Formulation and Evaluation of Sandwiched Osmotic Tablet System of Theophylline.

Osmotically controlled oral drug delivery system utilizes osmotic pressure for controlled delivery of active agents. This drug delivery system overcomes the numerous problems associated with matrix and reservoir types of controlled drug delivery system. Osmotic system achieves zero order drug release which is independent of pH of gastrointestinal tract, presence or absence of food, agitation, hydrodynamic conditions and concentration of drug. Sandwiched Osmotic Tablet System (SOTS) formulation consists of two layers of drug (theophylline) sandwitching a push layer (polyethylene oxide 301 or croscarmellose sodium) coated with cellulose acetate as semipermeable membrane and two delivery orifices drilled on both sides of tablet. This system is suitable for drugs causing local irritation. A successful attempt of formulation development of SOTS of theophylline was made. Hydroxy propyl methyl cellulose K100M was incorporated in drug layer to determine its effect on drug release. All the formulations were evaluated for hardness, friability, drug content and in vitro drug release. All the formulations showed zero order kinetics of drug release except F2 shows Korsemeyer-Peppas and F3 shows Hixon-Crowell kinetics of drug release. The formulation F4 showed 98.02% drug release within 24 hrs and was further subjected to accelerated stability testing for 3 months. The formulation F4 was found to be stable with no significant change in the drug content and drug release. [ABSTRACT FROM AUTHOR]