Time-programmed pulsatile release of dextran from calcium-alginate gel beads coated with carboxy-n-propylacrylamide copolymers

Iskakov, Rinat; Kikuchi, Akihiko; Okano, Teruo

doi:10.1016/s0168-3659(01)00551-x

Cited by 64 publications

(43 citation statements)

References 32 publications

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“…Sodium Alg is a naturally occurring polysaccharide polymer, extensively investigated for drug delivery and tissue engineering applications. 52,53) AOT-Alg nanoparticles can sustain the release of water-soluble drugs such as doxorubicin and verapamil over a period of 4 weeks.…”

Section: Emulsification-cross Linking Methodsmentioning

confidence: 99%

Chitosan Nanoparticles: A Promising System in Novel Drug Delivery

2010

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The ability of nanoparticles to manipulate the molecules and their structures has revolutionized the conventional drug delivery system. The chitosan nanoparticles, because of their biodegradability, biocompatibility, better stability, low toxicity, simple and mild preparation methods, offer a valuable tool to novel drug delivery systems in the present scenario. Besides ionotropic gelation method, other methods such as microemulsion method, emulsification solvent diffusion method, polyelectrolyte complex method, emulsification cross-linking method, complex coacervation method and solvent evaporation method are also in use. The chitosan nanoparticles have also been reported to have key applications in parentral drug delivery, per-oral administration of drugs, in nonviral gene delivery, in vaccine delivery, in ocular drug delivery, in electrodeposition, in brain targeting drug delivery, in stability improvement, in mucosal drug delivery in controlled drug delivery of drugs, in tissue engineering and in the effective delivery of insulin. The present review describes origin and properties of chitosan and its nanoparticles along with the different methods of its preparation and the various areas of novel drug delivery where it has got its application.

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Section: Emulsification-cross Linking Methodsmentioning

confidence: 99%

Chitosan Nanoparticles: A Promising System in Novel Drug Delivery

2010

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“…Kikuchi et al (1997) proposed that alginate dissolution is due to the calcium ion release from the hydrogels and integrated this concept with the pulsatile release of macromolecular dextran. Further different parameters like alginate concentration, alginate molecular weight or alginate gel bead diameter influences the onset time for the release of dextran (Okor et al, 1991;Iskakov et al, 2002).…”

Section: Alginate-calcium Ion Hydrogelsmentioning

confidence: 99%

Stimuli-responsive hydrogels in drug delivery and tissue engineering

Sood¹,

Bhardwaj²,

Mehta³

et al. 2014

Drug Delivery

308

194

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Hydrogels are the three-dimensional network structures obtained from a class of synthetic or natural polymers which can absorb and retain a significant amount of water. Hydrogels are one of the most studied classes of polymer-based controlled drug release. These have attracted considerable attention in biochemical and biomedical fields because of their characteristics, such as swelling in aqueous medium, biocompatibility, pH and temperature sensitivity or sensitivity towards other stimuli, which can be utilized for their controlled zero-order release. The hydrogels are expected to explore new generation of self-regulated delivery system having a wide array of desirable properties. This review highlights the exciting opportunities and challenges in the area of hydrogels. Here, we review different literatures on stimuli-sensitive hydrogels, such as role of temperature, electric potential, pH and ionic strength to control the release of drug from hydrogels.

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“…Therefore, several attempts have been made to control the drug release profile by modifying the structure of the gel matrix in AlgCa. [9][10][11] We previously reported the effects of polysaccharide additives, such as chitin or chitosan (CS) on drug release from Alg-Ca. 12,13) The additives may modify the structure of gel matrix that holds the drug in Alg-Ca.…”

Section: )mentioning

confidence: 99%

Properties of Calcium-Induced Gel Beads Prepared with Alginate and Hydrolysates

Murata

Jinno

Kofuji

et al. 2004

CHEMICAL & PHARMACEUTICAL BULLETIN

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Alginic acid (Alg) is an anionic polysaccharide that consists of a-L-guluronic acid (G) and b-D-mannuronic acid (M). The molecular weight of Alg, the ratio of the two uronic acids (M/G ratio), and the sequence referred to as block structure, are dominant factors in the characterization of the polymer.1) Three blocks, the G-block (GB), the M-block (MB) and the MG-block are present in the Alg molecule, and these are closely associated with the structure of calcium-induced Alg gel (Alg-Ca), which is formed in the presence of Ca 2ϩ . GB is particularly liable to form a Ca 2ϩ chelate and Alg with a low M/G ratio generally forms the cured gel matrix.2) Each block can be obtained by hydrolysis with dilute HCl solution followed by separation by pH-control of the aqueous solution containing these blocks. 3)An abundant natural polysaccharide, Alg has been used as a medicine as well as a food additive, and it is hoped that Alg-Ca can be used as a vehicle for drug delivery.4,5) Alg-Ca is able to incorporate a drug into the gel matrix and release it gradually in the gastrointestinal tract after oral administration. [6][7][8] However, arbitrary control of the drug release rate from Alg-Ca may be difficult because the Alg used to prepare the gel matrix does not necessarily possess the optimum molecular weight, M/G ratio or block structure. Therefore, several attempts have been made to control the drug release profile by modifying the structure of the gel matrix in AlgCa. [9][10][11] We previously reported the effects of polysaccharide additives, such as chitin or chitosan (CS) on drug release from Alg-Ca. 12,13) The additives may modify the structure of gel matrix that holds the drug in Alg-Ca. In the present study, we attempted to prepare Alg-Ca containing Alg hydrolysate and investigated the influence to the gel strength. In addition, the drug release profile from the modified Alg-Ca was investigated under simulated gastrointestinal conditions. ExperimentalChemicals Alg (sodium salt, degree of polymerization; 450) was obtained from Nacalai Tesque (Kyoto), and CS was obtained from Kimitsu Chem. Industries (CS fine powder, degree of deacetylation, 75-85%; Tokyo). Molecular weight of CS was determined by gel permeation chromatography.14) Hydrocortisone (HC) was purchased from Wako Pure Chemical Ind. (Osaka). All other reagents used were of analytical grade.Hydrolysis of Alg Alg was partially hydrolyzed (0.2 M HCl, 2 h, 100°C), and GB and MB were separated using the method of Haug et al.3)The solutions containing GB or MB were then neutralized with NaOH, followed by precipitation with ethanol and centrifugation (3000 rpm, 5 min). The pellet was washed 3 times with ethanol, and dried in vacuo over P 2 O 5 .Viscosity of Solution The viscosities of the solutions containing Alg and/or Alg hydrolysate were measured 5 times with a viscometer (VM-1G-M, CBC Materials Co., Ltd., Tokyo) at 37°C.Preparation of Modified Alg-Ca Alg-Ca modified by alginate hydrolysate and/or CS was prepared as follows: Alginate was dissolved in distilled and ...

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Time-programmed pulsatile release of dextran from calcium-alginate gel beads coated with carboxy-n-propylacrylamide copolymers

Cited by 64 publications

References 32 publications

Chitosan Nanoparticles: A Promising System in Novel Drug Delivery

Chitosan Nanoparticles: A Promising System in Novel Drug Delivery

Stimuli-responsive hydrogels in drug delivery and tissue engineering

Properties of Calcium-Induced Gel Beads Prepared with Alginate and Hydrolysates

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