Study on poly(D,L‐lactic) microspheres embedded in calcium alginate hydrogel beads as dual drug delivery systems

Abstract

This work is to develop a novel dual drug delivery system that can simultaneously load and release 18β‐glycyrrhetinic acid (GA, a hydrophobic drug) and bovine serum albumin (BSA, hydrophilic model drug) in a single formulation. The system consists of poly(D,L‐lactic) (PDLLA) microspheres embedded in calcium alginate hydrogel beads. The GA‐loaded microspheres were first prepared and then dispersed in the aqueous solution of sodium alginate and BSA. The resulting suspension was dropped into aqueous calcium chloride solution to obtain the dual drug delivery system. The morphology of the microspheres and beads, the drug content and loading efficiency, the interaction between GA and PDLLA, and the drug release behaviors were studied. Scanning electron microscope (SEM) revealed that the PDLLA microspheres were homogeneously distributed in the beads. Differential scanning calorimetry (DSC) measurement suggested certain interaction between GA and PDLLA, and the crystal structure of GA was influenced by the polymer. The dual release in vitro showed a rapid BSA release but a sustained GA release in all the systems. Furthermore, the release rate of BSA was accelerated by increasing PDLLA/alginate ratio, while the release rate of GA was decreased, and the release of both hydrophobic and hydrophilic drugs could be adjusted by changing the ratio of PDLLA/alginate. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 20122

How to circumvent untoward drug crystallization during emulsion‐templated microencapsulation process

“…These poor EE data arise from the fact that considerable amounts of progesterone are not encapsulated but dispersed as free drug crystals in the aqueous continuous phase. Using methylene chloride for solvent evaporation to encapsulate piroxicam and glycyrrhetinic acid into PLGA microspheres also led to poor EE values ranging from 15.1 to 33.6% . These data are in accordance with our results demonstrating that the preparation of microspheres through solvent evaporation has a tendency to show a poor EE value due to drug crystallization in a continuous phase.…”

Development of silver nanoparticle-based hydrogel composites for antimicrobial activity

“…Hydrogels are 3-dimensionally interconnected hydrophilic polymers, which can absorb an extensive amount of water within the structures without being dissolved in water. Since the chemical, electrical, and mechanical properties of polymer hydrogels could be quite analogous with those present in biological tissues, there have been extensive efforts to utilize the hydrogels in biological applications such as drug delivery (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12), wound/burn dressing (13,14), scaffolds for tissue engineering (15)(16)(17), and others (18)(19)(20)(21). In particular, the inclusion of drugs inside polymer hydrogels may represent an innovative drug delivery system because the release rate of the loaded drugs can be regulated by external stimuli (1,2,(4)(5)(6)(7)(8)(9).…”

“…In many cases, the change in pH (2,3), temperature (1,7,9), and light (4) has triggered the swelling, shrinkage, or degradation of the hydrogels to release the drugs in a controlled way. Alternatively, in the absence of the external stimuli, the slow diffusion nature of the drug release can ensure a constant delivery as well as prolonged duration of drugs, which is necessary for exerting long-term efficacy (10)(11)(12).…”

Comparison of the degradation and release behaviors of poly(lactide‐co‐glycolide)–methoxypoly(ethylene glycol) microspheres prepared with single‐ and double‐emulsion evaporation methods

“…The degradation diversity between the two types of microspheres were ascribed to their different interior structures. According to the reports, microspheres prepared by DEEM exhibited a capsule or honeycomb interior structure, and microspheres prepared by SEEM were solid spheres. Through the ultrasonic pulverization of microspheres, we confirmed that the microspheres prepared by DEEM in this study possessed a honeycomb interior structure [Figure (B)], but the microspheres prepared by SEEM was difficult to break; this, in turn, suggested that it was a solid sphere as reported.…”