The Relationship between the Human Immunodeficiency Virus and the Acquired Immunodeficiency Syndrome (Draft)

DRAFT
AZT and AIDS NJ -VJA
In vitro, AZT inhibits the reverse transcriptase of HIV and other retroviruses, including
animal lentiviruses (Richman, 1992; McLeod and Hammer, 1992). In patients with advanced
HIV infection, for whom a beneficial effect is measured in months, AZT appears to slow
disease progression and prolong life, according to double-blind, placebo-controlled clinical
studies (reviewed in Sande et al., 1993; McLeod and Hammer, 1992). A clinical trial known
as BW 02 compared AZT with placebo in 282 patients with AIDS or advanced signs or
symptoms of HIV disease. In this study, which led to the approval of AZT by the FDA, only 1
of 145 patients treated with AZT died compared with 19 of 137 placebo recipients.
Opportunistic infections occurred in 24 AZT recipients and 45 placebo recipients. In addition to
reducing mortality, AZT was shown to reduce the frequency and severity of AIDS-associated
opportunistic infections, improved body weight, prevented deterioration in Kamofsky
performance score, and increase counts of CD4+ T lymphocytes in the peripheral blood
(Fischl et al., 1987; Richman et al., 1987). Continued follow-up in 229 of these patients
showed that the survival benefit of AZT extended to at least 21 months after the initiation of
therapy; survival in the original treatment group was 57.6 percent at that time, whereas
survival among members of the original placebo group was 51.5 percent at 9 months.(Fischl
et al., 1988; Richman and Andrews, 1988).
In another placebo-controlled study known as ACTG 016, symptomatic HIV-infected
patients with CD4+ T cell counts between 200 and 500 cells mm3 taking AZT were less likely
to experience disease progression than those on placebo during a median study period of 11
months (Fischl et al., 1990).
Among asymptomatic HIV-infected individuals, several placebo controlled clinical trials
suggest that AZT can delay disease progression for 12 to 24 months but ultimately does not
increase survival. Significantly, long-term follow-up of these trials, although not showing
prolonged benefit of AZT, has never indicated that the drug increases disease progression or

21