Rat model of delirium: atropine dose-response relationships

The authors report dose-response relationships for atropine in their rat model of human delirium. In this model, anticholinergic mechanisms are an important cause and may be a neurochemical final common pathway for diverse etiologies of delirium. Four intravenous (i.v.) bolus doses of atropine (27.5, 13.5, 6.875, and 3.44 mg/kg) were studied along with the originally reported dose of 55 mg/kg and saline control. Subsequent iv infusions were also proportionately reduced. EEG frequency and amplitude, maze performance, and subjective behavioral descriptions were taken over 320-minute study periods. Repeated-measures analysis of variance compared data between groups, and effect sizes were calculated. Dosages to be used in future studies are discussed.