Amphiphilic prodrugs of general formula A-X are disclosed, wherein A is a biologically active agent or may be metabolised to a biologically active agent; and X is selected from the group consisting of R, or up to three R moieties attached to a linker, Y1, Y2 or Y3, wherein R is selected from a group consisting of alkyl, alkenyl, alkynyl, branched alkyl, branched alkenyl, branched alkynyl, substituted alkyl, substituted alkenyl and substituted alkynyl groups and their analogues; Y1 is a linker group which covalently attached to an R group at one site and is attached to A at a further independent site; Y2 is a linker group which is covalently attached to two R groups at two independent sites and is attached to A at a further independent site; and Y3 is a linker group which is covalently attached to three R groups at three independent sites and is attached to A at a further independent site. Self-assembly of the amphiphilic prodrugs into reverse lyotropic phases, particularly hexagonal, cubic and sponge, is disclosed. In preferred embodiments A is dopamine or a 5-fluorouracil prodrug.