Tenofovir Renal Toxicity: Evaluation of Cohorts and Clinical Studies—Part One

Tenofovir is one of the most commonly used antiretrovirals in adolescents and adults because of its potency and favorable pharmacokinetic and relative safety toxicological profile. It has been combined successfully with antiretroviral drugs from classes such as protease inhibitors, non-nucleoside reverse transcriptase inhibitors and nucleoside reverse transcriptase inhibitors to achieve virologic suppression in a high percentage of recipients. Despite its therapeutic success, quite a number of cohorts and clinical studies have associated tenofovir with the development of renal toxicity with few studies on the opposing end. This stimulated us to review reported cohorts and clinical studies on tenofovir renal toxicity. In this study it was observed that literature reported incidence of tenofovir renal toxicity falls within the range of 0.7%-17%. Available studies gave different appellations to tenofovir renaltoxicity, which include fanconis syndrome, proximal tubule dysfunction, acute renal failure, chronic renal failure, chronic kidney disease and nephrogenic diabetes insipidus. Markers of renal toxicity (tubulopathy) which include glycosuria, hyperaminoaciduria, proteinuria, hyperphosphaturia, hyperuricosuria, retinol-binding protein, beta2-microglobulinuria, decreased creatinine clearance and decreased glomerular filtration rate were also reported. In some studies renal biopsy demonstrated cytoplasmic vacuolization, apical localization of nuclei and reduction of the brush border on proximal tubule epithelial cells. This study observed that tenofovir renal toxicity could be reversible on discontinuation of tenofovir therapy despite contrary views by some studies. Regardless of tenofovir reported renal toxicity, it is well tolerated with a relative safety profile but it is advised that renal profile of patients should be evaluated before and routinely during tenofovir therapy.