The present invention relates to a method of preparing a nanoparticulate topical composition of a water soluble, water-susceptible active ingredient or its pharmaceutically acceptable salt, the method comprising steps of milling the water soluble, water-susceptible active ingredient or its salt, a wetting agent and a non-aqueous liquid vehicle to obtain a non-aqueous nanosuspension and converting the non-aqueous nanosuspension into a topical composition.
