with concomitant av-951 Tivozanib ritonavir use. More studies have further showed that tenofovir/boosted PI regimens cause faster/greater eGFR decline compared to tenofovir/NNRTI regimens. More in vitro systems revealed that MRP4 overexpressing cells had less intracellular tenofovir accumulation and were less likely to develop cytotoxicity. In OAT1 knock out mice tubular toxicity was prevented, whereas susceptibility increased in MRP4 knock outs. Genetic polymorphisms in the renal CYP450 system may also increase drug concentration by altered enzyme activity and suggest yet another mechanism. If glomerular function is reduced before tenofovir introduction, concentrations in renal tubular cells will increase due to the reduced filtration and thereby possibly worsen existing impairment.
Clinical Evidence of Tenofovir Nephrotoxicity WZ8040 EGFR inhibitor Pre marketing clinical trials did not indicate increased risks of tenofovir nephrotoxicity compared to controls, but case reports of a new/accelerated renal impairment in tenofovir treated individuals began to emerge in 2002 and have become extensive. Most cases are of proximal renal tubulopathy and less frequently of glomerular affection. In a few reports impairment occurred in individuals with initial normal function. Commonly cases had other comorbidities. Some studies, including several randomized trials, suggest that ARV associated nephrotoxicity occurs most frequently in early treatment phases, but no study hasbeen able to firmly disentangle if the pathogenesis is a onehit or cumulative effect. There are numerous cross sectional studies suggesting tenofovir nephrotoxicity.
A recent French study identified tenofovir as an independent predictor of proximal tubular dysfunction. INCB018424 Persons previously exposed to tenofovir had an increased risk of dysfunction compared to those currently exposed, which may reflect that drug discontinuation was related to a declining function. Also in a US study tenofovir exposed individuals had larger eGFR declines and greater risk of proximal tubular dysfunction and drug discontinuation compared to controls. Similar findings were shown in other studies with different measures of kidney function. Despite major limitations related to study design and size, these cross sectional studies provide important information on tenofovir effects, because several different measures of kidney function concur that exposure is associated with excess risk of kidney impairment.
The studies do, however, not provide any clarity on the time course of onset of risk. Multiple observational studies have also studied the nephrotoxic potential for tenofovir. A safety event analysis reported a 0.5% incidence of any serious renal adverse event, 0.3% AKI/CKD, 0.1% Fanconi syndrome, and 2.2% any creatinine increase. All persons included had initial normal renal function and were followed for relatively short periods of time, which may contribute to the relatively low overall occurrence. The voluntary reporting system increases the risks of underreporting, which also apply to a 2008 FDA report on the same topic. A 2010 meta analysis included 17 studies of which 9 were randomized trials. A modest, but significantly increased risk of AKI and a larger median eGFR decline was shown for tenofovir exposed compared to controls. The modest