Deconvolution at steady state: determination of gastrointestinal bioavailability of sustained release theophylline.

A method is presented which enables the rate and extent of gastrointestinal release to be evaluated at steady state. The method requires a solution of the drug to be given orally as a reference in the same subject receiving the test product. The special mathematical and numerical aspect of the method is discussed. The method which makes use of the previously published deconvolution computer program DCON is demonstrated by evaluating the gastrointestinal release of a theophylline sustained release product at steady state.