Influence of sulbactam plus ampicillin on theophylline clearance

The effect of sulbactam/ampicillin (500 mg/1000 mg) every 12 hours taken for seven days on the steady-state pharmacokinetics of theophylline was studied among 12 patients suffering from chronic obstructive pulmonary disease. Theophylline concentrations were measured serially for 12 h by the method of polarized immunofluorescence (Abbott TDx system). No influence of sulbactam/ampicillin was detectable on the theophylline half-life, clearance or volume of distribution. It was concluded that both drugs could be administered concomitantly without any dosage adjustment of theophylline.