More Tenofovir PrEP Data on MSM: The CDC Safety Study
Demetre C. Daskalakis, MD, MPH
Findings from this trial suggest that tenofovir is safe to use for preexposure prophylaxis; such use was not associated with an increase in risky sexual behaviors.
Following FDA approval of tenofovir/FTC as antiretroviral preexposure prophylaxis (PrEP), studies continue to be reported on this intervention. In two recently published papers based on the same domestic trial involving men who have sex with men, researchers examined the safety and tolerability of tenofovoir PrEP and the sexual risk taking of participants.
The randomized, phase II CDC Safety Study involved four arms: delayed and immediate tenofovir PrEP and delayed and immediate placebo; follow-up lasted 24 months after drug initiation. The delayed arms were included to assess changes in risk-taking behaviors associated with taking the study drug. Of 400 participants enrolled, 373 received a study drug at least once and were included in the analysis. Study drugs were supplied by the manufacturer.
Focusing on the safety of tenofovir PrEP, Grohskopf and colleagues showed that tenofovir was not associated with an increase in any adverse events (AEs) other than back pain, including hypophosphatemia or creatinine elevation. Although 334 men (90%) reported AEs, 97% of such events were mild or moderate. Back pain was weakly associated with tenofovir PrEP in this analysis, but no tenofovir-attributable fractures occurred. No serious AEs were associated with tenofovir PrEP, and no seroconversions occurred among participants taking tenofovir.
Focusing on sexual risk-taking behaviors, Liu and colleagues found no evidence of risk compensation among trial participants. Over time, most risk indices decreased in both the delayed and immediate arms of the study. In multivariate analysis, substance abuse was significantly associated with risk taking.
Citation(s):
Grohskopf LA et al. Randomized trial of clinical safety of daily oral tenofovir disoproxil fumarate among HIV-uninfected men who have sex with men in the United States. J Acquir Immune Defic Syndr 2013 Sep 1; 64:79.
Liu AY et al. Sexual risk behavior among HIV-uninfected men who have sex with men participating in a tenofovir preexposure prophylaxis randomized trial in the United States. J Acquir Immune Defic Syndr 2013 Sep 1; 64:87.
