Spray Dried Polylactide Microsphere Preparation: Influence of the Technological Parameters

Abstract

Spray drying technique has been widely used in the pharmaceutical technological field with different applications. Recently it has been also successfully employed in the preparation of microparticulate drug delivery systems. The structure of the microparticles obtained is different according whether the drug is dispersed or dissolved in the polymeric solution to be spray dried.

Microcapsules are obtained by spraying a drug suspension in a solution of the polymeric coating, while polymeric matrices (microspheres), in which the drug is embedded, are obtained by spraying a solution of the drug and of the polymer.

The aim of this work is the investigation of several technological parameters that can affect the preparation and therefore the characteristics of the microparticles obtained by spray drying method. The effect of the inlet/outlet temperatures, spray rate of feed and of concentration of the starting polymeric solution on the characteristics of diazepam loaded poly-D, L-lactide microparticles are studied and evaluated with respect to yield of production, shape, size, and in vitro drug release behaviours.