This patient's clinical picture is consistent with intoxication with tricyclic antidepressants such as amitriptyline and imipramine. Toxic effects are mediated by peripheral anticholinergic activity and "quinidine-like" action. The anticholinergic effects include mydriasis, tachycardia, impaired sweating with flushed skin, dry mouth, constipation, and muscle twitching. Quinidine-like effects (due to block of sodium channels in the hea) result in cardiac arrhythmias, especially ventricular tachyarrhythmias. In this setting, prolongation of the QRS complex is paicularly impoant in the diagnosis. QRS width is, in fact, an even more faithful parameter of drug toxicity than serum drug levels. In severe intoxication, patients will develop seizures, severe hypotension, and coma. Acetaminophen results in liver toxicity. Liver enzymes would be elevated. Alcohol intoxication manifests with respiratory depression, hypothermia, and coma. The manifestations of benzodiazepine intoxication are similar to alcohol inasmuch as central nervous system depression is common to both drugs. Thus, acute benzodiazepine intoxication produces stupor, coma, and respiratory depression. The sympatholytic propeies of clonidine explain the clinical symptoms of intoxication. Clonidine overdose causes bradycardia, hypotension, miosis, and respiratory depression. Monoamine oxidase (MAO) inhibitors represent a second-line treatment for major depression. Overdose induces ataxia, excitement, hypeension, and tachycardia. Such reactions can be precipitated by concomitant ingestion of tyramine-containing foods. Reference: Kaplon and sadock, 11 th edition, synopsis of psychiatry, 11 th edition, pg no. 1144