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# Prazosin
## Overview
Prazosin is an alpha-1 adrenergic blocker used primarily for hypertension. It also has off-label uses for nightmares associated with PTSD and benign prostatic hyperplasia (BPH).
## Primary Indications
* Hypertension
* Nightmares associated with Post-Traumatic Stress Disorder (PTSD)
* Benign Prostatic Hyperplasia (BPH) - off-label
## Adult Dosing
**Hypertension:**
* Initial dose: 1 mg orally twice daily.
* Maintenance dose: Titrate gradually based on response, typically 1 mg to 10 mg orally per day, divided into two doses.
* Maximum dose: 20 mg orally per day.
**PTSD Nightmares:**
* Initial dose: 1 mg orally at bedtime.
* Maintenance dose: Titrate gradually based on response, typically 1 mg to 10 mg orally per night. Some patients may benefit from higher doses up to 16 mg/night, though efficacy at higher doses is less established.
**BPH:**
* Initial dose: 1 mg orally twice daily.
* Maintenance dose: Titrate gradually based on response, typically 1 mg to 5 mg orally per day, divided into two doses.
* Maximum dose: 10 mg orally per day.
Dosing is highly individualized and should be titrated slowly to minimize adverse effects.
## Pediatric Dosing
Dosing for pediatric patients is not well-established and is generally not recommended. Use with caution if prescribed by a specialist familiar with pediatric use.
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustment is recommended, but caution and close monitoring are advised due to potential accumulation.
* **Hepatic Impairment:** No specific dose adjustment is recommended, but caution and close monitoring are advised.
## Contraindications
* Hypersensitivity to prazosin or other quinazoline derivatives.
## Adverse Effects
* **Common:** Dizziness, lightheadedness, headache, drowsiness, weakness, nausea, palpitations.
* **Serious:** Orthostatic hypotension (especially with the first dose or dose increases), syncope, priapism.
## Key Drug Interactions
* **Other Antihypertensives:** Additive hypotensive effects.
* **Beta-blockers:** Increased risk of severe orthostatic hypotension.
* **Diuretics:** Additive hypotensive effects.
* **PDE5 Inhibitors (e.g., sildenafil):** Increased risk of symptomatic hypotension.
## Monitoring
* Blood pressure (lying and standing) especially after initiation or dose changes.
* Symptoms of dizziness or syncope.
* Urinary symptoms for BPH indication.
* For PTSD, monitor for reduction in nightmare frequency and severity.
## Clinical Pearls
* The first-dose phenomenon (significant orthostatic hypotension) is a major concern. Advise patients to take the first dose at bedtime and avoid driving or operating machinery until they know how the medication affects them.
* Titrate dose slowly, especially in elderly patients or those on other antihypertensives.
* Dosing frequency for hypertension is typically twice daily. For PTSD nightmares, it is usually once daily at bedtime.
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*Disclaimer: This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant guidelines before making clinical decisions. Local protocols may influence dosing and management.*
