Nucleoside reverse transcriptase inhibitors, mitochondrial DNA and AIDS therapy

NRTIs are cornerstones of antiretroviral therapy and perhaps the most important drugs developed for AIDS treatment. Judicious use of NRTIs in the fight against HIV infection has afforded significant clinical advances in AIDS treatment. Nonetheless, it is axiomatic to expect side effects from NRTIs as well. A principal toxicity of NRTIs relates to chronic and cumulative MT in various tissues. The long-term impact of this toxicity on affected patients is not clear except in extreme cases where morbidity was severe and mortality occurred. Because of chronicity and potential for severity, NRTI MT remains an important clinical problem. Further studies will help us unravel mechanisms of NRTI MT and the natural history of mitochondrial biogenesis in humans and other mammalian systems.     

Predictive factors and selection of thymidine analogue mutations by nucleoside reverse transcriptase inhibitors according to initial regimen received

Thymidine analogue mutations were determined and compared in patients who received zidovudine monotherapy and added didanosine or zalcitabine, and in patients who started with one of these dual nucleoside combinations. Although patients who started in the era of zidovudine monotherapy had a longer duration of therapy compared with the other group, there was no statistical difference in the number of mutations between the two groups. However, thymidine analogue mutations were more frequent in patients who added didanosine to zidovudine monotherapy compared with those who added zalcitabine. Patients who started with a dual nucleoside combination developed 215Y/F first, followed by 215Y/F+41L, then 215Y/F+41L+210W, then 215Y/F+67N+70R+41L or 219Q/E, and then 215Y/F+41L+67N+70R+219Q/E. Patients who started with zidovudine monotherapy had a different pathway with the mutation at codon 70 appearing first, followed by 215Y/F+70R or 210W, then 215Y/F+41L+210W, then 215Y/F+67N+70R+219Q/E, and then 215Y/F+41L+67N+70R+210W. Medication adherence was associated with the number of mutations in both groups of patients. Two distinct mutational patterns were noted. The first pattern involved mutations at codons 41, 210 and 215, while the second involved mutations at codons 67, 70 and 219.