SUMMARY Rifampicin induces a proliferation of the smooth endoplasmic reticulum in guinea-pig and human hepatocytes. This may support the hypothesis of enhancement of drug-metabolizing enzymes induced by the drug. However, the pattern of proliferation is not similar in man and in guinea-pig hepatocytes. Some caution is needed in the study of enzyme induction in man and in extrapolations fromn animal to human data. Meyer-Brunot, 1968;Curci, Ninni, and Iodice, 1969). On the other hand, repeated administration of rifampicin causes a decrease in the half-life and a fall in blood levels of the drug (Curci, Ninni, and Iodice, 1969;Furesz, 1970) together with an increase in biliary excretion of the antibiotic (Furesz, 1970 suspended in 1 % Methocel at a concentration of 16 mg/ml through a gastric tube. After two days of treatment three animals, after five days five, and after 10 days three animals were killed. Four animals received only 1 % Methocel at a dose of 0.5 ml/100 g body weight: at two days one was killed, at five days two,and at 10days one animal.Two animals did not receive any treatment. These animals were killed by section of the carotid; the abdomen was opened immediately and fragments of liver were processed for light and electron microscopy.
PATIENTSTwo patients received 20 mg/kg/day rifampicin (Rifadin, Lepetit-Milan) and four 10 mg/kg/day. A liver biopsy was taken after two days of treatment. A control biopsy before treatment was obtained in three of these patients.One patient received 10 mg/kg/day for five days followed by 16 mg/kg/day for two days. A liver biopsy was taken at the end of the seven days.
PROCESSING THE MATERIALFor light microscopy fragments of liver were fixed in 4% formalin, embedded in paraffin, and stained with haematoxylin-eosin. For electron microscopy, 1 mm3 fragments were fixed for one and a half hours in 1 % osmic acid in phosphate buffer pH 7.4. After dehydration with alcohol the fragments were embedded in an Epon/Araldite mixture.The blocks were cut with an LKB Ultrotome III 984