Liu, Yemin

Background: Ibrutinib is the only Bruton tyrosine kinase inhibitor (BTKi) with once-daily oral capsule, tablet, and oral suspension formulations approved in the United States across indications of chronic lymphocytic leukemia/small lymphocytic lymphoma, Waldenström macroglobulinemia, and previously treated chronic graft-versus-host disease, and for mantle cell lymphoma in Europe. Patients with difficulty swallowing capsules or tablets may require alternative formulations or administration options to optimize treatment. Objectives: To evaluate the relative bioavailability of ibrutinib oral suspension relative to capsule or tablet formulations and to examine compatibility for optimal administration methods. Methods: Relative bioavailability of ibrutinib oral suspension was evaluated in healthy volunteers or patients in comparison to capsule or tablet formulations. Dose recovery and delivery, presence of impurities, particle size, and hold time were evaluated after in vitro mock oral suspension administration via syringe and nasogastric and percutaneous endoscopic gastrostomy (PEG) tubes. Results: Clinical bioavailability was comparable for ibrutinib oral suspension and capsules (420 mg/day) under the fasted state in healthy volunteers. Dose-normalized pharmacokinetic values were similar across ibrutinib formulations in patient studies. All evaluated enteral tubes achieved 90%–110% ibrutinib dose recovery regardless of tube type or syringe after 2 × 3 mL water rinses. Oral suspension preservative may be adsorbed into enteral tubes after a 60-minute hold time. Conclusion: Ibrutinib oral suspension bioavailability was comparable with ibrutinib tablet and capsule formulations. When dosed via standard enteral tube administration methods, ibrutinib oral suspension is stable and compatible with polyurethane, silicone, or polyvinyl nasogastric or PEG tubes. To ensure full dose recovery and prevent drug preservative adsorption into tubes, ibrutinib oral suspension should be administered immediately and followed by two rinses of 3 mL of water each. Ibrutinib oral suspension is a viable BTKi treatment option for patients requiring or preferring alternatives to oral capsules and tablets.