Renal toxicity as a consequence of tenofovir treatment is rare in patients who switch to the drug as a result of nucleoside analogue toxicity, according to Spanish data presented to the 44th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) in Washington.
There have been a series of reports of acute renal failure and Fanconi syndrome in individuals taking tenofovir since the drug received regulatory approval in 2003. However, the frequency of kidney toxicities caused by tenofovir is still unclear.
Investigators from the ongoing Spanish RECOVER study presented interim data from 844 individuals. Individuals enrolled in the RECOVER cohort have switched from an NRTI to tenofovir due to side-effects.
The mean duration of follow-up was 37 weeks.
A total of five patients experienced acute renal failure, all had concomitant risk factors for renal failure including diabetes, a history of renal failure, sepsis and kidney failure caused by cidofovir.
Three of the five individuals were men, two individuals had a history of injecting drug use, and three patients were on their fourth or later HAART regimen.
Creatinine clearance was measured in two patients prior to starting tenofovir, and was found to be below 50ml/min, the level at which the tenofovir dosing interval is recommended to be adjusted from daily to every other day. However, in neither patient did this dose adjustment occur.
The incidence of renal impairment leading to the discontinuation of tenofovir was 0.6% (0.67 per 100 person years). The investigators conclude, “these data suggest that tenofovir is a renal safe drug.”
Estrada V et al. Renal safety of tenofovir DF in HIV treatment-experienced patients with adverse events related to NRTI use (RECOVER Study). 44th ICAAC, Washington, abstract H-169, 2004.