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Effects of allopurinol on theophylline metabolism and clearance
Author(s) -
Grygiel John J.,
Wing Lindon M. H.,
Farkas Julie,
Birkett Donald J.
Publication year - 1979
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1002/cpt1979265660
Subject(s) - allopurinol , theophylline , metabolite , xanthine oxidase , urine , theobromine , chemistry , dosing , metabolism , pharmacology , xanthine , pharmacokinetics , xanthine oxidase inhibitor , excretion , endocrinology , medicine , biochemistry , enzyme
The effects of allopurinol on the plasma clearance and metabolism of theophylline in man were investigated under single‐dose and multiple‐dosing conditions. No change in theophylline clearance was found with the concomitant use of allopurinol but 1‐methylxanthine (1MX), a theophylline metabolite not previously described in man, was detected in urine during control and allopurinol treatment phases under both single‐ and multiple‐dosing conditions. 1MX excretion increased at the expense of 1‐methyluric acid (IMU) during the allopurinol treatment phase. It is proposed that the secondary biotransformation of 1MX to IMU is mediated by xanthine oxidase.