Formulation and Evaluation of Press Coated Pulsatile Tablet of Valsartan
International journal of scientific research and reviews
The present study described the preparation of the valsartan (model drug) core-in-cup pulsatile release tablets based on pulse release pattern intended for chronotherapy in hypertension. By using different polymers with various combinations fails to give desired lag time. Then by various trials, ethyl cellulose and polyethylene oxide shows desired lag time. Hydrophilic polymers used were essential for achieving the desired release pattern. The combination of hydrophobic polymer (ethyl
... er (ethyl cellulose) and hydrophilic polymer (polyethylene oxide) gave optimum release profile by providing initial swelling in acidic pH followed by a pulse release after specific lag time. From the disintegration test of core tablets it was concluded that croscarmellose sodium (8%) show least disintegration time. In trial-1 in ethyl cellulose is used as impermeable cup and L-HPC as top layer, it showed lag time of 1-3 hrs which is not desired lag time because of top layer of hydrophilic polymer L-HPC it gets solubilise quickly and exposes tablet. In trial-2 ethyl cellulose and polyox-301, it showed lag time of 1-3 hrs which is not desired lag time because of erodible nature of polyox 301 it get eroded in contacts with dissolution media. In trial-3 ethyl cellulose and polyox-303, it showed lag time of 2-5 hrs which is desired lag time because of swelling nature of polyox 303 it get swelled in contacts with dissolution media and after lag time it exposes tablet. In impermeable cup method the concentration of hydrophobic polymer do not affect the release profile after fix concentration however the lag time increases and drug release decreases with increasing concentration of hydrophilic polymer.