Clinical Pharmacology of Bulevirtide: Focus on Known and Potential Drug-Drug Interactions

: Background: Hepatitis D virus (HDV) is a defective virus requiring co-infection with hepatitis B virus (HBV) to replicate, occurring in 5% of HBV+ patients. Bulevirtide (BLV) is now the first-in-class specific anti-HDV agent, inhibiting HDV binding to NTCP, with good tolerability and good virological and biochemical response rates. Currently, little is known about its pharmacokinetic/pharmacodynamic (PK/PD), as well as potential drug-drug interaction (DDI) profile. In this work we provide a systematic review of the current knowledge on these aspects. Methods: A literature review of PK, PD and DDI profiles of BLV was conducted from Pubmed and EMA websites. Experimentally tested interactions and hypothetical mechanisms of interaction were evaluated, mostly focusing on usually co-administered anti-infective agents and other drugs interacting on NTCP. Results: BLV shows non-linear PK, due to target-mediated drug disposition, so its PK as well as PD is expected to be influenced by interactions of other drugs with NTCP, while it is not substrate of CYPs and ABC transporters. In-vivo investigated DDIs showed no clinically relevant interactions, but a weak inhibitory effect was suggested on CYP3A4 in a work when used at high doses (10 mg instead of 2 mg). In vitro, a weak inhibitory effect on OATP transporters was observed, but at much higher concentrations than the ones expected in vivo. Conclusions: The drug-drug interaction potential of BLV can be considered generally very low, particularly at the currently approved dose of 2 mg/day. Some attention should be paid to the coadministration of drugs with known binding and/or inhibition of NTCP.