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# Prazosin
## Overview
Prazosin is an alpha-1 adrenergic blocker.
## Primary Indications
* Hypertension
* Symptomatic benign prostatic hyperplasia (BPH)
* Refractory PTSD-associated nightmares
## Adult Dosing
* **Hypertension:**
* Initial dose: 1 mg two to three times daily.
* Titration: Increase dose gradually every 2-4 days as needed.
* Usual maintenance dose: 1 mg to 5 mg three times daily.
* Maximum dose: 20 mg daily.
* **Symptomatic BPH:**
* Initial dose: 1 mg two to three times daily.
* Titration: Increase dose gradually as needed.
* Usual maintenance dose: 1 mg to 5 mg three times daily.
* Maximum dose: 20 mg daily.
* **PTSD-associated nightmares:**
* Initial dose: 1 mg at bedtime.
* Titration: Increase dose by 1 mg to 2 mg every 1-2 weeks as needed.
* Usual dose: 1 mg to 16 mg daily, typically given at bedtime or divided.
* Maximum dose: Not well-established, but doses up to 16 mg daily have been used.
## Pediatric Dosing
Prazosin is not FDA-approved for pediatric use. Limited data suggests potential use in certain conditions like severe hypertension, but dosing is highly individualized and should be managed by a specialist.
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustment is recommended, but caution and careful titration are advised.
## Contraindications
* Known hypersensitivity to prazosin or its components.
## Adverse Effects
* **Common:** Dizziness, lightheadedness, headache, drowsiness, weakness, nausea.
* **Orthostatic Hypotension:** Particularly with the first dose ("first-dose phenomenon") and with rapid dose increases. Patients should be advised to sit or lie down if symptoms occur.
* **Priapism:** Rare but serious side effect.
* **Syncope:** Can occur, especially with the first dose.
## Key Drug Interactions
* **Other Antihypertensives:** Additive hypotensive effects.
* **Beta-blockers:** Increased risk of severe orthostatic hypotension.
* **Diuretics:** Increased risk of orthostatic hypotension.
* **PDE5 inhibitors (e.g., sildenafil, tadalafil):** Significant additive hypotensive effects. Avoid concurrent use or use with extreme caution and at reduced doses.
## Monitoring
* Blood pressure (supine and standing) to assess for hypotension and efficacy.
* Symptoms of dizziness, lightheadedness, or syncope.
* Renal function (if clinically indicated).
## Clinical Pearls
* Administer the first dose at bedtime to minimize the risk of the first-dose phenomenon.
* Advise patients to avoid driving or operating heavy machinery until they know how prazosin affects them.
* Gradual titration is crucial to improve tolerability and minimize side effects.
* Ensure patients understand the importance of reporting any symptoms of dizziness, syncope, or fainting.
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***Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant literature for complete details, including full prescribing information, contraindications, warnings, precautions, adverse reactions, and drug interactions before making any clinical decisions. Dosing may vary based on individual patient factors and local protocols.*
