Abuse of prescription drugs is "epidemic," with teenagers the fastest-growing group of new abusers, yet the problem has not drawn adequate attention from health and law enforcement agencies, physicians, pharmacists and parents, according to a study released yesterday.

Abusers of prescription drugs -- 15.1 million people -- exceed the combined number abusing cocaine, hallucinogens, inhalants and heroin, the report by the National Center on Addiction and Substance Abuse at Columbia University said. Of those, 2.3 million are teenagers, but youngsters turn to prescription drugs at much higher rates than adults do, the study reports.

Teenagers arrange "pharming parties" where they swap drugs they have spirited from home or purchased off the streets or online, the report said.

"Availability is the mother of abuse," said Joseph A. Califano Jr., the center's chairman and former U.S. secretary of health, education and welfare. "When I was young my parents would lock their liquor cabinet. It may be parents should be thinking of locking their medicine cabinets."

The center's three-year study analyzed 15 national data sets, collected information on Internet pharmacies, and conducted original interviews and surveys among doctors and pharmacists.

The tally of abusers of medications is derived from the 2003 National Survey on Drug Use and Health, the most recent in which participants report their own use. An abuser is anyone who reported using an unprescribed drug or taking one only for the feeling it caused.

The number of prescriptions for controlled drugs and the number of abusers far outstripped U.S. population growth between 1992 and 2002, the study reports. The rise in prescriptions reflects the fact that some illnesses can now be treated by medication rather than by other means, Califano said, "so there is not a perfect relation between that and the rise in abuse. But there is enough to suggest there is a relation."

"Add in that we're inventing more and better and more powerful drugs of all these types all the time and you have to see that there are going to be more substances available, not fewer, " he said.

The Pharmaceutical Research and Manufacturers of America, whose members include major drug firms, "strongly supports efforts that help prevent the dangerous and illegal practice of diverting prescription drugs from their intended use," PhRMA Senior Vice President Ken Johnson said in a written statement. "Medicines cannot help patients if they are compromised by misuse or by breakdowns in the distribution system. "

Some drugstore chains have already tightened controls over cold and cough remedies abused by teenagers by putting them behind counters or selling them only to adults. The study suggests broader remedies, including improving monitoring of sales and distribution by enforcement agents, having doctors routinely ask patients about prescription drug use as they do tobacco use, and improving training to detect abuse. Pharmacists should ask about all controlled drugs a patient may be taking and become more aggressive about validating prescriptions, the study said.

At the federal level, Califano said, "we probably need laws on Internet sales, though the Internet is a hard one." At least seven attempts to control online drug sales or make the licensing and ownership of Web pharmacies more obvious have failed in Congress since 2004, the study reported.

The center's study was funded by a $1 million unrestricted grant from Purdue Pharma, manufacturer of OxyContin, a painkiller originally intended for end-stage cancer patients. It is now widely diverted and abused. The study notes that Purdue "aggressively marketed" the drug for lesser pain, leading to more prescriptions. The company also formulated OxyContin in a way that easily allowed abusers to crush and snort the pills, overcoming its time-release formula and allowing a narcotic rush.

Califano said the center and Purdue had a signed agreement that the company would not have input into the report.