Acid catalyzed poly (ortho ester) matrices for intermediate term drug delivery

Shih, Chung; Lucas, Stephanie J.; Zentner, Gaylen M.

doi:10.1016/0168-3659(91)90103-k

Cited by 11 publications

(2 citation statements)

References 14 publications

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“…Because hydrophobic poly(ortho esters) erode at very slow rates at body pH, many applications require an increased hydrolysis rate, which can be achieved by providing an acidic environment within the polymer matrix. Early work used acidic excipients such as anhydrides, , various aromatic and aliphatic acids, and sebacic acid to increase hydrolysis rates. However, when acidic excipients are used to accelerate hydrolysis, water intrusion into the inner core of the matrix leads to bulk erosion.…”

Section: Introductionmentioning

confidence: 99%

Hydrolysis and Erosion Studies of Autocatalyzed Poly(ortho esters) Containing Lactoyl−Lactyl Acid Dimers

1999

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Poly(ortho esters) based on 3,9-diethylidene-2,4,8,10-tetraoxaspiro[5.5]undecane, 1,10-decanediol, and 1,10-decanediol dilactate were prepared and their hydrolysis in phosphate buffer at 37 °C and pH 7.4 was determined as a function of time. Specifically, kinetics of polymer weight loss, polymer molecular weight changes, release of lactic acid and release of propionic acid were determined. A significant decrease in molecular weight occurred within about 20 days. Weight loss and evolution of hydrolysis product occurred after an induction period that decreased with increasing content of the lactoyl−lactyl segment in the polymer. After the induction period, a concomitant rate of weight loss and release of hydrolysis products was noted. The rate increased with increasing content of the lactoyl−lactide segment. After a certain time period, size-exclusion chromatography revealed the formation of a peak at an apparent molecular mass of about 550 Da. The compounds under the peak were analyzed by electrospray ionization/mass spectrometry (ESI/MS) and found to consist of a multiplicity of lower molecular weight polymer hydrolysis fragments. On the basis of expected hydrolysis products, it was possible to assign a structure to most molecular weight peaks in the ESI/MS spectrum. The data were found to be consistent with a hydrolysis that takes place predominantly in the surface layers of the solid polymer.

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Section: Introductionmentioning

confidence: 99%

Hydrolysis and Erosion Studies of Autocatalyzed Poly(ortho esters) Containing Lactoyl−Lactyl Acid Dimers

1999

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“…9,10 Its hydrolysis rate can be accelerated by using acidic excipients or copolymerization with hydrophilic monomers. 11,12 As we know, poly(ethylene glycol) (PEG) is a biocompatible, nontoxic, nonimmunogenic, watersoluble polymer of much use in biomaterials, biotechnology, and medicine. 13 In considering solubilization and hydrophilicity of PEG, a novel drug delivery system based on a poly(ortho esters)-poly(ethylene glycol) (POE-PEG) polyblend was developed to enhance drug release from POE.…”

Section: Introductionmentioning

confidence: 99%

Drug release from poly(ortho esters)-poly(ethylene glycol) polyblend

Wei

Chang

Yao

et al. 1999

J. Appl. Polym. Sci.

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A polyblend of poly(ortho esters)-poly(ethylene glycol) (POE-PEG) was prepared. The release behavior of the acetanilide-loaded film of the POE-PEG polyblend was studied. Blending POE with water-soluble PEG can promote the release of drug in pH 7.4 PBS buffer at 37°C, while POE has plasticizing effect on PEG. Infrared and X-ray diffraction studies reveal that there is some interaction between POE and acetanilide. The SEM micrographs disclose that the porosity of the drug-loaded film enhances with an increase immersing time.

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