Lack of influence of co-trimoxazole on theophylline pharmacokinetics.
In an open cross-over experiment, the influence of the antimicrobial agent co-trimoxazole on the single-dose pharmacokinetics of theophylline was studied in six healthy adults by comparing the pharmacokinetic parameters found after intravenous administration of theophylline without and with co-medication of co-trimoxazole for the previous 8 d. Theophylline concentrations in plasma were measured by high-performance liquid chromatography (HPLC) analysis. During each treatment, a concentration-time curve was evaluated. No influence of co-trimoxazole on the rate of elimination and volume of distribution of theophylline could be found, as a result of which theophylline concentrations in plasma were not significantly different in both periods of drug administration. A similar lack of influence of co-trimoxazole may apply to the steady-state pharmacokinetics of theophylline. The present study suggests that both drugs can be given concomitantly without the need for dosage adjustment of theophylline.
D000328:Adult; D000892:Anti-Infective Agents, Urinary / Q000494:pharmacology*; D004338:Drug Combinations / Q000494:pharmacology; D004347:Drug Interactions; D005260:Female; D006207:Half-Life; D006801:Humans; D007700:Kinetics; D008297:Male; D013420:Sulfamethoxazole / Q000494:pharmacology*; D013806:Theophylline / Q000097:blood / Q000378:metabolism*; D014295:Trimethoprim / Q000494:pharmacology*; D015662:Trimethoprim, Sulfamethoxazole Drug Combination
D000892:Anti-Infective Agents, Urinary; D004338:Drug Combinations; D015662:Trimethoprim, Sulfamethoxazole Drug Combination; D014295:Trimethoprim; D013806:Theophylline; D013420:Sulfamethoxazole