kg once 5 12 17 20 8 u00b1 6 1 115daily days 24 24 27 1 6 i p control 9 3 u00b1 0 45 15 mg kg once 5 21 27 45 6 u00b1 19 8 390daily days 3 u00d7 60 sup a i p control 9 3 u00b1 0 3______________________________________ sup a experiment ended at 60 days animal survival evaluated on this day however these animals were alive with no sign of tumor unexpectedly and for reasons as not yet understood the compounds of the invention have been found to be effective anti vital and most surprisingly anti retroviral agents the development of compounds useful for the prophylaxis and therapy of vital disease has presented more difficult problems than those encountered in the search for drugs effective in disorders produced by other microorganisms this is primarily because in contrast to most other infectious agents viruses are obligate intracellular parasites that require the active participation of the metabolic processes of the invaded cell thus agents that may inhibit or cause the death of viruses are also very likely to injure the host cells that harbor them although the search for substances that might be of use in the management of viral infections has been long and intensive very few agents have been found to have clinical applicability indeed even these have exhibited very narrow activity limited to one or only a few specific viruses the retroviruses lave presented an even.