Little ethnic variation in response to Paxil

A new study has found no major differences in how people of different ethnic groups respond to the anti-anxiety drug paroxetine, sold as Paxil.

Studies have documented worse quality mental health care for minorities, and minorities are rarely included in studies of drug treatment for psychiatric disorders, Dr. Peter P. Roy-Byrne of the Harborview Medical Center in Seattle and colleagues note. The percentage of people with certain genetic variations involved in metabolizing drugs varies by ethnic group, they add.

"Although these differences produce only 'average' variations in kinetics and dynamics, the dissimilarities could contribute to therapeutic or side effect profiles that vary from the norm," the researchers note in their report in the October issue of the Journal of Clinical Psychiatry.

To determine if there were ethnic variations in response to and tolerability of paroxetine, Roy-Byrne and his team analyzed results of 104 clinical trials including 14,875 patients. Eighty-nine percent of patients, or 13,250, were white, while the database included 610 black patients, 415 Hispanics, and 131 Asians.

The researchers found that Hispanic and Asian patients were slightly less likely to respond to the drug than whites and blacks. Among patients with anxiety disorders, Hispanics were least likely to achieve a full response to the drug, while Asian patients had the highest rate of full response. But there were no ethnic differences in the speed of response to the drug or the number of adverse effects, and ethnic differences in response rate were not seen among patients with depression.

"Perhaps the most important point to be made about this analysis is that there is still a strikingly low number of minorities recruited as subjects in these studies," the researchers write.

However, they add, the findings of little ethnic difference in drug response and tolerability may help demonstrate to minority groups the value of drugs for treating mood and anxiety disorders. "Negative attitudes" toward medication use, the researchers note, have been shown to be more common among minority patients.

SOURCE: Journal of Clinical Psychiatry, October 2005.