1. The relationship between serum triacylglycerol concentration and hepatic microsomal enzyme activity was examined in rats.
2. Two groups of rats were injected with diclofenac sodium at doses of 2.5 and 5 mg day−1 kg−1. A third group was injected with phenylbutazone at a dose of 20 mg day−1 kg−1. The treatment was continued for 15 days and the rats were killed 24 h after the last dose.
3. In all drug-treated rats, the serum triacylglycerol concentration and the hepatic microsomal activities of aminopyrine N-demethylase and aniline hydroxylase were significantly increased as compared with the corresponding values in control rats. The correlations between the serum triacylglycerol concentrations and the activities of the two enzymes, as indices of the hepatic microsomal activity, were highly significant.
4. These results indicate that the possibility of hypertriglyceridaemia as an adverse effect of the induction of the hepatic microsomal enzymes after the administration of phenylbutazone and diclofenac sodium should be considered.