Drug Interaction Report

GENERALLY AVOID: Coadministration of ritlecitinib with other immunosuppressive agents may potentiate the risk of infections as well as malignancies, including non-melanoma skin cancer (NMSC). Serious infections have been reported in patients who have received ritlecitinib. The most common serious infections reported with ritlecitinib included appendicitis, pneumonia, COVID-19, and sepsis. Herpes virus reactivation (e.g., herpes zoster) was also reported during clinical studies with ritlecitinib, as well as malignancies including NMSC.

MANAGEMENT: The safety and efficacy of ritlecitinib in combination with immunosuppressive agents has not been evaluated. It is recommended that the concomitant use of ritlecitinib with other Janus Kinase (JAK) inhibitors, biologic immunomodulators, cyclosporine, or other potent immunosuppressants be avoided. Some authorities recommend avoiding ritlecitinib with all systemic immunosuppressive agents. Patients receiving ritlecitinib should be closely monitored for the development of signs and symptoms of infection during and after treatment, including the possible development of tuberculosis in patients who tested negative for latent tuberculosis infection prior to initiating therapy. If a serious infection develops, ritlecitinib therapy should be interrupted until the infection is controlled.

ADJUST DOSING INTERVAL: Administration with food increases the oral bioavailability of belumosudil. The mechanism has not been described. Administration of belumosudil (200 mg single oral dose) in healthy subjects, with a fatty and calorie-rich meal (approximately half of the calories were contained in the fat) increased the mean belumosudil peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) by 120% and 100%, respectively, compared to administration under fasting conditions. The time to reach peak concentration (Tmax) was delayed by 30 minutes. Administration of oral belumosudil 200 mg once daily with food in patients with chronic graft-versus-host disease (chronic GVHD) lead to steady-state concentrations of the drug with an accumulation ration of 1.4.

MANAGEMENT: To ensure maximal oral absorption, belumosudil should be administered with a meal, every day at the same time.