The articles in this supplement demonstrate that ethnicity and ethnopharmacology have emerged as important considerations in the treatment of patients with mental illness. Patients from ethnically diverse backgrounds often demonstrate varying levels of response and tolerability to drugs such as atypical antipsychotics. In part, this response may be due to the particular agent itself, yet metabolic differences between populations may also impact these varied effects. Specific isoforms of the cytochrome P450 enzyme system can dictate the rate at which patients metabolize certain medications, thus genotypic variability among these enzymes predicts the phenotypic response or metabolic rate. For example, patients from certain ethnic groups such as Caucasians and Hispanics tend to be extensive metabolizers, while African Americans and Asians tend to be slower metabolizers.

Total dose and resulting plasma drug levels are closely related to adverse effects. Thus, patients exhibiting slow or poor oxidative enzyme activity may face increased drug exposure and potentially higher rates of adverse events. The undesirable antipsychotic-induced side effects include metabolic issues such as weight gain, insulin resistance, and dyslipidemia. Certain ethnic groups are at a higher risk for developing these metabolic problems. Side effects such as extrapyramidal symptoms and tardive dyskinesia, which have traditionally been attributed to conventional antipsychotics, may occur with atypicals although much less frequently. Movement disorders caused by the use of an atypical antipsychotic become particularly apparent when plasma drug levels are high. Patients with a slow metabolism will be exposed to high plasma drug levels, even on standard dosages of an atypical antipsychotic.

Therefore, given a genetic predisposition and the potential for metabolic side effects with atypical antipsychotics, a careful risk/benefit assessment is crucial for the successful management of patients with mental illness.

Other patient factors as well as clinician factors can influence the response and tolerability of treatment. Provider biases can affect access to certain medications, while misconceptions about how to treat certain ethnic groups can affect the initial choice of medication and dosage. Ultimately, sensitivity and an awareness of pharmacologic issues as they relate to an expanding and ethnically diverse population must become a high priority for clinicians treating patients with atypical antipsychotics. Side effects of these medications can be minimized with vigilance and a thorough understanding of the risks and benefits.

Continued research is necessary to further understand the field of ethnopharmacology and to lead psychiatry into the future of individualized, metabolically directed therapies.