Adenosine 5'-monophosphate (nucleotide) analog reverse transcriptase inhibitor
Mutations associated with drug resistance:
Mutations associated with tenofovir resistance include K65R, T69N/S/A/ins (high-level, multi-NRTI resistance) and Q151M (multi-NTRI resistance). In addition, the nucleotide excision mutations (NEMs) M41L, D67N, L210W, T215/F/Y and K219Q/E/N can contribute to TDF resistance. Substitutions at position 75 may also contribute to TDF resistance.
Phenotypic resistance:
In one study of 5,000 clinical isolates from predominantly treatment-experienced patients, isolates from 88% of patients had <3-fold reduced susceptibility to TDF and only 1% had >10-fold TDF resistance. In contrast, 18% had >10-fold decreases in susceptibility to AZT [Miller MD, et al. 2001]. Of the 51 patients with >10-fold reductions in TDF susceptibility, 48 had multiple NEMs and 18 had insertions at position 69 (associated with multinucleoside resistance). A "clinically relevant" cutoff for TDF resistance has yet to be established.
Tenofovir tenofovir disoproxil fumarate (TDF), PMPA, Viread
