Preparation of chitosan-reinforced alginate gel beads — effects of chitosan on gel matrix erosion

Murata, Yoshifumi; Maeda, Tetsuzo; Miyamoto, Etsuko; Kawashima, Susumu

doi:10.1016/0378-5173(93)90221-z

Cited by 116 publications

(58 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…3 Chitosan coating decreases drug release rate, and an incomplete release of Hb was obtained owing to suppression of erosion of alginate gel microspheres. 36 The initial burst effect observed for C1L and C1W microspheres, followed by a sustained release, is justifi ed by the presence of the alginate-chitosan complex membrane. C1D microspheres did not release Hb because the undispersed clumps obtained at acidic pH remained at pH 6.8, thereby decreasing the surface area for diffusion.…”

Section: In Vitro Release Studiesmentioning

confidence: 99%

“…36 The negatively charged carboxylic acid groups of alginate bind ionically with positively charged amino groups of chitosan, a cationic polymer, to form a polyelectrolyte complex on the basis of their opposite charges. 37 Moreover, chitosan has been reported to enhance absorption of various compounds across the mucosal barrier owing to its properties of mucoadhesion, which increase the contact time of the drug with the mucosa, and its ability to induce a transient opening of epithelial cell tight junctions.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Microencapsulation of hemoglobin in chitosan-coated alginate microspheres prepared by emulsification/internal gelation

Silva

Ribeiro²,

Figueiredo

et al. 2005

AAPS J

106

View full text Add to dashboard Cite

A BSTRACTChitosan-coated alginate microspheres prepared by emulsification/internal gelation were chosen as carriers for a model protein, hemoglobin (Hb), owing to nontoxicity of the polymers and mild conditions of the method. The infl uence of process variables related to the emulsifi cation step and microsphere recovering and formulation variables, such as alginate gelation and chitosan coating, on the size distribution and encapsulation effi ciency was studied. The effect of microsphere coating as well its drying procedure on the Hb release profi le was also evaluated. Chitosan coating was applied by either a continuous microencapsulation procedure or a 2-stage coating process. Microspheres with a mean diameter of less than 30 μm and an encapsulation effi ciency above 90% were obtained. Calcium alginate cross-linking was optimized by using an acid/CaCO 3 molar ratio of 2.5, and microsphere-recovery with acetate buffer led to higher encapsulation effi ciency. Hb release in gastric fl uid was minimal for air-dried microspheres. Coating effect revealed a total release of 27% for 2-stage coated wet microspheres, while other formulations showed an Hb release above 50%. Lyophilized microspheres behaved similar to wet microspheres, although a higher total protein release was obtained with 2-stage coating. At pH 6.8, uncoated microspheres dissolved in less than 1 hour; however, Hb release from air-dried microspheres was incomplete. Chitosan coating decreased the release rate of Hb, but an incomplete release was obtained. The 2-stage coated microspheres showed no burst effect, whereas the 1-stage coated microspheres permitted a higher protein release.

show abstract

Section: In Vitro Release Studiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Microencapsulation of hemoglobin in chitosan-coated alginate microspheres prepared by emulsification/internal gelation

Silva

Ribeiro²,

Figueiredo

et al. 2005

AAPS J

106

View full text Add to dashboard Cite

show abstract

“…This is supported by a report that calcium-induced gel matrix containing a G-rich alginate was more strongly reinforced after CS addition compared with one containing an M-rich alginate. 12) In this paper, modification of Alg-Ca was investigated in order to develop an oral dosage form for treatment of inflammatory bowel diseases. If inflammation is spread through the whole small intestine, the drug must be released gradually throughout the region.…”

Section: Resultsmentioning

confidence: 99%

Effects of Natural Polysaccharide Addition on Drug Release from Calcium-Induced Alginate Gel Beads.

et al. 2003

View full text Add to dashboard Cite

Natural polysaccharides have been utilized as additives for oral dosage forms of various medications. Chitosan (CS) has recently been studied as an excellent vehicle for drug delivery because of its biocompatibility and biodegradability. [1][2][3] CS has polycationic properties and forms a film-like complex with polyanionic compounds.4) Therefore, CS acts as an anion exchange resin, and the influence of CS intake on the human body has been studied. 5) In contrast, chitin (CT) has not been used as an additive, although it is both abundant and is the source of CS. 6) One of the reasons for this is that CT scarcely dissolves in most organic or inorganic solvents.Alginic acid is an anionic polysaccharide, which consists of a-L-guluronic acid (G) and b-D-mannuronic acid (M) subunits. Sodium alginate is administered to treat gastric ulcers by reducing gastric acid irritation. Alginate solution quickly forms a gel matrix in the presence of a divalent cation such as Ca 2ϩ and this gelation is known to arise primarily at junctions ("egg-box junctions") in G-G-sequence rich chain regions (G-blocks), rather than M-blocks. Alg-Ca is expected to be used as a vehicle for drug delivery because Alg-Ca is able to incorporate drugs or other polysaccharides within the matrix, and the relationship between drug release and alginate gel bead erosion has been investigated. 7)Colon targeting has recently been studied for drug delivery to the topical region. The release profile of an anti-inflammatory drug such as a steroid from orally administered forms in the gastrointestinal tract may affect the treatment of inflammatory bowel diseases such as Crohn's disease. 8) In the present study, we attempted to prepare Alg-Ca containing polysaccharides, including an alginate hydrolysate, and investigated the effects on the drug release profiles of Alg-Ca under mimic gastrointestinal conditions. ExperimentalChemicals A model drug, hydrocortisone (HC), was purchased from Wako Pure Chemical Ind. (Osaka, Japan). Sodium alginate (degree of polymerization; 450) was obtained from Nacalai Tesque (Kyoto, Japan), and alginic acid (non-swelling, NS) was obtained from Wako. CT and CS were obtained from Kimitsu Chem. Ind. (Tokyo, Japan) and agar (UP-16) was obtained from Ina Food Co. (Nagano, Japan). All other reagents used were of analytical grade.Viscosity of Alginate Solution Containing Polysaccharide Each polysaccharide was added to 1% sodium alginate solution and well stirred, and then the viscosity of the solution was measured with a Brookfield viscometer 5 times at room temperature (25°C).Hydrolysis of NS NS was partially hydrolyzed (0.3 M HCl, 2 h, 100°C) and the G-and M-blocks were separated by the method of Haug et al.9) Solutions containing each block were precipitated with ethanol after neutralization and centrifuged (3000 rpm, 10 min). The pellet was then washed with ethanol, and dried in vacuo over P 2 O 5 .Preparation of Modified Alg-Ca Alg-Ca was prepared as follows: One percent sodium alginate was dissolved in distilled and demineralized wa...

show abstract

“…Apesar de serem extensivamente utilizados, os "beads" de alginato de sódio apresentam inconvenientes quanto a sua utilização devido a um problema de erosão do gel com conseqüente liberação rápida do fármaco (MURATA et al, 1993a). A utilização da quitosana como agente superficial de revestimento (agente cross-linking) tem mostrado suprimir esta erosão resultando em uma liberação mais prolongada das moléculas encapsuladas (CHANDY; SHARMA, 1993;BODMEIER et al, 1989, KIM;LEE, 1992;MURATA et al, 1993a e b;AKBUGA, 1995AKBUGA, , 1999a.…”

Section: Coacervação/precipitaçãounclassified

“…BODMEIER et al, 1989, KIM;LEE, 1992;MURATA et al, 1993a e b;AKBUGA, 1995AKBUGA, , 1999a e b). Apesar de serem extensivamente utilizados, os "beads" de alginato de sódio, apresentam inconvenientes quanto a sua utilização devido a um problema de erosão do gel que resulta em uma liberação rápida do fármaco (MURATA et al, 1993a). A utilização da quitosana como agente superficial de revestimento tem mostrado suprimir esta erosão e assim, retardar a liberação (MURATA et al, 1993b).…”

Section: Concentraçãounclassified

Desenvolvimento, caracterização e avaliação de sistemas microestruturados para veiculação de ácido retinóico na pele

Lira¹

View full text Add to dashboard Cite

show abstract

Preparation of chitosan-reinforced alginate gel beads — effects of chitosan on gel matrix erosion

Cited by 116 publications

References 12 publications

Microencapsulation of hemoglobin in chitosan-coated alginate microspheres prepared by emulsification/internal gelation

Microencapsulation of hemoglobin in chitosan-coated alginate microspheres prepared by emulsification/internal gelation

Effects of Natural Polysaccharide Addition on Drug Release from Calcium-Induced Alginate Gel Beads.

Desenvolvimento, caracterização e avaliação de sistemas microestruturados para veiculação de ácido retinóico na pele

Contact Info

Product

Resources

About