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CYP (Cytochrome P450) Variability Table

Compiled By Jessica Oesterheld, M.D.

This table is an abridged guide to Cytochrome variability. To appreciate the full benefits of this information, click here to get a free 30-day trial version of GeneMedRx. This metabolism-based drug interaction software predicts response to medication combinations with optional input of genetic variations.

Last Update: November 1, 2007



   1A2  2A6  2B6  2C9  2C19  2D6  2E1  3A

Percent of Total CYPs

   10-15%  4%   1-10%%  15-20%  5%  2.5%  7%  30-40%

Inter-individual Variability

  40 fold 30 fold  50 fold  25-100 fold    2.5 fold  7 fold  40 fold

Common Polymorhphism

  1A2*1F     2C9*2 2C19*2  2D6*2    

  1A2*1C     2C9*3 2C19*3 2D6*4    

        2C9*5 2C19*4 2D6*5    

          2C19*5 2D6*10    

          2C19*17 2D6*17    



Slow Metabolizers    



 Caucasians    20%   18%  2-4%  7-10%    

 African Americans    2%   1%  1%  6-8%    

 Asians       1%    1-2%    


 Japanese       1%  18-23%      

 Chinese          5-17%      


Ultrafast Metabolizers  


 Caucasians            1%    

 Asians            1%    

Swedes         18%      

Chineses         4%      

Decreases with Age  

 Same as adult or dec ?  ? Dec Dec  No Conflictual results Same as adult or dec

Gender male/female 

Higher men     Equal Equal Equal Slightly higher men with some drugs ? effect on hepatic blood flow Slightly higher women


* Based on data from Rendic S, DiCarlo FJ, Human cytochrome P450 enzymes: a status report summarizing their reactions, substrates, inducers and inhibitors. Drug metab Reviews 29:413-580,1997 and Abernethy and Flockhart: Molecular basis of cardiovascular drug metabolism: implications for predicting clinically important drug interactions. Circulation 2000 101:1749-53 Cotreau MM, von Moltke LL, Greenblatt DJ.The influence of age and sex on the clearance of cytochrome P450 3A substrates. Clin Pharmacokinet. 2005;44(1):33-6 0Parkinson A, Mudra DR, Johnson C, Dwyer A, Carroll KM. effects of gender, age, ethnicity, and liver cirrhosis on cytochrome P450 enzyme activity in human liver microsomes and inducibility in cultured human hepatocytes.Toxicol Appl Pharmacol. 2004 Sep 15;199(3):193-209 and Benedetti MS, Whomsley R et al: Drug metabolism in the pediatric population and in the elderly Drug Discovery Today 60:3-12, 2007

GeneMedRx has not been reviewed or approved by the United States Food and Drug Administration and cannot be used to diagnose or treat any disease or other health condition.

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