What is the role of Prazosin in treating hypertension and other conditions?

From the Guidelines

Prazosin is primarily used to treat hypertension and benign prostatic hyperplasia (BPH), but its role in treating post-traumatic stress disorder (PTSD) nightmares is also significant, with doses ranging from 1-15 mg at bedtime, as supported by studies such as 1 and 1.

Key Points About Prazosin

• Prazosin works by blocking alpha-1 receptors in vascular smooth muscle, preventing norepinephrine from binding and causing vasoconstriction.
• For hypertension, prazosin is typically started at a low dose of 1 mg two to three times daily, gradually increasing to 20 mg daily in divided doses if needed, as indicated in guidelines such as 1 and 1.
• Beyond hypertension, prazosin is used to treat BPH by relaxing smooth muscle in the prostate and bladder neck, improving urinary symptoms.
• It's also prescribed off-label for PTSD nightmares at doses of 1-15 mg at bedtime, and for Raynaud's phenomenon.
• The medication commonly causes first-dose hypotension, which can lead to dizziness and fainting, so the initial dose should be taken at bedtime.
• Patients should be aware that prazosin may cause orthostatic hypotension, dizziness, drowsiness, and nasal congestion, as noted in studies like 1.

Important Considerations

• It's essential to rise slowly from sitting or lying positions to minimize dizziness and avoid driving until the body adjusts to these effects.
• Prazosin may be considered as a second-line agent in patients with concomitant BPH, as suggested in guidelines such as 1 and 1.
• The efficacy of prazosin in treating PTSD-associated nightmares has been demonstrated in several studies, including 1 and 1, although the most recent and highest quality study 1 shows mixed results, leading to a downgrade in recommendation for its use in nightmare disorder.
• Despite this, prazosin remains a valuable option for patients who respond well to it, and its use should be considered on a case-by-case basis, taking into account the potential benefits and risks, as well as the latest evidence from studies like 1.

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.

The role of Prazosin in treating hypertension is to lower blood pressure, which reduces the risk of fatal and nonfatal cardiovascular events, such as:

• Strokes
• Myocardial infarctions Prazosin can be used alone or in combination with other antihypertensive drugs, like diuretics or beta-adrenergic blocking agents 2.

From the Research

Role of Prazosin in Treating Hypertension

• Prazosin has been shown to be an effective antihypertensive agent over the entire range of hypertension (mild, moderate, and severe), when used alone or in multitherapy 3.
• It is particularly useful in specific subpopulations of hypertensive patients, such as those with impaired renal function, those on hemodialysis, and those with concomitant heart block, bronchospasm, diabetes mellitus, or disturbed carbohydrate metabolism, hyperlipidemia, or hyperuricemia 3.
• Prazosin acts by relaxing the smooth vascular muscles and blocking postsynaptic alpha-adrenoreceptors, resulting in a significant drop in systolic and diastolic arterial pressure 4.

Prazosin in Treating Other Conditions

• Prazosin has been shown to decrease the occurrence of trauma nightmares in both combat veterans and patients with non-combat-related posttraumatic stress disorder (PTSD) 5.
• It also improves sleep quality and patients' sense of wellbeing and ability to function in daily activities in patients with PTSD 5.
• Prazosin is traditionally used to treat benign prostatic hyperplasia, in addition to its use in treating hypertension 5.

Side Effects and Precautions

• The side effects of prazosin are usually mild and transient and seldom require discontinuation of the drug, with sexual dysfunction being uncommon 3.
• However, prazosin can cause orthostatic hypotension, particularly with the first dose, and patients should be monitored for this side effect 6, 7.
• A small initial dose of prazosin, ranging from 0.5 to 1 mg, is recommended to avoid the first-dose phenomenon 3, 6, 7.