Skin penetration enhancing components

The present invention relates to a topical formulation for the treatment of a dermatological condition which comprises a macrocyclic lactone antibiotic, immunosuppresive macrolide or a biologically active analogue, derivative or pro-drug thereof; characterized in that it further comprises a permeation modulator and the permeation modulator and the macrocyclic lactone or macrolide or the biologically active analogue, derivative or pro-drug thereof are present in relative amounts such that when a therapeutic amount is applied to the skin a minimal systemic effect is produced. The immunosuppressive macrolide may be sirolimus.