To assess the dose-related antiviral effects of SC-48334 and zidovudine (AZT) administered in combination or individually in HIV-1 positive patients with 200 - 500 CD4+ cells/mm3. To determine the safety of escalating doses of SC-48334 when administered in combination with any of three doses of AZT to symptomatic HIV-1 positive patients with 200 - 500 CD4+ cells/mm3, and to assess the pharmacokinetics of the two drugs, given separately and in combination.