Drug Interactions between infigratinib and lorlatinib

GENERALLY AVOID: Grapefruit and grapefruit juice may significantly increase the plasma concentrations of lorlatinib. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall induced by certain compounds present in grapefruit. Because grapefruit juice inhibits primarily intestinal rather than hepatic CYP450 3A4, the magnitude of interaction is greatest for those drugs that undergo significant presystemic metabolism by CYP450 3A4 (i.e., drugs with low oral bioavailability). 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. Pharmacokinetic interactions involving grapefruit juice are also subject to a high degree of interpatient variability, thus the extent to which a given patient may be affected is difficult to predict.

MANAGEMENT: Patients treated with lorlatinib should avoid consumption of grapefruit, grapefruit juice, and any supplement containing grapefruit extract. If coadministration is unavoidable, some authorities recommend reducing the initial dosage of lorlatinib from 100 mg orally once daily to 75 mg orally once daily. In patients who have had a dosage reduction to 75 mg orally once daily due to adverse reactions, the lorlatinib dosage should be further reduced to 50 mg orally once daily upon initiation of a potent CYP450 3A4 inhibitor. After 3 plasma half-lives following discontinuation of the potent CYP450 3A4 inhibitor, the lorlatinib dosage may be increased to that used prior to initiation of the inhibitor.

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ADJUST DOSING INTERVAL: Food may increase the oral bioavailability of infigratinib. Coadministration with a high-fat, high-calorie meal (800 to 1,000 calories, with approximately 50% of total calories from fat) in healthy subjects increased mean infigratinib peak plasma concentration (Cmax) and total systemic exposure (AUC) by 60% to 80% and 80% to 120%, respectively, and increased the median time to Cmax from 4 hours to 6 hours. When coadministered with a low-fat, low-calorie meal (approximately 330 calories, with 20% of total calories from fat), mean infigratinib Cmax and AUC increased by 90% and 70%, respectively, while the median time to Cmax did not change.

GENERALLY AVOID: Grapefruit juice may increase the plasma concentrations of infigratinib and one of its active metabolites, BHS697, both of which are primarily metabolized by CYP450 3A4 in vitro. 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. Coadministration of infigratinib with multiple doses of itraconazole, a potent CYP450 3A4 inhibitor, increased infigratinib peak plasma concentration (Cmax) and total systemic exposure (AUC) by 164% and 622%, respectively, and the AUC for the active metabolite, BHS697, by 174%. 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 exposure to infigratinib and BHS697 may increase the incidence and severity of serious adverse reactions such as infections, anemia, pyrexia, abdominal pain, hypercalcemia, hyperphosphatemia, ocular toxicity (e.g., retinal pigment epithelial detachment), sepsis, stomatitis, diarrhea, palmar-plantar erythrodysesthesia syndrome, increased blood creatinine, increased lipase, and onycholysis.

MANAGEMENT: Infigratinib should be administered on an empty stomach at least one hour before or two hours after food. Patients should avoid consumption of grapefruit, grapefruit juice, or supplements that contain grapefruit during treatment with infigratinib.

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The recommended maximum number of medicines in the 'multikinase inhibitors' category to be taken concurrently is usually one. Your list includes two medicines belonging to the 'multikinase inhibitors' category:

• infigratinib
• lorlatinib

Note: In certain circumstances, the benefits of taking this combination of drugs may outweigh any risks. Always consult your healthcare provider before making changes to your medications or dosage.