Pharmacokinetics of tolfenamic acid in patients with cirrhosis of the liver

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Abstract
Summary Six patients with alcoholic cirrhosis of the liver received 100 mg tolfenamic acid p.o. and i.v. The disposition of tolfenamic acid could be described by a two-compartment open body model, with a mean central compartment volume of 8.71, and a β-phase volume of 251. The elimination rate constant ke averaged 1.13 h−1 and the half-life of the β-phase was 1.73 h; the mean total plasma clearance was 159 ml/min. These pharmacokinetic parameters differed only slightly from those in two groups of healthy volunteers studied previously; ke was significantly reduced by about 30% in the patients but none of the other parameters differed significantly. There was good correlation between individual elimination rate constants or plasma clearances with the liver function tests, serum albumin and P-coagulation factors. Oral absorption was good and bioavailability of about 100% was shown by comparison of the areas under the plasma concentration — time curves after i.v. and p.o. administration. Metabolism was qualitatively and quantitatively very similar to previous observations in healthy volunteers. There seems no reason to reduce the dose of tolfenamic acid in patients with compensated alcoholic cirrhosis.