Preparation of an anhydrous reverse micelle delivery system to enhance oral bioavailability and anti-diabetic efficacy of berberine.

To enhance oral bioavailability and anti-diabetic efficacy of berberine (BER), an anhydrous reverse micelle (ARM) delivery system was prepared through lyophilization of water-in-oil (W/O) emulsions. Using soy phosphatidylcholine as emulsifiers, BER-containing W/O emulsions were prepared and then lyophilized to form dry products which, upon addition of oil, formed clear ARMs containing amorphous BER nanoparticles. BER-loaded ARMs or free BER solutions were administered to streptozocin-induced diabetic mice. In vivo measurements demonstrated that the blood glucose levels (BGLs) of diabetic mice reduced on average to 22% of the initial values 4h after intravenous injection of BER solution at the dose of 2.5mg/kg body weight, while the average BGL reduction was 57% in the group gavaged with ARMs at the dose of 100mg/kg body weight. No significant BGL reduction was noticed in mice orally received BER solutions. Compared to BER solutions, the oral bioavailability of BER-loaded ARMs was enhanced 2.4-fold, and the maximum blood concentration of BER was enhanced 2.1-fold with a 2-h time lag leading to a prolonged efficacy. Thus, this novel ARM delivery system provides a valid method to improve oral bioavailability and anti-diabetic efficacy of BER, offering a promising product alternative to other hypoglycemic drugs for diabetes therapy.