Prazosin initiation and dose titration in a patient with posttraumatic stress disorder on concurrent carvedilol

One mechanism involved in the pathophysiology of posttraumatic stress disorder (PTSD) is increased noradrenergic stimulation. Prazosin, a commonly utilized treatment for PTSD nightmares, works to block noradrenergic stimulation of the alpha-1 adrenoreceptor. Dual antagonism of this receptor would be expected to increase risk of adverse effects. Carvedilol has both alpha-1 adrenergic and nonselective beta-adrenoreceptor antagonist activity. To our knowledge, there is no clinical guidance on use of prazosin in patients concomitantly prescribed carvedilol for hypertension. This case describes the successful titration of prazosin for PTSD symptoms in a 49-year-old male concurrently prescribed carvedilol for hypertension. This patient had a previous unsuccessful prazosin trial due to adverse effects. His second trial of prazosin was efficacious and well tolerated using individualized titration with close monitoring by mental health clinical pharmacy specialists in the pharmacist-managed prazosin titration clinic. This case details the importance of utilizing caution and close follow-up in prazosin dose titration in patients prescribed concomitant alpha-1 antagonists. This appears to be the first case report describing the successful dose titration of prazosin for PTSD in a patient on a concurrent alpha-1 antagonist antihypertensive agent.