Ethnic differences pharmacokinetics

Ethnic differences in psychotropic drug response and pharmacokinetics... 

Chiu et al, 1992 Lin Finder, 1983 Lin et al, 1988b Potkin et al, 1984 Lin etal., 1989 Ruiz et al, 1996 Jann et al, 1989 Jann etal, 1992 Zhang-Wong etal., 1998). The majority of these studies were carried out with haloperidol. A number of studies examined differences between Caucasians and Hispanics, and African Americans and Caucasians (Midha et al., 1988b Midha etal, 1988a Ruiz et al., 1996). In general these studies provided mixed results. Another noteworthy feature of the research literature is that there appear to be no studies that have considered ethnic differences in pharmacokinetics and response for the depot antipsychotics. This may be an artifact of the low levels of depot prescribing found in the US, China, and Japan. 

There is little published information that directly examines ethnic differences in olanzapine pharmacokinetics or pharmacodynamics. Indirectly, examining stable... 

As amisulpride has no hepatic metabolism, low protein binding, and is directly excreted in urine, there is little reason to suspect pharmacokinetic ethnic differences. Of course body mass and pharmacodynamic differences might occur, but to date have received little investigative attention. 

Ethnic differences have been shown to influence response to psychotropic medications. Much of the focus on the explanation for such differences has been on drug-metabolizing (CYP) enzymes of the liver and their sway over pharmacokinetic factors. It is now well recognized that differences in the distribution of polymorphic variants of CYP enzymes exist between different ethnic groups. However, within ethnic groups there are considerable inter-individual variations in drug kinetics, which may not be accounted for solely by genetic variation. Responses to pharmacotherapy are multifaceted and involve the interaction of environmental and... 

Imipramine, a TCA, was the first pharmacological agent noted to treat panic disorder (Klein 1964). Other TCAs, notably clomipramine, have also been found to have significant anxiolytic properties (den Boer et al. 1990 Modigh 1992). Studies of ethnic differences in the pharmacokinetics of the TCAs in... 

Erratic DPD activity is a major cause of the marked pharmacokinetic variability of 5-FU. Drug-drug interactions (47,48), circadian patterns (12,49,50), and inter-gender (7,8) inter-ethnic differences (51,52,53,54,55) have been identified as putative causes for profound variations in DPD activities. Consequently, population studies of DPD activities displayed extremely wide ranges of values (17,56,57). 

Lee M, Min DI, Ku YM, Flanigan M. Effect of grapefruit juice on pharmacokinetics of microemulsion cyclosporine in African American subjects compared with Caucasian subjects does ethnic difference matter J Clin Pharmacol 2001 41(3) 317-323. 

Kalow W. Ethnic differences in drug metabolism. Clin Pharmacokinet 1982 7 373 100. 

Cultural and ethnic differences are more important than we would initially suspect Psychiatric syndromes present differently in different cultures—cultural and ethnic pathoplastic effects different attitudes toward medications and variations in pharmacokinetics and pharmacodynamics, depending on genetics and ethnic origin. Even when we examine the response to treatment in genders, the results differ. For example, women will do better than men when treated for depression with SSRIs than with TCAs. 

These differences in clinical response and pharmacokinetics have been attributed to ethnic differences in drug metabolism mediated through the cytochrome P450 microsomal enzyme system, which is responsible for the metabolism of most of the older psychotropic medications, including typical antipsychotics and TCAs (Lin et al. 1993 Silver et al. 1993). Earlier studies showed that Caucasians were more likely than Asians and African Americans to be poor metabolizers of psychotropic medication, a finding inconsistent with clinical experience, because poor metabolizers should require less medication. However, new mutations have recently been discovered in the enzymatic systems of the latter groups that are intermediate in the rate of metabolism. Thus, up to 47%-70% of African Americans and Asian Americans may be slow metabolizers, which could account for the higher incidence of side effects (Mendoza et al. 1999). 

The most studied ethnic differences in transcultural psychopharmacology have been those between Caucasian and Asian populations. In this chapter, we review pharmacokinetics, pharmacodynamics, and sociocultural influences on drug response in Asians, focusing on the major classes of psychotropic medications. 

Although research efforts in the field of ethnopharmacology have been limited, it is increasingly clear that medication dosing may be significantly affected by ethnic differences related to the pharmacodynamics, pharmacokinetics, and pharmacogenetics of certain medications. Fortunately, the literature on this subject is steadily proliferating. 

Wood AJJ, Zhou HH Ethnic differences in drug disposition and responsiveness. Clin Pharmacokinet 20 1-24,1991 Yamamoto J, Lin KM Psychopharmacology, ethnicity and culture, in American Psychiatric Press Review of Psychiatry, Vol 14. Edited by Oldham JM, Riba MB. Washington, DC, American Psychiatric Press, 1995, pp 529-541... 

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