Utility of Relative Activity Factors to Determine Fraction Glucuronidation and Clearance of Icenticaftor in Humans
Mitesh Patel1, Sahil Shaikh2, Felix Huth3
1Pharmacokinetic Sciences, Novartis Biomedical Research, 250 Massachusetts Avenue, Cambridge, MA, 02139, USA. mitesh.patel@novartis.com.
Purpose:
The purpose of this study is to quantify the contribution of individual UDP-glucuronosyl transferase (UGT) enzymes involved in the glucuronidation of icenticaftor, which is primarily glucuronidated in the human liver to two distinct glucuronide metabolites that are ultimately excreted in the urine.
Methods:
The formation of icenticaftor-glucuronide in recombinant UGT systems was scaled with relative activity factor (RAF) of involved UGT enzymes to determine the fraction glucuronidation in human liver.
Results:
Scaling of the glucuronidation activity of UGT enzymes in recombinant UGT systems demonstrated that hepatic UGT1A9 contributed to about two-third of the overall icenticaftor glucuronidation while the remaining was accounted by UGT2B7. Moreover, the predicted UGT-mediated clearance of icenticaftor, upon scaling the intrinsic clearance (CLint) with RAF, correlates well with that estimated in humans.
Conclusion:
Collectively, current data are indicative of the utility of activity-based scalars to predict fraction glucuronidation and clearance of icenticaftor in the clinic. UGT1A9 is identified as the major UGT enzyme in the glucuronidation of icenticaftor in human liver.
More Related Videos
Related Concept Videos
Effect of Hepatic Disease on Pharmacokinetics: Active Drug, Metabolite and Fraction of Metabolized Drug
Pharmacogenetics of Phase II Enzymes: N-acetyltransferase, Thiopurine S-methyltransferase, UDP-glucuronosyltransferase
Hepatic Drug Clearance: Role of Transporters
Clearance Models: Noncompartmental Models
The noncompartmental approach capitalizes on extensive sampling data, correlating the volume of distribution to systemic exposure and the administered dosage. This method enables...
Pharmacogenetics of Phase I Enzymes: Cytochrome P450 Isozymes
One-Compartment Open Model for IV Bolus Administration: Estimation of Clearance
In the one-compartment open model for intravenous (IV) bolus administration, clearance is estimated by dividing the elimination rate by the plasma drug concentration. This equation leverages the elimination rate constant and the apparent...


