Health and Prostate

Indications hypertension; congestive heart failure; Raynaud’s syndrome; benign prostatic hyperplasia

Cautions first dose may cause collapse due to hypotension (therefore should be taken on retiring to bed); elderly; cataract surgery (risk of intraoperative floppy iris syndrome); hepatic impairment; renal impairment; pregnancy; breast-feeding; interactions: alpha-blockers

Driving May affect performance of skilled tasks e.g. driving

Contra-indications not recommended for congestive heart failure due to mechanical obstruction (e.g. aortic stenosis)

Side-effects also gastro-intestinal disturbances; postural hypotension, oedema, palpitation; dyspnoea, nasal congestion; drowsiness, headache, depression, nervousness, vertigo; urinary frequency; weakness; blurred vision; less commonly tachycardia, insomnia, paraesthesia, sweating, impotence, arthralgia, eye disorders, tinnitus, epistaxis, allergic reactions including rash, pruritus, and urticaria; rarely pancreatitis, flushing, vasculitis, brady-cardia, hallucinations, worsening of narcolepsy gynaecomastia, priapism, urinary incontinence, and alopecia

Dose

• Hypertension (see notes above), 500 micrograms 2-3 times daily for 3-7 days, the initial dose on retiring to bed at night (to avoid collapse, see Cautions); increased to 1 mg 2-3 times daily for a further 3-7 days; further increased if necessary to max. 20 mg daily in divided doses

• Congestive heart failure, 500 micrograms 2-4 times daily (initial dose at bedtime, see above), increasing to 4 mg daily in divided doses; maintenance 4-20 mg daily in divided doses (but rarely used)

• Raynaud’s syndrome (but efficacy not established, see section 2.6.4), initially 500 micrograms twice daily (initial dose at bedtime, see above) increased, if necessary, after 3-7 days to usual maintenance 1-2 mg twice daily

Prazosin (Non-proprietary)

Tablets, prazosin (as hydrochloride) 500 micrograms, net price 56-tab pack = £2.51; 1 mg, 56-tab pack = £3.23; 2 mg, 56-tab pack = £4.39; 5 mg, 56-tab pack = £8.75. Counselling, initial dose, driving

Hypovase® (Pfizer)

Tablets, prazosin (as hydrochloride) 500 micrograms, net price 60-tab pack = £2.69; 1 mg, scored, 60-tab pack = £3.46. Counselling, initial dose, driving