New Biodegradable Poly(l-lactide)-Block-Poly(propylene adipate) Copolymer Microparticles for Long-Acting Injectables of Naltrexone Drug

Stavroula Nanaki; Athina Viziridou; Alexandra Zamboulis; Margaritis Kostoglou; Georgios Z Papageorgiou; Dimitrios N Bikiaris

doi:10.3390/polym12040852

New Biodegradable Poly(l-lactide)-Block-Poly(propylene adipate) Copolymer Microparticles for Long-Acting Injectables of Naltrexone Drug

Polymers (Basel). 2020 Apr 7;12(4):852. doi: 10.3390/polym12040852.

Authors

Stavroula Nanaki¹, Athina Viziridou², Alexandra Zamboulis¹, Margaritis Kostoglou³, Georgios Z Papageorgiou⁴, Dimitrios N Bikiaris¹

Affiliations

¹ Laboratory of Polymer Chemistry and Technology, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki, Greece.
² Department of Food Science and Technology, International Hellenic University, GR-57400 Thessaloniki, Greece.
³ Laboratory of General and Inorganic Chemical Technology, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki, Greece.
⁴ Chemistry Department, University of Ioannina, P.O. Box 1186, 45110 Ioannina, Greece.

Abstract

In the present study, novel block copolymers of poly(l-lactide)-block-poly(propylene adipate) (PLLA-b-PPAd) were synthesized in two ratios, 90/10 and 75/25 w/w and were further investigated as long-acting injectable (LAI) polymeric matrices in naltrexone base microparticle formulations. The synthesized polymers were characterized by ¹H-NMR, ¹³C-NMR, FTIR, XRD, TGA and DSC. NMR and FTIR spectroscopies confirmed the successful synthesis of copolymers while DSC showed that these are block copolymers with well-defined and separated blocks. Microparticles were prepared by single emulsification method and were further characterized. Nanoparticles in the range of 0.4-4.5 μm were prepared as indicated by SEM, with copolymers giving the lowest particle size. By XRD and DSC it was found that naltrexone was present in the amorphous state in its microparticles. Dissolution study showed a drug release extending over seven days, indicating that these novel PLLA-b-PPAd copolymers could be promising matrices for naltrexone's LAI formulations. It was evidenced that drug release depended on the copolymer composition. Model release studies showed that drug release is controlled by diffusion.

Keywords: amphiphilic block copolymers; controlled release; drug encapsulation; long-acting injectables; microspheres; naltrexone; poly(L-lactide); poly(propylene adipate).