Inhibition of efflux transporters by poly ADP‐ribose polymerase inhibitors

Abstract Poly ADP‐ribose polymerase (PARP) inhibitors have been approved for the treatment of various cancers. They share a similar mechanism of action but have differences in pharmacokinetic characteristics and potential for drug–drug interactions (DDI). This study evaluated the potential ATP‐binding cassette transporter‐mediated interactions between PARP inhibitors (niraparib, olaparib and rucaparib) and statins (atorvastatin and rosuvastatin). We studied the inhibitory activity of PARP inhibitors on breast cancer resistance protein (BCRP), multidrug resistance‐associated protein 3 (MRP3) and P‐glycoprotein (P‐gp) using vesicular transport assays and determined the concentrations required for 50% inhibition (IC 50 ). Then, we predicted the increase of statin exposure followed by the administration of PARP inhibitors using a mechanistic static model. Rucaparib was the strongest inhibitor of BCRP‐mediated rosuvastatin transport (IC 50 13.7 μM), followed by niraparib (42.6 μM) and olaparib (216 μM). PARP inhibitors did not affect MRP3. While niraparib appeared to inhibit P‐gp, the inhibition showed large variability. The inhibition of intestinal BCRP by rucaparib, niraparib and olaparib was predicted to elevate rosuvastatin exposure by 52%, 37% and 24%, respectively. The interactions between PARP inhibitors and rosuvastatin are probably of minor clinical significance alone, but combined with other predisposing factors, they may increase the risk of rosuvastatin‐associated adverse effects.