From the Guidelines
Prazosin is primarily used to treat high blood pressure (hypertension) and symptoms of benign prostatic hyperplasia (enlarged prostate). It belongs to a class of drugs called alpha-blockers, which work by relaxing blood vessels and smooth muscle tissue. Prazosin is typically prescribed at a dose of 2-20 mg taken two or three times daily, depending on the condition being treated and the patient's response, as indicated in the 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults 1. The medication is also sometimes used off-label for treating nightmares associated with post-traumatic stress disorder (PTSD). Common side effects include dizziness, drowsiness, headache, and a phenomenon called "first-dose effect," where the initial dose may cause significant lightheadedness or fainting. To minimize this risk, patients should take the first dose at bedtime and rise slowly from sitting or lying positions. Prazosin works by blocking alpha-1 adrenergic receptors, preventing norepinephrine from constricting blood vessels and thereby lowering blood pressure and improving urine flow in men with prostate enlargement. However, according to the AUA guideline on management of benign prostatic hyperplasia (2003), data are insufficient to support a recommendation for the use of prazosin as a treatment option for LUTS secondary to BPH 1. Therefore, prazosin should be used with caution and under the guidance of a healthcare professional, taking into account the patient's individual needs and medical history. Some key points to consider when prescribing prazosin include:
- Starting with a low dose and gradually increasing as needed
- Monitoring for common side effects such as dizziness and orthostatic hypotension
- Avoiding use in patients with certain medical conditions, such as severe renal dysfunction or significant renal disease
- Using with caution in patients with concomitant hypertension, as alpha blockers may not provide optimal management of hypertension.
From the FDA Drug Label
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 Prazosin Hydrochloride Capsules, USP can be used alone or in combination with other antihypertensive drugs such as diuretics or beta-adrenergic blocking agents.
Prazosin is used for the treatment of hypertension, to lower blood pressure and reduce the risk of cardiovascular events such as strokes and myocardial infarctions 2.
From the Research
Prazosin Uses
- Prazosin is used to treat benign prostatic hyperplasia (BPH) symptoms, including obstructive and irritative symptoms 3
- It is also used as an antihypertensive medication, although its use in BPH treatment may be less well-known 3
- Prazosin works by blocking the stimulation of alpha 1-receptors in the prostate tissue, which helps to relieve symptoms of BPH 3
Efficacy of Prazosin
- Studies have shown that prazosin is effective in reducing BPH symptoms, with 60-70% of treated patients experiencing real benefits from prazosin therapy 3
- Prazosin has been compared to other alpha-blocking agents, such as alfuzosin, and has been found to be similarly effective in improving voiding symptoms and urinary flow rates 4
- Prazosin has also been found to be well-tolerated, with few adverse events related to its use 4
Comparison to Other Treatments
- Prazosin is one of several alpha-blocking agents used to treat BPH, including terazosin, alfuzosin, and doxazosin 5
- Other treatments for BPH include antiandrogen therapy, such as finasteride, which can reduce prostate volume and relieve symptoms of bladder outlet obstruction 5
- Combination therapy of alpha 1-blockers and finasteride may be a future approach in the medical treatment of BPH 5