Elevated Temperature Degradation of a 50:50 Copolymer of PLA-PGA

Agrawal, C. Mauli; Huang, Dingyi; Schmitz, John P.; Athanasiou, Kyriacos A.

doi:10.1089/ten.1997.3.345

Cited by 108 publications

(73 citation statements)

References 21 publications

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“…For PLGA-H, there is not a range of constant energy activation throughout the entire process of thermal degradation. Previous studies presented activation energy of 115 kJ.mol -1 for bulk PLGA 50:50 [18] , 116 kJ.mol -1 for dexamethasone loaded PLGA microspheres 33 indicating that the activation energy value found for PLGA-Mag is close to that demonstrated in these studies. In a general way, both PLGA-H and PLGA-Mag show higher values of activation energy than those of PLGA-R.…”

Section: Resultssupporting

confidence: 85%

“…However, the degradation of most commonly used PLGA materials is relatively slow at 37 °C, and studies may take several weeks or even years to be completed. Consequently, there is a need to establish techniques to decrease the duration of these studies while ensuring that the results remain relevant and valid 18 . Thermal analytical methods have been widely used in the study of the relationship between a material and its processing conditions.…”

Section: Introductionmentioning

confidence: 99%

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Study of Thermal Degradation of PLGA, PLGA Nanospheres and PLGA/Maghemite Superparamagnetic Nanospheres

et al. 2015

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Poly(glycolide-co-lactide) (PLGA) nanospheres containing magnetic materials have been extensively studied because of its biomedical applications. Therefore, it is very important to know thermal properties of these materials in addition to other physical properties. Thermal degradation activation energy (E α ) of PLGA nanospheres with maghemite entrapment (PLGA-Mag), PLGA nanospheres (hollow spheres) (PLGA-H) obtained by an emulsion method and unprocessed PLGA (PLGA-R) were calculated by isoconversional Vyazovkin method based on data of TG analysis in order to evaluate modifications in thermal behavior caused by nanospheres obtainment process or by maghemite entrapment. Both hydrodynamic diameter in the range of 200-250 nm and polydispersity index lower than 0.3 are considered satisfactory. Thermal degradation of PLGA-R begins at higher temperatures than those of PLGA-H and PLGA-Mag, but processed samples presented increase in thermal stability, which was greater before processing by emulsion and in the presence of the magnetic materials. PLGA-Mag presents superparamagnetic behavior at room temperature.

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Section: Resultssupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Study of Thermal Degradation of PLGA, PLGA Nanospheres and PLGA/Maghemite Superparamagnetic Nanospheres

et al. 2015

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“…Buchholz 8 examined the effect of 2 temperatures, 37-C and 80-C, on the in vitro degradation of D,L -PLA. In another study by Bergsma et al, 10 degradation behavior of L -and D,L -PLA was studied at 90-C. Degradation at temperatures between 25-C and 50-C of polyglycolic acid (PGA) sutures 11 and 50:50 PLGA devices 12 has also been reported. Makino et al 9 reported the degradation of L -and D,L -PLA microcapsules at varying temperatures, ionic strength, and pH of medium.…”

Section: Introductionmentioning

confidence: 98%

“…This was highlighted in the guidelines, which resulted from an American Association of Pharmaceutical Scientists/International Pharmaceutical Federation (AAPS/FIP) sponsored conference on dissolution/in vitro release testing of novel/special dosage forms. 7 Recognizing that drug release is governed by the slowly degrading polymer, research in the past decade has focused on accelerating polymer degradation using elevated temperatures, 8 buffer type, and pH [9][10][11][12][13] and comparing the results to physiologically degraded material. Buchholz 8 examined the effect of 2 temperatures, 37-C and 80-C, on the in vitro degradation of D,L -PLA.…”

Section: Introductionmentioning

confidence: 99%

A model-dependent approach to correlate accelerated with real-time release from biodegradable microspheres

2005

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The purpose of this study was to determine the feasibility of applying accelerated in vitro release testing to correlate or predict long-term in vitro release of leuprolide poly(lactideco-glycolide) microspheres. Peptide release was studied using a dialysis technique at 37°C and at elevated temperatures (50°C-60°C) in 0.1M phosphate buffered saline (PBS) pH 7.4 and 0.1M acetate buffer pH 4.0. The data were analyzed using a modification of the Weibull equation. Peptide release was temperature dependent and complete within 30 days at 37°C and 3 to 5 days at the elevated temperatures. In vitro release profiles at the elevated temperatures correlated well with release at 37°C. The shapes of the release profiles at all temperatures were similar. Using the modified Weibull equation, an increase in temperature was characterized by an increase in the model parameter, α, a scaling factor for the apparent rate constant. Complete release at 37°C was shortened from 30 days to 5 days at 50°C, 3.5 days at 55°C, 2.25 days at 60°C in PBS pH 7.4, and 3 days at 50°C in acetate buffer pH 4.0. Values for the model parameter β indicated that the shape of the release profiles at 55°C in PBS pH 7.4 (2.740) and 50°C in 0.1M acetate buffer pH 4.0 (2.711) were similar to that at 37°C (2.677). The E a for hydration and erosion were determined to be 42.3 and 19.4 kcal/mol, respectively. Polymer degradation was also temperature dependent and had an E a of 31.6 kcal/mol. Short-term in vitro release studies offer the possibility of correlation with long-term release, thereby reducing the time and expense associated with longterm studies. Accelerated release methodology could be useful in the prediction of long-term release from extended release microsphere dosage forms and may serve as a quality control tool for the release of clinical or commercial batches.

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“…The degradation activation energies obtained were 87.9, 82.7 and 94.9 kJ mol −1 for LC16 : 4, LC18 : 2 and LC9 : 1 respectively. Arrhenius relation has been conducted for the change in several parameters of biodegradable polymers such as molecular weight, breaking strength, viscosity and mass loss [34,38,49,71,72]. The majority of previous publications used change in molecular weight over degradation time at different temperatures.…”

Section: Calculation Of Activation Energymentioning

confidence: 99%

In vitro degradation and mechanical properties of PLA-PCL copolymer unit cell scaffolds generated by two-photon polymerization

et al. 2016

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The manufacture of 3D scaffolds with specific controlled porous architecture, defined microstructure and an adjustable degradation profile was achieved using two-photon polymerization (TPP) with a size of 2 × 4 × 2 mm3. Scaffolds made from poly(D,L-lactide-co-ɛ-caprolactone) copolymer with varying lactic acid (LA) and ɛ -caprolactone (CL) ratios (LC16:4, 18:2 and 9:1) were generated via ring-opening-polymerization and photoactivation. The reactivity was quantified using photo-DSC, yielding a double bond conversion ranging from 70% to 90%. The pore sizes for all LC scaffolds were see 300 μm and throat sizes varied from 152 to 177 μm. In vitro degradation was conducted at different temperatures; 37, 50 and 65 °C. Change in compressive properties immersed at 37 °C over time was also measured. Variations in thermal, degradation and mechanical properties of the LC scaffolds were related to the LA/CL ratio. Scaffold LC16:4 showed significantly lower glass transition temperature (Tg) (4.8 °C) in comparison with the LC 18:2 and 9:1 (see 32 °C). Rates of mass loss for the LC16:4 scaffolds at all temperatures were significantly lower than that for LC18:2 and 9:1. The degradation activation energies for scaffold materials ranged from 82.7 to 94.9 kJ mol−1. A prediction for degradation time was applied through a correlation between long-term degradation studies at 37 °C and short-term studies at elevated temperatures (50 and 65 °C) using the half-life of mass loss (Time (M1/2)) parameter. However, the initial compressive moduli for LC18:2 and 9:1 scaffolds were 7 to 14 times higher than LC16:4 (see 0.27) which was suggested to be due to its higher CL content (20%). All scaffolds showed a gradual loss in their compressive strength and modulus over time as a result of progressive mass loss over time. The manufacturing process utilized and the scaffolds produced have potential for use in tissue engineering and regenerative medicine applications.

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Elevated Temperature Degradation of a 50:50 Copolymer of PLA-PGA

Cited by 108 publications

References 21 publications

Study of Thermal Degradation of PLGA, PLGA Nanospheres and PLGA/Maghemite Superparamagnetic Nanospheres

Study of Thermal Degradation of PLGA, PLGA Nanospheres and PLGA/Maghemite Superparamagnetic Nanospheres

A model-dependent approach to correlate accelerated with real-time release from biodegradable microspheres

In vitro degradation and mechanical properties of PLA-PCL copolymer unit cell scaffolds generated by two-photon polymerization

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