The invention relates to compounds of general formula (I), in which: R is an amino or guanidino group; R.sup.2 is acetyl or trifluoroacetyl; n and q are either the same or different and selected from 0, 1 or 2; and X is an optionally substituted phenyl, optionally substituted naphthyl or optionally substituted phenyl-Y-optionally substituted phenyl in which Y is selected from a covalent bond, CH.sub.2, CH.sub.2CH.sub.2, O or SO.sub.2, or a pharmaceutically acceptable derivative thereof, with the proviso that when X is phenyl or naphthyl, n and q are both 2 and when X is phenyl-Y-phenyl in which Y is a covalent bond, then n and q are not both 0, methods for their preparation, pharmaceutical formulations containing them or their use in the prevention or treatment of a viral infection.