Firstly, we should note that the use of prazosin for PTSD is off-label, i.e, not approved by the FDA.
Just for context, here is what the Prescribing Information for prazosin says about its dosing for the treatment of hypertension for which it has an FDA indication:
– Prazosin is dosed up to 20 mg per day given in divided doses.
– The dosages most commonly used have been from 6 mg to 15 mg per day.
– “Doses higher than 20 mg usually do not increase efficacy, however, a few patients may benefit from further increases up to a daily dose of 40 mg…”
What is the maximum dose of prazosin for PTSD?
The dose of prazosin used for the treatment of PTSD-associated nightmares and hyperarousal varies a lot. There is concern that prazosin is often underdosed.
Earlier studies used lower doses and the doses used in clinical practice were low as well. In 2010, in a very large sample of veterans with PTSD who were treated with prazosin, the mean maximum dose was about 3.5 mg/day and only about 15% of the patients reached a dose of 6 mg/day or more (Alexander et al., 2015).
But gradually it was realized that higher doses may be needed, so, later studies allowed higher doses for those who needed them. For example, in one large clinical trial, the maximum dose allowed was (Raskind et al., 2018):
– In men: 20 mg/day (More than 50% of male participants reached this dose.)
– In women: 12 mg/day.
Sometimes, even higher doses of prazosin have been used, but I think that these should be used only by those with extensive experience with this medication. For example:
– In one VA multicenter clinical trial, doses of up to 25 mg/day were used (Raskind et al. 2013).
– Two cases of successfully using very high doses (30 mg/day and 45 mg/day) have been published (Koola et al. 2014).
How is the total daily dose of prazosin divided?
Prazosin has a short half-life and is typically given in at least two divided doses per day, in the midmorning and at bedtime.
In patients in whom PTSD-associated nightmares are the main target symptom for treatment with prazosin, the majority of patients with PTSD to whom prazosin is given, most of the dose is given at bedtime.
For example, in men, when the maximum dose in men was 20 mg/day, it was given as 5 mg in the midmorning and 15 mg at bedtime, and in women, when the maximum dose was 12 mg/day, it was given as 2 mg in the midmorning and 10 mg at bedtime (Raskind et al., 2018).
How is prazosin titrated up?
Prazosin MUST be slowly titrated up over a few weeks. Otherwise, serious hypotension can occur.
As an example, here is the titration schedule that was used by one large clinical trial designed by top experts in the use of prazosin for PTSD (Raskind et al., 2018):
Titration schedule for male patients
|
Midmorning (9 am to 11 am) |
Bedtime |
|
| Days 1 and 2 |
None |
1 mg |
| Days 3 to 7 |
None |
2 mg |
| Week 2 |
1 mg |
4 mg |
| Week 3 |
2 mg |
6 mg |
| Week 4 |
2 mg |
10 mg |
| Week 5 |
5 mg |
15 mg |
Titration schedule for female patients
|
Midmorning (9 am to 11 am) |
Bedtime |
|
| Days 1 and 2 |
None |
1 mg |
| Days 3 to 7 |
None |
2 mg |
| Week 2 |
1 mg |
2 mg |
| Week 3 |
1 mg |
4 mg |
| Week 4 |
2 mg |
6 mg |
| Week 5 |
2 mg |
10 mg |
First-dose hypotension/ syncope
Before prescribing prazosin, it is important to know about the hypotension—or even syncope—that can sometimes occur after just the first dose of prazosin. For more on this, please see the following article on this website:
Warning! Prazosin can lead to hypotension/ syncope after the first dose
Related Pages
Does prazosin work for PTSD? If so, for which symptoms?
Warning! Prazosin can lead to hypotension/ syncope after the first dose
What is nightmare disorder and why is it important?
PTSD-associated nightmares: Menu of treatment options
Practice guidelines for posttraumatic stress disorder (PTSD)
References
Alexander B, Lund BC, Bernardy NC, Christopher ML, Friedman MJ. Early discontinuation and suboptimal dosing of prazosin: a potential missed opportunity for veterans with posttraumatic stress disorder. J Clin Psychiatry. 2015 May;76(5):e639-44. PubMed PMID: 26035198.
Koola MM, Varghese SP, Fawcett JA. High-dose prazosin for the treatment of post-traumatic stress disorder. Ther Adv Psychopharmacol. 2014 Feb;4(1):43-7. PubMed PMID: 24490030; PubMed Central PMCID: PMC3896131.
Raskind MA, Peskind ER, Chow B, Harris C, Davis-Karim A, Holmes HA, Hart KL, McFall M, Mellman TA, Reist C, Romesser J, Rosenheck R, Shih MC, Stein MB, Swift R, Gleason T, Lu Y, Huang GD. Trial of Prazosin for Post-Traumatic Stress Disorder in Military Veterans. N Engl J Med. 2018 Feb 8;378(6):507-517. doi: 10.1056/NEJMoa1507598. PMID: 29414272.
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