Drug Interactions between fedratinib and pirfenidone

ADJUST DOSING INTERVAL: Food significantly slows the rate but only modestly reduces the extent of absorption of pirfenidone. In healthy, older adult volunteers aged 50 to 66 years, administration of a single 801 mg oral dose of pirfenidone in the fed state resulted in an approximately 50% reduction in peak plasma concentration (Cmax) and a 15% to 20% reduction in systemic exposure (AUC) compared to administration in the fasted state. Median time to reach peak concentration (Tmax) increased from 0.5 hours to 3 hours with food. Less nausea and dizziness were observed in fed subjects compared to fasted subjects.

GENERALLY AVOID: Consumption of grapefruit juice is associated with inhibition of CYP450 1A2 and may increase the plasma concentrations of pirfenidone, which is primarily metabolized by the isoenzyme.

GENERALLY AVOID: Cigarette smoking may reduce pirfenidone exposure due to induction of CYP450 1A2, the isoenzyme primarily responsible for the metabolic clearance of pirfenidone. Following a single 801 mg oral dose of pirfenidone in 25 smokers and 25 healthy nonsmokers, the Cmax and AUC of pirfenidone in smokers were 68% and 46% of those in nonsmokers, respectively.

MANAGEMENT: Pirfenidone should be administered with food to reduce the likelihood of dizziness and gastrointestinal side effects such as nausea, diarrhea, dyspepsia, and vomiting. Patients who experience intolerance to therapy due to these adverse events should be reminded to take pirfenidone with food. If symptoms do not improve, or they worsen in severity, a dosage reduction or discontinuation of therapy may be warranted. Patients should be advised to avoid consumption of grapefruit and grapefruit juice during treatment with pirfenidone. Cigarette smoking should also be avoided during therapy to prevent reduced exposure to pirfenidone.

GENERALLY AVOID: Grapefruit juice may increase the plasma concentrations of fedratinib. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. Inhibition of hepatic CYP450 3A4 may also contribute. The interaction has not been studied with grapefruit juice, but has been reported for other CYP450 3A4 inhibitors. When a single 300 mg oral dose of fedratinib (0.75 times the recommended dose) was coadministered with 200 mg twice daily ketoconazole, a potent CYP450 3A4 inhibitor, fedratinib total systemic exposure (AUC(inf)) increased by approximately 3-fold. Using physiologically based pharmacokinetic (PBPK) simulations, coadministration of fedratinib 400 mg once daily and ketoconazole 400 mg once daily is predicted to increase fedratinib AUC at steady state by 2-fold. Coadministration with the moderate CYP450 3A4 inhibitors, erythromycin (500 mg three times daily) or diltiazem (120 mg twice daily), is predicted to increase fedratinib AUC by approximately 1.5- to 2-fold following single-dose administration and by approximately 1.2-fold at steady state. In general, the effect of grapefruit juice is concentration-, dose- and preparation-dependent, and can vary widely among brands. Certain preparations of grapefruit juice (e.g., high dose, double strength) have sometimes demonstrated potent inhibition of CYP450 3A4, while other preparations (e.g., low dose, single strength) have typically demonstrated moderate inhibition. Increased fedratinib exposure may potentiate the risk of adverse reactions such as nausea, vomiting, diarrhea, anemia, thrombocytopenia, neutropenia, encephalopathy (including Wernicke's), liver (ALT, AST) and pancreatic (amylase, lipase) enzyme elevations, increased blood creatinine, and secondary malignancies.

Food does not affect the oral bioavailability of fedratinib to a clinically significant extent. Administration of a single 500 mg dose (1.25 times the recommended dose) with a low-fat, low-calorie meal (162 calories; 6% from fat, 78% from carbohydrate, 16% from protein) or a high-fat, high-calorie meal (815 calories; 52% from fat, 33% from carbohydrate, 15% from protein) increased fedratinib peak plasma concentration (Cmax) and systemic exposure (AUC) by up to 14% and 24%, respectively.

MANAGEMENT: Fedratinib may be taken with or without food. However, administration with a high-fat meal may help reduce the incidence of nausea and vomiting. Patients should avoid consumption of grapefruit and grapefruit juice during treatment with fedratinib.