EFFICACY OF THE ACYCLIC NUCLEOSIDE PHOSPHONATES (S)-9-(3-FLUORO-2-PHOSPHONYLMETHOXYPROPYL)ADENINE (FPMPA) AND 9-(2-PHOSPHONYLMETHOXYETHYL)ADENINE (PMEA) AGAINST FELINE IMMUNODEFICIENCY VIRUS

The acyclic nucleoside phosphonates (S)-9-(3-fluoro-2-phosphonylmethox ypropyl)adenine (FPMPA) and 9-(2-phosphonylmethoxyethyl)adenine (PMEA) were evaluated for their efficacy and side effects in a double-blind placebo-controlled trial using naturally occurring feline immunodefici ency virus (FIV)-infected cats. This natural retrovirus animal model i s considered highly relevant for the pathogenesis and chemotherapy of HIV in humans. Both PMEA and FPMPA proved effective in ameliorating th e clinical symptoms of FIV-infected cats, as measured by several clini cal parameters including the incidence and severity of stomatitis, Kar nofsky's score, immunologic parameters such as relative and absolute C D4(+) lymphocyte counts, and virologic parameters including proviral D NA levels in peripheral blood mononuclear cells (PBMC) of drug-treated animals, in contrast with PMEA, FPMPA showed no hematologic side effe cts at a dose that was 2.5-foId higher than PMEA.