FOR the last 11 years, Joshua Frome has been taking fenfluramine, a prescription drug sold as Pondimin. But unlike the millions of other users who have taken this drug to lose weight, Joshua, a 19-year-old Glen Cove resident, has relied on fenfluramine to be able to function in his daily life.

Before taking fenfluramine, Joshua, who is autistic, was unable to sit still or to pay attention, said his mother, Paula. His behavior was unmanageable, she said, and his I.Q. so low as to be immeasurable. A daily dosage of 80 milligrams of fenfluramine taken four times a day has increased his ability to focus and raised his I.Q., making him able to function on a fourth-grade level in reading and mathematical skills.

But now Joshua will be unable to get fenfluramine. Following a recent Mayo Clinic study that warned of dangerous side effects from the drug combination fenfluramine and phentermine (known as fen-phen), as well as from a second weight-loss medication, dexfenfluramine, the manufacturer announced an immediate withdrawal from the market.

Wyeth-Ayerst Laboratories, a division of American Home Products Corporation, is the manufacturer of Pondimin (fenfluramine) and the distributor of dexfenfluramine (sold as Redux). The company recalled both diet products following the report by the Mayo clinic that cited 24 cases of heart valve disease in patients treated with the combination of phentermine and fenfluramine. These findings were published in the Aug. 28 issue of The New England Journal of Medicine.