Further Evaluation of Coproporphyrins as Clinical Endogenous Markers for OATP1B.

Coproporphyrins (CP-I and CP-III) in plasma are considered potential markers for assessing liver organic anion-transporting polypeptide transporter OATP1B activity and monitoring OATP1B-mediated drug-drug interactions (DDIs) in clinical settings. However, the effect of altered renal clearance (CLrenal ) on CP-I and CP-III plasma exposure has rarely been examined. Therefore, the purpose of this study is to further evaluate CP-I and CP-III as clinical endogenous markers for OATP1B activity and to investigate the impact of CLrenal on DDI assessments for the first time. In this study, 18 healthy participants were recruited to receive RO7049389 (a potential inhibitor of OATP1B) 800 mg twice daily for 6 days and a single dose of pitavastatin (a probe drug of OATP1B) before and after RO7049389 treatment. Plasma concentrations of pitavastatin, CP I, CP III, and the amounts of CP-I and CP-III excreted in urine were measured. Seventeen healthy participants completed the study. After multiple doses of RO7049389, the area under the plasma concentration-time curve from time 0 to 12 hours of pitavastatin increased 1.95-fold (90% confidence interval [CI], 1.58-2.41), while for CP-I and CP-III it increased 3.00-fold (90%CI, 2.35-3.82) and 2.84-fold (90%CI, 2.22-3.65), respectively. Concurrently, the CLrenal of CP-I decreased by 31% (90%CI, 23%-39%), and that of CP-III decreased by 70% (90%CI, 61%-77%). In conclusion, CP-I and CP-III in plasma display the potential to be applied as endogenous markers for the evaluation of OATP1B inhibition in clinical trials. While renal transporters contribute significantly to the CLrenal of CP-III, it would be better to investigate the impact of the CLrenal on plasma exposure of CP-III during clinical DDI assessments.

Evaluation of drug interaction potential of zanubrutinib with cocktail probes representative of CYP3A4, CYP2C9, CYP2C19, P-gp and BCRP.

AIM: This study aims to assess the potential effects of zanubrutinib on the activity of cytochrome P450 (CYP) enzymes and drug transporter proteins using a cocktail probe approach. METHODS: Patients received single oral doses of probe drugs alone and after at least 8 days of treatment with zanubrutinib 160 mg twice daily in a single-sequence study in 18 healthy male volunteers. Simultaneous doses of 10 mg warfarin (CYP2C9) and 2 mg midazolam (CYP3A) were administered on Day 1 and Day 14, 0.25 mg digoxin (P-glycoprotein [P-gp]) and 10 mg rosuvastatin (breast cancer resistance protein [BCRP]) on Day 3 and Day 16, and 20 mg omeprazole (CYP2C19) on Day 5 and Day 18. Pharmacokinetic (PK) parameters were estimated from samples obtained up to 12 h post dose for zanubrutinib; 24 h for digoxin, omeprazole and midazolam; 48 h for rosuvastatin; and 144 h for warfarin. RESULTS: The ratios (%) of geometric least squares means (90% confidence intervals) for the area under the concentration-time curve from time zero to the last quantifiable concentration in the presence/absence of zanubrutinib were 99.80% (97.41-102.2%) for S-warfarin; 52.52% (48.49-56.88%) for midazolam; 111.3% (103.8-119.3%) for digoxin; 89.45% (78.73-101.6%) for rosuvastatin; and 63.52% (57.40-70.30%) for omeprazole. Similar effects were observed for maximum plasma concentrations. CONCLUSIONS: Zanubrutinib 320 mg total daily dose had minimal or no effect on the activity of CYP2C9, BCRP and P-gp, but decreased the systemic exposure of CYP3A and CYP2C19 substrates (mean reduction <50%).