Prazosin, a postsynaptic alpha-1 adrenoceptor blocker, lowers blood pressure by relaxing blood vessels. Prazosin has a minimal effect on cardiac function due to its alpha-1 receptor selectivity. The recommended starting dose in adults is 0.5 or 1 milligram (mg) taken two or three times a day.
In a small (n=15) (Krum et al. 1992), but high quality RCT, Prazosin twice daily was well tolerated and did not affect the baseline blood pressure; AD episodes were also less severe and shorter in duration over a 2 week period. Phillips et al. (2015) revealed similar results during penile vibrostimulation trials, where Prazosin lowered systolic blood pressure when administered without affecting resting blood pressure.
There is level 1 evidence (from two RCTs: Phillips et al. 2015; Krum et al. 1992) that Prazosin is superior to placebo in the prophylactic management of AD.