Management of hypertension (alone or in combination with other classes of antihypertensive agents).
Current antihypertensive and urology guidelines (e.g., JNC 7) no longer recommend α1-blockers as preferred first-line therapy for patients with hypertension.
Acute management of severe hypertension in patients with increased concentrations of circulating catecholamines.
Benign Prostatic Hyperplasia (BPH)
Has been used to reduce urinary obstruction and relieve associated manifestations in patients with symptomatic BPH†; efficacy relative to other α1-adrenergic blockers remains to be established.
Dosage and Administration
Administration
Oral Administration
Administer orally in divided doses 2–3 times daily.
Manufacturer makes no specific recommendations regarding administration with meals.
Individualize dosage according to patient response and tolerance. Initiate at low dosage to minimize frequency of postural hypotension and syncope.
Postural effects are most likely to occur 2–6 hours after a dose; monitor BP during this period after first dose and with any dosage increases.
If therapy is interrupted for a few days, restart using initial dosage regimen.
Pediatric Patients
Hypertension
Oral
Initially, 0.05–0.1 mg/kg daily given in 3 divided doses. Increase dosage as necessary up to a maximum of 0.5 mg/kg daily given in 3 divided doses.†
Adults
Hypertension
Monotherapy
Oral
Initially, 1 mg 2 or 3 times daily. Do not initiate with higher dosages. May increase dosage gradually to 20 mg daily given in divided doses.
Usual maintenance dosage: 6–15 mg daily given in divided doses.
Careful monitoring of BP is recommended during initial titration or subsequent upward dosage adjustment; avoid large or abrupt reductions in BP.
For the acute management of severe hypertension, initially, 1–2 mg; dosage may be repeated after 1 hour, if necessary.
Combination Therapy
Oral
When other hypotensive agents or diuretics are added to existing prazosin therapy, reduce dosage to 1 or 2 mg 3 times daily; gradually increase according to patient's response and tolerance.
Initial use of fixed combination with polythiazide is not recommended; adjust by administering each drug separately, then use the fixed combination if the optimum maintenance dosage corresponds to the ratio of drugs in the combination preparation. Administer separately for subsequent dosage adjustment.
Prescribing Limits
Pediatric Patients
Hypertension
Oral
Maximum 0.5 mg/kg daily.†
Adults
Hypertension
Oral
Maximum 20 mg daily.
Special Populations
Hepatic Impairment
No specific dosage recommendations at this time.
Renal Impairment
Initially, 1 mg twice daily. Patients with chronic renal failure may require only small doses.
Geriatric Patients
No specific dosage recommendations at this time; generally increase dosage more slowly in geriatric hypertensive patients than in younger adults.
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