Tenofovir disoproxil fumarate/emtricitabine (TDF/FTC; Truvada or generic equivalents) for pre-exposure prophylaxis (PrEP) is generally safe for the kidneys, according to a recent study.

Jean-Michel Molina, MD, and colleagues with the French ANRS-PREVENIR Study Group assessed the impact of different PrEP dosing regimens on kidney function. The analysis included 1,235 participants, mostly gay and bisexual men, in the PREVENIR trial, which compared daily PrEP versus on-demand PrEP before and after sex. Because of TDF’s known effect on the kidneys, the trial was limited to people with adequate kidney function at baseline. For this analysis, they were divided into three groups: daily use (40%), on-demand use (39%) and those who switched (21%); the three groups took a median of 6.0, 1.7 and 4.0 pills per week, respectively.

The researchers looked at estimated glomerular filtration rate (eGFR), a measure of how fast the kidneys filter toxins such as creatinine out of the blood. Over a median follow-up period of about two years, eGFR declined slightly in the daily and switch groups but rose slightly in the on-demand group, but the researchers did not consider these small changes to be clinically important. Only five people, distributed across the groups, saw an eGFR decline of 25% or more.

“In our study, the renal safety of PrEP with tenofovir disoproxil fumarate/emtricitabine was good, whatever the dosing regimen,” the study authors concluded. “On-demand PrEP dosing had a smaller impact on eGFR evolution than daily PrEP, but the difference was not clinically relevant.”