No effect of cefaclor on theophylline pharmacokinetics

The effect of the antibiotic drug cefaclor on steady state pharmacokinetics of theophylline was studied in healthy adults by comparing the pharmacokinetic parameters as found during a 9 days course of theophylline alone and as obtained during comedication with cefaclor. Theophylline plasma concentrations were measured by means of HPLC analysis. On the ninth day of each of the 2 periods of drug administration, a concentration-time curve was evaluated. It showed no influence of cefaclor on volume of distribution and clearance of theophylline and only a slight, but significant (p less than 0.05) influence on the values for Cmax and tmax after cefaclor co-treatment. It is concluded that both drugs can be given concomitantly without any dosage adjustment of theophylline.