Abstract
Aims: The purpose of this research is to develop a novel expandable gastroretentive dosage form (GRDF), based on an unfolding mechanism. It consists of a drug loaded bilayer polymeric film, folded into a hard gelatin capsule. Gastric retention is achieved due to unfolding of the dosage form within 15-20 min. Captopril is selected as the drug candidate for this work. Due to its narrow absorption window, Captopril has to be administered to the upper parts of the intestine in order to maintain sustained therapeutic levels. This may be achieved by a GRDF.
Methodolgy: Films were prepared by solvent-casting technique using Ethyl cellulose, HPMC E15 and Eudragit RLPO as polymers and dibutyl-phthalate as the plasticizer in both layers. The film with zigzag folding in the capsule was shown to unfold in the gastric juice and provide drug release up to 12 h in the acidic medium. The films were evaluated for weight & thickness variation, mechanical properties, in vitro drug release and unfolding behaviour based on the mechanical shape memory of polymers. Absence of drug polymer interaction and uniform drug dispersion in the polymeric layers was revealed by DSC, XRD and SEM studies. The GRDF location in the gastrointestinal tract was determined by X-ray studies.
Results: X-ray studies revealed that the GRDF is retained in the stomach up to 6± 0.5 h in fasting condition and 8 h in fed state.
Conclusion: The polymers used in the development of GRDFs were safe and proper combination of these polymers will yield a novel expandable GRDF with good in vitro drug release in acidic media, mechanical properties, unfolding behaviour. These outcomes demonstrate that the GRDF may be used to improve Captopril therapy and can be applied to extend the absorption of other narrow absorption window drugs that require continuous input.
Keywords: Captopril, ethyl cellulose, expandable drug delivery systems, gastric retention, hydroxy propyl methyl cellulose, mechanical properties.
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