Applicability of non-halogenated methyl propionate to microencapsulation

Abstract

Applicability of methyl propionate to microencapsulation was evaluated with regard to volatility, capability of forming emulsions, and their quality. An emulsion-based technique was then developed to encapsulate progesterone into poly-d,l-lactide-co-glycolide microspheres. Their characteristics were compared with those prepared using ethyl acetate. Our results demonstrated that methyl propionate had greater evaporative tendency and less water miscibility than ethyl acetate did. The former allowed us to prepare good microspheres. Their average volume mean diameter was 68.3 ± 1.7 μm with a span index of 0.91 ± 0.13. Progesterone did not undergo polymorphic transition during microencapsulation, and its encapsulation efficiency ranged from 41.80 ± 1.83 to 85.64 ± 1.95%. Residual methyl propionate in various microspheres was found to be 0.97 ± 0.03 to 1.54 ± 0.07%. Such microsphere characteristics were quite similar to those prepared by the ethyl acetate-based microencapsulation process. Overall, our findings reflect that methyl propionate has a potential to become an invaluable solvent for microencapsulation.

Osmoprotectants in Hybrid Liposome/HPMC Systems as Potential Glaucoma Treatment

“…This change in solvents allowed the solubilization of a higher amount of acetazolamide, which is practically insoluble in chloroform but slightly soluble in ethanol. Furthermore, this change avoids the use of halogenated class 2 solvents, categorized as probable human carcinogens agents and also ozone-depleting chemical [55]. In fact, class 3 solvents, such as ethanol, are preferred for pharmaceutical preparations according to ICH Q3C guidelines [56].…”

How to circumvent untoward drug crystallization during emulsion‐templated microencapsulation process

“…In the practice of solvent evaporation, emulsion droplets experience dynamic changes such as breakups, the Ostwald ripening, solvent diffusion, and water influx. Since our dispersed solvent, methyl propionate, has the water solubility of 6.4%, it diffuses from emulsion droplets to the aqueous continuous phase . Therefore, the aqueous continuous phase contains a small amount of dissolved methyl propionate.…”

“…Progesterone eluting out of the analytical column was detected by a UV detector at 254 nm. Drug EE% was calculated as follows where actual loading = (progesterone weight found in microspheres)/(microsphere sample weight) and theoretical loading = (progesterone weight used for microencapsulation)/(combined weight of PLGA and progesterone used for microencapsulation)…”

“…Most widely used dispersed organic solvents for emulsion‐templated microencapsulation processes are methylene chloride, chloroform, and ethyl acetate. In our recent study, non‐halogenated methyl propionate was suggested as a new substitution for the organic solvents listed above . Therefore, our first microencapsulation process attempted to use methyl propionate as a dispersed solvent to encapsulate progesterone into PLGA microspheres through solvent evaporation.…”