Dissolution rate enhancement of sulfamethoxazole using the gas anti-solvent (GAS) process

• Precipitation of SMX and production of SMX–PVP composites were performed by GAS.
• Effects of GAS parameters on size of SMX were analyzed by statistical analysis.
• SMX–PVP composites could dissolve 10 times faster than the GAS precipitates.

The aim of this work was to improve the dissolution rate of a poorly water-soluble antibiotic drug, sulfamethoxazole (SMX), by precipitation and co-precipitation with poly(vinylpyrrolidone) (PVP) using the gas anti-solvent (GAS) process. In the precipitation study, the effects of solvent type (acetone, methanol and ethanol), temperature (35, 40, and 45 °C) and percent drug saturation (25, 50 and 75%) on the particle size were investigated using the Box-Behnken design of experiment. It was found that an increase in temperature resulted in a reduction in particle size. Moreover, smaller precipitates were produced when using ethanol as a solvent. An increase in percent saturation of the drug in acetone yielded larger particle size. It was also found that after passing through a 200 mesh sieve the precipitates obtained from the GAS process exhibited a higher dissolution rate than the micronized starting material. In the co-precipitation study, it was found that when using a mass ratio of drug and PVP polymer of 1:1, at 50% drug saturation in methanol and 35 °C, the highest % drug content (50.0%) was achieved. The dissolution rate of the prepared composites was found to be 10 times greater than that of the GAS precipitates.

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