Carfentanil or carfentanyl is a structural analog of the synthetic opioid analgesic fentanyl. Carfentanil was first synthesized in 1974 by a team of chemists at Janssen Pharmaceutica which included Paul Janssen. The effects of carfentanil, including overdose, can be reversed by naloxone.
Naloxone has been used to reverse carfentanil overdoses; however, greater than normal doses are required
to revive those who have overdosed. In response to the current opioid crisis in Alberta, overdose reversal kits
containing naloxone are publicly available at some pharmacies, walk-in clinics, and emergency services.
Carfentanil is one of the most toxic opioids currently known, with studies showing it to be 10,000 times more
potent than morphine, 4,000 times more potent than heroin, and 100 times more potent than fentanyl. In
humans, a dose as small as 1 microgram is enough to elicit a response to the drug, and about 20 micrograms,
which is less than a grain of salt, is enough to be fatal. Like fentanyl, carfentanil can be absorbed through
accidental inhalation of airborne powder, which makes its exposure and handling dangerous.
There are reports of drug dealers adding carfentanil to traditional drugs because it is cheaper, more potent,
and easier to obtain than heroin or cocaine. It is unlikely that drug users are aware that they are receiving drugs laced with carfentanil, and maybe more likely to overdose when taking their usual dose.