Despite warnings from the U.S. Food and Drug Administration (FDA) against combining rivaroxaban and boosted antiretroviral therapy, concomitant usage is common in the U.S., according to findings published in Clinical Infectious Diseases. The FDA warning exists because coadministering these drugs may increase the risk of bleeding.
The findings derive from a longitudinal cohort study in Washington, D.C. During the study’s January 2011-March 2017 observation period, 206 of the 8,315 participating PLWH received a total of 236 anticoagulant prescriptions—140 for warfarin and 96 for a direct oral anticoagulant (DOAC).
DOAC prescriptions increased in frequency throughout the study period and accounted for a majority of oral anticoagulant prescriptions by the end of 2016. (Warfarin, of course, has its own long history of safety risks and challenging dosing requirements, which has only fed the progressive switch to DOACs.) Rivaroxaban was the most frequently prescribed DOAC, accounting for 67% of all DOAC prescriptions.
Among study participants who began taking oral anticoagulants, 47% were on an antiretroviral regimen containing a booster drug (i.e., ritonavir or cobicistat). Although DOAC-booster interaction risks were sometimes caught and corrected, among people who began taking rivaroxaban, the proportion receiving a boosted antiretroviral only dropped from 56% to 41% after one month of anticoagulant therapy.
The observed prescribing pattern—which occurred in the face of drug interaction warnings—shows the importance of communication between different prescribers, including the need for a monitoring plan, study authors wrote. “This is especially important for DOACs given their relatively recent introduction and the potential unfamiliarity of prescribers with DOAC-ART interactions,” they concluded.
Further complicating the co-prescription of HIV and anti-clotting medications are varying recommendations for different drug combinations, as well as drug label differences between U.S. and European agencies.
Patients should be encouraged to fill all their prescriptions at the same pharmacy to allow pharmacy specialists to flag potential interactions, study authors recommended.