Fabrication of isradipine nanosuspension by anti-solvent microprecipitation-high-pressure homogenization method for enhancing dissolution rate and oral bioavailability

The aim of this study was to develop a nanosuspension of a highly hydrophobic drug, isradipine (ISR) by combination of anti-solvent microprecipitation and high-pressure homogenization to achieve the superior in vitro dissolution and in vivo pharmacokinetic profile. The nanosuspension was formulated using combination of stabilizers as vitamin E TPGS and sodium lauryl sulfate. The developed nanosuspension was characterized for particle size, shape, and zeta potential. The particle size of the developed ISR nanosuspension was observed to be approximately 538 nm (by laser diffraction) and 469 nm (by photon correlation spectroscopy) with -33.3 mV zeta potential. Scanning electron microscopy study revealed the good correlation with particle size measured by photon correlation spectroscopy and laser diffraction. The X-ray diffraction and differential scanning calorimetry showed that ISR was present as an amorphous state in the lyophilized form of nanosuspension. In vitro dissolution and saturation solubility study showed the dissolution rate of nanosuspensions (98.60 %) and saturation solubility (98.76 mu g/ml) compared with the coarse drug (11.53 % and 14.1 mu g/ml, respectively) had been significantly enhanced. The pharmacokinetic study showed that the nanosuspension exhibits increased in AUC(0-48) by 2.0-fold compared to coarse suspension. Further, there was increased in C-max and decreased in t(max) of ISR nanosuspension compared to coarse suspension of ISR. These studies proved that particle size reduction can influence ISR absorption in gastrointestinal tract and thus nanosuspension technology is responsible for enhancing oral bioavailability in rats.