Theophyllin. Absorption in verschiedenen Darmabschnitten

The absorption of a theophylline solution delivered to different sites of the gastrointestinal tract in doses between 80–120 mg has been determined in 7 male volunteers using a remote controlled drug release system (HF-capsule). Absorption measurements obtained by application of the substance with this method into the stomach was comparable to the conventional oral application of a theophylline solution as demonstrated by results with both methods in the same subject. No differences exist between the stomach, the ileum, and the colon in the amount of theophylline absorbed (AUG). The calculated T1/2abs of theophylline absorbed via the colon were prolonged when compared with the upper gastro-intestinal tract. Results provide a rational basis for the development of further theophylline formulations and are indespensible for the explanation of variations in bioavailabihty of theophylline-retard drug preparations. Therefore, the absorption characteristics of theophylline make it possible to develop sustained release products for b.i.d. dosing or less frequently.