A majority of 365 Internet sites that advertise or sell controlled meds by mail offer to supply the drugs without a proper prescription, according to a new study. Among the prescription pills cited are OxyContin, methadone and Vicodin, which are painkillers; anxiety meds such as Xanax and Valium, and stimulants such as Ritalin.

Government efforts to crack down on Internet sales apparently reduced the number of sites offering such drugs from 581 last year, according to the report from The National Center on Addiction and Substance Abuse at Columbia University. But of the sites not requiring prescriptions, 42 percent explicitly stated that no prescription was needed, 45 percent offered an “online consultation,” and 13 percent made no mention of a prescription.

“In spite of those efforts, anyone of any age can obtain dangerous and addictive prescription drugs with the click of a mouse,” Joseph Califano Jr., a former US Secretary of Health, Education, and Welfare, who heads CASA, says in a statement. “This problem is not going away. It is morphing into different outlets for controlled prescription drug trafficking like Internet script mills and membership sites that sell lists of online pharmacies, and different payment methods like eChecks, COD and money orders.”

In April, the Senate passed the Ryan Haight Online Pharmacy Consumer Protection Act, which would require certification of online pharmacies and that doctors see patients before prescribing controlled drugs, The New York Times writes, adding that the bill is now in committee in the House. At least eight states have passed laws barring electronic prescribing or sales without a legitimate prescription.

Federal drug authorities have begun working with credit card companies and banks to try to prevent online transactions, while major Internet search engines have used a verification program called Pharmacy Checker to confirm that advertisers are legitimate. But the system appears to be full of holes, the Times writes.

Califano sent letters this week to senior officials of Google, Yahoo and MSN asserting that they were “profiting from advertisements for illegal sales of controlled prescription drugs online,” and calling for stronger action, according to the paper.