What is the optimal dose of prazosin for post-traumatic stress disorder (PTSD)?

Optimal Dosing of Prazosin for PTSD

The optimal dose of prazosin for PTSD is typically 1-10+ mg, starting at 1 mg at bedtime and titrating up by 1-2 mg every 3-7 days until symptom improvement is achieved. 1

Dosing Protocol

Initial Dosing and Titration

• Start with 1 mg at bedtime
• Titrate upward by 1-2 mg every 3-7 days
• Monitor for orthostatic hypotension, especially after the first dose
• Typical effective dose range: 1-10+ mg 1

Population-Specific Dosing

• Military/combat-related PTSD may require higher doses:
  • Studies have used 10-16 mg at bedtime for military patients 2
  • In active-duty soldiers, mean achieved bedtime doses were 15.6 mg for men and 7.0 mg for women 3
  • Some treatment-resistant cases may benefit from much higher doses (up to 30-45 mg) 4

Dosing Schedule

• Consider twice-daily dosing for some patients 1
• For twice-daily regimens, a common approach is:
  • Lower dose in the morning (e.g., 4-5 mg for men, 1-2 mg for women)
  • Higher dose at bedtime (e.g., 15-20 mg for men, 7-10 mg for women) 3

Efficacy Considerations

• Prazosin has Level A evidence for PTSD-related nightmares 1
• Response typically seen within weeks 1
• Doses higher than 20 mg usually do not increase efficacy for most patients 1
• Treatment-resistant cases may require higher doses to achieve symptom control 4

Monitoring and Side Effects

• Evaluate orthostatic hypotension after the first dose
• Monitor blood pressure regularly during titration
• Assess treatment response after 4-6 weeks at maximum tolerated dose 1
• Common side effects include first-dose hypotension, dizziness, and sedation

Important Considerations

• Prazosin is particularly effective for PTSD-related nightmares and sleep disturbances
• For comprehensive PTSD management, consider combining with:
  • Image Rehearsal Therapy (IRT) - also has Level A evidence 1
  • Continued SSRI treatment for core PTSD symptoms 1

Common Pitfalls to Avoid

• Underdosing prazosin (inadequate symptom control)
• Failing to monitor blood pressure during titration
• Discontinuing treatment prematurely before adequate trial
• Not considering twice-daily dosing when nightmares return in latter half of sleep 1
• Using single nighttime dosing when daytime symptoms are also problematic

Alternative Considerations

• For patients who cannot tolerate prazosin, doxazosin may be considered as an alternative:
  • Longer half-life requiring only once-daily dosing
  • Available in extended-release form (GITS) allowing higher initial doses (4 mg/day)
  • May improve adherence due to simplified dosing schedule 5