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Alpha blockers

What are alpha blockers (prazosin) for PTSD?

Alpha blockers, such as prazosin, are medications that work as alpha-adrenergic receptor antagonists. They cross the blood-brain barrier, antagonise the alpha receptors in the central nervous system, and block the stress response. Higher than normal nocturnal central nervous system adrenergic activity that occurs in PTSD contributes to the disruption of normal rapid eye movement sleep. Prazosin reduces this adrenergic activity and therefore could be effective in treating posttraumatic arousal symptoms such as sleep disturbances and nightmares.

What is the evidence on prazosin for PTSD?

Moderate quality evidence found medium to large improvements in PTSD symptoms, nightmares, and sleep disturbances with prazosin than with placebo when compared at treatment endpoint. When comparing baseline to endpoint improvements over time, there was also a large reduction in nightmare frequency, and a trend, medium-sized improvement in PTSD symptoms with prazosin. However, there were no significant differences in sleep quality between prazosin and placebo, suggesting the placebo group may have had more sleep disturbances at baseline (the two reviews in this topic included mostly the same studies).

Prazosin resulted in more dry mouth than placebo, with no differences in dizziness, headache, nausea, lack of energy, muscle weakness or asthenia, drowsiness or somnolence, syncope, nasal congestion, or palpitations.

August 2021

Image: ©Wellford Tiller – stock.adobe.com

Last updated at: 4:54 am, 15th October 2021
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Fact Sheet Technical Commentary

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Title Colour Legend:
Green - Topic summary is available.
Orange - Topic summary is being compiled.
Red - Topic summary has no current systematic review available.