A Case Study of Prazosin-Induced Hypothermia

Abstract

A case report of prazosin-induced hypothermia in a treatment-naive patient with PTSD. A 65-year-old woman with bipolar disorder and nightmares resulting from previous traumas was admitted to an inpatient psychiatry unit for mixed state hypomania and depression with suicidal ideation. Prazosin 1mg was started to help manage nightmares and the patient developed asymptomatic hypothermia with a low of 33.5C after 5 days of therapy. After internal medicine and endocrinology consults and appropriate testing did not result in an explanation, prazosin was stopped and her temperature returned to normal. A rechallenge of prazosin again resulted in a temperature decrease and was then discontinued. Hypothermia is not a reported side effect of prazosin in humans, though one previous case study reports hypothermia with a 20mg total daily dose in the treatment of a patient with hypertension. Animal studies indicate two possible mechanisms of action including 1) increased heat dissipation from skin by inhibition of non-shivering thermogenesis and decreased metabolic rate and 2) temperature increases upon rapid eye movement sleep deprivation (REMSD) in rats by increasing noradrenaline. Prazosin modulates REMSD-induced changes in body temperature in rats by blocking the effects of noradrenaline in postsynaptic receptors. To our knowledge, this is only the second reported case of hypothermia induced by prazosin.