Doctors and frontline health-care workers say they are responding to an increasing number of overdoses involving opioids contaminated with benzodiazepines, restricted substances normally used to treat anxiety.

Benzodiazepines don’t respond to emergency treatments such as naloxone, or Narcan, which usually temporarily reverses the effects of an opioid overdose. Instead, drug users are left groggy, disoriented and suffering from memory loss. That means users may remain unconscious even after naloxone is administered, according to Overdose Prevention Society director Sarah Blyth.

“It’s way more challenging for all frontline workers because a person will overdose, you’ll give them Narcan, which normally brings them back into consciousness and fully awake and alert … but this means you give them Narcan and they still need to be monitored for most of the day,” said Blyth.

“It adds to everything. It adds to the crisis. It’s another level of stress.”

Blyth said the prevention society saw 16 such overdoses in a 24-hour period last weekend.

Dr. Keith Ahamad, a researcher at the B.C. Centre on Substance Use, said these overdoses are becoming more common at St. Paul’s Hospital.

“We’ve been hearing about it for months, but over the past couple of weeks the clinical presentations have been much more significant,” said Ahamad.

Opioids and benzodiazepines are both sedatives, but they work along different neurological pathways. That means using them together brings a magnified risk of overdose and different withdrawal syndromes, making it more challenging to treat. Health-care workers don’t know why the two drugs are being cut together.

“We’ve warned people using opioids to not take benzodiazepines because we know the combination can cause overdoses,” said Dr. Mark Lysyshyn, a medical health officer with Vancouver Coastal Health.

Samples of contaminated drugs taken earlier this year showed traces of etizolam, which is chemically related to benzodiazepine. Since then, Lysyshyn said stronger, illicitly-produced benzodiazepine variants have appeared.

“The illegal drug supply will produce dangerous drugs,” he said. “This is the last type of compound we’d want to see mixed with opioids, but here it is.”

Drugs cut with these contaminants have been reported in other B.C. communities, including Powell River this week. But the scope of the problem is unknown because benzodiazepine test strips do not detect etizolam.

“You see a little bit of it, and all of a sudden it’s in everything,” said Blyth.

Vancouver police seized just 47 grams of benzodiazepines in all of 2018, none of which were etizolam. But over 6,100 grams of seized drugs were classified as “unknown” and were not tested or identified, according to data obtained through a freedom of information request.

Medications to reverse benzodiazepine-caused overdoses exist, but are dangerous to use and restricted to hospitals, Lysyshyn said.

“It’s not easily administered like naloxone is, so it’s not the kind of thing we can make widely available,” he said.

Ahamad said the contaminated drugs makes treating withdrawal and addiction symptoms more complicated because users may develop a physical dependence to benzodiazepines without realizing it.

“We’re going to be hamstrung in our ability to treat people with our classic treatment (methods) if the drugs that are being used are of a different class,” said Ahamad.

B.C.’s overdose crisis killed 1,514 people last year. Most of those deaths involved fentanyl, but over 16 per cent involved “other” drugs including benzodiazepines, over-the-counter medications, and other drugs, according to coroner data.

Blyth said these overdoses are the consequence of a toxic drug supply and urged government to make responding to the crisis a central campaign issue in the coming federal election.

“We want to make sure people are safe, but we also want to make sure we’re getting somewhere, someday, where we’re not in this situation anymore,” she said.

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