Sildenafil opresses phosphodiesterase (PDE5) which is responsible for the guanosine monophosphate inactivation in the cavernous body. Cyclic guanosine monophosphate is formed in the issue of the activation guanilatcyklasa by nitric oxide.

NO is secreted in the cavernous body during sexual arousal (the necessary condition for Sildenafil action), relax its unstriated muscles and create favorable conditions for the rush of blood. Sildenafil is inactive in the absence of the sexual arousal.

Other types of phosphodiesterases are less sensitive to Sildenafil (type 6, existing in retina, in 10 times less, type 1 – in 80 times less, type 2 and 4 – in 100 times less and type 3, existing in myocardium – in 4000 times less). Color sense is the result of phosphodiesterase6 oppression.

Grave coronary and cardiac insufficiency, arterial hypotension, liver impairment, haemorrhage of the brain and myocardial infarction and pigmented retinitis. It is not recommended to women.

Erectile dysfunction, when the erection is not enough for satisfactory coitus.

Intensify the effect of nitrates and nitrites (risk of the serious hypertension). It is not prescribed with other aphrodisiacs.

For adults – swallow 50 mg taken about 1 hour prior to anticipate sexual activity. Depending on the effect and tolerance the dosage can be increased to 100 mg or decreased to 25 mg. The maximum dosage is 100 mg once a day.

For elderly people the initial dosage is 25 mg, and then according to the tolerance it may be increased to 50 mg or 100 mg once a day. The dosage is decreased when renal insufficiency.

Side effects are most evident Treatment should be symptomatic, based on the knowledge of the pharmacological action of the constituents.

Recommended to use with great care when liver impairment, sickle-cell disease, leukemia, multiple myeloma, penis pathology, gastric ulcer and diseases associated with bleeding (haemophilia).

Headache, facial flushing, dizziness, depression, stuffiness in nose, vision malfunction, vomiting, colitis, dysphagia, stomatitis, dry mouth, rectal haemorrhage, stenocardia, migraine, tachycardia, hypotension, postural syncope, cerebral thrombosis, cardiac insufficiency, cardiac arrest, cardiomyopathy, anaemia, leucocytopenia, arthritis, arthrosis, myalgia, myasthenia, edema, hyperglycemia, hyperuricemy, hypernatremia, depression, insomnia, nightmares, hyporeflexia, nettle rash, herpes simplex, bore, exfoliative dermatitis, mydriatic pupils, conjunctivitis, photophobia, eye hemorrhage, cataract, xerophthalmus, cystitis, nycturia, abnormal ejaculation, urinary incontinence, edema of genital organs, anorgasmia, asthma, breathlessness, laryngitis, pharyngitis, sinusitis, bronchitis, cough. The most frequent side effects are headache, facial flushing and digestive disorder, stuffiness in nose, urinary tract infection, vision malfunction, diarrhea, dizziness and skin eruption.