Drug Interactions between acalabrutinib and amoxicillin / clarithromycin / lansoprazole

GENERALLY AVOID: Coadministration with potent inhibitors of CYP450 3A4 may significantly increase the plasma concentrations of acalabrutinib, which is primarily metabolized by CYP450 3A enzymes to form its active metabolite, ACP-5862. In some instances, inhibition of P-glycoprotein (P-gp) may also contribute, as both acalabrutinib and ACP-5862 have been shown in vitro to be substrates of the efflux transporter. When acalabrutinib was administered with the potent CYP450 3A4 and P-gp inhibitor itraconazole (200 mg once daily for 5 days) in 17 healthy subjects, acalabrutinib peak plasma concentration (Cmax) and systemic exposure (AUC) increased by 3.9- and 5.1-fold, respectively. Increased acalabrutinib exposure may potentiate the risk of toxicities such as hemorrhage, infection, cytopenias, malignancies, and atrial fibrillation or flutter.

MANAGEMENT: Concomitant use of acalabrutinib with potent CYP450 3A4 inhibitors should generally be avoided, particularly those that are intended for chronic administration. Alternative agents with no or minimal CYP450 3A4 inhibitory potential are recommended whenever possible. If no alternatives exist and the CYP450 3A4 inhibitor is used short-term for 7 days or less, consider interrupting or delaying initiation of acalabrutinib treatment until therapy with the inhibitor is complete. If treatment is interrupted, the patient's previous dosage may be resumed after the strong inhibitor has been discontinued for at least 24 hours.

GENERALLY AVOID: Coadministration of acalabrutinib in its capsule formulation with proton pump inhibitors may significantly decrease the oral bioavailability of acalabrutinib and reduce its concentrations in plasma. The solubility of acalabrutinib is pH-dependent and decreases with increasing pH. According to the product labeling, acalabrutinib is freely soluble in water at pH below 3 and practically insoluble at pH above 6. Coadministration of acalabrutinib capsules with omeprazole 40 mg for 5 days decreased acalabrutinib systemic exposure (AUC) by 43% in healthy subjects. Due to the long-lasting effect of proton pump inhibitors, separation of dosing may not eliminate the interaction with acalabrutinib capsules. By contrast, no clinically significant differences in the pharmacokinetics of acalabrutinib were observed when the tablet formulation, which contains acalabrutinib maleate, was coadministered with the proton pump inhibitor, rabeprazole.

MANAGEMENT: No adjustments to therapy are required when using the tablet formulation containing acalabrutinib maleate. However, concomitant use of acalabrutinib capsules with proton pump inhibitors should generally be avoided. If gastric acid reducing agents are required during treatment with acalabrutinib capsules, antacids and/or H2-receptor antagonists should be considered, with dosing separated by a couple hours from acalabrutinib dosing as suggested in the manufacturer's labeling.

MONITOR: Coadministration with clarithromycin may increase the plasma concentrations of lansoprazole. The proposed mechanism is clarithromycin inhibition of intestinal (first-pass) and hepatic metabolism of lansoprazole via CYP450 3A4. Although lansoprazole is primarily metabolized by CYP450 2C19 in the liver, 3A4-mediated metabolism is the predominant pathway in individuals who are 2C19-deficient (approximately 3% to 5% of the Caucasian and 17% to 20% of the Asian population). Additionally, inhibition of P-glycoprotein intestinal efflux transporter by clarithromycin may also contribute to the interaction, resulting in increased bioavailability of lansoprazole. In 18 healthy volunteers--six each of homozygous extensive metabolizers (EMs), heterozygous EMs, and poor metabolizers (PMs) of CYP450 2C19--clarithromycin (400 mg orally twice a day for 6 days) increased the peak plasma concentration (Cmax) of a single 60 mg oral dose of lansoprazole by 1.47, 1.71- and 1.52-fold, respectively, and area under the concentration-time curve (AUC) by 1.55-, 1.74- and 1.80-fold, respectively, in each of these groups compared to placebo. The AUC ratio of lansoprazole to lansoprazole sulphone, which is considered an index of CYP450 3A4 activity, was significantly increased by clarithromycin in all three groups. However, elimination half-life of lansoprazole was prolonged by 1.54-fold only in PMs. Mild diarrhea was reported in two subjects and mild abdominal disturbance in six subjects during clarithromycin coadministration. These side effects continued until day 6 and ameliorated the day after discontinuation of clarithromycin, whereas no adverse events were reported during placebo administration or after lansoprazole plus placebo. In another study, clarithromycin induced dose-dependent increases in the plasma concentration of lansoprazole in a group of 20 patients receiving treatment for H. pylori eradication. Mean 3-hour plasma lansoprazole concentration was 385 ng/mL for the control subjects who received lansoprazole 30 mg and amoxicillin 750 mg twice a day for 7 days; 696 ng/mL for patients coadministered clarithromycin 200 mg twice a day; and 947 ng/mL for patients coadministered clarithromycin 400 mg twice a day.

MANAGEMENT: Although lansoprazole is generally well tolerated, caution may be advised during coadministration with clarithromycin, particularly if higher dosages of one or both drugs are used. Dosage adjustment may be necessary in patients who experience excessive adverse effects of lansoprazole.

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.