Silicone Adhesive Matrix of Verapamil Hydrochloride to Provide pH-Independent Sustained Release

Abstract

Providing pH-independent oral release of weakly basic drugs with conventional matrix tablets can be challenging because of the pH-dependent solubility characteristics of the drugs and the changing pH environment along the gastrointestinal tract. The aim of the present study was to use a hydrophobic polymer to overcome the issue of pH-dependent release of weakly basic model drug verapamil hydrochloride from matrix tablets without the use of organic buffers in the matrix formulations. Silicone pressure-sensitive adhesive (PSA) polymer was evaluated because of its unique properties of low surface energy, hydrophobicity, low glass transition temperature, high electrical resistance, and barrier to hydrogen ion diffusion. Drug release, hydrogen ion diffusion, tablet contact angle, and internal tablet microenvironment pH with matrix tablets prepared using PSA were compared with those using water-insoluble ethyl cellulose (EC). Silicone PSA films showed higher resistance to hydrogen ion diffusion compared with EC films. Verapamil hydrochloride tablets prepared using silicone PSA showed higher hydrophobicity and lower water uptake than EC tablets. Silicone PSA tablets also showed pH-independent release of verapamil and decreased in dimensions during drug dissolution. By contrast, verapamil hydrochloride tablets prepared using EC did not achieve pH-independent release.

Diffusion of uncharged solutes through human nail plate

“…Assuming a circular geometry and the nail thickness of 0.04 cm reported by this group, an aspect ratio (thickness/radius) of 0.32 can be readily calculated. The influence of lateral diffusion in such cases can be significant and dependent upon the total size of the membrane relative to the exposed surface (18). Prior to achievement of a steady state, lateral diffusion reduces the flux through the membrane (18).…”

“…The influence of lateral diffusion in such cases can be significant and dependent upon the total size of the membrane relative to the exposed surface (18). Prior to achievement of a steady state, lateral diffusion reduces the flux through the membrane (18). The time lag to achieve steady state increases.…”

Optimization of the sonication process for meloxicam nanocrystals preparation

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Gastric floating tablet improves the bioavailability and reduces the hypokalemia effect of gossypol in vivo

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