The buccoadhesive and in vitro release properties of patches formulated with ethylcellulose (EC) and hydroxypropyl methylcellulose (HPMC) interpolymer complexes of different ratios were studied. The patches containing hydrochlorothiazide (HCTZ) were prepared by casting and thereafter, evaluated using the following parameters: diameter, thickness, swelling behaviour, buccoadhesive strength, drug content analysis and in vitro release studies. An adapted Lecomte Du Nouy tensiometer was used to assess the buccoadhesion of the patches on freshly excised buccal mucosa of a pig. The release of HCTZ from the patches was studied in phosphate buffer (pH 7.5). The result of the study indicated that 1:2 ratio of EC and HPMC gave the highest buccoadhesive strength. All the patches had uniform diameters but varied thicknesses with their areas ranging from 2.06 to 2.16 cm2. The area swelling ratio (ASR) indicated that the patches did not swell up to two times their initial areas, with the batch containing 3:2 ratio of EC and HPMC possessing the highest ASR. Higuchi’s analysis of the release mechanism indicated that the release of HCTZ from the patches formulated with 1:1 and 2:1 ratios of EC and HPMC predominantly occurred by a diffusional process. This method could be used as an effective alternative delivery system for HCTZ compared with conventional tablet formulations.
Key words: Hydrochlorothiazide, ethylcellulose, hydroxypropyl methylcellulose, interpolymer complex, area swelling ratio, buccoadhesive delivery.
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