Effect of norfloxacin on theophylline metabolism.
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.
Davis
R L
RL
College of Pharmacy, School of Medicine, University of New Mexico, Albuquerque 87131.
Kelly
H W
HW
Quenzer
R W
RW
Standefer
J
J
Steinberg
B
B
Gallegos
J
J
D000328:Adult; D004347:Drug Interactions; D005260:Female; D006801:Humans; D008297:Male; D009643:Norfloxacin / Q000494:pharmacology*; D013806:Theophylline / Q000097:blood / Q000378:metabolism* / Q000652:urine
D013806:Theophylline; D009643:Norfloxacin