The new regulations close a "loophole" in the program that would allow restricted drugs — including ecstasy, LSD, 'magic' mushrooms and 'bath salts' — from being authorized for patients, she said.
"The prime minister and I do not believe we are serving the best interests of those addicted to drugs and those who need our help the most by giving them the very drugs they are addicted to," Ambrose said.
She added that the new rules will stop doctors from prescribing dangerous drugs and "abusing" the program, which is designed to let patients in exceptional cases obtain medications normally not allowed in Canada.
The ban comes a few weeks after Ambrose slammed her own department's decision to authorize some British Columbia doctors to prescribe heroin to 20 addicts for whom other treatments had failed.
The doctors were conducting a research study looking at whether the opioid painkiller hydromorphone is as effective as heroin in treating long-term addicts.
A previous study by the same researchers had concluded prescription heroin is a safe and effective treatment for the small group of addicts who did not benefit from conventional treatments such as methadone.
Those 20 addicts will have access to the drug for three months, but no more approvals will be made, Ambrose said.
The regulatory changes won't affect clinical trials or university studies, she said.
"We want to help people that have addiction, not to give them ways to maintain their dangerous and life-threatening addiction," she said.
"Drug treatment and recovery programs need to be focused on ending drug use."
Marshall Smith, a former addict who joined Ambrose at the news conference, said he supports the ban.
He said he lost his family, home and career to his addiction to alcohol and drugs, ending up homeless on the streets of Vancouver's Downtown Eastside.
"This disease of addiction doesn't occur in bottles, needles, pills or powder. It occurs in people," said Smith, who has been clean for six years.
"And as a result, recovery doesn't come in bottles, needles or powder. Recovery comes in people and it comes in communities."
Canadian actor and "Glee" star Corey Monteith's heroin-related death shows that it's a very far-reaching issue, Ambrose said.
People often associate heroin addiction with a "certain environment," she said. But it's destroyed the lives of even successful men like Smith and Monteith.
"I just use that to make the point that it touches on all aspects of our community," she said.
Meldon Kahan, a professor of medicine at the University of Toronto, said "flawed treatment approaches" like heroin are unsafe and very expensive.
There are serious questions about the results of the previous study, which provided heroin treatment to about 100 patients over a year at a cost of more than $9 million, he said.
The Harper government has also strongly opposed the Insite supervised injection site in Vancouver, but lost a long legal fight to close it.
The Conservatives are using the heroin issue as a fundraising platform, saying the NDP and Liberals would make the program permanent if elected in 2015.
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