The in vivo performance of theophylline microcapsules.

The possibility of using microcapsules as a sustained dosage form of theophylline has been investigated. The release characteristics of two formulae were compared with microcrystalline theophylline. Urine samples were assayed using H.P.L.C. to separate the unchanged theophylline which was detected by its U.V. spectrum. A single-compartment model for absorption and elimination could explain the results found. Both microencapsulated formulations showed a significantly extended absorption time over that of non-encapsulated theophylline.