Drug Interaction Report

MONITOR: Coadministration with moderate inducers of CYP450 3A4 may decrease the plasma concentrations of tofacitinib, which is primarily metabolized by the isoenzyme. The interaction may result in loss of or reduced clinical response; however, the extent to which these medications interact with tofacitinib has not been established. In study subjects, administration with the potent CYP450 3A4 inducer rifampin decreased tofacitinib peak plasma concentration (Cmax) and systemic exposure (AUC) by approximately 74% and 84%, respectively, compared to administration of tofacitinib alone.

MANAGEMENT: Caution is recommended if tofacitinib is to be used in combination with moderate CYP450 3A4 inducers. Alternative agents with no or minimal CYP450 3A4 induction potential are recommended when possible.

GENERALLY AVOID: Alcohol may cause hypoglycemia or hyperglycemia in patients with diabetes. Hypoglycemia most frequently occurs during acute consumption of alcohol. Even modest amounts can lower blood sugar significantly, especially when the alcohol is ingested on an empty stomach or following exercise. The mechanism involves inhibition of both gluconeogenesis as well as the counter-regulatory response to hypoglycemia. Episodes of hypoglycemia may last for 8 to 12 hours after ethanol ingestion. By contrast, chronic alcohol abuse can cause impaired glucose tolerance and hyperglycemia. Moderate alcohol consumption generally does not affect blood glucose levels in patients with well controlled diabetes. A disulfiram-like reaction (e.g., flushing, headache, and nausea) to alcohol has been reported frequently with the use of chlorpropamide and very rarely with other sulfonylureas.

MANAGEMENT: Patients with diabetes should avoid consuming alcohol if their blood glucose is not well controlled, or if they have hypertriglyceridemia, neuropathy, or pancreatitis. Patients with well controlled diabetes should limit their alcohol intake to one drink daily for women and two drinks daily for men (1 drink = 5 oz wine, 12 oz beer, or 1.5 oz distilled spirits) in conjunction with their normal meal plan. Alcohol should not be consumed on an empty stomach or following exercise.

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.