Effective therapeutic dosage of antipsychotic medications in patients with psychotic symptoms: Is there a racial difference?

Muideen O Bakare

doi:10.1186/1756-0500-1-25

Abstract

BackgroundGenetic make up had been known to influence pharmacokinetics and pharmacodynamics of psychotropic medications. Time separation in evolutionary trend in Africans, Orientals and Caucasians had been thought a possible explanation for the observed racial variation in activities of Cytochrome P 450 (CYP 450) enzymes, which are responsible for metabolism of psychotropic and other medications in human. Past studies on pharmacokinetics and pharmacodynamics of antipsychotic medications and socio-cultural factors influencing response to antipsychotic medications had consistently giving an inkling of possible racial difference in symptoms response to antipsychotic medications. Another growing body of evidence subscribing to possible racial difference in psychotic symptoms response to antipsychotic medications is the observed variation in antipsychotic medications prescription pattern and dosage across races and regions. Empirical observation had shown that dosage prescription pattern of antipsychotic medications in most Sub-Saharan African countries deviates from the standard prescription guidelines published for use in western parts of the world. Studies coming from the United States (U.S) had consistently reported a higher dosage of antipsychotic medications prescription for African-American patients compared to their Caucasian counterparts. Research on East Asia Psychotropic Prescription (REAP) study had also identified high dosage antipsychotic medications prescription pattern well above the recommended dose of 1,000 mg Chlorpromazine equivalent per day as common practices in some East Asian countries.Presentation of the HypothesisThe pertinent question is why the apparent differences in dosage prescription practices across races and regions? The possibility of racial differences in psychotic symptoms response to antipsychotic medications rather than clinicians' prescription attitudes was entertained.Testing the HypothesisFuture carefully controlled studies might be needed to test the proposed hypothesis of racial differences in psychotic symptoms response to antipsychotic medications.Implication of the HypothesisThere might be actual racial influence on psychotic symptoms response to antipsychotic medications. If future carefully controlled studies uphold the hypothesis of racial differences in psychotic symptoms response to antipsychotic medications, there might be need to draw up new treatment or prescription guidelines that would put into consideration variations in genetic make up and consequent racial differences in psychotic symptoms response to antipsychotic medications.

Highlights

Genetic make up had been known to influence pharmacokinetics and pharmacodynamics of psychotropic medications
The findings of these studies [5,6] could be due to racial differences in activities of cytochrome P 450 (CYP 450) enzymes, especially CYP2D6 and CYP2C19 which are largely responsible for metabolism of antipsychotic medications and other psychotropic drugs [1,2,3,4]
It had been found that African-Americans compared to their Caucasian counterparts often received antipsychotic medications for a longer period of time as maintenance treatment for Bipolar Affective Disorders (BAD) [16,17]

Summary

Background

Genetic make-up had been known to influence metabolism and utilization of psychotropic medications [1,2,3,4]. The deviation in dosage prescription practices from prescription guidelines published for use in western parts of the world [14,15] in most Sub-Saharan African countries and the consistent findings of studies coming from the United States [11,16,17,18,19,21,22], that documented high dosage prescription of antipsychotic medications among African-American patients compared to their Caucasian counterparts and the study by Sim et al [20] coming from East Asia give some support to the hypothesis that racial differences in psychotic symptoms response to antipsychotic medications might be responsible for the apparent difference in dosage prescription practices. If the hypothesis of racial differences in psychotic symptoms response to antipsychotic medications is upheld by future studies, there might be need to draw up new prescription or treatment guidelines that would take into consideration variations in genetic make-up and consequent racial differences in psychotic symptoms response to antipsychotic medications

Bertilsson L

14. British Medical Association and Royal Pharmaceutical Society