Food induced changes in theophylline absorption from a once-a-day theophylline product

Bioavailability and the absorption pattern of theophylline from the sustained release theophylline (SRT) product, Uniphyllin, were studied in eight adults and eight children under fasting conditions in the morning, after a standardised breakfast in the morning, and under fasting conditions in the evening (adults only). Theophylline given intravenously was used as a reference. The extent of absorption of theophylline was complete for all administrations of SRT both in adults and children. In adults the absorption profiles after the three administrations of SRT were very similar and at no time point was there any difference in serum theophylline concentration or fraction absorbed between the three regimens. In addition, inter and intra individual variations in absorption were small. In children food caused a substantial change in the absorption pattern of theophylline so that the profiles became rather unpredictable with delays in absorption and periods of rapidly increasing serum drug concentrations. In three of the patients the dose dumping phenomenon resulted in toxic serum drug concentrations. Dumping of the dose could take place at any time interval between 3 and 15 h post dosing. Cmax was about 50% higher after fed than after fasting medication (P less than 0.01). It is concluded that children should not take SRT in large doses in combination with food.