Release mechanisms of insulin from the internal phase of W/O/W multiple emulsions in different release mediums were studied in present work. A noval release mechanism of rupture of the oily membrane resulting from enzymatic hydrolysis of surfactant in artificial intestinal fluid was proposed. Multiple emulsions loading insulin were mixed with different release mediums and incubated in 37? bath for 8 hours. Insulin amounts in the internal aqueous phase of the remained oily droplets and in the release mediums at different incubation time were analyzed by HPLC respectively. The ratios of insulin remained in the oily droplets were used to calculate release rates at different incubation time and quantity of insulin in the release mediums were used to evaluate the effect of protease inhibitor to protect released insulin from protease degradation. Release rate of insulin from W/O/W multiple emulsions incubated in artificial intestinal fluid was distinctly faster than that incubated in iso-osmosis release medium (water) and hyper-osmosis release medium (phosphate buffer). Microscopic observation confirmed release mechanism is rupturing of the oily membrane resulting from enzymatic hydrolysis of surfactants. Insulin released into artificial intestinal fluid would be hydrolyzed immediately by proteases. Addition of protease inhibitor would improve the stability of this sensitive polypeptide drug by inhibiting enzymatic hydrolysis.

Study on release mechanism of insulin from W/O/W multiple emulsions in different mediums

246th National Meeting (2013)

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