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# Prazosin
## Overview
Prazosin is an alpha-1 adrenergic blocker used for hypertension and off-label for nightmares associated with PTSD and benign prostatic hyperplasia (BPH).
## Primary Indications
* Hypertension
* Nightmares associated with PTSD (off-label)
* Symptomatic BPH (off-label)
## Adult Dosing
* **Hypertension:** Initiate at 1 mg orally twice daily. Titrate slowly based on BP response, usually every 1-2 weeks. Common maintenance doses range from 3 mg to 9 mg orally per day, divided into two or three doses. Maximum recommended daily dose is 20 mg.
* **PTSD Nightmares:** Doses vary widely. Common starting doses are 1-2 mg orally at bedtime. Doses can be titrated up to 10 mg or higher at bedtime, depending on individual response and tolerability.
* **BPH:** Initiate at 1 mg orally twice daily. Titrate slowly based on symptom relief and tolerability. Doses typically range from 2 mg to 5 mg orally twice daily.
## Pediatric Dosing
Dosing in children is not well-established and should be based on specialist guidance and careful monitoring.
## Dose Adjustments
* **Hepatic Impairment:** Use with caution; dose reduction may be necessary.
* **Renal Impairment:** No specific dose adjustment is typically required, but patients should be monitored closely for adverse effects, especially hypotension.
## Contraindications
* Known hypersensitivity to prazosin or other quinazoline derivatives.
## Adverse Effects
The most common and significant adverse effect is **orthostatic hypotension**, especially upon initiation or dose increase. Other common effects include dizziness, drowsiness, headache, and palpitations. Syncope can occur.
## Key Drug Interactions
* **Other Antihypertensives:** Additive hypotensive effects.
* **Diuretics:** Increased risk of hypotension.
* **Beta-blockers:** Can exacerbate orthostatic hypotension.
* **Vasodilators:** Increased risk of hypotension.
## Monitoring
* **Blood Pressure:** Monitor closely, especially orthostatic vital signs (lying and standing BP and pulse) within 1-3 hours after the first dose and with each dose increase.
* **Symptoms:** Assess for dizziness, lightheadedness, and syncope.
## Clinical Pearls
* Initiate therapy at a low dose and titrate slowly, particularly in elderly patients or those with cardiac conditions.
* Advise patients to take the first dose at bedtime to minimize the risk of dizziness and syncope.
* Caution patients about potential drowsiness and avoid operating heavy machinery or driving until they know how the medication affects them.
* Advise patients to rise slowly from a sitting or lying position.
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*Disclaimer: This information is intended for clinical pharmacists and should not replace a thorough review of the current prescribing information and clinical judgment. Always verify current dosing and safety guidelines with official drug compendia.*
