The aim of the investigation was to develop a novel oral pulsatile drug delivery system based on enteric coated timerelease press coated (ETP) tablet. Tablet containing mainly three layers; a theophylline core tablet by direct compression, outer shell by different weight ratio of hydrophobic polymer of ethylcellulose (EC) and hydrophilic excipients such as low-substituted hydroxy propylcellulose (L-HPC) or hydroxypropyl methylcellulose (HPMC) and top layer of enteric coated polymer like Eudragit L-100. The effect of the formulation of an outer shell comprising both hydrophobic polymer and hydrophilic excipients on the lag time of drug release was investigated. The drug delivery system was designed to deliver the drug at such a time when it could be most needful to patient during nocturnal asthma. The time-release function should work more efficiently in the small intestine as compared the stomach. In the small intestine drug carrier will be delivered to the target side and drug release will begin at a predetermined time point after gastric emptying. The release profile tablet exhibited a time period without drug release (time lag) followed by a rapid and complete release phase, in which the outer shell ruptured. Dissolution studies were carried out in simulated gastric, intestinal fluid with 0.1 N HCl (pH 1.2) and phosphate buffer (pH 6.8), respectively. The optimized formulation complied with the ICH stability testing guidelines.
