Microencapsulation has become a common technique in the production of controlled release dosage forms. Many results have been reported, concerning the use of alginate beads as controlled release drug formulations. Alginate has a unique gel-forming property in the presence of multivalent cations, in an aqueous medium. Ibuprofen is an excellent analgesic and antipyretic, non-steroidal anti-inflammatory agent with a high therapeutic index. Formulation of ibuprofen in beads could reduce its gastric ulcerogenicity. Hence, in this study the formation of Ca-alginate ibuprofen beads, through ionotropic gelation has been investigated.For this purpose, different cross-linking agents including: Ca2+, Ba2+, Mn2+, CO2+, Sn2+and Pb2+, were used for bead preparation. Next, characterization of the beads, size distribution, encapsulation efficiency of ibuprofen within the beads, the bead swelling and the drug release kinetic were investigated.Results showed that only Ca ion is suitable for the formation of ibuprofen beads. A good swelling profile for beads in phosphate buffer (pH=7.4) and the lack of swelling in hydrochloric acid (pH= 1.2), show the suitable nature of the beads. In addition, formulation of Na-alginate (2%) and Ca-chloride (2%) beads, resulted in an encapsulation efficacy of around 90%. The drug release studies showed a rapid and complete ibuprofen release from the beads, specially those prepared from Na-alginate (2%) and Ca-chloride (2%), in phosphate buffer medium.However, no detectable drug release was observed within the acidic medium. In conclusion, ibuprofen is capable of being n be microencapsulated as a bead formulation, with suitable properties and release profile.

Introduction. Sodium alginate is a natural hydrogel polymer that is used to modulate drug release as adelivery system. The objective of this study was to investigate the effect of processing and structural variables of calcium alginate gel beads, on the swelling characteristics, loading efficiency, and drug release behaviour of this polymer.Methods. The studied variables consisted of polymer and cross-linking agent (CaCI2) concentrations, type of gelling cations, solubility and percentage of loaded drug, curring time of the polymer, pH and particle size of the alginate beads. The beads were then coated with Eudragit S-100 and drug release profiles were chracterized.Results and Discussion. Increasing the sodium alginate and CaCI2 concentration, prolonged the release time of caffeine (the model drug). Release kinetic of low-water-soluble drugs (i.e., theobromine) followed a zero-order kinetic while release of highly-water-soluble drugs was better fitted with a first order kinetic. Among the different cations which caused gelation. Ca2+ showed a better swelling profile. The effect of drug water solubility on the loading efficiency of beads, showed the order of caffeine <theophylline < theobromine. Increasing the curring time of the gels changeg the release kinetic of caffeine from first-order to Higuchi model. Drug loading method in the beads had no effect on the loading efficiency, while it was effective on the release profile of caffeine. Increasing the caffeine concentration in the beads, prolonged the release time of the drug. DSC studies confirmed an ionic interaction between calcium alginate and caffeine in high concentrations which slowed the drug release.

Background and the purpose of the study: Diclofenac sodium is a non-steroidal anti-inflammatory agent with a short biological half-life (1-2 hr) and requires multiple dosing.This research was carried out to develop and optimize diclofenac sodium loaded alginate-PVP K 30 microbeads to eliminate the need for multiple dosing and adverse effects.Methods: Diclofenac sodium loaded alginate-PVP K 30 microbeads were prepared by ionotropic gelation. Particle size, drug release, swelling, FTIR and SEM analyses were performed.Results: Optimized microbeads showed particle size of 0.589±0.054 to 0.620±0.067 mm, and drug entrapment efficiency of 97.88±2.86 to 98.60±3.55%. The in vitro drug release from microbeads was sustained over 10 hrs and followed controlled-release pattern. FTIR analysis indicated the possibility of intermolecular hydrogen bonding interactions, i.e., -OH…O=C in microbeads.Conclusion: Microbeads for oral controlled delivery of diclofenac sodium were successfully developed by ionotropic gelation.

Biocompatible materials, as efficient sorbent, are used for the removal of dyes and heavy metals ions from water and industrial wastewater. In this work, the optimal conditions for the maximum barium uptake in the formation process of Ba-alginate beads (Ba-ALG) were determined using the central composite design (CCD). The operational factors were evaluated for polymer/barium ratios of 1: 3, 1: 2, 1: 1, 2: 1, and 3: 1 and residence times of 20, 30, 75, 120, and 180 minutes. The optimal ratio of sodium alginate to barium concentration for cations uptake was obtained at 3: 1. Ba-ALG could not form a spherical and stable structure at higher polymer/cross-linker ratios. Validation tests illustrated the high accuracy of the selected model to determine the optimal experimental conditions in the barium uptake process. The maximum barium uptake is 88. 61%, which was achieved at XAB =1. 5 (optimal ratio of polymer to Ba+2) and Xt =1. 5 (180 min). The ability of Ba-ALG to adsorb dye was also evaluated. Kinetics, equilibrium, and thermodynamic studies for adsorption of malachite green (MG) by Ba-ALG were statistically described. The adsorption results match the pseudo-second-order kinetics, suggesting that there was MG dye uptake to the adsorbent in monolayers due to its chemical affinity. The thermodynamic parameters were also determined by the Gibbs free energy function, confirming that the adsorption process was spontaneous and accompanied by an endothermic reaction.

A Monte Carlo approach based on kinetic gelation model is used to simulate the kinetics of non-linear free radical copolymerization of vinyl-divinyl monomer mixture or chemical gelation, and to characterize kinetic effects on polymerization statistics and microstructures. New algorithm for random selection of the next neighbour site in a self-avoiding random walk and efficient mechanisms of mobility of components are introduced to improve the universality of the predictions by removing commonly occurring simulation deficiencies due to early trapping of radicals. The model has the capability of predicting the onset of the sol-gel transition, and the effect of chemical composition on the transition point. It is shown that it is attain a better understanding of microstructure evolution and appearance of gel phase during polymerization and chemical gelation. Finally, an important benefit of the simulation method is its ability to characterize the system in which, the dominant combination reaction leads to highly branched structure.

The present work investigated the preparation of biodegradable beads with alginate polymer by ionotropic gelation method to improve the control release properties of the antibiotic rifampicin. Ionotropic gelation method was applied to prepare beads using calcium chloride (CaCl2) as cationic component and alginate as an anionic component. In this method, adding 0.5% w/v polyvinyl alcohol (PVA) to sodium alginate (3.0% w/v) and 2% w/v of polyvinyl pyrrolidone (PVP) to the CaCl2 solution were maintained to study the drug-loading and its released characteristics. The results showed that the addition of PVA and PVP significantly improved drug-loading, encapsulation efficiency and release characteristics. This demonstrates that the ionic gelation of alginate molecules offers a flexible and easily controllable process.

The purpose of the present study was to develop glipizide controlled release nanoparticles using alginate and chitosan thorough ionotropic controlled gelation method. Glipizide is a frequently prescribed second generation sulfonylurea which lowers the blood glucose in type-two diabetics. Quick absorption of the drug from the gastrointestinal tract along with short half- life of elimination makes it a good candidate for controlled release formulations. Alginate-chitosan nanoparticles (ACNP) are convenient controlled delivery systems for glipizide, due to both the release limiting properties of the system, and the bioadhesive nature of the polymers. In the present study, glipizide loaded alginate-chitosan nanoparticles (GlACNP) were prepared, and the particle characteristics including particle size (PS), zeta potential (ZP), entrapment efficiency (EE%), loading percent (LP), and mean release time (MRT), as well as the morphology of the nanoparticles, the drug-excipient compatibility, and the release kinetics along with the drug diffusion mechanism were evaluated. The results suggested that ionotropic controlled gelation method offers the possibility of preparing the nanoparticles in mild conditions in an aqueous environment, and can lead to the preparation of particles with favorable size, controlled release characteristics, and high entrapment efficiency, serving as a convenient delivery system for glipizide. The particle and release characteristics can be efficiently optimized using the Box-Behnken design. Based on the findings of the present study, it is expected that this novel formulation be a superior therapeutic alternative to the currently available glipizide delivery systems.