Prazosin Dosing Frequency for Nightmares
Prazosin should be taken once daily at bedtime for the treatment of nightmares. 1, 2
Administration Schedule
- Prazosin is administered as a single bedtime dose for nightmare management in both civilian and military populations with PTSD-related nightmares 2
- The once-nightly dosing schedule aligns with the medication's primary indication to reduce trauma-related nightmares that occur during sleep 1
Dosing Algorithm
Starting Dose
- Begin with 1 mg at bedtime to minimize the risk of first-dose orthostatic hypotension 1, 2
- This conservative starting dose is critical for safety, particularly in elderly patients or those on concurrent antihypertensive medications 2
Titration Schedule
- Increase by 1-2 mg every few days until clinical response is achieved 1, 2
- Monitor blood pressure after the initial dose and with each significant dose increase 2, 3
- Assess nightmare frequency and intensity using standardized measures when possible 2
Target Dose Ranges
The effective dose varies significantly by population:
- Civilians with PTSD-related nightmares: Average effective dose is approximately 3-4 mg/day (mean 3.1 ± 1.3 mg) 2, 3
- Military veterans with PTSD: Higher doses are typically required, with mean effective doses ranging from 9.5-15.6 mg/day 2, 3
- Active-duty military personnel: Dosing varies by gender, with men requiring a mean of 15.6 ± 6.0 mg and women requiring 7.0 ± 3.5 mg 2
- Maximum recommended dose: Up to 20 mg at bedtime has been reported in some military populations 4
Divided Dosing Considerations
- For more severe cases, especially in military personnel, divided dosing may be considered 2
- One source suggests a maximum of 20 mg at bedtime plus 5 mg mid-morning for refractory cases 4
- However, the standard recommendation remains once-daily bedtime dosing for the vast majority of patients 1, 2
Critical Monitoring Parameters
Safety Monitoring
- Orthostatic hypotension is the primary concern, especially after initial doses and dose increases 1, 2
- Dizziness and lightheadedness are common but usually transient 2
- Blood pressure monitoring is essential at each visit during titration 2, 3
Efficacy Assessment
- Treatment length in clinical trials ranged from 3 to 9 weeks before full assessment 1
- Patients typically show improvement in nightmare frequency, sleep quality, and daytime fatigue 1
- If prazosin is discontinued, nightmares return to baseline intensity, indicating this is a maintenance treatment, not curative 2, 3
Important Clinical Caveats
- SSRIs may diminish prazosin's response in PTSD patients, so consider this interaction when co-prescribing 2, 5, 3
- Prazosin is not indicated as a general anxiolytic—it specifically targets trauma-related nightmares and associated sleep disturbances 5
- The medication was generally well tolerated across all studies, with the most common side effect being transient orthostatic hypotension 1
- Prazosin has Level A recommendation from the American Academy of Sleep Medicine for PTSD-associated nightmares 1, 5