GRECH-BELANGER, O: Clinical pharmacokinetics of mexiletine. The pharmacokinetics of mexiletine and the factors that have been shown to modify its disposition are reviewed. The clinical significatice of the modifications observed is discussed. Mexiletine is well absorbed from the gut and the bioavailability is 80-88%. The volume of distribution is large (5-9 L/kg) and 70% of the drug is bound to serum proteins. The elimination half-life varies between 6-12 hours. Concomitant administration of atropine, metoclopramide, gastric acids, narcotic analgesics and cimetidine modify the peak concentrations of mexiletine and the time required to attain these concentrations. Rifi:impicin, phenytoin, and cigarette smoking shorten the elimination half-life and increase the clearance. The volume of distribution of mexiletine is increased to the acute phase of myocardial infarction, whereas its elimination half-life is increased in both cardiac failure and cirrhosis. Factors modifying the elimination, unlike those affecting the absorption characteristics, of mexiletine are of clinical importance and may require a modification of the dosage regitiien.