The time clock system: a new oral dosage form for fast and complete release of drug after a predetermined lag time☆

A hydrophobic material and surfactant coating for an oral dosage form, which allows for rapid drug release after a predetermined lag time, is described. The pulsed release system has the advantage of being manufactured using conventional film coating techniques and uses excipients normally present in pharmaceutical formulations. The in vivo behaviour of the preparation has been evaluated in three scintigraphic studies. The lag time for the system was found to be independent of normal physiological conditions, such as pH, digestive state of the subject and the anatomical position at the time of release. At the end of the lag time, disaggregation of the core was both rapid and complete. Scintigraphic evaluation was also used to establish in vitro methodology capable of predicting the subsequent in vivo performance of the time clock system. Pharmacokinetic studies using salbutamol as a model drug demonstrated that drug absorption was not influenced by the in vivo behaviour of the time clock system.