EFFECT OF METHYL VINYL ETHER MALEIC ANHYDRIDE DECADIENE CROSS-POLYMERON DRUG-RELEASE FROM SPHEROIDS COATED WITH WATER-SOLUBLE POLYMERS/

The ability of an anionic polymer, methyl vinyl ether/maleic anhydride decadiene cross-polymer, to retard the release of cationic chlorpheni ramine maleate and non-ionic paracetamol from spheroid coated with hyd roxypropylmethyl cellulose or sodium carboxymethyl cellulose was exami ned. The retardation of inhibition of drug release was due to complexa tion by ionic binding between the ionic polymer and the oppositely cha rged drug. However, the release rate of non-ionic drug was not altered by the presence of methyl vinyl ether/maleic anhydride decadiene. In the dissolution medium of water, for hydroxypropylmethyl cellulose-met hyl vinyl ether/maleic anhydride decadiene coated spheroids containing chlorpheniramine maleate, an increase in percentage of methyl vinyl e ther/maleic anhydride decadiene or an increase in coating level genera lly prolonged the drug release rate, while for sodium carboxymethyl ce llulose-methyl vinyl ether/maleic anhydride decadiene coated spheroids , it was observed that there was a distinct minimum of the release rat e constants on the response surface and contour plots. The pH and ioni c concentration of the dissolution media also played an important role in controlling drug release. At pH, 1,2 and 7.2, drug polymer complex ation was reversible, resulting in a faster drug release rate. Drug re lease rate in 5 mM phosphate buffer was slower than that in 50 mM phos phate buffer.