Controlled release from bioerodible polymers: effect of drug type and polymer composition

Alexis, Frank; Rath, Santosh Kumar; Venkatraman, Subbu S.

doi:10.1016/j.jconrel.2004.10.019

Cited by 178 publications

(141 citation statements)

References 22 publications

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“…From the three curves for different heating temperature, it could be found that when the heating time was fixed, the higher the heating temperature, the lower the intrinsic viscosity, and when the heating temperature was fixed, the longer the heating time of PLA sample, the lower the intrinsic viscosity. It was consistent with that reported in the literature [32].…”

Section: Intrinsic Viscositysupporting

confidence: 94%

“…Since there were two factors affecting the release behavior of drug from polymeric matrix: One was the dispersion and the dissolution property of drug [32][33][34]; the other was the degradation property of the polymer matrix in release process [35][36][37], ultrasound assisted HME should be one potential method to prepare PLA-based controlled release system. Due to the degradation of PLA matrix could obviously affect the release behavior of drugs, it was necessary for us to investigate the molecular development of PLA matrix under ultrasound.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Ultrasound on Molecular Structure Development of Polylactide

Bao¹,

Wu²,

Guo³

et al. 2014

Polymer-Plastics Technology and Engineering

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ABSTRACT:In this work, effect of ultrasound on molecular structure development of Polylactide (PLA) was studied. It was found that the intrinsic viscosity of PLA decreased with increasing treating time, temperature and ultrasound time. Different from traditional thermal degradation of PLA, the degradation of PLA under ultrasound treatment showed that chain scission and chain combination of PLA competed with each other in the degradation process, which could be divided into two steps. The mechanism of ultrasound degradation of PLA was proposed. Furthermore, Thermal properties were characterized by DSC to show heat and ultrasound effects on molecular structure development of PLA.

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Section: Intrinsic Viscositysupporting

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Effect of Ultrasound on Molecular Structure Development of Polylactide

Bao¹,

Wu²,

Guo³

et al. 2014

Polymer-Plastics Technology and Engineering

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“…Several reports suggested that covalent conjugation between PLA and PCL significantly reduces the crystallinity of PCL (21,(30)(31)(32)(33). However, the effects of various isomers of PLA (L or DL) and PGA on the crystallinity of PCL-PEG-PCL triblock copolymers have not been reported previously.…”

Section: The [Eo]-[cl]-[la] (Ethylene Oxide (Eo)mentioning

confidence: 99%

Novel Pentablock Copolymer-Based Nanoparticulate Systems for Sustained Protein Delivery

et al. 2014

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Abstract. The design, synthesis, and application of novel biodegradable and biocompatible pentablock (PB) copolymers, i.e., polyglycolic acid-polycaprolactone-polyethylene glycol-polycaprolactonepolyglycolic acid (PGA-PCL-PEG-PCL-PGA) and polylactic acid-polycaprolactone-polyethylene glycolpolycaprolactone-polylactic acid (PLA-PCL-PEG-PCL-PLA) for sustained protein delivery, are reported. The PB copolymers can be engineered to generate sustained delivery of protein therapeutics to the posterior segment of the eye. PB copolymers with different block arrangements and molecular weights were synthesized by ring-opening polymerization and characterized by proton nuclear magnetic resonance ( 1 H-NMR), gel permeation chromatography (GPC), and X-ray diffraction (XRD) spectroscopy. Immunoglobulin G (IgG) was selected as a model protein due to its structural similarity to bevacizumab. The influence of polymer molecular weight, composition, and isomerism on formulation parameters such as entrapment efficiency, drug loading, and in vitro release profile was delineated. Crystallinity and molecular weight of copolymers exhibited a substantial effect on formulation parameters. A secondary structure of released IgG was confirmed by circular dichroism (CD) spectroscopy. In vitro cytotoxicity, cell viability, and biocompatibility studies performed on human retinal pigment epithelial cells (ARPE-19) and/or macrophage cell line (RAW 264.7) demonstrated PB copolymers to be excellent biomaterials. Novel PB polymers may be the answer to the unmet need of a sustained release protein formulation.

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“…There have been great advances in drug delivery devices made of biodegradable polymers. However, most of these rely on polymer erosion for control of drug delivery [9,10]. Since this erosion-based control is limited by the properties of the polymers and surrounding tissue, precise control of drug release may not be attainable.…”

Section: Introductionmentioning

confidence: 99%

Controlled Release of Growth Factors on Allograft Bone in vitro

Huang

Ryu

Ren

et al. 2008

Clin Orthop Relat Res

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Allografts are important alternatives to autografts for treating defects after major bone loss. Bone growth factors have both local autocrine and paracrine effects and regulate the growth, proliferation, and differentiation of osteoprogenitor cells. To study the effects of prolonged, continuous, local delivery of growth factors on bone growth, we developed a new microelectromechanical system (MEMS) drug delivery device. Bone marrow cells from mice were seeded on mouse allograft discs and cultured in osteogenic media with osteogenic protein 1 (OP-1) and/or basic fibroblast growth factor (FGF-2) delivered from MEMS devices for 6 weeks. We monitored bone formation by changes of bone volume using micro-CT scanning and release of osteocalcin using ELISA. The data suggest the MEMS devices delivered constant concentrations of OP-1 and FGF-2 to the media. Bone marrow cells grew on the allografts and increased bone volume. Addition of OP-1 increased bone formation whereas FGF-2 decreased bone formation. Local delivery of growth factors over a prolonged period modulated the differentiation of osteoprogenitor cells on allograft bone.

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Controlled release from bioerodible polymers: effect of drug type and polymer composition

Cited by 178 publications

References 22 publications

Effect of Ultrasound on Molecular Structure Development of Polylactide

Effect of Ultrasound on Molecular Structure Development of Polylactide

Novel Pentablock Copolymer-Based Nanoparticulate Systems for Sustained Protein Delivery

Controlled Release of Growth Factors on Allograft Bone in vitro

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