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# Prazosin
## Overview
Prazosin is a selective alpha-1 adrenergic blocker.
## Primary Indications
* Hypertension
* Symptomatic Benign Prostatic Hyperplasia (BPH)
* Off-label: PTSD-related nightmares
## Adult Dosing
* **Hypertension:** Initiate at 1 mg orally twice daily. Titrate up to 1 mg to 10 mg twice daily, or as needed. Maximum recommended dose is 20 mg orally per day, although some sources suggest up to 40 mg per day. Doses may be adjusted based on clinical response and tolerability.
* **BPH:** Initiate at 1 mg orally twice daily. Titrate up to 2 mg orally twice daily. Maximum recommended dose is 10 mg orally per day.
* **PTSD-related nightmares:** Initiate at 1 mg orally at bedtime. Titrate as needed, typically to 3 mg to 10 mg orally at bedtime.
## Pediatric Dosing
Prazosin is not FDA-approved for pediatric use. Limited data suggests use in pediatric hypertension may be initiated at 5-10 mcg/kg/dose orally every 6-8 hours, with a maximum of 20 mg/day. Dosing requires careful titration and close monitoring by a specialist.
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustment is recommended by the manufacturer, but caution and close monitoring are advised, especially in severe impairment.
## Contraindications
* Hypersensitivity to prazosin or other quinazolines.
## Adverse Effects
* **Common:** Dizziness, lightheadedness, drowsiness, headache, orthostatic hypotension (especially with first dose or dose increases).
* **Serious:** Syncope (especially with rapid dose increases or initiation), palpitations, dyspnea.
## Key Drug Interactions
* **Other Antihypertensives:** Additive hypotensive effects.
* **Beta-Blockers:** May increase the risk of severe orthostatic hypotension.
* **Diuretics:** Additive hypotensive effects.
## Monitoring
* Blood pressure (standing and supine) before and during treatment, especially after dose initiation or changes.
* Signs and symptoms of syncope or excessive dizziness.
* Renal and hepatic function, especially with long-term use or in patients with pre-existing impairment.
## Clinical Pearls
* The "first-dose phenomenon" (marked hypotension and syncope) can occur with the initial dose or with rapid dose increases. Advise patients to take the first dose at bedtime and avoid driving or hazardous activities until they know how the medication affects them.
* Dose titration should be gradual.
* It is important to counsel patients on the risk of orthostatic hypotension and advise them to rise slowly from sitting or lying positions.
**Disclaimer:** This information is intended for clinical use and is not a substitute for professional medical advice. Always consult the most current prescribing information and relevant clinical guidelines before making any treatment decisions. Dosing and indications can vary based on specific patient factors and local protocols.
