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The purpose of this study was to formulate and characterize a controlled-release biodegradable delivery system of progesterone for the treatment or prevention of osteoporosis. Microspheres of progesterone were formulated using copolymers of poly(glycolic acid-co-dl-lactic acid) (PGLA 50/50 and PGLA 15/85) and poly(L-lactic acid) (L-PLA) of similar molecular weight by the emulsion solvent evaporation technique. The effects of process variables, such as volume fraction, polyvinyl alcohol (PVA) concentration, polymer composition, and stir speed during preparation, on the yield, encapsulation efficiency (EEF), particle size distribution, in vitro release profiles of progesterone, and surface morphology of progesterone microspheres were investigated. Increasing the volume fraction from 9% to 22% increased the EEF without significantly increasing the yield; however, the rate of progesterone release from the microspheres decreased. Increasing the PVA concentration from 1% to 5% had no significant influence on the EEF, but the rate of progesterone release from microspheres increased. Polymer composition had no significant effect on the EEF, but had a significant effect on the particle size distribution, surface morphology, and release rate of progesterone from the microspheres. Stir speed did not have a significant influence on the EEF; however, stir speed influenced particle size distribution and the rate of progesterone release from microspheres of the same sieve-size range. The results suggest that controlled release of progesterone is possible by varying the different process variables, and that PGLA 50/50 provided the slowest release of progesterone. This should provide a means of delivering progesterone for months for the treatment or prevention of osteoporosis in postmenopausal women.

The purpose of this study was to enhance the dissolution of mefenamic acid (MFA) through the formation of solid dispersion systems, and to compare the dissolution of the unformulated dispersions with those of formulated dispersions in tablets. Solid dispersions of MFA were prepared in polyethylene glycol 3350 (PEG) as a binary system, and PEG and Tween 20 (TW) as a ternary system by the melt method. The dispersions were characterized by dissolution, scanning electron microscopy, and powder x-ray diffraction studies. A decrease in MFA composition in the binary dispersion systems from 50 to 5% w/w resulted in a 50% increase in the dissolution rate during the period of study, and this was threefold higher than that of pure MFA. Incorporation of TW in the preparation of ternary dispersion systems resulted in a further increase in MFA dissolution. A sevenfold increase in MFA dissolution was observed when the ternary system composition was MFA/PEG/TW 4.7:93:2.3 (% w/w). Scanning electron microscopy and x-ray diffraction pictures showed an increase in size and decrease in crystallinity of the dispersions, respectively. Compression of the dispersions into tablets did not have any effect on the dissolution of the drug from the dispersions. Compression of pure MFA and Avicel PH 101, which was used as a diluent and disintegrant, resulted in a threefold increase in dissolution. However, the dissolution of the uncompressed mixture was identical to that of pure MFA. Thus, further processing of the solid dispersions into tablets did not decrease the rate of dissolution of the drug in the dispersions. This may be very important in the formulation of solid dispersions as tablets, which could lead to a reduction in the dose of practically water-insoluble drugs.

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