Drug Interaction Report

MONITOR: Coadministration with inhibitors of CYP450 3A4 may increase the plasma concentrations of unconjugated monomethyl auristatin E (MMAE), the anti-mitotic and cytotoxic component of telisotuzumab vedotin. Telisotuzumab vedotin is an antibody-drug conjugate (ADC) that releases MMAE via proteolytic cleavage, and MMAE has been shown in vitro to be primarily metabolized by CYP450 3A4. MMAE systemic exposure (AUC) is predicted to increase by 1.4-fold following concomitant administration of telisotuzumab vedotin with the potent CYP450 3A4 inhibitor ketoconazole. It is not known if, and to what extent, MMAE may interact with less potent CYP450 3A4 inhibitors.

MANAGEMENT: Caution is advised when telisotuzumab vedotin is used concomitantly with CYP450 3A4 inhibitors. Patients should be closely monitored for development or exacerbation of toxicities such as ocular surface disorders (e.g., dry eyes, keratitis, blurred vision), peripheral neuropathy, interstitial lung disease/pneumonitis, and peripheral edema. If serious adverse reactions occur, the dosing of telisotuzumab vedotin should be adjusted or withheld as necessary in accordance with the product labeling.

ADJUST DOSING INTERVAL: Food may variably affect the bioavailability of different oral formulations and salt forms of erythromycin. The individual product package labeling should be consulted regarding the appropriate time of administration in relation to food ingestion. Grapefruit juice may increase the plasma concentrations of orally administered erythromycin. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruits. In an open-label, crossover study consisting of six healthy subjects, the coadministration with double-strength grapefruit juice increased the mean peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of a single dose of erythromycin (400 mg) by 52% and 49%, respectively, compared to water. The half-life was not affected. The clinical significance of this potential interaction is unknown.

MANAGEMENT: In general, optimal serum levels are achieved when erythromycin is taken in the fasting state, one-half to two hours before meals. However, some erythromycin products may be taken without regard to meals.

Ethanol, when combined with erythromycin, may delay absorption and therefore the clinical effects of the antibiotic. The mechanism appears to be due to slowed gastric emptying by ethanol. Data is available only for erythromycin ethylsuccinate. Patients should be advised to avoid ethanol while taking erythromycin salts.