Prescription drug overdose deaths in Florida fell sharply after the state began strengthening its prescribing laws and stepping up enforcement. Federal researchers said Tuesday that it was one of the first significant documented declines in the nation since the epidemic of prescription drug abuse took hold more than a decade ago.

The death rate from prescription drug overdoses in Florida fell by 23 percent from 2010 to 2012, according to a report by the Centers for Disease Control and Prevention, and by more than half in the same period for oxycodone, one of the most widely abused drugs and one that has been at the heart of the health crisis.

Florida began making legal and regulatory changes in 2010, for example requiring pain clinics to register with the state. At the same time, the authorities conducted statewide raids that resulted in drug seizures and the closing of pain clinics. Federal researchers who wrote the report said that the decline in deaths might not be exclusively attributable to the reduction in prescribing, but that the timing suggested it had been an important factor.

Dr. Thomas Frieden, director of the C.D.C., said the pattern provided a hopeful example of the effect that policy could have on one of this country’s most entrenched public health problems, one that takes the lives of more than 20,000 Americans a year.