Drug Interaction Report

MONITOR: Coadministration with trofinetide may increase the plasma concentrations of drugs that are substrates of CYP450 3A4 via inhibition of the isoenzyme. Based on pharmacokinetic modeling, concomitant use of trofinetide and oral midazolam, a sensitive CYP450 3A4 substrate, is predicted to increase midazolam systemic exposure (AUC) by approximately 1.33-fold. Clinical data are currently lacking.

MANAGEMENT: Caution is advised if trofinetide is coadministered with CYP450 3A4 substrates, particularly sensitive substrates or those with a narrow therapeutic range. If concomitant use is required, clinical and laboratory monitoring may be appropriate whenever trofinetide is added to or withdrawn from therapy. The prescribing information for concomitant medications should be consulted to assess the benefits versus risks of coadministration and for any dosage adjustments that may be required.

MONITOR: Coadministration with trofinetide may increase the plasma concentrations of drugs that are substrates of CYP450 3A4 via inhibition of the isoenzyme. Based on pharmacokinetic modeling, concomitant use of trofinetide and oral midazolam, a sensitive CYP450 3A4 substrate, is predicted to increase midazolam systemic exposure (AUC) by approximately 1.33-fold. Clinical data are currently lacking.

MANAGEMENT: Caution is advised if trofinetide is coadministered with CYP450 3A4 substrates, particularly sensitive substrates or those with a narrow therapeutic range. If concomitant use is required, clinical and laboratory monitoring may be appropriate whenever trofinetide is added to or withdrawn from therapy. The prescribing information for concomitant medications should be consulted to assess the benefits versus risks of coadministration and for any dosage adjustments that may be required.

Coadministration with grapefruit juice may increase the bioavailability of oral estrogens. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall induced by certain compounds present in grapefruits. In a small, randomized, crossover study, the administration of ethinyl estradiol with grapefruit juice (compared to herbal tea) increased peak plasma drug concentration (Cmax) by 37% and area under the concentration-time curve (AUC) by 28%. Based on these findings, grapefruit juice is unlikely to affect the overall safety profile of ethinyl estradiol. However, as with other drug interactions involving grapefruit juice, the pharmacokinetic alterations are subject to a high degree of interpatient variability. Also, the effect on other estrogens has not been studied.