Preparation, characterization and in vivo evaluation of 120-day poly(d,l-lactide) leuprolide microspheres

Woo, Byung Ho; Kostanski, Janusz W.; Gebrekidan, Sisay; Dani, Bhas A.; Thanoo, B. Chithambara; DeLuca, Patrick P.

doi:10.1016/s0168-3659(01)00403-5

Cited by 100 publications

(65 citation statements)

References 21 publications

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“…Therefore, we chose the dialysis method to study the in vitro drug release to avoid the above problems. 20) According to Woo et al, 21) the in vitro release profile obtained by the dialysis method permitted better correlation with in vivo release. Dialysis membrane with a MWCO of 8000-14400 was chosen for the fast equilibrium of drug (MW 242.32) between the inside and outside of the membrane.…”

Section: Resultsmentioning

confidence: 99%

In Vitro and in Vivo Characterization of Huperzine A Loaded Microspheres Made from End-Group Uncapped Poly(d,l-lactide acid) and Poly(d,l-lactide-co-glycolide acid)

Gao

Ding

et al. 2006

Chem. Pharm. Bull.

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Section: Resultsmentioning

confidence: 99%

In Vitro and in Vivo Characterization of Huperzine A Loaded Microspheres Made from End-Group Uncapped Poly(d,l-lactide acid) and Poly(d,l-lactide-co-glycolide acid)

Gao

Ding

et al. 2006

Chem. Pharm. Bull.

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“…Table 1 lists currently marketed formulations, indications for use, and duration of action. These depot formulations can deliver a sustained dose in vivo for varying periods of time, from weeks to months, [1][2][3][4][5][6] primarily owing to low degradation rates of the bulk eroding PLA and PLGA polymers.…”

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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“…Dialysis membranes having varying molecular weight exclusion cutoffs (MWCOs) and composition have been used in a variety of setups (eg, dialysis bag, diffusion cell). [15][16][17][18][19][20] Sampling and media replacement are convenient with the dialysis setup owing to a physical separation of the microspheres from the outer media. However, with all the reported techniques, an initial preparation step is required for the dialysis setup.…”

Section: Introductionmentioning

confidence: 99%

Development of a dialysis in vitro release method for biodegradable microspheres

2005

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The purpose of this research was to develop a simple and convenient in vitro release method for biodegradable microspheres using a commercially available dialyzer. A 25 KD MWCO Float-a-Lyzer was used to evaluate peptide diffusion at 37°C and 55°C in different buffers and assess the effect of peptide concentration. In vitro release of Leuprolide from PLGA microspheres, having a 1-month duration of action, was assessed using the dialyzer and compared with the commonly used ''sample and separate'' method with and without agitation. Peptide diffusion through the dialysis membrane was rapid at 37°C and 55°C in all buffers and was independent of peptide concentration. There was no detectable binding to the membrane under the conditions of the study. In vitro release of Leuprolide from PLGA microspheres was tri-phasic and was complete in 28 days with the dialysis technique. With the sample and separate technique, linear release profiles were obtained with complete release occurring under conditions of agitation. Diffusion through the dialysis membrane was sufficiently rapid to qualify the Float-a-Lyzer for an in vitro release system for microparticulate dosage forms. Membrane characteristics render it useful to study drug release under real-time and accelerated conditions.

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Preparation, characterization and in vivo evaluation of 120-day poly(d,l-lactide) leuprolide microspheres

Cited by 100 publications

References 21 publications

In Vitro and in Vivo Characterization of Huperzine A Loaded Microspheres Made from End-Group Uncapped Poly(d,l-lactide acid) and Poly(d,l-lactide-co-glycolide acid)

In Vitro and in Vivo Characterization of Huperzine A Loaded Microspheres Made from End-Group Uncapped Poly(d,l-lactide acid) and Poly(d,l-lactide-co-glycolide acid)

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

Development of a dialysis in vitro release method for biodegradable microspheres

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