AN ANTIVIRALLY ACTIVE PHARMACEUTICAL OIL-IN-WATER EMULSION CONTAINING 9- (2-HYDROXYETHOXY)METHYL]GUANINE (ACYCLOVIR) OR A SALT OR ESTER THEREOF

An antivirally active pharmaceutical oil-in-water emulsion containing 9-[(2-hydroxyethoxy)methyl]guanine (acyclovir) or a salt or ester thereof as an active ingredient in the continuous aqueous phase, said phase in addition to said active ingredient and the dispersed oil phase containing a water miscible organic solvent, wherein a polyhydric alcohol may form a constituent. The emulsion comprises from 1 % to 10 % w/w of acyclovir or a salt or ester thereof, from 20 % to 50 % w/w of organic solvent comprising from 5 % to 50 % w/w glycerol formal and from 0 % to 29 % w/w of a polyhydric alcohol, and from 20 % to 40 % w/w water, said percentages being based on the total weight of the formulation. As a polyhydric alcohol propylene glycol may be used, and the emulsion may be available as a cream, wherein the oil phase comprises white vaseline, liquid paraffin (paraffin oil), glycerol monostearate, and stearic acid.