Sildenafil
Sildenafil: instructions for use and reviews
- 1. Release form and composition
- 2. Pharmacological properties
- 3. Indications for use
- 4. Contraindications
- 5. Method of application and dosage
- 6. Side effects
- 7. Overdose
- 8. Special instructions
- 9. With impaired renal function
- 10. In case of impaired liver function
- 11. Drug interactions
- 12. Analogs
- 13. Terms and conditions of storage
- 14. Terms of dispensing from pharmacies
- 15. Reviews
- 16. Price in pharmacies
Latin name: Sildenafil
ATX code: G04BE03
Active ingredient: sildenafil (sildenafil)
Producer: Actavis LTD (Malta), Severnaya Zvezda CJSC (Russia), Vertes St. Petersburg CJSC (Russia), Sandoz (Russia)
Description and photo update: 2018-26-10
Prices in pharmacies: from 47 rubles.
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Sildenafil is a drug for the treatment of erectile dysfunction.
Release form and composition
Sildenafil dosage form - film-coated tablets (25/50/100 mg): diamond-shaped, biconvex, blue on the outside and white or almost white at the break, with an engraving "I" on the side and "35" (for 25 mg tablets), “36” (for 50 mg tablets) and “58” (for 100 mg tablets).
Composition of 1 tablet 25/50/100 mg:
- active substance: sildenafil citrate - 35.12 / 70.24 / 140.48 mg (in terms of sildenafil - 25/50/100 mg);
- auxiliary components: microcrystalline cellulose, anhydrous calcium hydrogen phosphate, croscarmellose sodium, magnesium stearate, blue opadray II (lactose monohydrate, hypromellose HPMC 2910, titanium dioxide, triacetin, blue / indigo carmine dye), transparent opadry (hypromellose, triacetin HPMC 2910).
Pharmacological properties
Pharmacodynamics
Sildenafil is a selective inhibitor of cyclic guanosine monophosphate (cGMP), a specific phosphodiesterase type 5 (PDE5).
The mechanism of erection is associated with the release of nitric oxide in the corpus cavernosum, which leads to an increase in cGMP levels, relaxation of the smooth muscle tissue of the corpus cavernosum and an increase in blood flow.
The effect of the drug is due to the enhancement of the effect of nitric oxide by inhibiting phosphodiesterase 5 (PDE5), which is responsible for the breakdown of cGMP.
Sexual stimulation is a prerequisite for the effectiveness of sildenafil.
Pharmacokinetics
The drug is rapidly absorbed when taken orally. Its bioavailability is about 40%. In vitro, sildenafil at a concentration of about 1.7 ng / ml (3.5 nM) inhibits human PDE5 activity by 50%. With a single dose of the drug on an empty stomach at a dose of 100 mg, the maximum concentration of free sildenafil is reached within 30–120 minutes and is 18 ng / ml (38 nM). Taking the drug together with fatty foods reduces the rate of its absorption.
The volume of distribution averages 105 liters. Plasma protein binding is about 96%. The main metabolism of sildenafil occurs in the liver. Its half-life is 3-5 hours. Excretion of the drug occurs mainly by the intestines, to a lesser extent by the kidneys.
Indications for use
According to the instructions, Sildenafil is indicated for the treatment of erectile dysfunction, in particular with an inability to achieve and maintain an erection sufficient for intercourse.
Contraindications
Absolute contraindications:
- arterial hypotension;
- conditions in which sexual activity is undesirable;
- condition after a recent myocardial infarction or cerebrovascular accident (within the last 6 months);
- degenerative diseases of the retina (hereditary), including rhinitis pigmentosa;
- severe liver failure;
- female;
- increased sensitivity to drug components;
- age up to 18 years.
Relative contraindications:
- anatomical deformity of the penis;
- conditions accompanied by bleeding;
- diseases that contribute to the development of priapism, such as sickle cell anemia, leukemia, multiple myeloma, thrombocythemia;
- peptic ulcer in the acute stage;
- arrhythmia, arterial hypertension, heart failure, obstructive diseases of the left ventricular outflow tract, such as aortic stenosis, hypertrophic obstructive cardiomyopathy;
- history of episodes of development of anterior non-arteritic ischemic neuropathy of the optic nerve.
Sildenafil instructions for use: method and dosage
Sildenafil tablets are recommended to be taken 1 hour before sexual activity, the usual recommended dose is 50 mg, if necessary and depending on the tolerance of the drug, it may be increased to 100 mg or decreased to 25 mg.
The maximum recommended dose is 100 mg / day.
Side effects
- nervous system: headache, dizziness, hypesthesia, drowsiness, stroke, fainting, transient ischemic attack, convulsions (including recurrent);
- cardiovascular system: hot flashes, palpitations, tachycardia, decrease or increase in blood pressure (BP), myocardial infarction, atrial fibrillation, ventricular arrhythmia, unstable angina pectoris, sudden death;
- organ of vision: impaired vision and color perception, damage to the conjunctiva, impaired lacrimation, anterior ischemic optic neuropathy, occlusion of retinal vessels, visual field defects;
- organ of hearing: vertigo, tinnitus, nosebleeds;
- gastrointestinal tract (GIT): dyspepsia, nausea, vomiting, dryness of the oral mucosa;
- allergic reactions: skin rash, Stevens-Johnson syndrome, Lyell's syndrome;
- genitals: hematospermia, bleeding from the penis, priapism, prolonged erection;
- musculoskeletal system: myalgia;
- other: chest pain, fatigue.
Overdose
Overdose leads to an increase in the frequency and severity of side effects.
Symptomatic treatment is recommended. Hemodialysis is ineffective.
special instructions
Before using Sildenafil, it is recommended to conduct a medical examination aimed at identifying the causes of erectile dysfunction, as well as conditions in which sexual activity poses a certain risk, such as diseases of the cardiovascular system. The risk of undesirable effects of the vasodilating effect of the drug should be carefully evaluated, especially in patients with obstruction of the left ventricular outflow tract (aortic stenosis, hypertrophic obstructive cardiomyopathy), as well as with the rare syndrome of multiple systemic atrophy, manifested by severe dysregulation of blood pressure by the autonomic nervous system.
When taking PDE5 inhibitors, there were cases of development of anterior ischemic-optic neuropathy of non-arterial genesis. Risk factors are excavation of the optic nerve head, age over 50, diabetes mellitus, coronary heart disease, arterial hypertension, hyperlipidemia, smoking.
Sildenafil tablets should be used with caution with active peptic ulcer and internal bleeding.
According to some studies, there are cases of sudden hearing loss or loss, observed mainly in patients with risk factors for their development. The causal relationship of these phenomena with the intake of PDE5 inhibitors has not been established, however, in the event of a sudden decrease or loss of hearing, it is recommended to stop taking the drug and consult a doctor.
It is also necessary to immediately consult a doctor if an erection persists for more than 4 hours, as this can lead to damage to the tissues of the penis and irreversible loss of potency.
Influence on the ability to drive vehicles and complex mechanisms
In connection with the possible development of undesirable effects of the drug, such as blurred vision, dizziness, etc., care should be taken when driving vehicles and other mechanisms that require the speed of psychomotor reactions.
With impaired renal function
In severe renal failure with creatinine clearance <30 ml / min, it is recommended to reduce the dose of the drug to 25 mg.
If liver function is impaired
Patients with impaired liver function are advised to reduce the dose of the drug to 25 mg.
Drug interactions
The effect of drugs on the pharmacokinetics of sildenafil:
- inhibitors of isoenzymes CYP3A4 and CYP2C9: reduce its clearance;
- inducers of isoenzymes CYP3A4 and CYP2C9: increase its clearance;
- cimetidine (800 mg) + 50 mg of sildenafil: the concentration of the latter in plasma increases by 56%;
- erythromycin (500 mg / day 2 times for 5 days) + 100 mg sildenafil: the area under the sildenafil curve increases by 182%;
- saquinavir (1200 mg / day 3 times) + 100 mg sildenafil: its area under the curve increases by 210%, and the maximum concentration by 140%;
- ritonavir: leads to an increase in the maximum concentration of sildenafil by 4 times, and the area under the curve by 11 times, and therefore the maximum recommended dose of sildenafil is 25 mg once every 48 hours;
- bosentan: the area under the curve decreases by 62.6% and the maximum concentration by 52.4%.
Do not affect the pharmacokinetics of the drug tolbutamide, warfarin, selective serotonin reuptake inhibitors, tricyclic antidepressants, thiazide and thiazide-like diuretics, ACE inhibitors, calcium antagonists, azithromycin.
Effect of sildenafil on other drugs:
- nitrates and nitric oxide donors: enhances their hypotensive effect, and therefore the combined use is contraindicated;
- doxazosin (alpha-blocker): in rare cases, symptomatic postural hypotension may develop, in patients with hypersensitivity, there is a risk of symptomatic hypotension;
- bosentan: its area under the curve increases by 49.8%, and its maximum concentration increases by 42%.
There was no clinically significant interaction of sildenafil with tolbutamide, warfarin, HIV protease inhibitors, saquinavir, ritonavir, acetylsalicylic acid, amlodipine, antihypertensive drugs.
Taking the drug together with beta-blockers is possible only after reaching stable hemodynamics, which reduces the risk of postural hypotension. You should also consider the feasibility of reducing the initial dose of Sildenafil.
The combined use of Sildenafil with other drugs for the treatment of erectile dysfunction is not recommended due to the lack of data on the safety and effectiveness of their combination.
Analogs
The analogues of Sildenafil are Viagra, Vigrande, Vizarsin, Dynamiko.
Terms and conditions of storage
Store at a temperature not exceeding 25 ° C. Keep out of the reach of children.
Shelf life is 3 years.
Terms of dispensing from pharmacies
Dispensed by prescription.
Reviews about Sildenafil
Reviews of Sildenafil are mostly positive, the effectiveness and good tolerance of the drug are noted. Among the disadvantages are the occurrence of transient side effects, such as facial flushing, headache, dyspepsia, nasal congestion and changes in color perception when taking 100 mg of Sildenafil.
The price of Sildenafil in pharmacies
The approximate price for Sildenafil is 530 rubles per pack containing 10 tablets of 50 mg each.
Sildenafil: prices in online pharmacies
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Drug name Price Pharmacy |
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Effex Sildenafil 100 mg film-coated tablets 1 pc. RUB 47 Buy |
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Sildenafil Vertex 25 mg film-coated tablets 1 pc. RUB 64 Buy |
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Sildenafil 50 mg film-coated tablets 2 pcs. RUB 95 Buy |
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Sildenafil Vertex 100 mg film-coated tablets 1 pc. RUB 105 Buy |
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Sildenafil tablets p.o. 100mg 2 pcs. RUB 150 Buy |
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Sildenafil tablets p.o. 100mg 10 pcs. Vertex 320 RUB Buy |
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Maria Kulkes Medical journalist About the author
Education: First Moscow State Medical University named after I. M. Sechenov, specialty "General Medicine".
Information about the drug is generalized, provided for informational purposes only and does not replace the official instructions. Self-medication is hazardous to health!
