The influence of antacid on the absorption of two different sustained-release formulations of theophylline.
Twelve healthy volunteers were treated with two different sustained-release formulations of theophylline (Nuelin Depot 350 mg and Theo-Dur 300 mg) twice daily in an open cross-over study. The serum levels in steady state without and with concomitant administration of antacid were studied. Antacid did not influence the serum theophylline levels in the Theo-Dur treatment period, while in the Nuelin Depot treatment period antacids caused a significantly larger increase in serum levels of theophylline after drug intake. The difference between morning and peak concentrations were also much higher with the combination Nuelin Depot/antacid. This implies that physicochemical factors such as gastrointestinal fluid pH might influence the degradation and/or absorption of some slow-release theophylline formulations as reflected in serum concentrations, and thereby contribute to the therapeutic and side effects of such drugs.
D000042:Absorption; D000328:Adult; D000863:Antacids / Q000494:pharmacology*; D003692:Delayed-Action Preparations; D004347:Drug Interactions; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008297:Male; D013806:Theophylline / Q000008:administration & dosage / Q000378:metabolism*
D000863:Antacids; D003692:Delayed-Action Preparations; D013806:Theophylline