First-administrated and actual drug regimens while failing treatment.

aAll except 5 received NRTIs as part of the first regimen. A few received mono- or duo-therapy or combinations of PIs and NNRTIs.
bAll 78 treatment-failing patients received NRTI backbone. Thirty-four received also PI and 39 NNRTI as additional drug.
3TC – lamivudine; EFV – efavirenz; FTC – emtricitabine; LPV/r – lopinavir/r; NNRTI – Non-Nucleoside Reverse Trancriptase Inhibitor; NRTI – Nucleoside Reverse Trancriptase Inhibitor; NVP – nevirapine; PI – Protease inhibitor; r – ritonavir; TDF – tenofovir; ZDV – zidovudine.