Role of the Pharmacist
There are various factors for pharmacists to consider with the currently approved PARP inhibitors. Niraparib does not require dosage modifications with respect to CYP3A4 (i.e., olaparib is a CYP3A4 substrate, while rucaparib weakly inhibits CYP3A4).[4–6] This is significant because most patients who receive chemotherapy are often taking medications that interact with various metabolizing enzymes. Niraparib is also the only PARP inhibitor administered once daily.[6] Olaparib is available in capsule and tablet formulations, with the tablets having a higher bioavailability; therefore, the two dosage forms cannot be interchanged.[4] All three drugs can be taken with food, which may relieve some of the nausea that patients can experience while taking these medications.[4–6] Niraparib and rucaparib are moderately emetogenic, and may require using antinausea medications.[5,6] While no dosage adjustment is required for mild hepatic (Child-Pugh classification A) disease or renal impairment (CrCl >30 mL/min) for niraparib or rucaparib, the AUC and Cmax of olaparib are greatly increased in the presence of hepatic or renal impairment, warranting close monitoring and potential dosage changes (especially with regard to renal function for olaparib).[4–6] All three PARP inhibitors are administered orally, which allows patients to take medications at the setting of their choice, rather than at an infusion or oncology center.[4–6] Common adverse effects of approved PARP inhibitors are listed in Table 2.
US Pharmacist. 2018;43(9):HS10-HS17. © 2018 Jobson Publishing
