Enteric-coated Ca-alginate hydrogel beads: a promising tool for colon targeted drug delivery system
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Enteric‑coated Ca‑alginate hydrogel beads: a promising tool for colon targeted drug delivery system Sadia Rehman1,2 · Nazar Muhammad Ranjha3 · M. Rafi Raza4 · Muhammad Hanif1 · Abdul Majed1 · Nabeela Ameer1 Received: 11 May 2020 / Revised: 18 July 2020 / Accepted: 4 September 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Enteric coating of hydrogel beads is an effective approach to resolve the drug entrapment problem reported in previous studies. In the present study, microencapsulation of drug in hydrogel beads with extrusion-dripping technique was used for the improvement of the drug entrapment efficiency. Calcium chloride dehydrate was used as a cross-linking agent and oil-in-oil solution of eudragit S-100 was used as coating material while diclofenac sodium was used as a model drug. Optical microscopy, scanning electron microscopy, weight, elemental, and size variation of prepared hydrogels beads were analyzed and found within the acceptable limits. The drug loading and release studies of the coated beads were evaluated. Retardation of the model drug in gastric and intestinal pH environment until 8 h was observed which made the prepared hydrogels more targeted and colon-specific. In acidic pH 1.2, negligible percentage release was observed, whereas at pH 7.4, 98% diclofenac sodium was estimated after 8 h. In vitro release, kinetic studies proved that concentration-dependent release behavior of diclofenac sodium followed Fick’s law of diffusion in coated form, while non-Fickian behavior was observed in uncoated beads. Prepared hydrogel beads may be used as a promising tool for sustained release of drug targeting colon. Keywords Hydrogel beads · Extrusion-dripping technique · Targeted delivery · Swelling · Drug release kinetics · pH sensitive
* Sadia Rehman [email protected] * M. Rafi Raza [email protected] Extended author information available on the last page of the article
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Polymer Bulletin
Introduction The hydrogel may have some limitations in which elevated burst effect due to the accumulation of hydrophilic drugs and degradation of the drug in an acidic pH are considered much important. To overcome the drug leaking problem from the hydrogel beads, pH-sensitive polymers may be a better choice to coat the beads. Usually, these pH-dependent polymers contain methacrylic acid copolymer such as eudragit S-100 [1]. A polymeric system which can overcome such problems and is more effective than simple hydrogel can be considered as a targeted drug delivery system. Hydrogel are beads spherical in shape having drug encapsulated in the dimensional, polymeric network which can imbibe an extensive amount of water or biological fluids like other living tissues [2–5]. Their physicochemical properties can be altered by varying their cross-linking degree, thus making it suitable for modulated drug delivery [6]. The enteric coating of this polymeric network with a pH-sensitive polymer makes it possible to release the drug at colon. The protective coating v
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