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Read Now: News and Research From ICAAC 2014

Truvada as PrEP Does Not Cause Kidney Damage, Study Suggests

March 4, 2014

Taking tenofovir/emtricitabine (Truvada) as pre-exposure prophylaxis (PrEP) has little effect on kidney function, according to a study recently published in AIDS. The study, known as IPrEx (Iniciativa Profilaxis Pre-Exposicion), showed a very mild decrease in creatinine clearance (CrCl) -- a measure of kidney function -- among participants taking tenofovir/emtricitabine, but the change was reversible, as CrCl returned to baseline levels after the drug was discontinued at the end of the study.

IPrEx followed 2,499 HIV-negative men who have sex with men (MSM) and transgender women, across sites in Latin America, the U.S. and Thailand. The study previously demonstrated that once-daily tenofovir/emtricitabine was 44% effective in decreasing HIV infection rates, compared to taking a placebo, despite low adherence in a subset of participants.

Study participants were randomized to take either tenofovir/emtricitabine or a placebo for an average of 81 weeks. A statistically significant decrease in CrCl (which reflects an increase in serum creatinine) was observed starting at week 4 (mean change: -2.4 vs. -1.1 ml/min; P = .02) and lasted through the end of treatment (mean change: +0.3 vs. +1.8 ml/min; P = .02), but CrCl returned to baseline after stopping the study drug (mean change: 0.1 vs. 0.0 ml/min; P =.83). These mean changes reflected a small difference in a large portion of the treatment group.

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Week 4 of the study also saw a trend toward a greater decrease in serum phosphorus levels among study participants (mean change from baseline tenofovir/emtricitabine: -0.06 mg/dl vs. placebo: mean -0.01 mg/dl; P = .06), although phosphorus levels did not significantly change over time.

Previous studies, such as the Swiss HIV Cohort Study, had associated tenofovir (Viread) with another kidney problem, proximal renal tubulopathy (PRT). However, a substudy of 1,137 IPrEx participants found no indication of PRT in 94% of that group. Those who did develop PRT had been randomized to the placebo arm of the study, so their renal troubles were not related to being on PrEP.

Similar studies in HIV-positive people had shown a somewhat higher degree of renal function impairment, which did not always resolve itself after tenofovir/emtricitabine was stopped. By contrast, the almost 2,500 participants in this study had no pre-existing risk factors for renal disease, such as infection with HIV or hepatitis B. However, the low adherence to PrEP might have mitigated some of the renal effects of the medication.

While tenofovir/emtricitabine as PrEP does not appear to cause kidney damage, the study authors recommend monitoring the renal safety of PrEP as it becomes more widely available to people who may be predisposed to kidney problems. They also caution that a second test for kidney function should be performed before stopping tenofovir/emtricitabine, because most creatinine elevations are self-limiting.

Barbara Jungwirth is a freelance writer and translator based in New York.

Follow Barbara on Twitter: @reliabletran.


Copyright © 2014 Remedy Health Media, LLC. All rights reserved.



 

Reader Comments:

Comment by: TonyDewitt (Newark, NJ) Thu., Mar. 13, 2014 at 3:49 pm EDT
I agree that short term studies on a drug already known to cause kidney damage accomplish little. Rather than live in the past, studies should be done to show that the NEW formulation of tenofovir (TAF, not TDF) is much less toxic, and all patients should be switched to that drug, instead of milking the patent for the older drug.
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Comment by: Bert Pannapacker (Philadelphia, PA.) Thu., Mar. 13, 2014 at 3:24 pm EDT
A year and seven months is hardly sufficient time to gauge the long term effects of any medication
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Comment by: Dave R (Amsterdam, Netherlands) Thu., Mar. 13, 2014 at 2:44 pm EDT
Apparently, the kidney problems that did show up, disappeared after stopping the drug. However, PrEP is not meant to be a stop-start treatment and it is well known that kidney problems begin after some years on Truvada. This study, is therefore too short for a long-term use analysis.
As an aside; it's not exactly reassuring that PrEP only has a 44% success rate in reducing infection - not exactly confidence inspiring!
I wonder also why the study group (Wolters Kluwer Health) is back tracking on its own warnings about kidney damage (http://www.drugs.com/cdi/emtricitabine-tenofovir.html) in March this year and also doesn't follow up on this group's own conclusions that Truvada casues lactic acidosis build up and liver problems. A few too many inconsistencies for my taste.
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