DESIGN AND EVALUATION OF PULSATILE DRUG DELIVERY SYSTEM FOR CHRONOTHERAPEUTIC RELEASE OF METOPROLOL TARTRATE
The aim of the present study is to design and evaluate press-coated pulsatile release tablets of Metoprolol tartrate which releases the drug in time intervals for chrono pharmacotherapy of cardiovascular diseases like hypertension, where blood pressure is at its lowest during the sleep cycle and raises steeply during the morning awakening period. The inner immediate release core tablet containing Metoprolol tartrate (100 mg) as a bioactive compound was prepared by compression method using 3 different disintegrants like croscarmellose sodium, crospovidone, and sodium starch glycolate. The optimized core tablet was then coated with a mixture of rate controlling polymers like HPMC K15M, HPMC K 100M and ethyl cellulose at different core: polymer ratios. The core and press-coated tablets were evaluated for their physico-chemical properties, in-vitro release. From the in-vitro release studies of press-coated tablets, it was observed that the lag time increased as the viscosity grade and concentration of the Polymer in the outer coat increased. The formulations TF8 produced with blend of HPMC K100M (hydrophilic) and ethyl cellulose (hydrophobic) at core: polymer ratio of 1:2.5 had given a predetermined lag time of 6hrs with drug release of 94.11% at the end of 8th hr. Hence the formulation TF8 was considered as the optimized formulation. Initially compatibility study was carried out by FTIR study showing that all the excipients and polymers were compatible with drug.