Dermal and Ocular Safety of the New Phospholipase A₂ Inhibitors PX-18 and PX-13 Formulated as Drug Nanosuspension

PX-18 and PX-13 are new secreted phospholipase A₂ inhibitors. An increased expression of secreted phospholipase A₂ in psoriatic epidermis and dermis was reported in the literature, hence the dermal application of PX-18 and PX-13 seems to be a promising approach for psoriasis treatment. Both compounds are practically insoluble in aqueous media and hard to formulate using conventional techniques. Therefore, nanosuspensions were prepared by high pressure homogenization. Pre-clinical skin and eye irritation tests were performed with PX-18 and PX-13 bulk material and 5% (w/w) PX-18 and PX-13 nanosuspensions using the EPISKIN and the HET-CAM test to aid safety assessment and to facilitate the design of safe and efficient human studies. It could be shown that nanosuspensions with an active content of 5% (w/w) with a particle size well in the nanometer range can be produced applying high pressure homogenisation. The results of the EPISKIN test allow the classification of PX-18 and PX-13 bulk material and the according nanosuspensions as non irritant to the skin. According to the test protocol applied for the HET-CAM test, the bulk material of the new secreted phospholipase A₂ inhibitors as well as the nanosuspensions can be classified as non/slightly irritant to the eye.