Drug Interaction Report

Coadministration of niraparib with a P-glycoprotein (P-gp) and/or Breast Cancer Resistance Protein (BCRP) inhibitor may increase the plasma concentration of niraparib, which is a substrate of these efflux transporters. However, due to the high permeability and bioavailability of niraparib, the risk of a clinically relevant interaction with inhibitors of these transporters is unlikely. No dose adjustment is recommended if a P-gp and/or BCRP inhibitor is added to treatment with niraparib.

Grapefruit juice may delay the gastrointestinal absorption of clarithromycin but does not appear to affect the overall extent of absorption or inhibit the metabolism of clarithromycin. The mechanism of interaction is unknown but may be related to competition for intestinal CYP450 3A4 and/or absorptive sites. In an open-label, randomized, crossover study consisting of 12 healthy subjects, coadministration with grapefruit juice increased the time to reach peak plasma concentration (Tmax) of both clarithromycin and 14-hydroxyclarithromycin (the active metabolite) by 80% and 104%, respectively, compared to water. Other pharmacokinetic parameters were not significantly altered. This interaction is unlikely to be of clinical significance.