Impact of cefaclor on the pharmacokinetics of theophylline

The influence of cefaclor taken for 8 days (250 mg every 8 h) on the pharmacokinetics of a single intravenous dose of theophylline (2 mg/kg administered on the 8th cefaclor day) was studied in a crossover fashion among 11 healthy adults (10 men and one woman). Theophylline concentrations were measured serially for 12 h by an immunofluorescence polarization technique. No influence of cefaclor was detectable on theophylline clearance, half-life, or volume of distribution. It is concluded that cefaclor and theophylline can be administered together safely.