Abstract
PURPOSE: Drug-drug interaction (DDI) potentials of lusutrombopag, a thrombopoietin receptor agonist, on the activity of cytochrome P450 (CYP) 3A and of cyclosporine, which inhibits P-glycoprotein and breast cancer resistance protein, on lusutrombopag pharmacokinetics were assessed via clinical studies and physiologically based pharmacokinetic (PBPK) modeling. METHODS: The effect of lusutrombopag on midazolam (a CYP3A probe substrate) pharmacokinetics was assessed in 15 healthy subjects receiving a single midazolam 5-mg dose with or without coadministration of lusutrombopag 0.75 mg for 6 days (first dose: 1.5-mg dose). The effect of cyclosporine on lusutrombopag pharmacokinetics was assessed in 16 healthy subjects receiving a single lusutrombopag 3-mg dose with or without a single cyclosporine 400- to 600-mg dose. PBPK modeling was employed to extrapolate the effect of lusutrombopag at the clinical dose (3 mg once daily) on midazolam pharmacokinetics. RESULTS: In the clinical study, mean ratios (90% confidence intervals [CIs]) of with/without lusutrombopag for maximum plasma concentration (C(max)) and area under the plasma concentration-time curve (AUC) of midazolam were 1.01 (0.908-1.13) and 1.04 (0.967-1.11), respectively, indicating no effect of lusutrombopag on midazolam pharmacokinetics. PBPK modeling suggested no effect of lusutrombopag at the clinical dose on midazolam pharmacokinetics. Mean ratios (90% CIs) of with/without cyclosporine for lusutrombopag C(max) and AUC were 1.18 (1.11-1.24) and 1.19 (1.13-1.25), respectively, indicating a slight increase in lusutrombopag exposure. CONCLUSIONS: In consideration with in vitro data, the in vivo and in silico results suggested no clinically significant DDI potential of lusutrombopag with other medical products via metabolic enzymes and transporters.