Drug Interactions between Sprycel and tofacitinib

Do not consume grapefruit or grapefruit juice during treatment with dasatinib. Grapefruit juice can significantly increase the blood levels and effects of dasatinib, which may result in excessive slowing of heart rate or other conduction disturbances and it may affect your bone marrow function, resulting in low numbers of different types of blood cells. You may be more likely to develop anemia, bleeding problems, or infections due to low blood cell counts. Talk to your doctor if you have any questions or concerns. You should seek immediate medical attention if you develop sudden dizziness, lightheadedness, fainting, shortness of breath, heart palpitations, paleness, fatigue, unusual bruising or bleeding, fever, chills, diarrhea, sore throat, muscle aches, blood in phlegm, weight loss, pain or burning during urination, red or inflamed skin, or body sores during treatment with dasatinib. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Consumer information for this interaction is not currently available.

MONITOR: Grapefruit juice may increase the plasma concentrations of tofacitinib. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruits. The extent and clinical significance are unknown. Moreover, pharmacokinetic alterations associated with interactions involving grapefruit juice are often subject to a high degree of interpatient variability.

MANAGEMENT: Until more information is available, some authorities recommend avoiding consumption of grapefruit juice during tofacitinib therapy (Canada). Patients receiving tofacitinib therapy who ingest grapefruits or grapefruit juice should be monitored for adverse effects and undue fluctuations in plasma drug levels.