ABSTRACT
Tacrine is extensively metabolized in the liver by the hepatic microsomal enzymes, particularly cytochrome P450 isoenzyme CYP1A2. Concurrent tacrine pharmacotherapy may decrease the metabolism of succinylcholine and related drugs by means of inactivation of cholinesterases. Concurrent tacrine and theophylline pharmacotherapy may result in a 2-fold increase in the average blood concentration and half-life of elimination of theophylline. Tacrine blood concentrations among smokers are, on average, approximately one-third the blood concentrations seen in non-smokers. Close patient monitoring and higher tacrine dosages generally are required for patients who smoke one or more packages of tobacco cigarettes daily. Tacrine pharmacotherapy commonly has been associated with dizziness, elevated serum transaminase concentrations, and headache. Signs and symptoms of tacrine overdosage may result in cholinergic crisis and bradycardia, cardiovascular collapse, convulsions, hypotension, muscle weakness, nausea, salivation, sweating, and vomiting. Tacrine overdosage should be treated as a medical emergency requiring symptomatic medical support of body systems with attention to increasing tacrine elimination.
