Drug Interactions between acalabrutinib and famotidine / ibuprofen

MONITOR CLOSELY: Coadministration of acalabrutinib and drugs that interfere with platelet function or coagulation may potentiate the risk of bleeding complications. Serious and fatal hemorrhagic events have been reported during acalabrutinib therapy. In the combined safety database of 1040 patients with hematologic malignancies treated with acalabrutinib monotherapy, major hemorrhage (serious or >= Grade 3 bleeding events or any central nervous system bleeding) occurred in 3.6% of patients, with fatalities occurring in 0.1% of patients. Overall, bleeding events of any grade, including bruising and petechiae, occurred in 46% of patients. The mechanism is not well understood, as bleeding events have occurred in patients both with and without thrombocytopenia. In clinical trials, major hemorrhagic events were experienced by 3% of patients taking acalabrutinib without concurrent antithrombotic agents. The addition of antithrombotic agents increased this percentage to 4.3%.

MANAGEMENT: Concomitant use of acalabrutinib with antithrombotic agents or other drugs that increase bleeding risk should be approached with caution. Close clinical and laboratory monitoring for bleeding complications is recommended during therapy. Patients should be advised to promptly report any signs and symptoms of bleeding to their physician. Refer to the product labeling for guidance on acalabrutinib dosage adjustments in patients with concurrent Grade 3 thrombocytopenia and bleeding.

ADJUST DOSING INTERVAL: Coadministration of acalabrutinib in its capsule formulation with drugs that increase gastric pH 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 an antacid (1 gram calcium carbonate) decreased acalabrutinib systemic exposure (AUC) by 53% in healthy subjects, and coadministration with a proton pump inhibitor (omeprazole 40 mg for 5 days) decreased acalabrutinib AUC by 43%. 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, if gastric acid reducing agents are required during treatment with acalabrutinib capsules, H2-receptor antagonists and/or antacids should be considered. The manufacturer recommends taking acalabrutinib 2 hours before (or 10 hours after) H2-receptor antagonists and separating the dosing with antacids by at least 2 hours.

H2 antagonists may alter the pharmacokinetic disposition of some nonsteroidal anti-inflammatory drugs (NSAIDs), resulting in increased or decreased plasma concentrations. Data have been varied, even for the same NSAID. The mechanism may involve inhibition of metabolism, changes in gastric pH resulting in altered absorption, and/or reduced urinary elimination of the affected NSAIDs. Statistically significant changes have been small and of limited clinical significance when interactions have been observed.