PRAZOSIN FOR TREATING PTSD
Prazosin is an alpha-1 adrenergic receptor antagonist. Prazosin crosses the blood-brain barrier [goes from the body into the brain] and is felt to reduce the fear response associated with increased adrenergic activity that is seen when PTSD symptoms are triggered. Prazosin is prescribed for hypertension [high blood pressure] and is then dispensed three times a day.
There are a number of placebo controlled studies that show the benefit of prazosin taken at bedtime for PTSD related sleep disorders [mostly nightmares] and then an additional benefit of reducing daytime PTSD symptoms. This daytime benefit was enhanced when daytime doses were utilized with one study having 5 mg in morning and 20 mg at night. Another, had 2 mg in morning and 2 mg at 4 pm and 10 mg at night. The doses are started at 1 mg in the evening and then there is monitoring for dizziness, light headedness or other indications of low blood pressure. Even with an increasing evening dose, there were no significant blood pressure changes and no low blood pressure symptoms. Also, daytime benefit was enhanced by taking doses during the day. However, there have been only a few trials using daytime doses so even though there are positive results, it involves only a small number of people.
I have had a few patients initially take prazosin to treat nightmares and then I had a couple patients referred to me already taking it 3 times a day all without blood pressure changes. It has been helpful in reducing PTSD symptoms such as hyperarousal, vigilance, avoidance and intrusive thoughts. The main side-effects, although infrequent, were tiredness related to lowered blood pressure to below normal range as these patients were not hypertensive. Lowering the dose would frquently reduce the tiredness.
I have also have had a good response by my patients to propranolol [a beta adrenergic receptor antagonist] as it also readily crosses the blood-brain barrier and will reduce or even eliminate stress connected to memories that seem to trigger a significant number of PTSD symptoms. Most of my patients have not had their blood pressure lowered or their heart rate lowered as it seems to only act on their brains to reduce stress associated with past stressful events. A few of my patients have had their blood pressure lowered and they could not take the propranolol. Otherwise, my patients have not experienced any side effects, even at higher doses. However, some of my patients have not been helped by propranolol and they have benefited from prazosin. They seem to have a very intense, persistent and easily triggered startle response which might be why they benefit from prazosin.
