Prazosin

Also known as: Minipress (brand), alpha-1 adrenergic antagonist

Other

In plain English

Prazosin relaxes blood vessels and is used for high blood pressure and urinary symptoms from an enlarged prostate. It is also used off-label at bedtime to reduce trauma-related nightmares and improve sleep in PTSD. The first doses can cause dizziness or fainting from a blood-pressure drop, so it is started low and taken at night.

The science

Prazosin is a selective alpha-1 adrenergic receptor antagonist that produces vasodilation (lowering blood pressure) and relaxes smooth muscle in the bladder neck/prostate. As a CNS-active alpha-1 blocker it reduces noradrenergic hyperarousal implicated in PTSD nightmares; several randomized trials (e.g., Raskind and colleagues) showed benefit for trauma nightmares and sleep, although a large multisite VA trial (PACT) did not find superiority over placebo, so evidence is mixed and it is no longer uniformly first-line.

References

• Raskind MA et al., reduction of nightmares and PTSD symptoms by prazosin (placebo-controlled study), Am J Psychiatry 2003
• Raskind MA et al., trial of prazosin for PTSD in military veterans (PACT), N Engl J Med 2018