DRUG-RELEASE KINETICS OF BILAYER-COATED SPHEROIDS

Citation
Lsc. Wan et al., DRUG-RELEASE KINETICS OF BILAYER-COATED SPHEROIDS, STP PHARMA SCIENCES, 8(2), 1998, pp. 113-122
Citations number
14
Categorie Soggetti
Pharmacology & Pharmacy
Journal title
ISSN journal
11571489
Volume
8
Issue
2
Year of publication
1998
Pages
113 - 122
Database
ISI
SICI code
1157-1489(1998)8:2<113:DKOBS>2.0.ZU;2-S
Abstract
Bilayer coating of drug spheroids with a fixed inner coat of plasticiz ed hydrophilic cellulose ether and varying amount of plasticized metha crylic acid copolymer outer coat was formulated. These coated spheroid s were able to demonstrate a greater sustained-release effect at pH 1 than spheroids coated with solely plasticized methacrylic acid copolym er. The swelling dynamics of the cellulose ether had an important role in achieving the desirable sustained release property as was well dem onstrated by spheroids coated with an inner coat of plasticized hydrox ypropylmethyl cellulose of high viscosity grade and an outer coat of p lasticized Eudragit L30D. However, substituting the inner coat with fa st-disintegrating sodium carboxymethyl cellulose of moderate viscosity grade was less superior in its sustained release effect than an inter ior coat of plasticized hydroxypropylmethyl cellulose. When plasticize d methacrylate ester copolymer was utilized as the outer coat, the inc orporation of plasticised cellulose ether whether hydroxypropylmethyl cellulose or sodium carboxymethyl cellulose, as the inner coat, showed faster release than the plasticized Eudragit RS30D coat alone at both pH 1 and pH 72. Nevertheless, the results provided a useful basis for rite design and formulation of bilayer coated spheroids consisting of a swellable inner layer, made of high viscosity plasticized hydroxypr opylmethyl cellulose and an outer coat of an enteric material. The und issolved and intact membrane coat that swelled to different extent was directly correlated to the coating level or thickness of the outer L3 0D-PEG6000 coat. The swollen coat had attained a constant diffusion pa thway for drug release, exhibiting a zero-order drug release kinetics nt gastric pH.