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## Prazosin
### Overview
Prazosin is an alpha-1 adrenergic blocker.
### Primary Indications
* Hypertension (off-label, not a first-line agent)
* Symptomatic Benign Prostatic Hyperplasia (BPH) (off-label)
* Post-Traumatic Stress Disorder (PTSD)-related nightmares
### Adult Dosing
**Hypertension:**
* Initiate with 1 mg orally twice daily.
* Titrate slowly, increasing the dose every 2-4 days as needed and tolerated.
* Usual maintenance dose: 3-15 mg per day divided into two or three doses.
* Maximum recommended dose: 20 mg per day.
**PTSD-related nightmares:**
* Initiate with 1 mg orally at bedtime.
* Increase dose as needed and tolerated.
* Typical doses range from 2-6 mg at bedtime.
* Maximum reported dose: 10 mg at bedtime.
**Symptomatic BPH:**
* Dosing is variable and not FDA-approved. Doses are generally lower than for hypertension.
* Commonly initiated at 0.5-1 mg orally twice daily, with slow titration.
### Pediatric Dosing
There is no established pediatric dosing for prazosin. Use in children is off-label and requires extreme caution and expert consultation.
### Dose Adjustments
* **Renal Impairment:** No specific dose adjustment recommended, but caution is advised. Monitor blood pressure closely.
### Contraindications
* Hypersensitivity to prazosin or other quinazolines.
### Adverse Effects
* **Common:** Dizziness, lightheadedness, headache, drowsiness, nausea, weakness, blurred vision.
* **Orthostatic Hypotension:** A significant risk, especially upon initiation and with dose increases. Advise patients to rise slowly from sitting or lying positions.
* **Priapism:** Rare but serious. Patients should seek immediate medical attention if they experience a prolonged or inappropriate erection.
* **Syncope:** Can occur, particularly with the first dose or rapid dose escalation.
### Key Drug Interactions
* **Other Antihypertensives:** Additive hypotensive effects may occur.
* **Diuretics:** Concomitant use can potentiate hypotensive effects.
* **Beta-blockers:** May increase the risk of severe orthostatic hypotension, especially with the first dose of prazosin.
### Monitoring
* Blood pressure, especially orthostatic vital signs (sitting vs. standing) upon initiation and dose changes.
* Monitor for symptoms of dizziness, lightheadedness, and syncope.
### Clinical Pearls
* The "first-dose phenomenon" characterized by severe orthostatic hypotension, dizziness, and syncope can occur with the initial dose or with rapid increases in dose. Administer the first dose at bedtime to minimize risk.
* Prazosin is generally not recommended as a first-line agent for hypertension due to the availability of agents with better cardiovascular outcomes data.
* When used for BPH, it is primarily to help with urinary symptoms, not to treat the underlying condition.
* For PTSD nightmares, titrate slowly and consider the bedtime dose to help with sleep.
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*This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant clinical guidelines before making any treatment decisions.*
