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The object of the study was to develop a quick and reproducible accelerated in vitro release method to predict and deduce the function of the real time (37 °C) release for long acting PLGA microspheres. The method could be described in several steps. First, the release of the microspheres were studied using the sample and separate method at 37 °C with normal orbital shaking and elevated temperatures with magnetic stirring to further accelerate the release. Second, the most similar profile at elevated temperatures with the real time release was chosen with the help of the n value in the fitted Korsmeyer-Peppas Function. Third, the Weibull function and conversion ratio were used to deduce the function of real time release according to the chosen profile at elevated temperatures. The key point in this study was to provide a quick and precise method to predict the real time release for long acting progesterone PLGA microspheres. So the elevated temperatures coupled with magnetic stirring were used to accelerate the release further, and when there have many similar release profiles with the real time release at elevated temperatures, releasing time at elevated temperatures and the R2 of the final deduced function will be used to help choosing the most similar release profile with the real time release. Four different types of progesterone PLGA microspheres were used to verify the method, and all the deduced function correlated well with the real time releases, for R2 = 0.9912, 0.9781, 0.9918 and 0.9972, respectively. Keywords: Long acting PLGA, Microspheres, Elevated temperatures, Korsmeyer-Peppas equation, Weibull function

The aim of this study was to produce fine particles with different corrugated degree of surface by spray-drying and to investigate the effect of surface morphology on in vitro aerosol performance of the particles within HFA 134a based metered dose formulations. Compositions of rizatriptan and scutellarin were spray-dried using different spray-drying parameters, and particles were suspended within HFA 134a. The surface morphology were determined using scanning electron microscopy (SEM), while the aerodynamic performance of MDIs was evaluated using a next generation pharmaceutical impactor. The surface morphology of spray-dried particles could vary from smooth to moderately corrugated, and to raisin-like depending upon spray-drying parameters and preparation compositions. In general, increasing inlet temperature, decreasing feed concentration and/or adding leucine to the feed solution tended to increase the corrugated degree of particle surface. Deposition results indicated that raisin-like particle based MDIs for all compositions of the two drugs produced significantly better aerodynamic performance in terms of fine particle fractions and mass median aerodynamic diameters relative to the formulations of the corresponding smooth or slightly corrugated particles when the particle compositions were the same. The present results demonstrated that wrinkled particles increased fine particle fractions within surfactant-free MDI formulations.