Search

OBJECTIVE: To review the data generated by studies examining interethnic/racial differences in response to antipsychotics.DATA SOURCES: A MEDLINE search (1966-19%) identified all articles examining differences in antipsychotic response among Caucasians, Asians, Hispanics, and African-Americans, as well as articles evaluating postulated mechanisms for these differences.STUDY SELECTION: All abstracts, studies, and review articles were evaluated.DATA SYNTHESIS: Ethnic/racial differences in response to antipsychotic medications have been reported and may be due to genetics, kinetic variations, dietary or environmental factors, or variations in the prescribing practices of clinicians. Studies suggest that Asians may respond to lower doses of antipsychotics due to pharmacokinetic and pharmacodynamic differences. Research relevant to African-Americans is limited, but some studies suggest that differences in this group may be due to clinician biases and prescribing practices, rather than to pharmacokinetic or pharmacodynamic variability.CONCLUSIONS: Future research directed at validating the hypotheses that different ethnic/racial groups show variations in response to antipsychotics should focus on homogenous ethnic groups, use recent advances in pharmacogenetic testing, and control for such variables as observer bias, gender, disease chronicity, dietary and environmental factors, and exposure to enzyme-inducing and -inhibiting agents. Clinicians should be aware that potential interethnic/racial differences in pharmacodynamics and pharmacokinetics may exist that can alter response to antipsychotics.

A retrospective review of neuroleptic dosages over a five-year period in 19 chronic schizophrenic patients revealed that the majority (85 percent) had either consistent yearly increases or decreases in dosage, although clinical status remained unchanged. The authors present differences in adverse effects between the two groups and discuss the implications of their findings for the concepts of neuroleptic drug tolerance and supersensitivity psychosis.

An ongoing screening program using pharmacists to detect tardive dyskinesia (TD) was developed, and a pharmacy-based prevalence survey of TD in chronic hospitalized psychiatric patients was undertaken to determine the extent of abnormal involuntary movements. The results show that older patients and women in particular are at higher risk for developing abnormal movements. Higher doses of neuroleptics were used in non-TD patients, indicating a possible masking effect caused by these drugs. By using a standardized rating method such as the Abnormal Involuntary Movement Scale, pharmacists can and should be utilized in the surveillance of TD.

Six treatment-resistant schizophrenic patients were given a ten-week single-blind trial of carbamazepine. Treatment resistance was determined on the basis of documented failure to respond to treatment with at least three neuroleptic drugs from two different chemical classes. The adjunctive use of carbamazepine resulted in a significant improvement of the negative symptoms of schizophrenia. These symptoms are often poorly responsive to conventional antipsychotic drugs. Therefore, controlled studies should be performed to further assess the possible efficacy of carbamazepine in schizophrenia.