interactions and contraindications

Last reviewed 01/2018

• organic nitrates interact with sildenafil to cause severe hypotension - concurrent use of sildenafil with nitric oxide donors or nitrites is contraindicated
• other contraindications include hypotension (blood pressure below 90/50 mmHg), severe hepatic impairment, hereditary degenerative retinal disorders such as retinitis pigmentosa, recent stroke or myocardial infarction.
• sildenafil should be used with caution in patients with a condition predisposing to priapism e.g. sickle cell anaemia, multiple myeloma, or leukaemia; in any patient with a penile deformity (e.g. Peyronie's disease); in those patients with active peptic ulcer disease or a bleeding disorder.
• sildenafil is metabolised mainly by the cytochrome P450 system - the plasma levels of sildenafil are increased if there is concurrent use of another drug that is a cytochrome P450 inhibitor e.g. cimetidine. The manufacturer recommends that a starting dose dose of sildenafil 25mg should be considered if concurrently using a drug that is metabolised by the cytochrome P450 system.
• there is no data, at present, for the use of sildenafil in males under 18 years of age, or women, and therefore sildenafil is at present contraindicated for these groups