APO-PRAZOSIN

What it is

APO-PRAZOSIN contains prazosin hydrochloride and is available in tablet strengths of 1 mg, 2 mg or 5 mg prazosin base.

Approved indications

— Treatment of hypertension of varied aetiology and all grades of severity. — Treatment of severe refractory congestive heart failure. — Treatment of Raynaud's phenomenon and Raynaud's disease. — Symptomatic treatment of urinary obstruction caused by benign prostatic hyperplasia in patients awaiting prostatic surgery.

Dosing overview

Dosing varies significantly by indication. For hypertension, the suggested initial dose range is 0.5 mg twice daily increasing to 1.0 mg twice daily or three times daily, with a usual maintenance dose of 3.0 mg to 20 mg daily in divided doses. For congestive heart failure, the suggested initial daily dose range is 0.5 mg increasing to 4.0 mg in divided doses, with a usual daily maintenance dose of 4.0 mg to 20 mg in divided doses. For Raynaud's phenomenon and Raynaud's disease, the suggested starting dosage is 0.5 mg twice daily with a usual daily maintenance dosage of 1 mg or 2 mg twice daily. For benign prostatic hyperplasia, the recommended starting dose is 0.5 mg twice daily for 3 to 7 days with a maintenance dosage of 2 mg twice daily.

Key safety warnings

APO-PRAZOSIN may cause syncope with sudden loss of consciousness, usually believed to be due to excessive postural hypotensive effect, occurring within 30 to 90 minutes of the initial dose or occasionally with rapid dosage increases. Syncopal episodes can be minimised by limiting the initial dose to 0.5 mg, by subsequently increasing the dosage slowly and by introducing any additional antihypertensive drugs cautiously. Patients should always be started at a dose of 0.5 mg, and the 2 mg and 5 mg tablets are not indicated for initial therapy. Prolonged erections and priapism have been reported with alpha-1 blockers including APO-PRAZOSIN in post-marketing experience; if an erection persists longer than 4 hours, the patient should seek immediate medical assistance as untreated priapism could result in penile tissue damage and permanent loss of potency. Postural hypotension, especially in elderly patients with cerebrovascular disease, may be dangerous; exacerbation of pre-existing angina, new-onset angina and myocardial infarction have been associated with prazosin, although a causal relationship has not been established.

Contraindications

APO-PRAZOSIN is contraindicated in patients with a known sensitivity to quinazolines, prazosin or any other component of the tablets.

PBS listing

APO-PRAZOSIN is listed on the PBS in three strengths: the 1 mg tablet at A$3.84 ex-manufacturer price, the 2 mg tablet at A$5.47 ex-manufacturer price, and the 5 mg tablet at A$9.82 ex-manufacturer price, with each strength having two PBS items with mixed restrictions (restricted and unrestricted).

Regulatory history

APO-PRAZOSIN was first registered on the ARTG on 19 June 2000, with all three strengths (1 mg, 2 mg and 5 mg tablets) listed simultaneously under licence category RE.