Glucose-sensitive polymeric matrices for controlled drug delivery

Goldraich, Marganit; Kost, Joseph

doi:10.1016/0267-6605(93)90100-l

Cited by 44 publications

(11 citation statements)

References 7 publications

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“…Delivery systems can also be designed to release macromolecules in response to increased concentration of a specific compound or changes in the surrounding environment. 72,73 …”

Section: Polymers and Gels Used In Protein Ddssmentioning

confidence: 99%

Past, Present, and Future Technologies for Oral Delivery of Therapeutic Proteins

Singh

Lillard

2008

Journal of Pharmaceutical Sciences

164

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Biological drugs are usually complex proteins and cannot be orally delivered due to problems related to degradation in the acidic and protease-rich environment of the gastrointestinal (GI) tract. The high molecular weight of these drugs often results in poor absorption into the periphery when administered orally. The most common route of administration for these therapeutic proteins is injection. Most of these proteins have short serum half-lives and need to be administered frequently or in high doses to be effective. So, difficulties in the administration of protein-based drugs provides the motivation for developing drug delivery systems (DDSs) capable of maintaining therapeutic drug levels without side effects as well as traversing the deleterious mucosal environment. Employing a polymer as an entrapment matrix is a common feature among the different types of systems currently being pursued for protein delivery. Protein release from these matrices can occur through various mechanisms, such as diffusion through or erosion of the polymer matrix, and sometimes a combination of both. Encapsulation of proteins in liposomes has also been a widely investigated technology for protein delivery. All of these systems have merit and our worthy of pursuit.

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“…Delivery systems can also be designed to release macromolecules in response to increased concentration of a specific compound or changes in the surrounding environment. 72,73 …”

Section: Polymers and Gels Used In Protein Ddssmentioning

confidence: 99%

Past, Present, and Future Technologies for Oral Delivery of Therapeutic Proteins

Singh

Lillard

2008

Journal of Pharmaceutical Sciences

164

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“…Polyelectrolyte hydrogels of a type widely studied in the literature [3,[13][14][15] were prepared from three monomers: hydroxypropyl methacrylate(HPMA), (N,N-dimethylamino)ethyl methacrylate (DMA), and tetraethylene glycol dimethacrylate (TEGDMA). The monomer DMA contains a pH-sensitive tertiary amine, TEGDMA is a crosslinker, and HPMA was included to obtain a transition pH ≈ 8 [13,15].…”

Section: Experimental Materials and Hydrogel Synthesismentioning

confidence: 99%

Separation of the effects of pH and polymer concentration on the swelling pressure and elastic modulus of a pH-responsive hydrogel

Horkay

Han

et al. 2006

Polymer

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The elastic shear modulus G and swelling pressure ω are studied for a basic, pH-responsive hydrogel synthesized by crosslinking copolymerization of co-monomers hydroxypropyl methacrylate and N,N-dimethylaminoethyl methacrylate with crosslinker tetraethylene glycol dimethacrylate. Under normal conditions of use as a "smart" material, hydrogel swelling ratio Q and pH vary simultaneously, but here G and ω values are presented as a function of pH with Q held constant and vice-versa. At fixed pH, G decreases with increase in Q in a power law dependence, as predicted by the FloryRehner model. However, at fixed Q, G increases with decrease in pH (i.e, increase in degree of ionization). The pH effect is more pronounced than the volume effect, thus the hydrogel stiffens as it swells in response to pH change. At high pH, ω values of the uncharged hydrogel obey the FloryRehner model, whereas explicit ionic contributions can be identified at lower pH values.

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“…Incorporation of DMAEMA at high loading (18.5 wt%) and a low cross-linking ratio (0.3 vol%) enhanced the swelling and release kinetics and enabled the hydrogel to display sensitivity to glucose at physiological concentrations. Nevertheless, mass transfer limitations and enzyme deactivation limited the performance of the matrix and the gel displayed rather slow response times in terms of insulin release to changes in glucose concentration [60]. As oxygen is only poorly soluble in aqueous solutions, the conversion of glucose to gluconic acid becomes rate limited by oxygen availability in the polymer microenvironment and this consequently limits the rate of matrix swelling and insulin release.…”

Section: Chemically-responsive Polymersmentioning

confidence: 99%

Synthetic polymer systems in drug delivery

Alexander

2001

Expert Opinion on Emerging Drugs

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The development of synthetic polymers for applications in drug delivery is reviewed, with particular reference to polymers that can be activated to release a medicinal agent in vivo or that can respond to changes in environment to enhance the effectiveness of therapy. The mechanisms by which these polymers are designed to deliver drugs are highlighted, along with the challenges facing synthetic chemists and pharmaceutical scientists in designing new and more active therapeutic vehicles. Currently, synthetic materials with biomimetic properties are attracting growing attention as possible new dosage formulations and the potential applications of these increasingly sophisticated polymers in cell-specific drug targeting and in the emerging field of gene therapy are also considered. Finally, the potential development issues for delivery of therapeutics using active or 'smart' polymers are discussed with an analysis of the future trends in this rapidly expanding area of research.

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Glucose-sensitive polymeric matrices for controlled drug delivery

Cited by 44 publications

References 7 publications

Past, Present, and Future Technologies for Oral Delivery of Therapeutic Proteins

Past, Present, and Future Technologies for Oral Delivery of Therapeutic Proteins

Separation of the effects of pH and polymer concentration on the swelling pressure and elastic modulus of a pH-responsive hydrogel

Synthetic polymer systems in drug delivery

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