Guo Yu1,2,3, Hong-Hao Zhou3, Qing-Shan Zheng4, Guo-Fu Li5,6,7. 1. National Institution of Drug Clinical Trial, Subei People's Hospital, Yangzhou, Jiangsu, China. 2. Department of Pharmacotherapy and Translational Research, University of Florida, Gainesville, FL, 32610, USA. 3. Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha, Hunan, China. 4. Center for Drug Clinical Research, Shanghai University of Chinese Medicine, Shanghai, China. 5. National Institution of Drug Clinical Trial, Subei People's Hospital, Yangzhou, Jiangsu, China. guofu.g.li@gmail.com. 6. Center for Drug Clinical Research, Shanghai University of Chinese Medicine, Shanghai, China. guofu.g.li@gmail.com. 7. Department of Pharmaceutics, College of Pharmacy, University of Florida, 1345 Center Drive, P3-06, Gainesville, FL, 32610-0494, USA. guofu.g.li@gmail.com.
Abstract
PURPOSE: Prospective prediction of pharmacokinetic properties for individuals of different ethnic groups could provide useful information for the design of multiregional clinical trials. The accuracy of interethnic scaling of fraction unbound (fu) of a drug could determine in large part the predictive capability of volume of distribution as well as renal clearance. As such, exploring the interethnic extrapolation of fu from healthy Caucasian to Chinese subjects and associated effect on the scaling of volume of distribution is highly warranted. METHODS: This study assessed the interethnic scaling of fu from healthy Caucasians to Chinese by using physiologically based principles and verified the approach after examining with experimentally determined fu values of a variety of reference compounds with differing binding characteristics. Moreover, the fundamental assumption of interethnic extrapolation of volume of distribution (Vd), namely the equivalency of unbound Vd (Vd,u) across different ethnic groups, was tested on the basis of observed Vd data derived from comprehensive literature analysis and scaled fu values through qualified extrapolation method. RESULTS: The interethnic extrapolation approach of fu provided a high accuracy with 94.7% scaled Chinese fu values (n = 19) being within a 1.25%-fold error range. Specifically, 100% of scaled Chinese fu values for the albumin-bound compounds and 90% for those bound to alpha 1-acid glycoprotein fell within the 1.25%-fold error range. All the percentage prediction errors of scaled Chinese fu values were ≤ 30%, with a majority of those ≤ 20%. Additionally, correlation between the prediction errors and the observed fu levels was not observed. Regarding interethnic scaling of Vd, the bodyweight-normalized Vd,u instead of Vd was similar across ethnic groups. CONCLUSION: The current study verified for the first time the ability to scale Chinese fu from Caucasian values after examining with experimentally determined fu values of a variety of reference compounds. Similarities in bodyweight-normalized Vd,u between non-obese Caucasians and Chinese have also been shown for the first time. This investigation could greatly enhance the confidence in the interethnic extrapolation of fu and Vd from healthy non-obese Caucasian to Chinese subjects.
PURPOSE: Prospective prediction of pharmacokinetic properties for individuals of different ethnic groups could provide useful information for the design of multiregional clinical trials. The accuracy of interethnic scaling of fraction unbound (fu) of a drug could determine in large part the predictive capability of volume of distribution as well as renal clearance. As such, exploring the interethnic extrapolation of fu from healthy Caucasian to Chinese subjects and associated effect on the scaling of volume of distribution is highly warranted. METHODS: This study assessed the interethnic scaling of fu from healthy Caucasians to Chinese by using physiologically based principles and verified the approach after examining with experimentally determined fu values of a variety of reference compounds with differing binding characteristics. Moreover, the fundamental assumption of interethnic extrapolation of volume of distribution (Vd), namely the equivalency of unbound Vd (Vd,u) across different ethnic groups, was tested on the basis of observed Vd data derived from comprehensive literature analysis and scaled fu values through qualified extrapolation method. RESULTS: The interethnic extrapolation approach of fu provided a high accuracy with 94.7% scaled Chinese fu values (n = 19) being within a 1.25%-fold error range. Specifically, 100% of scaled Chinese fu values for the albumin-bound compounds and 90% for those bound to alpha 1-acid glycoprotein fell within the 1.25%-fold error range. All the percentage prediction errors of scaled Chinese fu values were ≤ 30%, with a majority of those ≤ 20%. Additionally, correlation between the prediction errors and the observed fu levels was not observed. Regarding interethnic scaling of Vd, the bodyweight-normalized Vd,u instead of Vd was similar across ethnic groups. CONCLUSION: The current study verified for the first time the ability to scale Chinese fu from Caucasian values after examining with experimentally determined fu values of a variety of reference compounds. Similarities in bodyweight-normalized Vd,u between non-obese Caucasians and Chinese have also been shown for the first time. This investigation could greatly enhance the confidence in the interethnic extrapolation of fu and Vd from healthy non-obese Caucasian to Chinese subjects.
Entities:
Keywords:
Clinical pharmacokinetics; Fraction unbound; Healthy subjects; Interethnic scaling; Volume of distribution
Authors: M M Ghoneim; K Korttila; C K Chiang; L Jacobs; R D Schoenwald; S P Mewaldt; K O Kayaba Journal: Clin Pharmacol Ther Date: 1981-06 Impact factor: 6.875