:

premature ejaculation,
lack of potency
poor erection of the penis.

The drug is available in tablet form (20 mg, 50 mg, 100 mg).

Drug properties

The drug Viagra stimulates the filling of the cavernous bodies of the penis with blood. As a result, the erection becomes long, and the sexual intercourse is long. Nitric oxide is released in the tissues of the penis. Relaxation happens smooth muscles the genital organ, blood flow to the cavernous bodies increases. After taking Viagra, a long erection occurs, sexual desire increases. The drug provides a vivid and rich impression of sex, a long and powerful orgasm.

The tool helps to cope with various problems in the intimate sphere. Tablets help to restore male sexual functions, prevent premature ejaculation, improve sperm quality.

The drug helps to increase the natural production of testosterone. Viagra stabilizes the hormonal balance in the male body, helps to synthesize the necessary substances for sexual intercourse. The remedy is prescribed for erectile dysfunction, weak potency, premature ejaculation, psychogenic sexual disorders.

Taking Viagra, every man can feel like a real tiger in bed with a woman. It gives self-confidence, eliminates the fear of failure, increases sexual desire before sexual intercourse.

The drug is not effective if there is no sexual stimulation. The tool is intended for sexual intercourse and the treatment of erectile dysfunction. Before using this medication, you should consult your doctor. You should not take Viagra if there are contraindications to use.

On the drug reviews of men can be found, mostly positive. A large number of representatives of the stronger sex note that after taking this drug, there is a significant increase in potency. The penis quickly becomes erect in the process intimacy. His erection lasts for a long time and allows you to have sexual intercourse in such a way as to fully satisfy your sexual partner.

The tool causes adverse reactions in isolated cases. In general, the drug is well tolerated by the body.

For a quick and reliable improvement in potency, our readers advise M16 spray. This is a natural remedy that comprehensively affects the causes of erectile dysfunction. The composition of "M16" includes only natural ingredients with maximum efficiency. Due to its composition, the drug is absolutely safe, has no contraindications and side effects.

Composition of Viagra

The drug contains sildenafil citrate. 1 tablet contains 25 mg of sildenafil. This substance provides a stable erection, due to the improvement of blood circulation in the genitals. The substance has a beneficial effect on sexual functions, provides excellent potency and long sexual intercourse. Sildenafil quickly dilates blood vessels, relieves spasms, blocks the production of enzymes that constrict blood vessels in the male genital organs.

As additional substances Viagra includes microcrystalline cellulose, calcium, magnesium, sodium.

There is also a separate- read his instructions and reviews.

Viagra: indications for use

The main indications for taking this drug:

impaired erection of the penis;
sexual disorders of unknown etiology;
maintaining an erection of the penis during intercourse;
providing a bright and long orgasm;
stabilization of testosterone production;
erectile disfunction;
adjustment of male sexual functions.

The drug is intended to improve the sexual performance of men. It is prescribed to eliminate sexual disorders, restore potency and erection. The drug is indicated for reduced desire for sex, short intercourse, soft orgasm.

Contraindications for admission

There are contraindications to the use of Viagra. The drug should not be taken if present:

heart disease;
kidney failure;
bleeding;
anemia;
thrombosis;
leukemia;
heart rhythm disturbances;
hypotension;
arterial hypertension;
hypertension;
angina.

It is better to refrain from taking the medication after a stroke and myocardial infarction. The drug has a strong effect on the work of the heart, so you should be careful to take pills to all cores.

Viagra is not prescribed in children's and adolescence. Also, the medicine is contraindicated in women. For women, there are other drugs that mimic the exciting effect of Viagra.

Tablets are incompatible for use in conjunction with medicines that enhance the effects of sildenafil. Viagra increases the hypotensive effect of nitrates. It is unacceptable to use the drug with individual intolerance.

When planning to take the drug, consider contraindications. With the development of various undesirable effects, you should stop the pills and be sure to consult a medical specialist. Perhaps the doctor will change the remedy.

Instructions for use and optimal dosages

The tablet is taken orally, ie. inside the body. It is necessary to swallow the whole capsule and drink it with water. The recommended dose is 50 mg. The tablet must be taken 1 hour before the intended sexual intercourse. In some cases, the dosage is increased to 100 mg or, conversely, reduced to 25 mg. The dose of the tablet is calculated individually, depending on the present violations of sexual function.

The maximum allowed to use no more than 100 mg per day. It is recommended to take the drug once a day.

Elderly men do not require a special correction of the dosage of the drug. The drug is indicated for admission from 18 years to old age.

Compatibility with other drugs

Side effects of the pathogen

This drug can cause unwanted reactions from the body. Often there is a headache and a flush of heat. With an increase in the dose of the drug, the development of side effects is observed. Often develop:

allergy;
blurred vision;
discomfort in the eyeballs;
increased intraocular pressure;
vascular disease;
hearing loss;
leukopenia;
anemia;
respiratory disorders;
heartbeat;
dyspepsia;
nausea;
digestive disorders;
ejaculation disorder.

In the event of any adverse reaction from the side male body you need to stop using the medicine.

Viagra analogs

Similar potency stimulants have similar pharmacological effects. Means of this group are used to correct sexual dysfunction in men. The drugs have a beneficial effect on the potency and erection of the penis. Viagra appeared on the domestic market in 1998. Since then, many similar products have been developed. The most famous analogues of Viagra:

What is better Cialis or Viagra

Cialis can be an effective replacement for Viagra. The tool increases potency and allows you to have sexual intercourse without any problems. The drug provides a stable erection of the penis, filling the penis with blood. Cialis can be taken by men aged 18-70. Active medicinal substance this drug is tadalafil. The component provides a rush of blood to the penis and has a positive effect on the sexual functions of men.

The average price of Cialis is 2289 rubles.

Comparison with Levitra

Levitra is a well-known analogue of Viagra, which can be used for erectile dysfunction. The drug has the same pharmachologic effect like Viagra. Levitra - a means to improve potency. It provides a stable long erection of the penis, improved sexual life, getting a brighter and longer orgasm. Active substance Levitra - vardenafil.

The average price of Levitra is 1487 rubles per pack.

Impaza or Viagra

Impaza - good alternative Viagra in the event that the reception this medicine not possible for some reason. Impaza provides a long-lasting erection to the penis, fills the male genital organ with blood. Taking the remedy helps prevent premature ejaculation and impotence.

The average cost of Impaza is 460 rubles.

Eroton is a drug that is designed to eliminate erectile dysfunction in men. The drug is well tolerated by the body and rarely causes side effects. The drug provides good potency, enhances sexual desire, promotes the natural production of male hormones. Eroton - pills that will help prolong sexual intercourse, relieve fatigue and fear of intimacy.

Potential - an analogue of Viagra, used for poor potency. The effect of the drug remains for a long time. It is important to take into account the features of the remedy - the drug can cause headache and dizziness. In general, all pills to improve potency have a powerful vasodilating effect. They should be used with caution with a tendency to high blood pressure, after a stroke and heart attack.

The average price of Potencil is 335 rubles.

Price and terms of use of the drug

As for Viagra itself, this medicinal drug begins to act immediately after absorption in the body. The effect of Viagra is felt within 20 minutes after taking and lasts more than 4 hours. It is recommended to take Viagra immediately before sexual intimacy. The drug is quite effective. It, like analogues, provides a long-lasting erection of the penis. It should be noted that such a kind of remedy as Royal Viagra provides therapeutic effect about 7 days. The drug has a prolonged action and gives a powerful positive result.

The price of Viagra is about 620 rubles (25 mg) - 685 rubles (50 mg). The cost of tablets of the drug 100 mg - 811 rubles.

The drug should be stored at room temperature in dark place. It is undesirable to use these tablets without prior consultation with a doctor. The remedy must be taken to eliminate the present sexual disorders under the supervision of a physician. Medical correction provides complete relief from erectile dysfunction. Treatment of sexual dysfunction should be under medical supervision. It is impossible to self-medicate, this is fraught with deterioration in health and the wrong choice of therapeutic agents.

P N015875/01 dated 12.08.2009
Tradename medicinal product: Viagra®
International generic name : sildenafil
Dosage form : film-coated tablets

Compound

1 film-coated tablet contains:
Active substance:
sildenafil citrate (equivalent to 25 mg, 50 mg, or 100 mg sildenafil)
Excipients:
microcrystalline cellulose, calcium hydrogen phosphate, sodium croscarmellose, magnesium stearate; film shell: opadry blue OY-LS-20921 (contains hypromellose, lactose, triacetin, titanium dioxide (E171) and aluminum varnish based on indigo carmine (E132)) and opadry transparent YS-2-19114-A (contains hypromellose and triacetin)

Up to 30 µg/g vanillin and/or biotin can be added to the blue film coat; the content of one or both components in the film coating will be up to 0.75 μg, 1.5 μg and 3.0 μg for dosages of 25 mg, 50 mg and 100 mg, respectively.

Description

Blue film-coated tablets, diamond-shaped, slightly biconvex, with cut and rounded edges, debossed with "Pfizer" on one side and "VGR 25", "VGR 50" or "VGR 100" on the other side, respectively.

Pharmacotherapeutic group:

erectile dysfunction treatment - PDE5 inhibitor

ATX code: G04BE03

Pharmacological properties

Pharmacodynamics

Sildenafil is a potent selective inhibitor of cycloguanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5).

Mechanism of action

Sildenafil does not have a direct relaxing effect on the isolated human corpus cavernosum, but enhances the effect of nitric oxide (NO) through the inhibition of PDE5, which is responsible for the breakdown of cGMP.

Sildenafil is selective for PDE5 in vitro, its activity against PDE5 exceeds activity against other known phosphodiesterase isoenzymes: PDE6 - 10 times; PDE1 - more than 80 times; PDE2, PDE4, PDE7-PDE11 - more than 700 times. Sildenafil is 4,000 times more selective for PDE5 than PDE3, which is of paramount importance, since PDE3 is one of the key enzymes in the regulation of myocardial contractility.

A prerequisite for the effectiveness of sildenafil is sexual stimulation.

Clinical Data

Cardiac research

The use of sildenafil in doses up to 100 mg did not lead to clinically significant ECG changes in healthy volunteers. The maximum decrease in systolic pressure in the supine position after taking sildenafil at a dose of 100 mg was 8.3 mm Hg. Art., and diastolic pressure - 5.3 mm Hg. Art. More pronounced, but also transient effect on arterial pressure(AD) was observed in patients taking nitrates (see sections "Contraindications" and "Interaction with other drugs").

In a study of the hemodynamic effect of sildenafil at a single dose of 100 mg in 14 patients with severe coronary artery disease (CHD) (more than 70% of patients had stenosis of at least one coronary artery), resting systolic and diastolic pressure decreased by 7 % and 6%, respectively, and pulmonary systolic pressure decreased by 9%. Sildenafil did not affect cardiac output and did not impair blood flow in stenotic coronary arteries, and also led to an increase (by approximately 13%) of adenosine-induced coronary flow in both stenotic and intact coronary arteries.

In a double-blind, placebo-controlled study, 144 patients with erectile dysfunction and stable angina who were taking antianginal drugs (except nitrates) performed physical exercise until the severity of angina symptoms improved. The duration of the exercise was significantly longer (19.9 seconds; 0.9 - 38.9 seconds) in patients taking sildenafil at a single dose of 100 mg compared with patients receiving placebo.

In a randomized, double-blind, placebo-controlled study, the effect of changing the dose of sildenafil (up to 100 mg) was studied in men (n = 568) with erectile dysfunction and arterial hypertension taking more than two antihypertensive drugs. Sildenafil improved erections in 71% of men compared to 18% in the placebo group. The frequency of adverse effects was comparable to that in other groups of patients, as well as in individuals taking more than three antihypertensive drugs.

Research on visual impairment
In some patients, 1 hour after taking sildenafil at a dose of 100 mg using the Farnsworth-Munsel 100 test, a slight and transient impairment in the ability to distinguish shades of color (blue / green) was detected. 2 hours after taking the drug, these changes were absent. It is believed that the violation of color vision is caused by inhibition of PDE6, which is involved in the process of light transmission in the retina. Sildenafil had no effect on visual acuity, contrast perception, electroretinogram, intraocular pressure, or pupil diameter.
In a placebo-controlled crossover study of patients with proven early age-related macular degeneration (n = 9), sildenafil at a single dose of 100 mg was well tolerated. There were no clinically significant changes in vision assessed by special visual tests (visual acuity, Amsler grating, color perception, color passage simulation, Humphrey perimeter and photostress).

Efficiency
The efficacy and safety of sildenafil was evaluated in 21 randomized, double-blind, placebo-controlled trials lasting up to 6 months in 3000 patients aged 19 to 87, with erectile dysfunction of various etiologies (organic, psychogenic or mixed). The effectiveness of the drug was assessed globally using an erection diary, an international index of erectile function (a validated questionnaire on the state of sexual function) and a partner survey. The effectiveness of sildenafil, defined as the ability to achieve and maintain an erection sufficient for satisfactory intercourse, has been demonstrated in all studies conducted and has been confirmed in long-term studies lasting 1 year. In fixed-dose studies, the ratio of patients reporting that the therapy improved their erections was: 62% (sildenafil 25 mg dose), 74% (sildenafil 50 mg dose) and 82% (sildenafil 100 mg dose) compared to 25% in the placebo group. An analysis of the international index of erectile function showed that, in addition to improving erection, treatment with sildenafil also increased the quality of orgasm, made it possible to achieve satisfaction from sexual intercourse and overall satisfaction.

According to the pooled data, among patients reporting improvement in erection with sildenafil treatment, there were 59% of patients with diabetes, 43% of patients undergoing radical prostatectomy and 83% of patients with spinal cord injuries (vs. 16%, 15% and 12% in the placebo group, respectively). ).

Pharmacokinetics

Suction

Sildenafil is rapidly absorbed after oral administration. Absolute bioavailability averages about 40% (from 25% to 63%). In vitro Sildenafil at a concentration of about 1.7 ng / ml (3.5 nM) inhibits human PDE5 activity by 50%. After a single dose of sildenafil at a dose of 100 mg, the average maximum concentration of free sildenafil in the blood plasma (Cmax) of men is about 18 ng / ml (38 nM). Cmax when taking sildenafil orally on an empty stomach is achieved on average within 60 minutes (from 30 minutes to 120 minutes). When taken in combination with fatty foods, the absorption rate decreases: Cmax decreases by an average of 29%, and the time to reach maximum concentration (Tmax) increases by 60 minutes, but the degree of absorption does not change significantly (the area under the concentration-time pharmacokinetic curve (AUC) decreases by 11%.

Distribution

The volume of distribution of sildenafil in the equilibrium state averages 105 liters.
The relationship of sildenafil and its main circulating N-demethyl metabolite with plasma proteins is about 96% and does not depend on the total concentration of the drug. Less than 0.0002% of the dose of sildenafil (mean 188 ng) was found in semen 90 minutes after taking the drug.

Metabolism
Sildenafil is metabolized mainly in the liver by the cytochrome CYP3A4 isoenzyme (major pathway) and the cytochrome CYP2C9 isoenzyme (minor pathway). The main circulating active metabolite resulting from the N-demethylation of sildenafil undergoes further metabolism. The selectivity of this metabolite for PDE is comparable to that of sildenafil, and its activity for PDE5 in vitro is about 50% of the activity of sildenafil. The concentration of the metabolite in the blood plasma of healthy volunteers was about 40% of the concentration of sildenafil. The N-demethyl metabolite undergoes further metabolism; its half-life (T1 / 2) is about 4 hours.

breeding

The total clearance of sildenafil is 41 l / h, and the final T1 / 2 is 3-5 hours. After oral administration, as well as after intravenous administration, sildenafil is excreted as metabolites, mainly by the intestines (about 80% of the oral dose) and, to a lesser extent, by the kidneys (about 13% of the oral dose).

Pharmacokinetics in special groups patients

Elderly patients
In healthy elderly patients (over 65 years of age), the clearance of sildenafil is reduced, and the concentration of free sildenafil in the blood plasma is approximately 40% higher than in young people (18-45 years). Age does not have a clinically significant effect on the incidence of side effects.

Kidney dysfunction
With mild (creatinine clearance (CC) 50-80 ml / min) and moderate (CC 30-49 ml / min) degree of renal failure, the pharmacokinetics of sildenafil after a single oral dose of 50 mg does not change. In severe renal insufficiency (CC (30 ml / min)), the clearance of sildenafil is reduced, which leads to an approximately twofold increase in AUC (100%) and Cmax (88%) compared with those with normal renal function in patients of the same age group.

Liver dysfunction
In patients with cirrhosis of the liver (Child-Pugh stages A and B), the clearance of sildenafil is reduced, which leads to an increase in AUC (84%) and Cmax (47%) compared with those with normal liver function in patients of the same age. groups. The pharmacokinetics of sildenafil in patients with severe hepatic impairment (Child-Pugh grade C) has not been studied.

Indications for use

Treatment of erectile dysfunction characterized by an inability to achieve or maintain an erection of the penis sufficient for satisfactory intercourse. Sildenafil is only effective with sexual stimulation.

Contraindications

Hypersensitivity to sildenafil or to any other component of the drug.
Use in patients receiving continuously or intermittently nitric oxide donators, organic nitrates or nitrites in any form, since sildenafil enhances the hypotensive effect of nitrates (see section "Interaction with other drugs")
The safety and efficacy of Viagra® when used in combination with other treatments for erectile dysfunction have not been studied, so the use of such combinations is not recommended (see section "Special Instructions")
According to the registered indication, Viagra® is not intended for use in children under 18 years of age.
According to the registered indication, Viagra® is not intended for use in women.

Carefully

Anatomical deformity of the penis (angulation, cavernous fibrosis or Peyronie's disease) (see section "Special Instructions")
- Diseases predisposing to the development of priapism (sickle cell anemia, multiple myeloma, leukemia, thrombocythemia) (see section "Special Instructions")
- Diseases accompanied by bleeding
- Exacerbation of peptic ulcer
- Hereditary retinitis pigmentosa (see section "Special Instructions")
- Heart failure, unstable angina, past 6 months of myocardial infarction, stroke or life-threatening arrhythmias, hypertension (BP > 170/100 mmHg) or hypotension (BP< 90/50 мм рт. ст.) (см. раздел «Особые указания»)

Pregnancy and lactation

According to the registered indication, the drug is not intended for use in women.

Dosage and administration
inside.

The recommended dose for most adult patients is 50 mg approximately 1 hour before sexual activity. Based on efficacy and tolerability, the dose may be increased to 100 mg or reduced to 25 mg. The maximum recommended dose is 100 mg. The maximum recommended frequency of use is once a day.

Kidney dysfunction
With mild and moderate renal insufficiency (CC 30-80 ml / min), dose adjustment is not required, with severe renal insufficiency (CC< 30 мл/мин) – дозу силденафила следует снизить до 25 мг.

Liver dysfunction
Since the excretion of sildenafil is impaired in patients with liver damage (in particular, with cirrhosis), the dose of Viagra® should be reduced to 25 mg.

Joint use with other drugs
When used together with ritonavir, the maximum single dose of Viagra® should not exceed 25 mg, and the frequency of use should not exceed 1 time in 48 hours (see section "Interaction with other drugs").
When used together with inhibitors of the cytochrome CYP3A4 isoenzyme (erythromycin, saquinavir, ketoconazole, itraconazole), the initial dose of Viagra® should be 25 mg (see section "Interaction with other drugs").
To minimize the risk of postural hypotension in patients taking?-blockers, Viagra® should be started only after hemodynamic stabilization has been achieved in these patients. You should also consider the advisability of reducing the initial dose of sildenafil (see sections "Special instructions" and "Interaction with other drugs").

Elderly patients
Dose adjustment of Viagra® is not required.

Side effect

Usually, the side effects of Viagra® are mild or moderate and are transient.
Fixed-dose studies have shown that the incidence of some adverse events increases with dose.

Organs and organ systems	Side effects	Sildenafil, %	Placebo, %
Most common side effects (> 1/10)
Nervous system	Headache	10,8	2,8
The cardiovascular system	Vasodilation ("hot flashes" of blood to facial skin)	10,9	1,4
Common side effects (> 1/100 and< 1/10)
Nervous system	Dizziness	2,9	1,0
Organ of vision	Vision changes (blurred vision, sensory changes to the light)	2,5	0,4
	Chromatopsia (mild and transient, mainly changes in color perception)	1,1	0,03
The cardiovascular system	Cardiopalmus	1,0	0,2
Respiratory system	Rhinitis (stuffy nose)	2,1	0,3
Digestive system	Dyspepsia	3,0	0,4

When using the drug Viagra® in doses exceeding the recommended, adverse events were similar to those noted above, but usually occurred more often.
General disorders: hypersensitivity reactions (including skin rash).
Changes in the central and peripheral nervous system: convulsions.
Changes in the cardiovascular system: tachycardia, decreased blood pressure, fainting, epistaxis.
Gastrointestinal disorders: vomit.
Changes in the organ of vision: eye pain, eye redness/scleral injections.

Reproductive system disorders: prolonged erection and / or priapism.

Overdose

With a single dose of Viagra® at a dose of up to 800 mg, adverse events were comparable to those when taking the drug at lower doses, but were more common. Treatment is symptomatic. Hemodialysis does not accelerate the clearance of sildenafil, since the latter is actively bound to plasma proteins and is not excreted by the kidneys.

Interaction with other drugs
Effect of other drugs on the pharmacokinetics of sildenafil

The metabolism of sildenafil occurs mainly under the action of cytochrome isoenzymes CYP3A4 (the main pathway) and CYP2C9, therefore inhibitors of these isoenzymes can reduce the clearance of sildenafil, and inducers, respectively, increase the clearance of sildenafil. A decrease in the clearance of sildenafil was noted with the simultaneous use of inhibitors of the cytochrome CYP3A4 isoenzyme (ketoconazole, erythromycin, cimetidine). Cimetidine (800 mg), a non-specific inhibitor of the cytochrome CYP3A4 isoenzyme, when co-administered with sildenafil (50 mg), causes an increase in plasma concentration of sildenafil by 56%. A single dose of 100 mg of sildenafil together with erythromycin (500 mg / day 2 times a day for 5 days), a specific inhibitor of the cytochrome CYP3A4 isoenzyme, against the background of achieving a constant concentration of erythromycin in the blood, leads to an increase in the AUC of sildenafil by 182%. When co-administered sildenafil (once 100 mg) and saquinavir (1200 mg/day 3 times a day), an inhibitor of HIV protease and cytochrome isoenzyme CYP3A4, against the background of achieving a constant concentration of saquinavir in the blood, Cmax of sildenafil increased by 140%, and AUC increased by 210%. Sildenafil does not affect the pharmacokinetics of saquinavir. Stronger inhibitors of the cytochrome CYP3A4 isoenzyme, such as ketoconazole and itraconazole, can also cause stronger changes in the pharmacokinetics of sildenafil.
The simultaneous use of sildenafil (once 100 mg) and ritonavir (500 mg 2 times a day), an inhibitor of HIV protease and a strong inhibitor of cytochrome P450, against the background of achieving a constant concentration of ritonavir in the blood, leads to an increase in Cmax of sildenafil by 300% (4 times ), and AUC by 1000% (11 times). After 24 hours, the concentration of sildenafil in the blood plasma is about 200 ng / ml (after a single application of one sildenafil - 5 ng / ml).
If sildenafil is taken at the recommended doses by patients receiving simultaneously strong inhibitors of the cytochrome CYP3A4 isoenzyme, then the Cmax of free sildenafil does not exceed 200 nM, and the drug is well tolerated.
A single dose of an antacid (magnesium hydroxide / aluminum hydroxide) does not affect the bioavailability of sildenafil.
Inhibitors of the cytochrome CYP2C9 isoenzyme (tolbutamide, warfarin), the cytochrome CYP2D6 isoenzyme (selective serotonin reuptake inhibitors, tricyclic antidepressants), thiazide and thiazide-like diuretics, ACE inhibitors and calcium antagonists do not affect the pharmacokinetics of sildenafil.
Azithromycin (500 mg/day for 3 days) has no effect on AUC, Cmax, Tmax, excretion rate constant and T1 / 2 of sildenafil or its main circulating metabolite.

Effect of sildenafil on other medicinal products
Sildenafil is a weak inhibitor of cytochrome P450 isoenzymes - 1A2, 2C9, 2C19, 2D6, 2E1 and 3A4 (IC50>150 µmol). When taking sildenafil at recommended doses, its Cmax is about 1 μmol, so it is unlikely that sildenafil can affect the clearance of substrates of these isoenzymes.

Sildenafil enhances the hypotensive effect of nitrates both with long-term use of the latter and with their appointment for acute indications. In this regard, the use of sildenafil in combination with nitrates or nitric oxide donators is contraindicated.
With the simultaneous administration of the ?-blocker doxazosin (4 mg and 8 mg) and sildenafil (25 mg, 50 mg and 100 mg) in patients with benign prostatic hyperplasia with stable hemodynamics, the average additional decrease in systolic / diastolic blood pressure in the supine position was 7 / 7 mmHg Art., 9/5 mm Hg. Art. and 8/4 mm Hg. Art., respectively, and in a standing position - 6/6 mm Hg. Art., 11/4 mm Hg. Art. and 4/5 mm Hg. Art., respectively. Rare cases have been reported in these patients of symptomatic postural hypotension, manifested in the form of dizziness (without syncope). In selected sensitive patients receiving .?-blockers, the simultaneous use of sildenafil can lead to symptomatic hypotension.
Signs of significant interaction with tolbutamide (250 mg) or warfarin (40 mg), which are metabolized by the cytochrome isoenzyme CYP2C9, have not been identified.
Sildenafil (100 mg) does not affect the pharmacokinetics of HIV protease inhibitors, saquinavir and ritonavir, which are substrates of the cytochrome isoenzyme CYP3A4, at a constant level in the blood.
Sildenafil (50 mg) does not cause an additional increase in bleeding time when taking acetylsalicylic acid (150 mg).
Sildenafil (50 mg) does not increase the hypotensive effect of alcohol in healthy volunteers, with a maximum blood alcohol concentration of 0.08% (80 mg/dL) on average.
In patients with arterial hypertension, there were no signs of the interaction of sildenafil (100 mg) with amlodipine. The average additional decrease in blood pressure in the prone position is 8 mm Hg. Art. (systolic) and 7 mm Hg. Art. (diastolic).
The use of sildenafil in combination with antihypertensive agents does not lead to additional side effects.

special instructions

To diagnose erectile dysfunction, determine their possible causes and select adequate treatment, it is necessary to collect a complete medical history and conduct a thorough physical examination.

Sexual activity poses a certain risk in the presence of heart disease, therefore, before starting any therapy for erectile dysfunction, the doctor should refer the patient to a cardiovascular examination. Sexual activity is undesirable in patients with heart failure, unstable angina, myocardial infarction or stroke in the last 6 months, life-threatening arrhythmias, arterial hypertension (BP > 170/100 mmHg), or hypotension (BP< 90/50 мм рт. ст.) (см. раздел «С осторожностью»). В клинических исследованиях показано отсутствие различий в частоте развития инфаркта миокарда (1,1 на 100 человек в год) или частоте смертности от сердечно-сосудистых заболеваний (0,3 на 100 человек в год) у пациентов, получавших препарат Виагра®, по сравнению с пациентами, получавшими плацебо.

Drugs intended for the treatment of erectile dysfunction should not be prescribed to men for whom sexual activity is undesirable.

The drug Viagra® has a systemic vasodilatory effect, leading to a transient decrease in blood pressure, which is not a clinically significant phenomenon and does not lead to any consequences in most patients. However, before prescribing Viagra®, the doctor should carefully assess the risk of possible adverse manifestations of the vasodilating effect in patients with relevant diseases, especially against the background of sexual activity. Increased susceptibility to vasodilators is observed in patients with left ventricular outflow tract obstruction (aortic stenosis, hypertrophic obstructive cardiomyopathy), as well as in rare multiple system atrophy syndrome, manifested by severe dysregulation of blood pressure from the autonomic nervous system.

Rare cases of anterior ischemic optic neuropathy of non-arterial origin have been noted as a cause of deterioration or loss of vision during the use of all PDE5 inhibitors, including sildenafil. Most of these patients had risk factors such as excavation (deepening) of the optic nerve head, age over 50 years, diabetes mellitus, arterial hypertension, ischemic disease heart disease (CHD), hyperlipidemia and smoking. A causal relationship between the use of PDE5 inhibitors and the development of non-arterial anterior ischemic optic neuropathy has not been identified. The physician should inform the patient about the increased risk of anterior ischemic optic neuropathy of non-arterial origin, if this condition has already been noted in him before. Since the combined use of sildenafil and .?-blockers can lead to symptomatic hypotension in some sensitive patients, Viagra® should be used with caution in patients taking ?-blockers (see section "Interaction with other drugs"). To minimize the risk of postural hypotension in patients taking beta-blockers, Viagra® should be started only after hemodynamic stabilization has been achieved in these patients. You should also consider the feasibility of reducing the initial dose of the drug Viagra® (see section "Method of application and dosage"). The physician should inform patients about what actions to take if symptoms of postural hypotension appear.

A small number of patients with hereditary retinitis pigmentosa have genetically determined disorders of the functions of retinal phosphodiesterases. There is no information on the safety of using Viagra® in patients with retinitis pigmentosa, so sildenafil should be used with caution (see section "With caution").

Sildenafil enhances the antiaggregatory effect of sodium nitroprusside (nitric oxide donor) on human platelets in vitro. There is no information on the safety of using Viagra® in patients with internal bleeding or an active peptic ulcer of the stomach, so it should be used with caution (see the section "With caution").

Treatments for erectile dysfunction should be used with caution in patients with anatomical deformity of the penis (angulation, cavernous fibrosis, Peyronie's disease), or in patients with risk factors for priapism (sickle cell anemia, multiple myeloma, leukemia) (see section "With caution). ness").

The safety and efficacy of Viagra® in conjunction with other treatments for erectile dysfunction have not been studied, so the use of such combinations is not recommended (see section "Contraindications").

In some post-marketing and clinical studies using all PDE5 inhibitors, including sildenafil, a sudden decrease or loss of hearing in patients has been reported. However, most of these patients had risk factors for the development of this pathology, and no correlation was found between the use of PDE5 inhibitors and sudden decrease or loss of hearing. In the event of a sudden decrease or loss of hearing, sildenafil therapy should be discontinued and a physician should be consulted immediately.

Influence on the ability to drive a car and control mechanisms

Against the background of taking sildenafil, no negative effect on the ability to drive a car or other technical means was observed. However, since when taking sildenafil, a decrease in blood pressure, the development of chromatopsia, blurred vision, etc. is possible. side effects, you should carefully consider the individual effect of the drug in these situations, especially at the beginning of treatment and when changing the dosing regimen.

Release form

Film-coated tablets 25 mg, 50 mg or 100 mg

1, 2, 4, 8 or 12 tablets in PVC/polyethylene/aclar/aluminum foil blister

1, 2 or 3 blisters in a carton box along with instructions for use

On the reverse side of the blister, an additional security logo is applied (in Latin letters "Pfizer" in white on a dark blue background), which changes color when the angle of view changes. At the corners of the blister there are empty round contour cells for fixing in the production machine.

On the front side of the cardboard pack, from both edges on the right and on the left, perforated lines of the control of the first opening are applied in the form of red semicircles. A protective holographic sticker that changes color with a change in the angle of view is located in the lower right corner of the front surface of the pack.

The side surfaces of the pack are tightly glued when the drug is packed.

Storage conditions

List B. Store in a dry place at a temperature not exceeding 30 .C
Keep out of the reach of children

Best before date

5 years
Do not use after the expiry date stated on the packaging

Terms of dispensing from pharmacies
On prescription

Company manufacturer:

Pfizer PGM, France
Zon Endustriel, 29 rue des Endustris, 37530 Posay-sur-Cies, France
Submit consumer complaints
at the address of the company's representative office in the Russian Federation:
109147 Moscow, Taganskaya street, 21