Federal Drug Enforcement Administration agents arrested Dr. Daniel J. Healy, 52, of Arcadia, operator of Dr. Healy's Diet Centers and Clinics in Duarte and Rancho Cucamonga. He is accused of selling addictive painkillers from his office over a 3-year period to patients he often did not examine. Federal authorities allege Healy dispensed oxycodone and hydrocodone, among other drugs, essentially using his practice as a drug-dealing operation.