Therapeutic response ethnic differences

Ethnic differences in CYP2D6 have been more thoroughly documented than with the other isoenzyme (Bradford, 2002). Over 70% of Caucasians but only about half of Asians, Sub-Saharan Africans, and African Americans have fully functional CYP2D6 alleles - alleles that code for normal metabolic activity. Approximately 50% of Asian and people of African ancestry have reduced function or nonfunctioning alleles. As a consequence, many older psychotropic medications are metabolized more slowly and plasma levels would be higher. Thus individuals of African and Asian ancestry would have an increased risk of side effects and should receive lower dose for a therapeutic response when compared to Caucasians of European descent (Lin, 2001 Lawson, 2000). 

Gender, age, and ethnic background have all been reported to influence the incidence of antibody response to specific therapeutic proteins. However, the only patient characteristic that consistently has been identified for a number of different products is the disease that the patients suffer from. Cancer patients are less likely to produce antibodies to therapeutic protein than other patients. The most widely accepted explanation for this difference is the immune-compromised state of cancer patients, both by the disease as by anticancer treatment. Also the median survival of patients on treatment by therapeutic proteins may be too short to develop an antibody response. In any case, cancer reduces the probability of an antibody response to a protein considerably. 

To enhance therapeutic safety, clinical pharmacology has led efforts to discover the causes responsible for interindividual drug responsiveness in patients. This field of research is called pharmacogenetics. Often the underlying reason is a difference in enzyme property or activity. Ethnic variations are additionally observed. Prudent physicians will attempt to determine the metabolic status of a patient before prescribing a particular drug. 

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