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The New York research institute recently criticized for using a now-banned diet drug in experiments on young children has revealed that until this month the drug, fenfluramine, was still used in separate psychiatric tests with adolescents.

The study that first drew attention, non-therapeutic research into aggression in poor, young, non-white boys, was actually stopped in 1995, two years before fenfluramine — part of the diet-drug combination Fen-Phen — was withdrawn from the market after evidence that it caused serious heart-valve damage in adults who used it for months (see Nature 392, 747; 1998).

But the New York State Psychiatric Institute continued a separate study using the drug until this month, with approval from the US Food and Drug Administration (FDA). Claudia Bial, a spokeswoman for the Manhattan-based institute, says that the goal of this work was “to determine if adolescents with major depressive disorder, and who attempt suicide, show evidence of abnormal brain-serotonin function”.

Fenfluramine increases brain serotonin levels. Bial says that the study, funded by the National Institute of Mental Health, was begun in 1992, and had enrolled 98 subjects before it ceased temporarily when the FDA withdrew fenfluramine in September, 1997.

After researchers gained FDA permission, the study was restarted in March this year, and two more subjects received single doses of fenfluramine before the investigators stopped the study this month because of the storm unleashed by local press reports of the work on children.

The FDA defended both studies at a congressional hearing last week. While declining to comment on the scientific significance of the work, Michael Friedman, the acting FDA commissioner, said he felt it was “appropriate and ethical and that it is being conducted under carefully scrutinized circumstances”. But, he added, “I can assure you that I'm going to be looking into it much more carefully.”

Friedman told the House of Representatives Government Reform and Oversight Committee that after fenfluramine was recalled from clinical use as a diet drug, researchers using it were allowed to continue on three conditions: that informed consent forms were revised to reflect the risk of heart damage (parents sign these on behalf of their children); that echocardiograms of subjects' heart valves were conducted before and after the research; and that local institutional review boards consented to the research in the light of the new findings about valve damage.

Bial said these conditions were met, and provided an informed consent form for the adolescent study that warned of “potentially life-threatening ⃛ heart-valve damage”. She said that echocardiograms on the two recent subjects revealed no damage. Friedman also stressed participation in the research was “voluntary”. He told committee chairman Dan Burton (Republican, Indiana) it was “a question of personal choice”.

But Burton said that he could not understand the government's approval of a child's exposure to a drug whose effects in adults had proved so damaging.

Friedman said that there had “never” been a case of heart-valve damage from one dose of fenfluramine in an adult, but conceded that data on children was scant.

Adil Shamoo, of Citizens for Responsible Care in Psychiatry and Research, an advocacy group, told the hearing that the researchers had “no therapeutic or medical cause” to use fenfluramine on the youngsters.