d4T (stavudine, Zerit) is able to reduce HIV viral load and increase CD4 cell counts in the majority of people when taken in combination with at least two other antiretroviral drugs. It is regarded as an alternative to AZT (zidovudine, Retrovir) as a basis for multi-drug combinations, with early studies showing comparative virological results of the two drugs when combined with 3TC (lamivudine, Epivir) and indinavir (Crixivan)^[1][2]. The first of these studies revealed that patients taking d4T had larger increases in CD4 cell counts than those taking AZT^[3].

d4T crosses the blood-brain barrier and is effective against HIV in the brain and the central nervous system^[4].

d4T was first licensed after a clinical study showed that d4T monotherapy reduced the rates of death and progression to AIDS, when compared to AZT. All of the patients had taken AZT for at least six months before entry into the study^[5]. This conclusion was confirmed by a large trial of over 13,000 patients that assessed the effectiveness of d4T in patients who had experienced failure of treatment with AZT, ddI (didanosine, Videx / VidexEC) or ddC (zalcitabine, Hivid)^[6].

More recently, studies comparing the standard version of d4T to a new extended release version have provided evidence of the drug’s effectiveness when combined with 3TC (lamivudine, Epivir) and efavirenz (Sustiva). Two separate studies showed that triple drug combinations including d4T were safe and effective in patients who had not taken any anti-HIV drugs before and those with treatment experience^[7][8].