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Background: Hydroxyapatite (HAp) is a biocompatible bioceramic compound by nature and widely utilized in a broad range of biomedical applications, especially in drug delivery, tissue engineering, orthopedics, dentistry, etc. To intensify its usage, HAp is being reinforced with different biopolymer(s). In these bioceramicbiopolymeric systems, HAp crystallites have been well inviolate with the alginate molecules. The objective of this review article is to present a comprehensive discussion of different recently researched drug-releasing potential by HAp-alginate based matrices., Methods: During past few years, HAp particles (both synthesized and naturally derived) have been reinforced within different alginate-based systems to load a variety of drug candidates. Most of the reported drug-releasing HAp-alginate based matrices were prepared by the methodology of ionic-gelation of sodium alginate followed by air-drying/spray drying process., Results: HAp-alginate systems have already been proved as useful for loading a variety of drugs and also resulting sustained drug delivery with minimizing the drawbacks of pure alginate matrices (such as burst drug-releasing and low mechanical property in the alkaline pH)., Conclusion: HAp-alginate composites loaded with different kinds of drugs have already been reported to exhibit sustained releasing of loaded drugs over a longer period., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Alginate-based bipolymeric-nanobioceramic composite matrices for sustained drug release were developed through incorporation of nano-hydroxyapatite [nHAp] powders within ionotropically-gelled calcium ion-induced alginate-poly (vinyl pyrrolidone) blends polymeric systems. nHAp powders were synthesized by precipitation technique using calcium hydroxide [Ca(OH)2] and orthophosphoric acid [H3PO4] as raw materials. The average particle size of these was synthesized. nHAp powders was found as 19.04 nm and used to prepare nHAp-alginate-PVP beads containing DS. These beads exhibited drug entrapment efficiency (%) of 65.82±1.88 to 94.45±3.72% and average bead sizes of 0.98±0.07 to 1.23±0.15 mm. These beads were characterized by scanning electron microscopy (SEM) and Fourier transform-infra red (FTIR) spectroscopy analyses. Various nHAp-alginate-PVP beads containing DS exhibited prolonged sustained drug release and followed the Koresmeyer-Peppas model of drug release (R2=0.9908-0.9978) with non-Fickian release (anomalous transport) mechanism (n=0.73-0.84) for drug release over 8 h., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The paper describes the preparation, characterization, in vitro swelling and in vitro drug release of metformin HCl-loaded tamarind seed polysaccharide (TSP)-alginate beads were prepared by ionotropic-gelation technique and using CaCl2 as cross-linker. The prepared beads exhibited 32.73 ± 1.41% of drug loading (%), 94.86 ± 3.92% of drug encapsulation efficiency (%), and 1.24 ± 0.07 mm of average bead size. The bead surface morphology was analyzed by SEM. The drug-polymer interaction in the bead matrix was analyzed by FTIR analyses. These metformin HCl-loaded ionotropically gelled TSP-alginate beads demonstrated sustained in vitro drug release profile over 10h. These in vitro drug release exhibited pH-dependent drug release behavior. The in vitro drug release from these metformin HCl-loaded beads followed controlled-release (zero-order) pattern with super case-II transport mechanism. The swelling and degradation of these metformin HCl-loaded polymeric beads were found to be influenced by the pH of test mediums., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Zinc (Zn(2+))-ion induced diclofenac sodium (DS)-loaded alginate-okra (Hibiscus esculentus) gum (OG) blend beads was successfully formulated through Zn(2+)-ion induced ionic-gelation cross-linking method in a complete aqueous environment. Effects of polymer-blend ratio and cross-linker concentration on drug encapsulation efficiency (DEE) and cumulative drug release at 8 h (R8h) were optimized by 3(2)-factorial design. The optimized formulation of Zn(2+)-ion induced DS-loaded alginate-OG beads demonstrated 89.27±3.58% of DEE and 43.73±2.83% of R8h. The bead sizes were within 1.10±0.07 to 1.38±0.14 mm. The bead surface morphology was analyzed by SEM. The drug-polymer interaction in the optimized bead matrix was analyzed by FTIR and P-XRD. These beads exhibited sustained in vitro drug release over a prolonged period of 8h and followed controlled-release (zero-order) pattern with super case-II transport mechanism. The swelling and degradation of the optimized beads was influenced by the pH of test mediums, which might be suitable for intestinal drug delivery., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Novel floating-mucoadhesive oil-entrapped alginate beads coated with crossslinked alginate-sterculia gum gel membrane was developed for gastroretentive risperidone delivery. Oil-entrapped alginate beads containing risperidone as core were prepared by ionotropic gelation technique. Effects of polymer to drug ratio and oil to water ratio on drug entrapment efficiency (%) and cumulative drug release after 8h (%) were studied to optimize the core beads by a 3(2) factorial design. The optimized beads (F-O) demonstrated drug entrapment efficiency of 83.73±0.81% and cumulative drug release of 70.84±0.27% after 8h. The biopolymeric-coated optimized beads exhibited excellent buoyancy, better ex vivo mucoadhesion and slower drug release rate. The drug release profiles of risperidone-loaded uncoated and coated beads were best fitted in Korsmeyer-Peppas model with Fickian diffusion mechanism. The beads were also examined for the drug-excipients compatibility, drug crystallinity and surface morphology by FTIR, P-XRD and SEM analyses, respectively., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

A novel hydrogel system was successfully developed based on core-shell approach for the delivery of ranitidine HCl and aceclofenac. Aceclofenac-loaded alginate microspheres coated with eudragit L-100 was used as core material and that of freeze-thaw cross-linked chitosan-PVA gels containing ranitidine HCl served as the shell-forming material. The alginate microspheres coated with eudragit L-100 showed drug encapsulation efficiency of 56.06±1.12 to 68.03±2.16% and had average particle sizes of 551.29±25.92 to 677.18±27.05 μm. The viscosity of chitosan-PVA gels ranged between 505.74±1.04 and 582.41±2.09 cps. The formulations were characterized by FTIR, SEM and polarized microscopy analyses. The release of ranitidine HCl was comparatively higher in acidic medium (pH 1.2) than in alkaline medium (pH 7.4). The release of aceclofenac became slower in alkaline medium (pH 7.4) and continued up to 3.5 h. Super case-II transport mechanism was assumed for the release of ranitidine HCl in both media; whereas non-Fickian (anomalous) diffusion mechanism predominated in the release of aceclofenc. Thus, hydrogel-based core-shell formulations were found suitable for simultaneous delivery of aceclofenac and ranitidine HCl which could minimize the chances of excessive gastric acid secretion through suitable ranitidine HCl release in gastric region., (Copyright © 2014. Published by Elsevier B.V.)

A novel alginate gel-coated oil-entrapped calcium-alginate-tamarind gum (TG)-magnesium stearate (MS) composite floating beads was developed for intragastric risperidone delivery with a view to improving its oral bioavailability. The TG-blended alginate core beads containing olive oil and MS as low-density materials were accomplished by ionotropic gelation technique. Effects of polymer-blend ratio (sodium alginate:TG) and crosslinker (CaCl2) concentration on drug entrapment efficiency (DEE, %) and cumulative drug release after 8 h (Q8h, %) were studied to optimize the core beads by a 3(2) factorial design. The optimized beads (F-O) exhibited DEE of 75.19±0.75% and Q8h of 78.04±0.38% with minimum errors in prediction. The alginate gel-coated optimized beads displayed superior buoyancy and sustained drug release property. The drug release profiles of the drug-loaded uncoated and coated beads were best fitted in Higuchi kinetic model with Fickian and anomalous diffusion driven mechanisms, respectively. The optimized beads yielded a notable sustained drug release profile as compared to marketed immediate release preparation. The uncoated and coated Ca-alginate-TG-MS beads were also characterized by SEM, FTIR and P-XRD analyses. Thus, the newly developed alginate-gel coated oil-entrapped alginate-TG-MS composite beads are suitable for intragastric delivery of risperidone over a prolonged period of time., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The utility of isolated okra (Hibiscus esculentus) gum (OG) was evaluated as a potential sustained drug release polymer-blends with sodium alginate in the development of controlled glibenclamide release ionically-gelled beads for oral use. OG was isolated from okra fruits and its solubility, pH, viscosity and moisture content were studied. Glibenclamide-loaded OG-alginate blend beads were prepared using CaCl2 as cross-linking agent through ionic-gelation technique. These ionically gelled beads showed drug entrapment efficiency of 64.19 ± 2.02 to 91.86 ± 3.24%. The bead sizes were within 1.12 ± 0.11 to 1.28 ± 0.15 mm. These glibenclamide-loaded OG-alginate blend beads exhibited sustained in vitro drug release over a prolonged period of 8 h. The in vitro drug release from these OG-alginate beads were followed controlled-release (zero-order) pattern with super case-II transport mechanism. The beads were also characterized by SEM and FTIR. The swelling and degradation of these beads was influenced by the pH of the test medium. These beads also exhibited good mucoadhesivity with goat intestinal mucosa.

Isoxsuprine HCl-loaded microbeads using sodium alginate (SA)-carboxymethyl cashew gum (CMCG) polymer-blends were developed through ionotropic-gelation technique using ZnSO4 as cross-linker. Effects of polymer-blend ratio and cross-linker concentration on drug encapsulation efficiency (DEE) and cumulative drug release at 7 h (R7 h) were optimized by 3(2) factorial design. Optimized microbeads were of excellent combination of high DEE (79.92±2.51%) and suitable sustained drug release pattern over a prolonged period of 7 h (58.67±2.26%). The microbead surface morphology was analyzed by SEM. The physical state of isoxsuprine HCl within the optimized microbead matrix was analyzed by FTIR and DSC. In vitro isoxsuprine HCl release from alginate-CMCG microbeads in phosphate buffer (pH, 6.8) showed prolonged sustained drug release and Korsmeyer-Peppas model (R2=0.9959-0.9992) over 7 h., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The present study deals with the development and evaluations of stomach-specific floating capsules containing salbutamol sulfate-loaded oil-entrapped alginate-based beads. Salbutamol sulfate-loaded oil-entrapped beads were prepared and capsulated within hard gelatin capsules (size 1). The effects of HPMC K4M and potato starch weight masses on drug encapsulation efficiency (DEE) of beads and cumulative drug release at 10h (R10 h) from capsules was analyzed by 3(2) factorial design. The optimization results indicate increasing of DEE in the oil-entrapped beads and decreasing R10 h from capsules with increment of HPMC K4M and potato starch weight masses. The optimized formulation showed DEE of 70.02 ± 3.16% and R10 h of 56.96 ± 2.92%. These capsules showed floatation over 6h and sustained drug release over 10h in gastric pH (1.2). In vivo X-ray imaging study of optimized floating capsules in rabbits showed stomach-specific gastroretention over a prolonged period., (Copyright © 2013 Elsevier B.V. All rights reserved.)

The present investigation describes development and optimization of pioglitazone-loaded jackfruit seed starch (JFSS)-alginate beads by ionotropic-gelation using 3(2) factorial design. The effect of polymer-blend ratio and CaCl2 concentration on the drug encapsulation efficiency (DEE, %), and cumulative drug release after 10 hours (R10h, %) was optimized. The DEE (%) of these beads were 64.80 ± 1.92 to 94.07 ± 3.82 % with sustained in vitro drug release of 64.± 1.83 to 92.66 ± 4.54 % over 10 hours. The in vitro drug release from these beads followed controlled-release pattern with super case-II transport. Particle size range of these beads was 0.77 ± 0.04 to 1.24 ± 0.09 mm. The beads were also characterized by SEM and FTIR. The swelling of these beads was influenced by pH of the test medium. The optimized pioglitazone-loaded JFSS-alginate beads showed significant hypoglycemic effect in alloxan-induced diabetic rats over prolonged period after oral administration.

The present study deals with the formulation optimization of jackfruit (Artocarpus heterophyllus Lam., family: Moraceae) seed starch (JFSS)-alginate mucoadhesive beads containing metformin HCl through ionotropic gelation using 3(2) factorial design. The effect of sodium alginate to JFSS ratio and CaCl2 concentration on the drug encapsulation efficiency (DEE, %), and cumulative drug release at 10h (R10h, %) was optimized. The optimized beads containing metformin HCl showed DEE of 97.48±3.92%, R10h of 65.70±2.22%, and mean diameter of 1.16±0.11mm. The in vitro drug release from these beads was followed controlled-release (zero-order) pattern with super case-II transport mechanism. The beads were also characterized by SEM and FTIR. The swelling and degradation of these beads were influenced by pH of the test medium. The optimized beads also exhibited good mucoadhesivity and significant hypoglycemic effect in alloxan-induced diabetic rats over prolonged period after oral administration., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Aceclofenac-loaded alginate/gellan gum microspheres for prolonged aceclofenac release were prepared through maleic anhydride-induced unsaturated esterification. The drug entrapment efficiency of these microspheres was found 39.30 ± 1.28% to 98.46 ± 0.40% and their average particle sizes were 270-490 μm. These microspheres were characterized by FTIR, DSC, P-XRD and SEM analysis. The in vitro dissolution indicated prolonged sustained release of aceclofenac over 6h, which also followed the Korsmeyer-Peppas model (R(2)=0.9571-0.9952). The microspheres prepared through 3% (w/v) maleic anhydride-induced esterification exhibited comparatively slower drug-release. Most of the microspheres were followed Fickian diffusion mechanism except the microspheres containing higher gellan gum content, which followed anomalous (non-Fickian) diffusion. The in vivo results showed sustained systemic absorption of aceclofenac in rabbits and excellent anti-inflammatory activity in carrageenan-induced rats after oral administration over prolonged period., (Copyright © 2013 Elsevier B.V. All rights reserved.)

The current investigation deals with the development and optimization of oil-entrapped sterculia gum-alginate buoyant beads containing aceclofenac by ionotropic emulsion-gelation technique using 3(2) factorial design. The effect of polymer to drug ratio and sodium alginate to sterculia gum ratio on the drug entrapment efficiency (%), and cumulative drug release after 7 h (%) was optimized. The optimized oil-entrapped sterculia gum-alginate buoyant beads containing aceclofenac (F-O) showed drug entrapment efficiency of 90.92±2.34%, cumulative drug release of 41.65±3.97% after 7 h in simulated gastric fluid (pH 1.2), and well buoyancy over 8 h in simulated gastric fluid (pH 1.2) with 5.20 min buoyant lag-time. The in vitro drug release from these buoyant beads followed Korsmeyer-Peppas model (R(2)=0.9866-0.9995) with anomalous (non-Fickian) diffusion drug release mechanism. These new sterculia gum-alginate buoyant beads containing aceclofenac were also characterized using SEM, FTIR, and P-XRD analysis., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The work investigates the development and optimization of fenugreek (Trigonella foenum-graecum L.) seed mucilage (FSM)-alginate mucoadhesive beads containing metformin HCl through ionotropic gelation using 3(2) factorial design. The effect of polymer-blend ratio (sodium alginate to FSM) and cross-linker (CaCl(2)) concentration on the drug encapsulation efficiency (DEE, %), and cumulative drug release after 10h (R(10h), %) was optimized. The DEE (%) of all these beads was within the range of 71.63 ± 2.32 to 95.08 ± 3.73% with sustained in vitro drug release of 69.78 ± 2.43% to 95.70 ± 4.26% over 10h. The in vitro drug release from these beads was followed controlled-release (zero-order) pattern (R(2)=0.9910 to 0.9953) with super case-II transport mechanism. The average size of these beads was within the range of 0.92 ± 0.05 to 1.30 ± 0.14 mm. The beads were also characterized by SEM, FTIR and (1)H NMR. The swelling and degradation of FSM-alginate beads containing metformin HCl were influenced by pH of the test medium. These beads also exhibited good mucoadhesivity in wash-off test. The optimized FSM-alginate mucoadhesive beads containing metformin HCl showed significant hypoglycemic effect in alloxan-induced diabetic rats over prolonged period after oral administration., (Copyright © 2012 Elsevier B.V. All rights reserved.)

This work investigates the development, optimization and in vitro characterization of calcium alginate/gum Arabic beads by an ionotropic gelation method for prolonged sustained release of glibenclamide. The effects of amount of sodium alginate and gum Arabic as independent process variables on the drug encapsulation efficiency and drug release were optimized and analyzed based on central composite design and response surface methodology. Increment in drug encapsulation efficiency and decrease in drug release were found with the increase of both the amounts of sodium alginate and gum Arabic, used as polymer-blend. These optimized beads showed high drug encapsulation efficiency (86.02±2.97%), and suitable sustained drug release pattern over prolonged period (cumulative drug release after 7 h of 35.68±1.38%). The average size of these formulated dried beads containing glibenclamide ranged from 1.15±0.11 to 1.55±0.19 mm. The in vitro dissolution of these beads showed prolonged sustained release of glibenclamide over 7 h, which followed first-order model (R(2)=0.9886-0.9985) with anomalous (non-Fickian) diffusion mechanism (release exponent, n=0.72-0.81). The swelling and degradation of the optimized beads were influenced by pH of test mediums. These beads were also characterized by SEM and FTIR spectroscopy for surface morphology and excipients-drug interaction analysis, respectively. These developed calcium alginate/gum Arabic beads containing glibenclamide could possibly be advantageous in terms of advanced patient compliance with reduced dosing interval., (Copyright © 2012 Elsevier B.V. All rights reserved.)

This work investigates the development, optimization and in vitro evaluation of liquid paraffin-entrapped multiple-unit alginate-based floating system containing cloxacillin by emulsion-gelation method for gastro retentive delivery. The effect of process variables like drug to polymer ratio by weight, and liquid paraffin to water ratio by volume on various physicochemical properties in case of liquid paraffin-entrapped calcium alginate beads containing cloxacillin applicable to drug entrapment efficiency, density and drug release was optimized using 3(2) factorial design and analyzed using response surface methodology. The observed (actual values) responses were coincided well with the predicted values, given by the optimization technique. The optimized beads showed drug entrapment efficiency of 64.63±0.78%, density of 0.90±0.05 g/cm(3), and drug release of 56.72±0.85% in simulated gastric fluid (pH 1.2) after 8h with floating lag time of 8.45 min and floated well over 12h in simulated gastric fluid (pH 1.2). The average size of all dried beads ranged from 1.73±0.04 to 1.97±0.08 mm. The beads were characterized by SEM and FTIR for surface morphology and excipients-drug interaction analysis, respectively. All these beads showed prolonged sustained release of cloxacillin over 8h in simulated gastric fluid (pH 1.2). The cloxacillin release profile from liquid paraffin beads followed Korsmeyer-Peppas model over a period of 8h with anomalous (non-Fickian) diffusion mechanism for drug release., (Copyright © 2011 Elsevier B.V. All rights reserved.)

The purpose of this work was to develop and optimize gliclazide-loaded alginate-methyl cellulose mucoadhesive microcapsules by ionotropic gelation using central composite design. The effect of formulation parameters like polymer blend ratio and cross-linker (CaCl(2)) concentration on properties of gliclazide-loaded alginate-methyl cellulose microcapsules like drug encapsulation efficiency and drug release were optimized. The optimized microcapsules were subjected to swelling, mucoadhesive, and in vivo studies. The observed responses coincided well with the predicted values from the optimization technique. The optimized microcapsules showed high drug encapsulation efficiency (83.57 ± 2.59% to 85.52 ± 3.07%) with low T(50%) (time for 50% drug release, 5.68 ± 0.09 to 5.83 ± 0.11 h). The in vitro drug release pattern from optimized microcapsules was found to be controlled-release pattern (zero order) with case II transport release mechanism. Particle sizes of these optimized microcapsules were 0.767 ± 0.085 to 0.937 ± 0.086 mm. These microcapsules also exhibited good mucoadhesive properties. The in vivo studies on alloxan-induced diabetic rats indicated the significant hypoglycemic effect that was observed 12 h after oral administration of optimized mucoadhesive microcapsules. The developed and optimized alginate-methyl cellulose microcapsules are suitable for prolonged systemic absorption of gliclazide to maintain lower blood glucose level and improved patient compliance.

The present study deals with the development of novel pH-sensitive tamarind seed polysaccharide (TSP)-alginate composite beads for controlled diclofenac sodium delivery using response surface methodology by full 3(2) factorial design. The effect of polymer-blend ratio (sodium alginate:TSP) and cross-linker (CaCl(2)) concentration on the drug encapsulation efficiency (DEE, %) and drug release from diclofenac sodium loaded TSP-alginate composite beads prepared by ionotropic gelation was optimized. The observed responses were coincided well with the predicted values by the experimental design. The DEE (%) of these beads containing diclofenac sodium was within the range between 72.23±2.14 and 97.32±4.03% with sustained in vitro drug release (69.08±2.36-96.07±3.54% in 10 h). The in vitro drug release from TSP-alginate composite beads containing diclofenac sodium was followed by controlled-release pattern (zero-order kinetics) with case-II transport mechanism. Particle size range of these beads was 0.71±0.03-1.33±0.04 mm. The swelling and degradation of the developed beads were influenced by different pH of the test medium. The FTIR and NMR analyses confirmed the compatibility of the diclofenac sodium with TSP and sodium alginate used to prepare the diclofenac sodium loaded TSP-alginate composite beads. The newly developed TSP-alginate composite beads are suitable for controlled delivery of diclofenac sodium for prolonged period., (Copyright © 2011 Elsevier B.V. All rights reserved.)