Sildenafil citrate is indicated for the treatment of erectile dysfunctional. The usual dose is 50mg about 1 hour before sexual intercourse. The dose may be increased to 100mg once a day or decreased to 25mg once a day depending on response. An initial dose of 25mg is recommended in elderly patients and in those with severe renal or hepatic impairment, increased according to response if appropriate.
It is contraindicated in treatment with nitrates, recent stroke, myocardial infarction, blood pressure below 90/50mmHg and retinal disorders. It is also contraindicated with a known hypersensitivity to any component of the tablet.
Side effects and adverse reactions
Common adverse effects are headache, flushing, dyspepsia, visual disturbance, dizzness, nasal congestion, diarrhoea, increased intraocular pressure, hypersensitivity reactions and cardiovascular side effects.
Sildenafil is contraindicated in anyone taking organic nitrates as it may potentiate their hypotensive effects. Concomitant administration of sildenafil with drugs that inhibit cytochrome CYP3A4, such as cimetidine, may reduce sildenafil clearance.
Precautions and warnings
The cardiovascular risk of sexual activity should be considered before beginning therapy with sildenafil; in some patients, sexual activity may be inadivisable.
Caution is required in patients with renal or hepatic impairment and dosage reduction may be necessary.
Care is also needed in patients with anatomical or haematological disorders which may predispose them to priapism and may be advisable in those with bleeding disorders or active peptic ulceration.
The safety of sildenafil is uncertain in patients with hypotension, a recent history of stroke or myocardial infarction or retinal disorders. Patients who experience dizzness or visual disturbances should not drive or operate hazardous machinery.