Preparation and characterization of a novel pH-sensitive chitosan-g-poly (acrylic acid)/attapulgite/sodium alginate composite hydrogel bead for controlled release of diclofenac sodium

Wang, Qin; Zhang, Junping; Wang, Aiqin

doi:10.1016/j.carbpol.2009.06.010

Cited by 261 publications

(83 citation statements)

References 27 publications

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“…If n>0.85, swelling-controlled drug release occurs. The intermediary values of n ranging between 0.43 and 0.85 are indicative of both diffusion and swelling-controlled drug release i.e., anomalous-type release (30). The estimated values of n along with correlation coefficient, r, for all the formulations presented in Table II vary between 0.44 and 0.58 for formulations whose release study was performed in pH1.2 release media at 37°C.…”

Section: Release Kineticsmentioning

confidence: 95%

Novel pH- and Temperature-Responsive Blend Hydrogel Microspheres of Sodium Alginate and PNIPAAm-g-GG for Controlled Release of Isoniazid

2012

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Abstract. This paper reports the preparation and characterization of novel pH-and thermo-responsive blend hydrogel microspheres of sodium alginate (NaAlg) and poly(N-isopropylacrylamide)(PNIPAAm)-grafted-guar gum (GG) i.e., PNIPAAm-g-GG by emulsion cross-linking method using glutaraldehyde (GA) as a cross-linker. Isoniazid (INZ) was chosen as the model antituberculosis drug to achieve encapsulation up to 62%. INZ has a plasma half-life of 1.5 h, whose release was extended up to 12 h. Fourier transform infrared spectroscopy was used to confirm the grafting reaction and chemical stability of INZ during the encapsulation. Differential scanning calorimetry was used to investigate the drug's physical state, while powder X-ray diffraction confirmed the molecular level dispersion of INZ in the matrix. Scanning electron microscopy confirmed varying surface morphologies of the drug-loaded microspheres. Temperature-and pH-responsive nature of the blend hydrogel microspheres were investigated by equilibrium swelling, and in vitro release experiments were performed in pH1.2 and pH7.4 buffer media at 37°C as well as at 25°C. Kinetics of INZ release was analyzed by Ritger-Peppas empirical equation to compute the diffusional exponent parameter (n), whose value ranged between 0.27 and 0.58, indicating the release of INZ follows a diffusion swelling controlled release mechanism.

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Section: Release Kineticsmentioning

confidence: 95%

Novel pH- and Temperature-Responsive Blend Hydrogel Microspheres of Sodium Alginate and PNIPAAm-g-GG for Controlled Release of Isoniazid

2012

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“…[13,[78][79][80][81][82][83][84][85][86][87] Chitosan derivative may be added directly to alginate before crosslinking by calcium chloride via ionotropic gelation method, or as coat added to alginate or alginate-chitosan derivative formulation.…”

Section: Oral Drug Deliverymentioning

confidence: 99%

“…[1] The alginate shrinks at low pH values following reduced electrostatic repulsion between the carboxylate moieties of alginate chains as a result of protonation in the acidic milieu. [1,86,94] This transcribes to a reduction in pore size of matrix thereby rendering a low propensity of drug release. [1] In a higher-pH medium simulating the intestinal fluid, the alginic acid ionizes and converts into a soluble viscous layer.…”

Section: B-cyclodextrinmentioning

confidence: 99%

“…The rise in drug release is also ascribed to loss of calcium alginate crosslinkages through reaction of Ca 2+ with PO4 3-and are removed by precipitation as Ca3(PO4)2. [86,94] An abrupt drug release, following the transit of dosage form from the gastric to the intestinal milieu, can result in drug degradation under the influence of proteolytic enzymes. [1] The inability of the dosage form to sustain drug release may negate drug bioavailability and its elements of colon-specific delivery.…”

Section: B-cyclodextrinmentioning

confidence: 99%

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Alginate graft copolymers and alginate–co-excipient physical mixture in oral drug delivery

Wong

2011

Journal of Pharmacy and Pharmacology

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Objectives Use of alginate graft copolymers in oral drug delivery reduces dosage form manufacture complexity with reference to mixing or coating processes. It is deemed to give constant or approximately steady weight ratio of alginate to covalently attached co-excipient in copolymers, thereby leading to controllable matrix processing and drug release. This review describes various grafting approaches and their outcome on oral drug release behaviour of alginate graft copolymeric matrices. It examines drug release modulation mechanism of alginate graft copolymers against that of co-excipients in non-grafted formulations. Key findings Drug release from alginate matrices can be modulated through using either co-excipients or graft copolymers via changing their swelling, erosion, hydrophobicity/ hydrophilicity, porosity and/or drug adsorption capacity. However, it is not known if the drug delivery performance of formulations prepared using alginate graft copolymers is superior to those incorporating graft-equivalent co-excipient physically in a dosage form without grafting but at the corresponding graft weight, owing to limited studies being available. Conclusions The value of alginate graft copolymers as the potential alternative to alginate-co-excipient physical mixture in oral drug delivery cannot be entirely defined by past and present research. Such an issue is complicated by the lack of green chemistry graft copolymer synthesis approach, high grafting process cost, complications and hazards, and the formed graft copolymers having unknown toxicity. Future research will need to address these matters to achieve a widespread commercialization and industrial application of alginate graft copolymers in oral drug delivery

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“…Furthermore, they should also be biocompatible or biodegradable. Recent approaches suggested the use of drug delivery vehicles which are non-toxic natural or synthetic polymers that will be eliminated harmlessly from the body (2). Oxycellulose (OC) (Fig.…”

Section: Introductionmentioning

confidence: 99%

Oxycellulose Beads with Drug Exhibiting pH-Dependent Solubility

Bajerová

Krejčová²,

Rabišková

et al. 2011

AAPS PharmSciTech

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Abstract. The aim of this study was to develop novel hydrogel-based beads and characterize their potential to deliver and release a drug exhibiting pH-dependent solubility into distal parts of gastrointestinal (GI) tract. Oxycellulose beads containing diclofenac sodium as a model drug were prepared by the ionotropic external gelation technique using calcium chloride solution as the crosslinking medium. Resulting beads were characterized in terms of particle shape and size, encapsulation efficacy, swelling ability and in vitro drug release. Also, potential drug-polymer interactions were evaluated using Fourier transform infrared spectroscopy. The particle size was found to be 0.92-0.96 mm for inactive (oxycellulose only) and 1.47-1.60 mm for active (oxycellulose-diclofenac sodium) beads, respectively. In all cases, the sphericity factor was between 0.70 and 0.81 with higher values observed for samples containing higher polymer and drug concentrations. The swelling of inactive beads was found to be strongly influenced by the pH and composition (i.e. Na + concentration) of the selected media (simulated gastric fluid vs. phosphate buffer pH 6.8). The encapsulation efficiency of the prepared particles ranged from 58% to 65%. Results of dissolution tests showed that the drug loading inside of the particles influenced the rate of its release. In general, prepared particles were able to release the drug within 12-16 h after a lag time of 4 h. Fickian diffusion was found as the predominant drug release mechanism. Thus, this novel particulate system showed a good potential to deliver drugs specifically to the distal parts of the human GI tract.

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Preparation and characterization of a novel pH-sensitive chitosan-g-poly (acrylic acid)/attapulgite/sodium alginate composite hydrogel bead for controlled release of diclofenac sodium

Cited by 261 publications

References 27 publications

Novel pH- and Temperature-Responsive Blend Hydrogel Microspheres of Sodium Alginate and PNIPAAm-g-GG for Controlled Release of Isoniazid

Novel pH- and Temperature-Responsive Blend Hydrogel Microspheres of Sodium Alginate and PNIPAAm-g-GG for Controlled Release of Isoniazid

Alginate graft copolymers and alginate–co-excipient physical mixture in oral drug delivery

Oxycellulose Beads with Drug Exhibiting pH-Dependent Solubility

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