title: Effect of norfloxacin on theophylline metabolism.
abstract: The purpose of this study was to investigate the effect of norfloxacin on theophylline elimination. Ten normal volunteers were studied. In a randomized crossover sequence, each subject received 6 mg of aminophylline per kg of body weight by a 30-min intravenous infusion on day 4 of taking norfloxacin (400 mg every 12 h) or while drug free. Mean theophylline clearance decreased and mean elimination half-life increased after norfloxacin administration (from 0.036 +/- 0.006 to 0.033 +/- 0.004 liter/h per kg and from 8.7 +/- 1.2 to 9.5 +/- 1.5 h, respectively; P less than 0.05, Wilcoxon signed-ranks test). We conclude that norfloxacin taken in recommended doses for 3 days has a small inhibitory effect on theophylline metabolism that would probably not cause clinically important elevations in theophylline concentrations in most patients.
authors.affiliation: College of Pharmacy, School of Medicine, University of New Mexico, Albuquerque 87131.
authors.forename: R L
authors.initials: RL
authors.lastname: Davis
authors.forename: H W
authors.initials: HW
authors.lastname: Kelly
authors.forename: R W
authors.initials: RW
authors.lastname: Quenzer
authors.forename: J
authors.initials: J
authors.lastname: Standefer
authors.forename: B
authors.initials: B
authors.lastname: Steinberg
authors.forename: J
authors.initials: J
authors.lastname: Gallegos
mesh_terms: D000328:Adult; D004347:Drug Interactions; D005260:Female; D006801:Humans; D008297:Male; D009643:Norfloxacin / Q000494:pharmacology*; D013806:Theophylline / Q000097:blood / Q000378:metabolism* / Q000652:urine
chemical_list: D013806:Theophylline; D009643:Norfloxacin