Nanosuspensions: a promising formulation for the new phospholipase A2 inhibitor PX-18

PX-18 is a new highly potent phospholipase A(2) inhibitor with a poor aqueous solubility. Therefore, it was formulated as nanosuspensions with an active content of 1% (w/w), 5% (w/w) and 10% (w/w) using high-pressure homogenization. By contact angle measurements on compressed discs of PX-18, Tween 80 was identified as best wetting agent of PX-18 and therefore used to stabilize the nanosuspensions. The achieved particle size of all nanosuspensions was well in the nanometer range. For the 1% (w/w) PX-18 nanosuspension an average particle size below 50 nm was measured by photon correlation spectroscopy (PCS). A good reproducibility of the mean particle size was found in between different batches. As postulated by the zeta potential of the nanosuspensions, a good physical stability over an observation period of 180 days was obtained when stored at 5+/-3 degrees C. PX-18 formulated as nanosuspensions was chemically stabile. An increase in saturation solubility was found after formulating PX-18 as nanosuspension compared to bulk material, favourable for increasing bioavailability.