Drugs suspected to be involved in the DDI
Complete list of drugs taken by the patient
Llevetiracetam 1000 mg BID, Lamotrigine 75 mg BID
Clinical case description
A 73-year-old male treated with ritonavir boosted darunavir was initially started on warfarin for the treatment of a newly diagnosed non-valvular atrial fibrillation. Due to the difficulty in normalizing INR while receiving warfarin treatment and due to bleeding episodes that occurred while the patient was receiving this medication, it was decided to switch warfarin to the direct oral anticoagulant apixaban. The patient received apixaban at a dose of 2.5 mg twice daily together with darunavir/ritonavir and did not present adverse effects including bleeding or recurrent thrombus. The present case has been published by Lomakina V et al. J Pharm Pract 2022.
The product labels for apixaban do not recommend the concomitant use with strong dual CYP3A4 and P-gp inhibitors, although the US label for apixaban gives the option to use apixaban at a reduced dose (i.e., 2.5 mg) if needed.
This case is consistent with previous observations in six HIV infected patients who were successfully treated a reduced dose of apixaban while on ritonavir boosted regimens (Nisly SA et al. Int J STD AIDS 2019).