AN INVESTIGATION OF IN-VITRO RELEASE OF RABEPRAZOLE SODIUM FROM PULSATILE RELEASE TABLETS CONTAINING HPMC-EC BLEND AS TIME LAGGED PRESS COATING

To develop new pulsatile release tablets of Rabeprazole sodium (RS), that can suppress drug release in stomach and release the drug rapidly after a predetermined lag time for about 4 h in intestine, a multiple unit dosage forms was designed that contain, drug-containing core, a coating to achieve time lag in drug release and an outermost acid resistant enteric coating. Time lagged press coating was performed using ethyl cellulose (EC) and different grades of hydroxypropyl methylcellulose (HPMC) in different ratios. The press-coated tablets were optimized by the drug release study and finally the formulation F₁₇ containing 7:1 ratio of EC and HPMC K4M was selected as optimized formulation. This press coated tablet was further enteric coated with Cellulose acetate phthalate (CAP). The weight gain of the enteric coating was optimized based on the integrity of coating in an acidic solution for about 2 h. Formulation F₂₁ was finally selected with 10% weight gain and rupture time of 120 minutes in 0.1N HCl. Further, the drug release from F₂₁ formulation started after 270 minutes (4.5 h). The results indicate that the drug release was successfully suppressed till 4.5 hrs as per the need of pulsatile dosing of RS as the drug concentration needed between 12 am to 6 am. By considering the dosing time of 8: 00 pm, the formulation release only 15.1 % of the drug till 1 am (after 5 hrs) and 90 % of the drug release after 7.25 h.