Simvastatin nanoemulsion for improved oral delivery: design, characterisation, in vitro and in vivo studies

Simvastatin is poorly bioavailable as it is practically insoluble in water and shows dissolution rate-limited absorption. Therefore, the present study was aimed at preparing nanoemulsion (NE) of simvastatin for improving its solubility and/or dissolution rate for enhancing its bioavailability. The NEs were evaluated for particle size (PS), zeta potential, transmission electron microscopy (TEM), viscosity, in vitro release and stability studies. The optimised NE showed PS of 132 +/- 9nm and zeta potential of 17.1 +/- 1.2 mV. TEM studies demonstrated spherical shape and size of the globules. In vitro release studies showed increased dissolution rate of NE compared with plain drug (PD). Pharmacokinetic studies showed relative bioavailability of simvastatin NE was 369.0% with respect to PD suspension. Pharmacodynamic studies conducted in hyperlipidemic rats showed that significant decrease in the total cholesterol and triglyceride levels for NE as compared with PD proving improvement in bioavailability. In conclusion, NE has great potential for improving bioavailability of poorly water-soluble drugs like simvastatin.