The influence of  spray drying parameters on particle composition, structure and in vitro release of injectable microspheres for controlled release

Joke Meeus1, Maité Lenaerts1, David J. Scurr2, Katie Amssoms3, Martyn C. Davies2, Clive J. Roberts2, Guy Van den Mooter1

1 Drug Disposition and Delivery, University of Leuven, Belgium
2Laboratory of Biophysics and Surface Analysis, School of Pharmacy, The University of Nottingham, United Kingdom
3Pharmaceutical Companies of Johnson & Johnson, Janssen, Discovery Sciences, Belgium


This study shows how formulation (feed concentration) and process parameters (feed rate, inlet temperature and atomizing air pressure) can influence the characteristics of spray-dried microspheres. The microspheres consist of a double layered PLGA/PVP matrix containing a molecularly dispersed poorly soluble API. Differences were observed in component miscibility and phase heterogeneity of the samples, particle size and morphology as well as API surface coverage. Observed differences are likely due to changes in the droplet evaporation rate and thus particle formation process. However, varying particle characteristics did not influence the drug release behavior of the formulations studied, indicating the robustness of this approach to produce particles of consistent drug release characteristics. This is likely due to the fact that the first stage of release is dominated by diffusion from the PVP layer through pores and that observed differences in the PLGA surface layer have no influence in this stage of the release.

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