Prazosin: uses, appearance and warnings

Prazosin Hydrochloride Capsules, USP is indicated for the treatment of hypertension, to lower blood pressure. Lowering blood pressure reduces the risk of fatal and nonfatal cardiovascular events, primarily strokes and myocardial infarctions. These benefits have been seen in controlled trials of antihypertensive drugs from a wide variety of pharmacologic classes, including this drug. Control of high blood pressure should be part of comprehensive cardiovascular risk management, including, as appropriate, lipid control, diabetes management, antithrombotic therapy, smoking cessation, exercise, and limited sodium intake. Many patients will require more than one drug to achieve blood pressure goals. For specific advice on goals and management, see published guidelines, such as those of the National High Blood Pressure Education Program's Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC). Numerous antihypertensive drugs, from a variety of pharmacologic classes and with different mechanisms of action, have been shown in randomized controlled trials to reduce cardiovascular morbidity and mortality, and it can be concluded that it is blood pressure reduction, and not some other pharmacologic property of the drugs, that is largely responsible for those benefits. The largest and most consistent cardiovascular outcome benefit has been a reduction in the risk of stroke, but reductions in myocardial infarction and cardiovascular mortality also have been seen regularly. Elevated systolic or diastolic pressure causes increased cardiovascular risk, and the absolute risk increase per mmHg is greater at higher blood pressures, so that even modest reductions of severe hypertension can provide substantial benefit. Relative risk reduction from blood pressure reduction is similar across populations with varying absolute risk, so the absolute benefit is greater in patients who are at higher risk independent of their hypertension (for example, patients with diabetes or hyperlipidemia), and such patients would be expected to benefit from more aggressive treatment to a lower blood pressure goal. Some antihypertensive drugs have smaller blood pressure effects (as monotherapy) in black patients, and many antihypertensive drugs have additional approved indications and effects (e.g., on angina, heart failure, or diabetic kidney disease). These considerations may guide selection of therapy. Prazosin Hydrochloride Capsules, USP can be used alone or in combination with other antihypertensive drugs such as diuretics or beta-adrenergic blocking agents.

Prazosin Hydrochloride Capsules, USP 1 mg for oral administration containing prazosin hydrochloride, USP equivalent to 1 mg of prazosin, are supplied as follows: Hard gelatin capsule shell with dark green colored cap and light brown colored body, imprinted with white ink as 019 on cap and novitium on body, filled with white to off-white powder blend. NDC 70954- 019 -50 Bottles of 90 capsules NDC 70954- 019 -10 Bottles of 100 capsules NDC 70954- 019 -20 Bottles of 1000 capsules NDC 70954- 019 -40 Unit dose blister packages of 100 (10 cards of 10 capsules each) Prazosin Hydrochloride Capsules, USP 2 mg for oral administration containing prazosin hydrochloride, USP equivalent to 2 mg of prazosin, are supplied as follows: Hard gelatin capsule shell with brown colored cap and light brown colored body, imprinted with white ink as 020 on cap and novitium on body, filled with white to off-white powder blend. NDC 70954- 020- 10 Bottles of 100 capsules NDC 70954- 020 -20 Bottles of 1000 capsules NDC 70954- 020 -40 Unit dose blister packages of 100 (10 cards of 10 capsules each) Prazosin Hydrochloride Capsules, USP 5 mg for oral administration containing prazosin hydrochloride, USP equivalent to 5 mg of prazosin, are supplied as follows: Hard gelatin capsule shell with light blue colored cap and light brown colored body, imprinted with white ink as 021 on cap and novitium on body, filled with white to off-white powder blend. NDC 70954- 021 -10 Bottles of 100 capsules NDC 70954- 021 -20 Bottles of 250 capsules NDC 70954- 021 -40 Unit dose blister packages of 100 (10 cards of 10 capsules each) Store at 20° to 25°C (68° to 77°F). [See USP Controlled Room Temperature.] Protect from moisture and light. Dispense in a tight, light-resistant container as defined in the USP. Manufactured by: Esjay Pharma Private Limited Sipcot Industrial Park, Kanchipuram, Tamilnadu, India – 602117 Distributed by: Novitium Pharma LLC East Windsor, NJ 08520 P3319/00/25 Rev. 05/25

Prazosin Hydrochloride Capsules are contraindicated in patients with known sensitivity to quinazolines, prazosin, or any of the inert ingredients.

As with all alpha-blockers, prazosin hydrochloride may cause syncope with sudden loss of consciousness. In most cases, this is believed to be due to an excessive postural hypotensive effect, although occasionally the syncopal episode has been preceded by a bout of severe tachycardia with heart rates of 120–160 beats per minute. Syncopal episodes have usually occurred within 30 to 90 minutes of the initial dose of the drug; occasionally, they have been reported in association with rapid dosage increases or the introduction of another antihypertensive drug into the regimen of a patient taking high doses of prazosin hydrochloride. The incidence of syncopal episodes is approximately 1% in patients given an initial dose of 2 mg or greater. Clinical trials conducted during the investigational phase of this drug suggest that syncopal episodes can be minimized by limiting the initial dose of the drug to 1 mg, by subsequently increasing the dosage slowly, and by introducing any additional antihypertensive drugs into the patient's regimen with caution (see DOSAGE AND ADMINISTRATION). Hypotension may develop in patients given prazosin hydrochloride who are also receiving a beta-blocker such as propranolol. If syncope occurs, the patient should be placed in the recumbent position and treated supportively as necessary. This adverse effect is self-limiting and in most cases does not recur after the initial period of therapy or during subsequent dose titration. Patients should always be started on the 1 mg capsules of prazosin hydrochloride. The 2 mg and 5 mg capsules are not indicated for initial therapy. More common than loss of consciousness are the symptoms often associated with lowering of the blood pressure, namely, dizziness and lightheadedness. The patient should be cautioned about these possible adverse effects and advised what measures to take should they develop. The patient should also be cautioned to avoid situations where injury could result should syncope occur during the initiation of prazosin hydrochloride therapy. Priapism Prolonged erections and priapism have been reported with alpha-1 blockers including prazosin in post marketing experience. In the event of an erection that persists longer than 4 hours, seek immediate medical assistance. If priapism is not treated immediately, penile tissue damage and permanent loss of potency could result.

Clinical trials were conducted on more than 900 patients. During these trials and subsequent marketing experience, the most frequent reactions associated with prazosin hydrochloride therapy are: dizziness 10.3%, headache 7.8%, drowsiness 7.6%, lack of energy 6.9%, weakness 6.5%, palpitations 5.3%, and nausea 4.9%. In most instances, side effects have disappeared with continued therapy or have been tolerated with no decrease in dose of drug. Less frequent adverse reactions which are reported to occur in 1% to 4% of patients are: Gastrointestinal: vomiting, diarrhea, constipation. Cardiovascular: edema, orthostatic hypotension, dyspnea, syncope. Central Nervous System: vertigo, depression, nervousness. Dermatologic: rash. Genitourinary: urinary frequency. EENT: blurred vision, reddened sclera, epistaxis, dry mouth, nasal congestion. …

Prazosin hydrochloride has been administered without any adverse drug interaction in limited clinical experience to date with the following: (1) cardiac glycosides-digitalis and digoxin; (2) hypoglycemics-insulin, chlorpropamide, phenformin, tolazamide, and tolbutamide; (3) tranquilizers and sedatives-chlordiazepoxide, diazepam, and phenobarbital; (4) antigout-allopurinol, colchicine, and probenecid; (5) antiarrhythmics-procainamide, propranolol (see WARNINGS however), and quinidine; and (6) analgesics, antipyretics and anti-inflammatories-propoxyphene, aspirin, indomethacin, and phenylbutazone. Addition of a diuretic or other antihypertensive agent to prazosin hydrochloride has been shown to cause an additive hypotensive effect. …