TAMPA, Florida (Reuters) - U.S. authorities arrested 22 people in Florida on Friday, including pharmacists and doctors, in a crackdown against prescription drug abuse that officials say is the nation’s fastest growing drug problem.

The arrests in Orlando and Tampa were the latest steps in successive operations by federal and local authorities to shut down so-called “pill mill” pain clinics, prescription forgery rings and illegal online pharmacies involved in the illegal distribution of prescription drugs such as painkillers.

At a news conference in Tampa, U.S. Attorney General Eric Holder said these operations, dubbed Pill Nation I and II, had led so far to 118 arrests, the seizure of more than $19 million in assets and the closure of at least 40 Florida pain clinics.

“Our targeted, aggressive enforcement actions are sending a clear message that -- here in Florida, which has long been the nation’s epicenter for the illegal distribution of prescription drugs -- the days of easily acquiring these drugs from corrupt doctors and pharmacists are coming to an end,” Holder said.

He was accompanied by the administrator of the U.S. Drug Enforcement Administration (DEA), Michele Leonhart, and Florida state officials.

Those arrested in Florida on Friday, who included five doctors and two pharmacists, were charged with illegally diverting controlled substances.

Holder said in prepared remarks the abuse of prescription drugs, such as painkiller oxycodone and methadone, which is used for drug addiction detoxification, was now the fastest-growing drug problem in the country.

DEA chief Leonhart called it an “epidemic.” Prescription drugs now caused more overdose deaths in the United States than “street drugs” such as cocaine, heroin and methamphetamine.

Holder said an estimated 7 million people in the United States regularly used prescription drugs for nonmedical purposes and this abuse contributed to nearly 40,000 deaths and almost $200 billion in healthcare costs annually.

Last year alone, one in seven teens abused prescription drugs to get high, officials said.

Holder said the problem had reached “crisis proportions” in Florida, where between 2005 and 2010 the number of oxycodone-related deaths increased by 345 percent.

On Saturday, the DEA was sponsoring a National Prescription Drug Take Back Day which will allow people to dispose of expired, unused and unwanted prescription drugs at more than 5,000 collection sites throughout the United States.