Please check your internet connection and try again.
# Prazosin
## Overview
Prazosin is an alpha-1 adrenergic blocker used primarily for hypertension and off-label for PTSD-related nightmares.
## Primary Indications
* Hypertension
* Symptomatic relief of nightmares associated with post-traumatic stress disorder (PTSD)
## Adult Dosing
* **Hypertension:** Initiate at 1 mg orally twice or three times daily. Titrate slowly based on blood pressure response. Usual maintenance dose: 3-20 mg/day divided into two or three doses. Maximum dose: 20 mg/day.
* **PTSD-related nightmares:** Initiate at 1 mg orally at bedtime. Titrate slowly as tolerated and needed. Usual dose range: 1-10 mg/night. Some sources suggest higher doses up to 16 mg/night may be used, but caution is advised.
## Pediatric Dosing
There is no established or FDA-approved pediatric dosing for prazosin. Use in pediatric populations is off-label and requires careful consideration and specialized guidance. Dosing is highly individualized and based on clinical response and tolerability, often starting at very low doses (e.g., 0.1 mg/kg/day divided into 2-3 doses).
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustment is typically recommended, but use with caution and monitor closely for adverse effects, especially hypotension.
* **Hepatic Impairment:** No specific dose adjustment is typically recommended, but use with caution.
## Contraindications
* Known hypersensitivity to prazosin or other quinazoline derivatives.
## Adverse Effects
The most common and significant adverse effect is **orthostatic hypotension**, which can lead to dizziness, lightheadedness, and syncope, particularly with the first few doses or dose increases. Other adverse effects include:
* Headache
* Drowsiness
* Weakness
* Nausea
* Palpitations
* Nasal congestion
* Blurred vision
A rare but serious adverse effect is **priapism**.
## Key Drug Interactions
* **Other antihypertensives (including diuretics, beta-blockers):** Additive hypotensive effects.
* **Phosphodiesterase-5 (PDE5) inhibitors (e.g., sildenafil, tadalafil):** Potentiation of hypotensive effects. Coadministration should be approached with caution.
* **Beta-blockers:** May increase the risk of severe hypotension, especially orthostatic hypotension, due to unopposed alpha-blockade.
## Monitoring
* **Blood Pressure:** Monitor closely, especially during initiation and titration, and check for orthostatic changes (lying, sitting, standing).
* **Symptoms of Hypotension:** Educate patients to report dizziness, lightheadedness, or fainting.
* **Fluid Balance:** Assess for signs of fluid retention.
* **Renal and Hepatic Function:** Monitor periodically, especially in patients with pre-existing impairment.
## Clinical Pearls
* Administer the first dose at bedtime to minimize the risk of syncope and orthostatic hypotension.
* Advise patients to avoid sudden changes in posture and to rise slowly from a sitting or lying position.
* Caution patients about operating machinery or driving until they know how prazosin affects them.
* For PTSD nightmares, prazosin is typically used nightly, and a consistent dosing schedule is important. Some patients may require long-term therapy.
* The effectiveness for PTSD nightmares is not universally established across all guidelines, and its use is often considered off-label.
***
*Please verify current prescribing information for the most up-to-date recommendations.*
