| PEC hydrogels |
Chitosan and XG/Opadry |
• Incorporation of metronidazole into pre-formed hydrogels in significant amount is possible by diffusion technique |
131
|
| • Hydrogels swell less in simulated gastric medium |
| • Enteric coating allowed 50% drug for release in colonic pH |
| PEC hydrogels |
N-Trimehtyl chitosan (TMC)/carboxymethyl xanthan gum (CMXG) |
• Encapsulation efficiency of ciprofloxacin reached to about 93.8% at higher drug load |
132
|
| • Drug-loaded hydrogel was highly effective against the Gram positive and Gram negative bacterial strains |
| • Highest diameter of inhibition zone against Escherichia coli as compared to gentamicin |
| • Highest cell viability (97%) in lung human normal cell lines was noted at concentration up to 50 μg mL−1
|
| Ionic and polyelectrolyte complexation |
Polyethyleneimine (PEI)/CMXG/AlCl3
|
• Increasing PEI (0.5–2%) and exposure time (5–30 min) decreased drug entrapment efficiency from 96.50 to 77.50% and from 92.25 to 70.37%, respectively |
133
|
| • PEI treatment reduced swelling of the beads |
| • Depending on formulation variables, 40% and 80% drug released in 2 h in pH 1.2 and in 5–6 h in pH 6.8, respectively |
| • PEI treated diltiazem–resin complex beads released the drug following non-Fickian transport mechanism |
| • Bioavailability was 1.59 times higher with PEI-treated formulation than pure drug solution in rabbit model |
| • Data showed good in vitro–in vivo (IVIVC) correlation |
| Magnetically responsive polyelectrolyte complex hydro-gels |
XG and chitosan in the presence of iron oxide magnetic nanoparticles (MNPs) using d-(+)-glucuronic acid δ-lactone as a green acidifying agent |
• Incorporation of Fe3O4 MNPs (8 nm size) into complex hydrogels induced porosity and greatly improved mechanical properties and storage modulus |
134
|
| • Magnetically responsive hydrogels improved NIH3T3 fibroblasts cell proliferation and adhesion in an external magnetic field relative to pristine hydrogels without MNPs in vitro
|
| • Suitable for use as a magnetically stimulated system in tissue engineering applications |
| Tablets |
Polyethylene glycol/XG/chitosan |
• Drug release profiles of tested metronidazole tablets and commercial ER formulation were similar in 0.1 M HCl and phosphate buffer pH 6.8 |
135
|
| • Bioadhesion of tested tablets was three times higher than commercial tablets to sheep duodenum |
| • Absorption of metronidazole from test product was faster than that of commercial product with a maximum plasma level attained at 4.37 and 6.14 h, respectively |
| Interenetrating network (IPN) hydrogel beads |
CMXG and carboxymethyl cellulose/AlCl3
|
• Methacrylic acid-based ion exchange resins (IER) were synthesized using ethylene glycol dimethacrylate, N,N′-methylene bis acrylamide, and divinyl benzene coded as ME, MB and MD respectively |
136
|
| • IER : ofloxacin ratio of 1 : 2 provided highest drug loading ∼98% MD and MB; however, the same was ∼85% for ME |
| • Taste masking studies at salivary pH 6.8 showed that MD : ofloxacin (1 : 4) showed lowest (1.22%) release of drug for a contact time of 30 s than others |
| • Presence of bulky divinylbenzene imparted steric hindrance for the exchange of phosphate groups with the amine groups present in drug at salivary pH, ultimately resulting in slow release of the drug |
| • CMXG beads containing MD : ofloxacin (1 : 4) (636 μm) had highest drug entrapment efficiency of 91.90% following treatment with 2% AlCl3
|
| • MD : ofloxacin (1 : 4)-carboxymethyl XG/carboxymethyl cellulose IPN beads (1122 μm) had 90.23% drug entrapment efficiency |
| • Compared to gastric pH, drug release from MD : ofloxacin (1 : 4)-carboxymethyl XG beads and carboxymethyl XG/carboxymethyl cellulose IPN beads at intestinal pH 7.4 became prolonged and extended up to 10 h |
| IPN hydrogel beads |
Casein and CMXG/aluminium chloride/glutaraldehyde |
• Glutaraldehyde treatment prohibited extent of degradation of hydrogels in pH 7.4 phosphate buffer containing 0.2% lysozyme |
137
|
| • Theophylline release was slower in pH 1.2 buffer solution than in pH 6.8 buffer |
| • Increasing carboxymethyl XG : casein ratio decreased the extent of drug release marginally both in acidic media and alkaline media in 2 h |
| • Higher carboxymethyl XG : casein ratio and drug loading improved drug entrapment efficiency from 28.6 to 53.81% and from 53.81% to 83.59%, respectively |
| • Increase in glutaraldehyde concentration caused lowering of drug entrapment efficiency from 83.01 to 40.03% upon 15 min exposure. Reduction of exposure time to 5 min increased DEE to 85.12% |
| • Theophylline transformed into amorphous state after entrapment |
| • Shifting of pH of dissolution medium from 1.2 to 6.8 caused significant swelling of beads |
| • Increase in AlCl3 concentration (2–8%) increased swelling of beads by 10.26% and 11.62% in pH 1.2 buffer and pH 6.8 buffer solutions, respectively |
| IPN hydrogel beads |
Pectin/CMXG/Al3+ ions and covalent cross-linking with glutaraldehyde |
• Both swelling and drug release were relatively low in pacidic medium than in pH 6.8 buffer |
138
|
| • In vitro delivery of diltiazem was dependent upon the extent of cross-linking and amount of drug used in the IPN hydrogel beads |
| IPN hydrogel beads |
CMXG and sodium alginate/AlCl3
|
• Cmax was significantly less and Tmax (2.91 ± 0.5) was relatively higher from the drug loaded IPN beads than those from the control and reference in rabbit model |
139
|
| • Relative bioavailability of test formulation was 109.02% and 112.79% compared to control and reference, respectively |
| Compression coated tablets |
CMXG and sodium alginate/CaCl2
|
• Compression-coated tablets of Ca2+ ion crosslinked CMXG and sodium alginate could deliver prednisolone without the need of colonic bacterial intervention for degradation of the polysaccharide coat |
140
|
| • Blend of CMXG and alginate (1.5 : 3.5) provided Tlag of 5.12 h and Trap (time required for immediate release following Tlag) of 6.50 h |
| Hydrogel beads |
CMXG/AlCl3/glutaraldehyde |
• Diltiazem–cation exchange resin was loaded into carboxymethyl XG hydrogel beads |
141
|
| • Sequential cross-linking involving glutaraldehyde treatment of ionically preformed hydrogel beads produced smaller beads with higher drug entrapment efficacy (86.52%) and prolonged release characteristics than ionic cross-linking, and simultaneous ionic/covalent cross-linking |
| • Swelling of the beads was higher in acid solution of pH 1.2 than in buffer solution of pH 6.8 |
| • Burst release (∼50%) in acid solution, followed by extended release up to about 7 h |
| Tablets |
CMXG/CaCl2
|
• Increase in degree of calcium co-ordination/cross-linking reduced swelling of Ca–CMXG matrix tablets compared with carboxymethyl XG matrix |
142
|
| • Erosion of Ca–CMXG matrices was higher than CMXG matrix |
| • Release of prednisolone from Ca–CMXG matrices containing upto 33.33% (w/w) CaCl2 was less than that from CMXG matrix |
| • Release of drug from the matrix containing 50% (w/w) of CaCl2 was rapid and approached almost to that from CMXG matrix |
| IPN beads |
Carboxymethyl cellulose and CMXG/AlCl3
|
• Higher extent of cross-linking led to decreased particle size from 1080 to 1420 μm |
143
|
| • Variation in cellulose to gum ratio from 1 : 1 to 2 : 1 dropped drug encapsulation efficiency of IPN beads from 96.96 to 77.45% |
| • Drug entrapment efficiency of the beads decreased at higher salt strength |
| • Increase in salt strength from 4 to 8% slowed drug release rate in acidic and alkaline media |
| • Drug release continued up to 8 h in pH 7.4, indicating better intestinal drug release |
| Homopolymeric and IPN beads |
CMXG and sodium alginate/AlCl3
|
• Entire ibuprofen can be loaded into the beads with a maximum coefficient variation of 1.87% |
144
|
| • IPN hydrogel beads provided more sustained release of ibuprofen than homopolymeric beads |
| • Rapid drug release from Al–CMXG beads, accounting 42.5% release in 2 h |
| • Incorporation of higher amounts of alginate in IPN beads decreased drug release |
| • Release of drug from Al–alginate beads was the lowest, releasing 25.4% drug in 2 h in acidic medium |
| • Release of drug was the fastest from Al–CMXG in same duration |
| • Drug release from Al–alginate beads was faster than those from the IPN beads in pH 6.8 phosphate buffer |
| IPN beads |
CMXG and sodium alginate/aluminium chloride |
• Ulcerogenicity decreased significantly with ibuprofen-loaded IPN beads in comparison to the pure drug in adult male albino Wistar rats |
145
|
| Microparticles |
CMXG/aluminium chloride |
• CMXG or alginate-coated Al–CMXG microparticles were prepared |
146
|
| • Higher salt concentration decreased BSA entrapment efficiency of the uncoated microparticles from 86–61% |
| • BSA entrapment in coated microparticles was found lower (78–79%) than uncoated microparticles |
| • Uncoated microparticles released almost half of its content in NaCl–HCl buffer solution (pH 1.2) in 2 h |
| • Alginate and xanthan coated microparticles did not liberate a substantial amount of entrapped protein in acidic medium, rather prolonged protein release in PBS solution (pH 7.4) up to 10 and 12 h, respectively |
| • Sodium dodecyl sulfate–polyacrylamide gel electrophoresis indicated retention of protein integrity in the microparticles |
| Microparticles |
CMXG/aluminium chloride |
• Variation in pH of carboxymethyl XG solution did not affect protein entrapment and release significantly |
147
|
| • Increase in initial protein loading tended to increase protein release in buffer solution of pH 1.2 and in PBS solution (pH 7.4) |
| • Higher polymer concentration suppressed protein release substantially in both acidic and alkaline media |
| • Maximum 86.39% protein entrapment efficiency was noted |
| Hydrogel beads |
CMXG/aluminium chloride |
• Diltiazem–resin complex was loaded into CMXG beads |
148
|
| • Higher gelation period (5–20 min) and AlCl3 concentration (1–3%) decreased drug entrapment efficiency from 95 to 79% and 88.5 to 84.6%, respectively |
| • Gum concentration up to 2.5% improved drug entrapment efficiency to 90.7% |
| • Higher swelling was accounted for faster drug release in simulated gastric fluid than in intestinal fluid |
| Hydrogel beads |
CMXG/aluminium chloride |
• Viscosity of CMXG was always lower than that of XG |
149
|
| • Formation of discrete and spherical BSA-loaded microparticles were dependent on microenvironmental pH |
| • BSA entrapment efficiency was 82% |
| • Higher swelling contributed faster protein release in acidic medium than that in alkaline medium |
| • pH of the gum solution influenced the swelling and protein release considerably |
| Nanoparticles |
XG/sorbitan monooleate/oleylamine |
• XG-functionalised sorbitan monooleate/oleylamine nanoparticles had average diameter of 146.8 nm and high surface charge (−48 mV) |
150
|
| • Core–shell morphology of enhanced green fluorescent protein plasmid (pEGFP) loaded nanoparticles was evident |
| • Cytotoxicity and transfection capacity of nanoparticles were excellent in human umbilical vein endothelial cells (HUVECs) |
| • Pre-clinical study confirmed the potential of XG-functionalized span nanoparticles for gene targeting to endothelial cells |
| • Xanthan shell protected associated DNA from DNase degradation, a prerequisite for intact delivery of bioactives to its site of action |
| Layered Fe–XG hydrogels |
XG/FeCl3
|
• Fe3+-coordination enabled XG to form hydrogels under ambient temperature |
151
|
| • Fe–XG hydrogel exhibited a regular laminated structure under scanning electron microscope |
| • XG hydrogels possessed uniform layered structure, enhanced mechanical strength and excellent swelling behavior |
| • Sol–gel conversion of XG-based hydrogel could be realized by UV light in the presence of sodium lactate |
| • Sol–gel conversion ability of Fe–XG hydrogel could provide data for using as sensor to detect oxidizing or reducing agents, as an actuator under UV light with enough sodium lactate, or for the drug release in the future study |
| Floating hydrogel beads |
Chitosan/XG |
• Variation in chitosan to XG ratio did not affect glipizide release behaviors of the beads in phosphate buffer pH 7.4 up to 24 h |
152
|
| • Drug entrapment efficiency was 80–95% |
| • Beads possessed comparable buoyancy in gastric fluids and satisfactory bioadhesive strength |
| • Swelling kinetics differed significantly in pH 1.2 and 7.4 buffer |
| Hydrogel beads |
CMXG/carboxymethyl cellulose/AlCl3
|
• Beads released considerably less amount of aceclofenac in acid solution (maximum 14.2%) and provided controlled release in phosphate buffer solution (pH 6.8) |
153
|
| • Aceclofenac was compatible with the matrix |
| • Morphology, size and drug entrapment efficiency of beads, and in vitro drug release was affected by viscosity of polymer dispersion, initial drug load, and concentration of total polymer and AlCl3
|
