Physostigmine in coma due to drug overdose

Abstract

Twelve patients with coma due to drug overdose were treated with physostigmine salicylate in a double‐blind, placebo‐controlled crossover trial. Three of the 9 patients who had taken drugs without anticholinergic action (methyprylon, barbiturates, ethchlorvynol, benzodiazepines) and 2 of 3 who had taken drugs with anticholinergic action (amitriptyline) showed dramatic decrease of depth of coma after physostigmine. Among patients with non‐anticholinergic overdose, in 10 min physostigmine induced an increase in mean arterial pressure from a mean of 80.3 mm Hg to 103.8 mm Hg (p < 0.05) and in heart rate from a mean of 87.9 beats/min to 98.3 beats/min (p < 0.001). When given to patients with anticholinergic drug intoxication, physostigmine induced a fall in mean arterial pressure from a mean of 105.4 mm Hg to 96.1 mm Hg (p < 0.01) and in heart rate from a mean of 104 beats Imin to 91.3 beats/min (p < 0.10). Physostigmine induced dilation of pupils in all patients with non‐anticholinergic overdose and in none with anticholinergic overdose (p < 0.01). The effects of physostigmine in non‐anticholinergic overdose appear to be due to a nonspecific action on the central nervous system. Physostigmine may also be of value in the differential diagnosis of coma. Its routine use in the treatment of drug‐induced coma is not recommended except in anticholinergic drug overdose unless standard measures fail and artificial mechanical ventilation cannot be provided to patients with severe drug‐induced respiratory depression.