Information update

Health Canada clarifies position on W-18

Starting date:
June 13, 2016
Posting date:
June 13, 2016
Type of communication:
Information Update
Source of recall:
Health Canada
Important Safety Information
General Public
Identification number:


The purpose of this Information Update is to clarify Health Canada's position on W-18, a potentially harmful substance that Health Canada has taken action to control under the Controlled Drugs and Substances Act (CDSA).

In statements regarding W-18, Health Canada has referred to this substance as a synthetic opioid. This terminology was used, in part, to align with public communications from multiple credible sources, including the European Monitoring Centre for Drugs and Drug Abuse, where W-18 was classified as an opioid. Further, the limited scientific information publicly available on W-18 compared the substance to morphine with respect to its analgesic potency.

However, doubts about this classification have been raised recently by a number of credible sources. It has been noted that, at present, while the only publicly available scientific report compares W-18 and related compounds to opioids, it does not determine whether or not W-18 binds to opioid receptors in the body. The Department is aware of ongoing studies to determine the mode of action of W-18 and will continue to assess new information as it becomes available.

The purpose of the Controlled Drugs and Substances Act (CDSA) is to control substances that may cause harm to the health of an individual or to society when diverted or misused. The CDSA states that amendments may be made to the schedules to the CDSA if it is deemed to be in the public interest.

Health Canada is moving to add W-18 and related compounds (its salts, derivatives, isomers, analogues, and salts of derivatives, isomers and analogues) to Schedule I of the CDSA. This decision was taken after careful consideration of a series of factors.

First, although no pharmacological data is available about the mode of action of W-18, in the only publicly available report - the patent application - a pain test on mice showed W-18 to be substantially more able to relieve pain than morphine. W-18 was reported to be active at 1/10,000 of the dose as compared to morphine. This suggests a potentially severe risk for harm to individuals.

In addition, the lack of data about toxicity, bioavailability, tolerance, half-life and onset of effects for W-18 could lead users to rely on self-reported experiences and other information from user web forums, which may be inaccurate. Individuals may be tempted to experiment with W-18, mistakenly believing that it is safer than substances controlled under the CDSA.

Further, W-18 was found in samples seized by Canadian law enforcement authorities in 2015. Counterfeit tablets had W-18 as the only active ingredient, but were made to appear like prescription oxycodone tablets. There have since been additional seizures of W-18 from the illicit market.

Finally, although W-18 was initially developed for its analgesic (pain killing) potential, there are no published studies or case reports regarding legitimate uses for W-18.

Health Canada would like to emphasize that given the absence of specific knowledge on the mechanisms of action and the pharmacology of W-18, it is not currently known whether naloxone would be effective if it were administered to someone who had taken W-18. Administering naloxone to someone who has taken W-18 would not hurt the person. When someone has overdosed on any drug, it is important to always dial 9-1-1 to seek emergency medical assistance.

The sale of any unapproved drug product is illegal under the Food and Drugs Act. Controlling W-18 under the CDSA will provide options to law enforcement, with additional offences and penalties, when they identify illicit activities involving W-18.

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