Drug Interactions between amoxicillin / clarithromycin / omeprazole and pirtobrutinib

GENERALLY AVOID: Coadministration with potent inhibitors of CYP450 3A4 may significantly increase the plasma concentrations of pirtobrutinib, which is primarily metabolized by the isoenzyme. When pirtobrutinib (200 mg single dose) was administered with itraconazole, a potent CYP450 3A4 inhibitor, pirtobrutinib systemic exposure (AUC) increased by 49%. Increased exposure to pirtobrutinib may increase the risk of infection, bruising, bleeding, fatigue, musculoskeletal pain, diarrhea, edema, and dyspnea.

MANAGEMENT: Coadministration of pirtobrutinib with potent CYP450 3A4 inhibitors should be avoided. If concomitant use of a potent CYP450 3A4 inhibitor is unavoidable, reduce the pirtobrutinib dose by 50 mg. If the current dosage is 50 mg once daily, interrupt pirtobrutinib treatment for the duration of potent CYP450 3A4 inhibitor use. After discontinuation of a potent CYP450 3A4 inhibitor for 5 half-lives, resume the pirtobrutinib dose that was taken prior to initiating the potent CYP450 3A4 inhibitor.

MONITOR: Coadministration with pirtobrutinib may increase the plasma concentrations of drugs that are substrates of CYP450 2C8, 2C19, 3A4, P-glycoprotein (P-gp), and/or breast cancer resistance protein (BCRP). The peak plasma concentration (Cmax) and systemic exposure (AUC) of repaglinide, a CYP450 2C8 substrate, increased by 98% and 130%, respectively, and the Cmax and AUC of omeprazole, a CYP450 2C19 substrate, increased by 49% and 56%, respectively, when administered with pirtobrutinib. The Cmax and AUC of oral midazolam, a CYP450 3A4 substrate, increased by 58% and 70%, respectively, while exposure to IV midazolam was not significantly affected, when administered with pirtobrutinib. The Cmax and AUC of digoxin, a P-gp substrate, increased by 51% and 17%, respectively, when administered with a single pirtobrutinib dose (200 mg), and 55% and 35%, respectively, when administered with multiple pirtobrutinib doses (200 mg daily). The Cmax and AUC of rosuvastatin, a BCRP substrate, increased by 146% and 140%, respectively, when administered with pirtobrutinib. The risk of adverse reactions related to these substrates may be increased.

MANAGEMENT: Caution is advised if pirtobrutinib is used concomitantly with substrates of CYP450 2C8, 2C19, 3A4, P-gp, and/or BCRP, particularly sensitive substrates or those with a narrow therapeutic range. The prescribing information for concomitant medications should be consulted to assess the benefits versus risks of coadministration and for any dosage adjustments that may be required.

Although some in vitro data indicate synergism between macrolide antibiotics and penicillins, other in vitro data indicate antagonism. When these drugs are given together, neither has predictable therapeutic efficacy. Data are available for erythromycin, although theoretically this interaction could occur with any macrolide. Except for monitoring of the effectiveness of antibiotic therapy, no special precautions appear to be necessary.

Clarithromycin may increase and prolong the omeprazole plasma concentration. The mechanism may be related to clarithromycin inhibition of hepatic cytochrome P450 enzymes responsible for omeprazole metabolism. Coadministration of omeprazole may result in an increase in clarithromycin and 14-(R)-hydroxyclarithromycin plasma concentrations. These increases may be due to the effect of omeprazole on gastric pH.