Single phase pharmaceutical compositions for topical application, in addition to kits and methods of use and administration are provided. The compositions comprise a biologically active agent; a delivery vehicle comprising at least a non-polymeric crystallization inhibitor and a film-former; and a volatile solvent; wherein the biologically active agent is present in the composition in a subsaturated state, the biologically active agent is present in the delivery vehicle in a supersaturated state, and the crystallization inhibitor is capable of delaying crystallization of the biologically active agent in the delivery vehicle. Biologically active agents include terbinafine and acyclovir. Treatments for onychomycosis and Varicella zoster infection, HSV-1 infection or HSV-2 infection are provided.