Dual-mechanism gastroretentive drug delivery system loaded with an amorphous solid dispersion prepared by hot-melt extrusion

Abstract

In the present study, we aimed to prepare a gastroretentive drug delivery system that would be both highly resistant to gastric emptying via multiple mechanisms and would also potentially induce in situ supersaturation. The bioadhesive floating pellets, loaded with an amorphous solid dispersion, were prepared in a single step of hot-melt extrusion technology. Hydroxypropyl cellulose (Klucel™ MF) and hypromellose (Benecel™ K15M) were used as matrix-forming polymers, and felodipine was used as the model drug. The foam pellets were fabricated based on the expansion of CO2, which was generated from sodium bicarbonate during the melt-extrusion process. A 2n full factorial experimental design was utilized to investigate the effects of formulation compositions to the pellet properties. The melt-extrusion process transformed the crystalline felodipine into an amorphous state that was dispersed and “frozen” in the polymer matrix. All formulations showed high porosity and were able to float immediately, without lag time, on top of gastric fluid, and maintained their buoyancy over 12 h. The pellet-specific floating force, which could be as high as 4800 μN/g, increased significantly during the first hour, and was relatively stable until 9 h. The sodium bicarbonate percentage was found to be most significantly effect to the floating force. The ex vivo bioadhesion force of the pellets to porcine stomach mucosa was approximately 5 mN/pellet, which was more than five times higher than the gravitation force of the pellet saturated with water. Drug release was well controlled up to 12 h in the sink condition of 0.5% sodium lauryl sulphate in 0.1 N HCl. The dissolution at 1, 3, 5, and 8 h were 5–12%, 25–45%, 55–80%, and ≥ 75% respectively for all 11 formulations. In biorelevant dissolution medium, a supersaturated solution was formed, and the concentration was maintained at around 2 μg/mL, approximately 10-folds higher than that of the pure felodipine. All input factors significantly affected dissolution in the first 3 h, but afterwards, only drug load and hypromellose (HPMC) content had significant effects. The prepared drug delivery system has great potential in overcoming low and fluctuating bioavailability of poorly soluble drugs.

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