What is the dosing regimen for prazosin (an alpha-1 (alpha-1 adrenergic receptor) blocker) to manage night terrors and anxiety?

Prazosin Dosing for Night Terrors and Anxiety

For the treatment of night terrors and anxiety, prazosin should be initiated at 1 mg at bedtime and gradually titrated upward by 1-2 mg every few days until an effective dose is reached, with typical effective doses ranging from 3-15 mg/day depending on patient population. 1

Initial Dosing and Titration

• Start with 1 mg at bedtime to minimize risk of first-dose hypotension 1, 2
• Increase by 1-2 mg every few days until clinical response is achieved 1
• Monitor for orthostatic hypotension after the first dose and during dose increases 2, 3
• Initial doses should be lower in elderly patients or those on concurrent antihypertensive medications 2

Effective Dose Ranges

• For civilians with PTSD-related nightmares: average effective dose is approximately 3-4 mg/day 1

  • In one study of civilian trauma victims, the mean effective dose was 3.1 ± 1.3 mg 1
  • Lower doses (2-6 mg) are typically effective in civilian populations 4

• For military veterans with PTSD-related nightmares: higher doses are often required 1

  • Mean effective doses in veteran studies ranged from 9.5-15.6 mg/day 1
  • In combat veterans, doses up to 15-20 mg may be necessary 1

• For active-duty military personnel: dosing varies by gender 1

  • Men: mean effective dose of 15.6 ± 6.0 mg 1
  • Women: mean effective dose of 7.0 ± 3.5 mg 1

Administration Schedule

• Initially, prazosin should be given as a single bedtime dose for nightmare management 1, 4
• For more severe cases, especially in military personnel, divided dosing may be considered 1, 3
• According to FDA labeling, the total daily dose may be divided into 2-3 doses per day 3
• Maximum recommended daily dose is 20 mg, with doses above this rarely providing additional benefit 3

Monitoring and Adjustments

• Monitor blood pressure after initial dose and with each significant dose increase 2, 3
• Assess nightmare frequency and intensity using standardized measures when possible 1
• If patient is also taking selective serotonin reuptake inhibitors (SSRIs), be aware that the response to prazosin may be diminished 1
• If adding other antihypertensive medications, reduce prazosin dose to 1-2 mg and retitrate 3

Common Side Effects and Management

• Dizziness and lightheadedness are common, especially after initial doses 1, 2
• Transient orthostatic hypotension may occur but usually resolves during treatment 1
• Falls and syncope are rare but possible, particularly in elderly patients 2
• Use caution when co-administering with PDE-5 inhibitors due to additive hypotensive effects 3

Special Considerations

• Prazosin appears effective in both civilian and military populations with trauma-related nightmares 1, 5, 6
• Treatment response is typically seen within weeks 4, 7
• If prazosin is discontinued, nightmares may return to baseline intensity 1
• For patients who cannot tolerate prazosin, doxazosin (another alpha-1 antagonist with longer half-life) may be considered as an alternative 8