[Anti-HIV drugs and drug delivery system]

A number of candidate drugs for therapy of HIV-1 infection which show significant activity against the virus in vitro were reported; however, many of them have been dropped from drug development due to (i) insufficient intracellular activation in certain human target cells (particularly in case of nucleoside reverse transcriptase inhibitors), (ii) poor pharmacokinetic profiles, or (iii) intolerable in vitro and/or in vivo toxicities. To circumvent some of these problems, certain drug delivery systems have been applied and several candidate drugs including two novel nucleoside reverse transcriptase inhibitors, abacavir and adefovir, have acquired favorable properties in the clinical setting. This paper reviews several avenues for developing prodrugs of anti-HIV-1 agents to overcome their inherent limitations.