A combination of three anti-HIV compounds (AZT, ddC and saquinavir) has been studied in vitro. In confirmation and extension of previous studies, a greater than additive effect was found against both HIV-1GB8 and HIV-1N1T, when any two compounds were combined. Synergy of action was also found against both virus strains when all three compounds were employed together. Cytotoxicological studies indicated that a high therapeutic index could be maintained for this treatment. The potential benefits of improved anti-HIV surveillance, reduced risk of the development of resistance to the treatment and reduced requirement for drugs in quantities that produce toxic side-effects support the extension of clinical trials of saquinavir to investigate this combination.
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