Pharmaceutical Factors Affecting The Formulation Of Verapamil HCl Floating Capsules
Floating sustained release Verapamil HCl capsules were prepared using different polymers. Hydroxypropylmethyl cellulose 4000 and 50 (HPMC 4000 & HPMC 50), Carbopol 934, sodium alginate (Na alginate), carboxymethyl cellulose (CMC) and Pectin were used to study their effect on the release of Verapamil HCl from its capsules. Three different ratios of drug: polymer were adopted namely 1:1, 1:0.5 and 1:0.25 w/w. The effect of the weight of the prepared capsules on the dissolution rate of the drug using avicel to adjust the weight of the capsule to 300, 400 and 500 mg. The incorporation of effervescent mixture in the prepared capsules was tried to prepare floating dosage form with an in – situ gas generating mechanism for the seek of buoyancy improved drug release characteristics. Monobasic potassium citrate and potassium bicarbonate (1:1 w/w) as an effervescent mixture were used to generate CO2 gas. The effervescent mixture was mixed with the polymers in each capsule in 0, 1 and 2% w/w of the total weight of the formula. In-vitro release studies were performed to observe the effect of effervescence on the duration of drug release. It was observed that increasing the ratio of the polymer in the formula retard the drug release. The release profile gave a faster release rate in case of light weight capsule than heavy weight capsule. Increasing the amount of effervescent mixture per capsule retarded the rate of the drug release.
Egyptian Journal of Biomedical Sciences Vol. 23 (1) 2007: pp. 244-256