Rivastigmine to treat anticholinergic toxicity following drug overdose – case series

Overdose involving anticholinergic agents frequently cause delirium and agitation, for which the antidote of choice is physostigmine. Due to unpredictable physostigmine availability, rivastigmine has been proposed as an alternative therapy though limited research has been conducted. We conducted a retrospective review of one regional poison center’s records of patients who received rivastigmine to treat anticholinergic delirium between January 01, 2021, and March 31, 2023. Thirty patients received oral rivastigmine. Two patients additionally received transdermal rivastigmine and two patients physostigmine. The most common initial oral rivastigmine dose was 3 mg. Thirteen patients received more than one dose of rivastigmine. Following rivastigmine, 20 patients demonstrated symptom improvement, and 10 patients showed no clear benefit. Symptom improvement occurred within 1 h for 4 patients, within 4 h for 11 patients, and after 4 h for 5 patients. No cholinergic adverse effects were reported with rivastigmine use. Rivastigmine, whether transdermal or oral, may be beneficial when treating anticholinergic toxicity. Our small cohort had no reported adverse effects from rivastigmine. Larger studies are warranted to determine appropriate starting doses, dosing strategies, and safety of rivastigmine in treating anticholinergic toxicity.