Spray drying technique to produce controlled release formulations of zidovudine—an anti‐HIV drug

This article explores the application of spray drying technique to produce microparticles of poly(D ,L ‐lactide‐co‐glycolic acid) (PLGA), as well as di‐block copolymer of polylactic acid (PLA) and polyethylene glycol (PEG) (PLA‐PEG), containing zidovudine (AZT), an anti‐HIV drug, to achieve its controlled release over an extended period of time. Of the two polymers studied, PLGA is hydrophobic, whereas PLA‐PEG is hydrophilic and the drug, AZT is water‐soluble. Formulations were developed containing 10 and 25 wt % of AZT giving encapsulation efficiencies (EE) of 66 to 86% for PLGA and 90 to 94% for PLA‐PEG di‐block copolymer. All the formulations were characterized by Fourier transform spectroscopy (FTIR) to investigate the interaction of AZT with polymers and to characterize PLA‐PEG. NMR was also employed to confirm the formation of PLA‐PEG. X‐ray diffraction was used to understand the molecular level dispersion of AZT within the polymeric matrices, while differential scanning calorimetry was employed to assess thermal properties. Scanning electron microscopy was employed to understand the surface morphology of AZT‐loaded microparticles. In vitro release experiments performed in pH 7.4 buffer media extended the release of AZT up to 125 h with PLGA, whereas 30 h were required for releasing AZT through PLA‐PEG microparticles. Cumulative release data were fitted to an empirical equation to understand the nature of release characteristics. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci 000: 000–000, 2011