CYP3A and CYP2C19 Activity Determined by Microdosed Probe Drugs Accurately Predict Voriconazole Clearance in Healthy Adults

BACKGROUND AND OBJECTIVE: Voriconazole is an important broad-spectrum anti-fungal drug with nonlinear pharmacokinetics. The aim of this single centre fixed-sequence open-label drug–drug interaction trial in healthy participants (N = 17) was to determine whether microdosed probe drugs for CYP3A and CYP2C19 reliably predict voriconazole clearance (CL(VRZ)). METHODS: At baseline, a single oral microdose of the paradigm substrates midazolam (CYP3A) and omeprazole (CYP2C19) were given to estimate their clearances (CL). Thereafter, a single oral dose of voriconazole was administered (50, 100, 200 or 400 mg), followed by the microdosed probe drugs. RESULTS: The clearances of midazolam (CL(MDZ) 790–2790 mL/min at baseline; 248–1316 mL/min during voriconazole) and omeprazole (CL(OMZ) 66.4–2710 mL/min at baseline; 30.1–1420 mL/min during voriconazole) were highly variable. CL(MDZ) [geometric mean ratio (GMR) 0.586 at 50 mg voriconazole decreasing to GMR 0.196 at 400 mg voriconazole] and CL(OMZ) (GMR 0.590 at 50 mg decreasing to GMR 0.166 at 400 mg) were reduced with higher voriconazole doses. CL(MDZ) was linearly correlated with CL(VRZ) (slope 1.458; adjusted R(2) 0.528) as was CL(OMZ) (slope 0.807; adjusted R(2) 0.898). Multiple linear regression resulted in an adjusted R(2) of 0.997 for the relationship CL(VRZ) ~ log CL(OMZ) + log CL(MDZ) using data during voriconazole treatment and an adjusted R(2) of 0.997 for the relationship CL(VRZ) ~ log CL(OMZ) + log CL(MDZ) + voriconazole dose, using baseline data for CL(MDZ) and CL(OMZ). CONCLUSION: Microdosed midazolam and omeprazole accurately described and predicted total CL(VRZ) TRIAL REGISTRATION: EudraCT No: 2020-001017-20, registered on March 5th, 2020. DRKS: DRKS00022547, registered on August 6th, 2020. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40262-023-01287-7.