d4T

The K65R mutation indicates high-level resistance to TDF, DDI and D4T, but low to intermediate-level resistance to 3TC and FTC.

Higher-level ART variables were generated as follows: participants were positively coded for NNRTI-based regimens if they were on a regimen containing either EFV or NVP, for NRTI-based regimens if they were on a regimen containing either ABC or tenofovir (TDF) or d4T or AZT, and for PI-based regimens if they were on a regimen containing LPV/r, darunavir-ritonavir (DRV/r), atazanavir (ATV), raltegravir or DRV/retravirine.

In terms of the NRTI backbone, the combination of stavudine (d4T) and didanosine (ddI) was prescribed least frequently but was the most modified, due to nonadherence.

Study subjects received HAART as per the NACO guidelines, consisting of zidovudine (AZT) (300 mg BID)/stavudine (d4T) (30 mg BID)+lamivudine (3TC) (150 mg BID)+nevirapine (NVP) (200 mg OD)/efavirenz (EFV) (600 mg OD).

* For patients who were receiving d4T, 3TC and EFV who have a detectable VL, clinicians should do additional adherence counselling and repeat the VL in 2-3 months.

[1,8] Naive patients or those switching from the d4T wash-out protocol received the first-line antiretrovirals that contain AZT at the daily dose of 500 mg if their body weight <60 kg and 600 mg if >60 kg.

Second, AZT should not be used as the first-line drug and instead use d4T as the first drug and use AZT as a switch therapy after sometime and while on AZT patients should be carefully and closely monitored.

The drugs most commonly prescribed were stavudine (d4T), lamivudine (3TC) and efavirenz (EFV).

At week 48, the proportion of patients with a viral load below 50 copies/ml was 76.3% and 79.7% for the TDF and d4T arms, respectively.

Switching away from d4T has shown benefits, although often slow and modest.

Age Sex drugs received start of ART 2-29 46 F 3TC, ZDV, EFV 33 2-44 49 F 3TC, ZDV, EFV 10 2-47 42 M 3TC, ZDV, IDV 10 2-59 36 F 3TC, ZDV, EFV, 52 IDV 2-66 36 M 3TC, ZDV, d4T, 21 ddl, EFV 2-70 30 M d4T, ddl, EFV 6 2-75 37 F 3TC, d4T, IDV 9 2-76 34 M 3TC, d4T, EFV 10 2-84 51 M 3TC, ZDV, d4T, 48 ddl, NFV 2-91 44 M 3TC, d4T, EFV, 6 IDV 2-98 32 F d4T, ddl, IDV 7 22-2 42 M 3TC, ZDV, EFV 14 22-9 33 F 3TC, ZDV, d4T, 31 ddl, EFV, IDV 22-25 30 F 3TC, ZDV, EFV, 18 IDV 22-31 42 M 3TC, d4T, IDV 8 22-33 41 F 3TC, ZDV, IDV 18 22-35 58 M 3TC, ZDV, IDV 17 22-47A 48 F 3TC, ZDV, EFV, 45 IDV 22-50 32 M 3TC, d4T, NVP 6 22-57 53 M 3TC, ZDV, EFV 7 221-75 50 F 3TC, ZDV, d4T, 29 ddl, EFV, IDV Patient no.

Additionally, to show the feasibility for use of the assay in a clinical setting, we evaluated the in vivo effects of initiating antiretroviral treatment with zidovudine (AZT), lamivudine (3TC), and indinavir (IDV), and on the mtDNA content in PBMCs derived from patients over time after switching to stavudine (d4T) with didanosine (ddI) and IDV as well as in a study in which protease inhibitors were either continued or switched to non-NRTIs.