Improvement in renal function and bone mineral density after a switch from tenofovir/emtricitabine plus ritonavir-boosted protease inhibitor to raltegravir plus nevirapine: a pilot study

Background: The antiretroviral regimens including tenofovir and a ritonavir-boosted protease inhibitor (r/PI) have been associated with a reduced bone mineral density (BMD), increased bone turnover markers and renal tubular dysfunction. Methods: An observational, prospective study was performed including HIV-1-infected, virologically suppressed patients treated with tenofovir/emtricitabine plus an r/PI for at least 12 months who switched to raltegravir plus nevirapine. The primary end point was changes after 48 weeks in estimated glomerular filtration rate (eGFR), prevalence of tubular dysfunction, BMD and concentration of two serum markers of bone turnover: collagen type-1 cross-linked C-telopeptide (CTX) and bone-specific alkaline phosphatase (BAP). Results: A total of 46 patients were enrolled: 78% were male, 96% were Caucasian, the mean age was 45 years and the mean CD4 T-lymphocyte count was 681 cells/mm(3). A renal impairment was present in 72% of patients and was the main reason for the switch. After 48 weeks, prevalence of proximal tubular dysfunction decreased significantly (-72%; P<0.001), whereas the mean value of eGFR did not change significantly. At the same time, after 48 weeks a significant increase in both lumbar spine and total hip BMD, T-score and Z-score was reported (+11.5% in lumbar spine T-score; P<0.001), and there was a significant reduction in both CTX and BAP mean serum concentrations (-15% and -13%, respectively; P<0.001). Two (4.3%) patients had virological failure due to suboptimal adherence and one (2.2%) subject discontinued treatment due to a skin rash. Conclusions: Switching virologically suppressed patients from tenofovir/emtricitabine plus one WI to raltegravir plus nevirapine after 48 weeks significantly improved proximal tubular function, increased