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Structural and thermal properties of spray-dried methotrexate-loaded biodegradable microparticles

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Abstract

Drug–polymer interactions, structural properties, thermal behavior, and stability of biodegradable microparticles are fundamental aspects in the developing of new polymeric drug delivery systems. In this study, poly (d,l-lactide-co-glycolide) (PLGA) microparticles containing methotrexate (MTX) were successfully obtained by spray drying. Scanning electronic microscopy, differential scanning calorimetry (DSC), thermogravimetry (TG), X-ray diffraction (XRD), and drug-loading efficiency were used to investigate the effect of drug–polymer ratio and its interactions, in a new MTX-loaded PLGA spray-dried microparticles. High levels of encapsulation efficiency (about 90 %) and a prevalent spherical shape were identified for different drug–polymer ratios used (9, 18, and 27 % m/m). The thermal analyses (DSC and TG) and XRD indicate that MTX is homogeneously distributed in the polymeric matrix, with a prevalent amorphous state in a stable molecular dispersion. Therefore, a correlation between drug content and the structural-thermal properties of drug-loaded PLGA microparticles was established using the thermal analysis data. The biodegradable microparticle leads to an increment of thermal stability of MTX, confirming that spray drying is an efficient process for obtaining MTX-loaded PLGA microparticles.

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Acknowledgements

The authors wish to thank the National Council for Scientific and Technological Development (CNPq) (grant number: 479195/2008; 483073/2010-5), the Coordination for the Improvement of Higher Level Education Personnel (CAPES) (scholarship of Alice R. Oliveira), and the Federal University of Rio Grande do Norte (UFRN) (Scholarship of Philippe C. Mesquita) for their financial support. The authors also acknowledge the help extended by Andrew Alastair Cumming in proofreading the English text.

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  1. Laboratório de Tecnologia e Biotecnologia Farmacêutica – TecBioFar, Programa de Pós-Graduação em Ciências Farmacêuticas, Departamento de Farmácia, Federal University of Rio Grande do Norte (UFRN), Av. Coronel Gustavo Cordeiro de Farias s/n, Petrópolis, Natal, RN, CEP 59012-570, Brazil

    Alice Rodrigues de Oliveira, Matheus de Freitas Fernandes-Pedrosa & Arnóbio Antônio da Silva-Júnior

  2. State University of São Paulo, UNESP, Araraquara, SP, Brazil

    Eduardo Ferreira Molina, Gustavo Rossanezi & Anselmo Gomes de Oliveira

  3. Undergraduate Course of Pharmacy, UFRN, Natal, RN, Brazil

    Philippe de Castro Mesquita

  4. Institute of Chemistry, UFRN, Natal, Brazil

    José Luís Cardozo Fonseca

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  1. Alice Rodrigues de Oliveira
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  2. Eduardo Ferreira Molina
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  7. Anselmo Gomes de Oliveira
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Correspondence to Arnóbio Antônio da Silva-Júnior.

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de Oliveira, A.R., Molina, E.F., de Castro Mesquita, P. et al. Structural and thermal properties of spray-dried methotrexate-loaded biodegradable microparticles. J Therm Anal Calorim 112, 555–565 (2013). https://doi.org/10.1007/s10973-012-2580-3

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