title: Hepatic mixed function oxidase induction during rifampicin/isoniazid therapy in Indian vegetarians.
abstract: To determine the effect of rifampicin therapy on hepatic oxidase activity in animal protein deficient patients antipyrine and quinine t 1/2 and 6B-hydroxycortisol (6B-OHF) excretion was studied in 8 Indian vegetarians during treatment for tuberculosis. In 4 patients at the start of treatment rifampicin/streptomycin caused a steady decline in by time antipyrine t 1/2 which was complete in 3 weeks, in one patient introduction of isoniazid produced a temporary reversal. After 4 months rifampicin/isoniazid 6B-OHF excretion was increased 2 to 10 fold in all patients although one followed serially showed a marked fall when isoniazid was begun. Decline in antipyrine t 1/2 persisted in 4 patients at the end of 18 months therapy and in one of these concurrent quinine t 1/2 confirmed partial isoniazid reversal of this decline. Rifampicin-mediated mixed function oxidase induction appeared similar to that reported for non-vegetarians and largely persists with combination therapy throughout treatment. Isoniazid can act as a competitive inhibitor of hepatic oxidase activity in some patients.
mesh_terms: D000983:Antipyrine / Q000378:metabolism; D014676:Diet, Vegetarian; D004359:Drug Therapy, Combination; D004790:Enzyme Induction / Q000187:drug effects; D005260:Female; D006207:Half-Life; D006801:Humans; D006854:Hydrocortisone / Q000031:analogs & derivatives / Q000378:metabolism; D007194:India; D007538:Isoniazid / Q000494:pharmacology / Q000627:therapeutic use*; D008099:Liver / Q000201:enzymology*; D008297:Male; D006899:Mixed Function Oxygenases / Q000096:biosynthesis*; D011803:Quinine / Q000378:metabolism; D012293:Rifampin / Q000494:pharmacology / Q000627:therapeutic use*; D013307:Streptomycin / Q000494:pharmacology / Q000627:therapeutic use; D014376:Tuberculosis / Q000188:drug therapy / Q000378:metabolism
chemical_list: C001380:6 beta-hydroxycortisol; D011803:Quinine; D006899:Mixed Function Oxygenases; D000983:Antipyrine; D007538:Isoniazid; D012293:Rifampin; D006854:Hydrocortisone; D013307:Streptomycin