Sustained drug delivery systems. I. The permeability of poly(ϵ‐caprolactone), poly(<scp>DL</scp>‐lactic acid), and their copolymers

Pitt, Colin G.; Jeffcoat, A; Zweidinger, Roy B.; Schindler, A.

doi:10.1002/jbm.820130313

Cited by 262 publications

(105 citation statements)

References 8 publications

(1 reference statement)

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“…Two amorphous polymers were chosen in this study: a PDLLA homopolymer and a PLGA copolymer with a 75:25 LA/GA ratio, the latter being known to degrade faster than the homopolymer. Such biodegradable polyesters degrade with random chain scission by ester hydrolysis in a process autocatalysed by the generation of carboxylic acid end groups [38]. As a result, the degradation of polyester devices is known to be heterogeneous and divided into a fast degrading centre and a slowly degrading outer layer, which stays intact and retains degradation products until the swelling of the implants or mechanical failure cause it to break, after about 32 weeks in vitro in case of polylactide [39].…”

Section: Discussionmentioning

confidence: 99%

Porous poly(α-hydroxyacid)/Bioglass® composite scaffolds for bone tissue engineering. I: preparation and in vitro characterisation

et al. 2004

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Highly porous composites scaffolds of poly-D,L-lactide (PDLLA) and poly(lactide-co-glycolide) (PLGA) containing different amounts (10, 25 and 50wt%) of bioactive glass (45S5 bioglass ® ) were prepared by thermally induced solid-liquid phase separation (TIPS) and subsequent solvent sublimation. The addition of increasing amounts of bioglass ® into the polymer foams decreased the pore volume. Conversely, the mechanical properties of the polymer materials were improved. The composites were incubated in phosphate buffer saline at 37°C to study the in vitro degradation of the polymer by measurement of water absorption, weight loss as well as changes in the average molecular weight of the polymer and in the pH of the incubation medium as a function of the incubation time. The addition of bioglass ® to polymer foams increased the water absorption and weight loss compared to neat polymer foams. However, the polymer molecular weight, determined by size exclusion chromatography, was found to decrease more rapidly and to a larger extent in absence of bioglass ® . The presence of the bioactive filler was therefore found to delay the degradation rate of the polymer as compared to the neat polymer foams. Formation of hydroxyapatite on the surface of composites, as an indication of their bioactivity, was recorded by EDXA, X-ray diffractometry and confirmed by Raman spectroscopy.

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Section: Discussionmentioning

confidence: 99%

Porous poly(α-hydroxyacid)/Bioglass® composite scaffolds for bone tissue engineering. I: preparation and in vitro characterisation

et al. 2004

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“…Additional potential problems with these synthetic materials include poor clearance -particularly for high MW polymers -and chronic inflammatory response (Kirker-Head, 2000; Li and Wozney, 2001). For this reason, research has been focusing on other synthetic materials, such as poly(ε-caprolactone) (ε-PCL), which was, for instance, found to meet the requirements of a biodegradable reservoir or monolithic device for controlled drug delivery, especially in the contraceptive field (Pitt et al, 1979;Dubertnet et al, 1987).…”

Section: Incorporation and Releasementioning

confidence: 99%

Materials in particulate form for tissue engineering. 1. Basic concepts

Silva

Ducheyne

Reis

2007

J Tissue Eng Regen Med

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For biomedical applications, materials small in size are growing in importance. In an era where 'nano' is the new trend, micro-and nano-materials are in the forefront of developments. Materials in the particulate form aim to designate systems with a reduced size, such as micro-and nanoparticles. These systems can be produced starting from a diversity of materials, of which polymers are the most used. Similarly, a multitude of methods are to produce particulate systems, and both materials and methods are critically reviewed here. Among the varied applications that materials in the particulate form can have, drug delivery systems are probably the most prominent, as these have been in the forefront of interest for biomedical applications. The basic concepts pertaining to drug delivery are summarized, and the role of polymers as drug delivery systems conclude this review. JOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE R E V I E W A R T I C L E

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“…Among United States Food and Drug Administration (FDA)-approved polyesters, poly(ɛ-caprolactone) (PCL) possesses unique properties such as enhanced biocompatibility, higher hydrophobicity, and neutral biodegradation end products that do not disturb the pH balance of the degradation medium (9)(10)(11)(12)(13). Over the years, an array of drug delivery systems has been developed using PCL (14)(15)(16)(17)(18)(19)(20)(21).…”

Section: Introductionmentioning

confidence: 99%

Poly(Ethylene Oxide)-Modified Poly(β-Amino Ester) Nanoparticles as a pH-Sensitive System for Tumor-Targeted Delivery of Hydrophobic Drugs: Part 2. In Vivo Distribution and Tumor Localization Studies

et al. 2005

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Purpose.-This study was carried out to determine the biodistribution profiles and tumor localization potential of poly(ethylene oxide) (PEO)-modified poly (β-amino ester) (PbAE) as a novel, pH-sensitive biodegradable polymeric nanoparticulate system for tumor-targeted drug delivery.Methods.-The biodistribution studies of PEO-modified PbAE and PEO-modified poly(ɛ-caplactone) (PCL), a non-pH sensitive polymer, nanoparticle systems were carried out in normal mice using 111 indiumoxine [ 111 In] as a lipophilic radiolabel encapsulated within the polymeric matrix and the distribution of the nanoparticles was studied in plasma and all the vital organs following intravenous administration. Solid tumors were developed on nude mice using human ovarian carcinoma xenograft (SKOV-3) and the change in concentrations of tritium [ 3 H]-labeled paclitaxel encapsulated in polymeric nanoparticles was examined in blood, tumor mass and liver.Results.-Study in normal mice with a gamma-emitting isotope [ 111 In] provided a thorough biodistribution analysis of the PEO-modified nanoparticulate carrier systems, while the 3 H-paclitaxel was useful to understand the change in concentration and tumor localization of anticancer compound directly in major sites of distribution. Both PEO-PbAE and PEO-PCL nanoparticles showed long systemic circulating properties by virtue of surface modification with PEO-containing triblock block copolymer (Pluronic ® ) stabilizer. While the PCL nanoparticles showed higher uptake by the reticuloendothelial system (RES), the PbAE nanoparticles effectively delivered the encapsulated payload into the tumor mass.Conclusions.-PEO-modified PbAE nanoparticles showed considerable passive tumor targeting potential in early stages of biodistribution via the enhanced permeation and retention (EPR) mechanism. This prompts a detailed biodistribution profiling of the nanocarrier for prolonged periods of time to provide conclusive evidence for superiority of the delivery system.

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Sustained drug delivery systems. I. The permeability of poly(ϵ‐caprolactone), poly(DL‐lactic acid), and their copolymers

Cited by 262 publications

References 8 publications

Porous poly(α-hydroxyacid)/Bioglass® composite scaffolds for bone tissue engineering. I: preparation and in vitro characterisation

Porous poly(α-hydroxyacid)/Bioglass® composite scaffolds for bone tissue engineering. I: preparation and in vitro characterisation

Materials in particulate form for tissue engineering. 1. Basic concepts

Poly(Ethylene Oxide)-Modified Poly(β-Amino Ester) Nanoparticles as a pH-Sensitive System for Tumor-Targeted Delivery of Hydrophobic Drugs: Part 2. In Vivo Distribution and Tumor Localization Studies

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