A powerful mood-altering medication with potentially life-threatening side effects was for years being prescribed in Canadian prisons for unapproved purposes, raising concerns the drug was being used to "subdue" or "sedate" inmates, a joint CBC News/Canadian Press investigation has revealed.

The investigation also found a dramatic spike over the last decade in prescriptions for all mood-altering medications among female prisoners, according to previously unpublished statistics.

The revelations have led Canada’s prison watchdog to investigate prescribing practices at Correctional Service Canada.

One medication under scrutiny, quetiapine (widely known under the brand name Seroquel), is approved only for treating bipolar diseases and schizophrenia; however, it is sometimes prescribed off-label as well, most commonly as a sleep aid.

According to a memo obtained by CBC News and The Canadian Press, Correctional Service Canada felt compelled to order a halt to those kinds of unapproved uses of quetiapine in February 2011.

"Seroquel was known as the 'sleeping pill' in the prison system," a former female inmate, whose identity cannot be revealed because she was convicted as a youth, said in an interview. "From the youth system and the adult system, whenever I spoke with people who had medication for sleeping problems, it was usually Seroquel."

Dr. David Juurlink, a pharmacologist at one of Canada's leading teaching hospitals, said using quetiapine to help people sleep is dangerous.

"That's just bad medicine," said Juurlink, head of clinical pharmacology and toxicology at Sunnybrook Health Sciences Centre in Toronto. "These are drugs that used even in the right indications, have side effects that can be lethal. [Quetiapine] is an anti-psychotic drug, and when it’s used indiscriminately it can kill people."

According to its product monograph, quetiapine has a long list of rare but serious side effects that include diabetes, muscle twitching and even death.

Misuse alleged among female prisoners

A 2008 University of Ottawa study warned the drug had been misused in female prisons and jails for years. Twenty-one out of 22 women interviewed for the study said they had been prescribed quetiapine in either a federal or provincial institution — yet only one was aware of being diagnosed with a disease the drug is approved to treat.

They like to heavily medicate people, and I’m a prime example. I was a walking zombie - Former federal inmate

"The one thing with prison is that they like to heavily medicate people, and I’m a prime example," one of the women interviewed for the study said. "Seroquel, stuff like that. I was on a lot of medications. I was a walking zombie. I could not function. I do not remember half of my time."

The Correctional Service Canada internal memo, obtained by CBC News and The Canadian Press through access to information, shows that the medication was being prescribed for unapproved uses in federal prisons until at least 2011.

The memo said new rules were being put in place to "better control the circulation" of quetiapine in prisons.

Kim Pate, executive director of the national association of Elizabeth Fry societies, says she's heard for years that quetiapine and other drugs are being used to control inmates. (CBC)

"Those that do not meet the criteria should be discontinued," the document reads. "Gradual withdrawal over a period of at least one to two weeks is advisable."

Jennifer Kilty, a professor of criminology at the University of Ottawa and the author of the 2008 study, said the memo proves the powerful drug was being used improperly, something she has long suspected.

"I would hope that when this story breaks that it's going to anger Canadian citizens and there will be backlash," Kilty said. "I hope it shames the Correctional Service of Canada."

The CSC declined to be interviewed, but it did offer statements in writing.

"Quetiapine is a drug approved for the treatment of schizophrenia and bipolar disorder," the federal agency wrote.

"As part of our ongoing process of quality improvement, medications provided by CSC are regularly reviewed and additional criteria are occasionally put in place. Effective June 2011, quetiapine was listed with limited use criteria to further ensure its safe use. CSC respects Health Canada's standards when providing prescription medications to inmates."

Surge in psychotropic medications

The joint CBC News/Canadian Press investigation also revealed skyrocketing numbers of prescriptions for mood altering medications in general among women in Canadian prisons.

If you have more information about this story, please email us at investigations@cbc.ca

New, exclusively obtained statistics show the prescription rate for so-called psychotropic medications surged in 2013 to 63 per cent of female prisoners. In one prison, Nova Institution for Women in Truro, N.S., as many as three out of every four female inmates were prescribed some type of mood-altering medication.

That's up significantly from 2002 when a Correctional Service Canada study showed that 42 per cent of female inmates were being prescribed psychotropic medications. The CSC called the numbers at the time "problematic" and suggested that "over-prescribing" was taking place.

Female federal inmates with prescriptions for psychotropic drugs as of Aug. 7: Institution # prescribed psychotropic Prison population Percentage on psychotropic Fraser Valley 55 76 72.4 EIFW/RPC 82 145 56.6 Grand Valley 111 201 55.2 Joliette 64 91 70.3 Nova 58 78 74.4 Total 370 591 62.6 Source: Correctional Service Canada and Office of the Correctional Investigator

"It's absolutely outrageous," Kilty said. "When you start to see side effects where the women are experiencing sedation, fatigue, drowsiness — you are seeing these drugs as a way to really calm a population."

Kilty said shrinking resources and growing prison populations are leaving correctional staff with fewer options to manage prisoners. She believes the statistics indicate the drugs are being used to control them.

The former female prisoner interviewed by CBC News and The Canadian Press agreed, saying prescription medications were widely available when she was incarcerated.

"Going to prison was the first time when I saw medication being handed out on a large scale. It seemed like almost everyone had some prescription or other," she said.

"I started to notice that the medication seemed to be a trend to control behaviour. It seems far easier to give a prescription than to help someone address past trauma or help them find a different way to manage their time."

CSC's prescription practices probed

The revelations have prompted the country's federal prison ombudsman to probe prescription practices in Canadian penitentiaries.

Howard Sapers, Canada’s correctional investigator, examines inmate complaints and makes recommendations to the government. He said he's concerned by the statistics that show a dramatic increase in prescriptions for psychotropic medications among female prisoners.

Howard Sapers, the federal correctional investigator, says Canada's prisons need to have a system in place that 'controls and prohibits' the off-label use of prescription drugs.

"One explanation is that the population of offenders is increasingly mentally ill and requiring an increasing amount of medication," he said in an interview. "Another explanation is that drugs are being used in a way that perhaps is inappropriate."

The off-label use of quetiapine and its branded version, Seroquel, has caught his attention in particular.

"Are we seeing drugs being used to somehow sedate or subdue people when that's not really the therapeutic intent of the medication?" he asked. "I can tell you we are concerned if we find medications are being used off-label…. So the challenge is again to make sure the Correction Service of Canada has a regime in place that controls and prohibits the off-label use of prescription drugs."

According to the CSC, a total of 454 inmates were being prescribed quetiapine as of last month. But the department said it can't determine how many of those prescriptions went to its 610 female prisoners versus its more than 14,000 male prisoners.

It's 'bad medicine' to prescribe quetiapine for insomnia, according to David Juurlink, a pharmacologist and toxicologist at Sunnybrook Health Sciences Centre in Toronto. (CBC)

"A breakdown of offenders receiving Seroquel by gender is not available," a CSC spokesperson wrote in an email. "CSC does not have these figures available, nor do we have a system that allows us to readily track this information."

Advocates say it's time someone dug further into the issue.

Kim Pate, executive director of the national association of Elizabeth Fry societies, said her group has been hearing reports for years that quetiapine and other drugs are being used to control inmates, in particular female prisoners.

"I think it's far easier to control individuals in prison if you're medicating them and sedating them than it is to actually engage in the sorts of supports and services that you want to see people have," Pate said. "I'm pleased to hear [Howard Sapers] is investigating, and hopefully that will mean the general public will have more accurate information about what is happening."

Controversial history

Seroquel has a controversial history of off-label use around the world.

In 2010, the company that manufactures the drug, AstraZeneca, agreed to pay $520 million US to settle an investigation into its marketing practices for Seroquel in the United States. Among the allegations by two whistleblowers: the company paid "kickbacks" to doctors and encouraged them to prescribe the medication for unapproved uses, including in U.S. prisons.

AstraZeneca denied the allegations, but said it agreed to pay the settlement to end the investigation.

"By pushing Seroquel for unapproved purposes, AstraZeneca made patients into guinea pigs in an unsupervised drug test," U.S. Department of Justice lawyer Michael Levy said at the time.

There is no evidence AstraZeneca played a role in the Canadian decision to use Seroquel for unapproved uses in Canadian prisons.

In a response to a question, Health Canada sent a statement Monday saying it "has not received any complaint regarding the off-label advertising of Seroquel in Canada. However, should we become aware of such off-label promotion activities, necessary actions will be taken to protect the health and safety of Canadians," the department said in an email.

"With respect to AstraZeneca’s settlement case in the U.S., Health Canada is not aware of similar advertising tactics taking place in Canada."

If you have more information about this story, please email us at investigations@cbc.ca.

2011 CSC internal memo about quetiapine: