Last month, a 30-year-old woman, surnamed Wu, reported to the police that she was approached and possibly drugged by a mysterious man at night near the Tsim Sha Tsui MTR station.

Wu claimed she was chatting on phone at that time, and was interrupted by a Mandarin-speaking man as he touched her shoulder. Wu refused to talk to the man and immediately fled into the MTR station. Yet, by the time she had reached the platform, she felt light headed and her heart beating fast.

Fortunately, Wu was able to make her way back home. Still feeling a tad lightheaded when she woke up the following morning – as if experiencing motion sickness – Wu decided to conduct a medical-checkup at Queen Elizabeth Hospital (QEH). There, she reported the incident to the doctors and police, and she was informed that she was not the first victim lodging similar report with the authority. Currently, the police department is investigating the matter with the Yau Tsim District Criminal Investigation Department (CID).

The incident went viral online, with some within the medical community suspecting the man using a substance, known as carfentanil, to drug the woman.

Carfentanil is an extremely potent drug with only a small amount required for overdose.
Carfentanil is an extremely potent drug with only a small amount required for overdose.

Carfentanil: 10,000 times more potent than morphine

Carfentanil, a synthetic opioid, is an extremely powerful opioid analgesic (painkiller) derived from a similar drug, fentanyl. Originally developed as a general anaesthetic agent for large animals, carfentanil is 100 times more potent than fentanyl and 10,000 times more powerful than morphine, according to the United States’ Drug Enforcement Administration (DEA).

First developed in 1974 under the name Wildnil, carfentanil was reserved as a painkiller or tranquiliser for large animals such as elephants. Only 10mg of carfentanil is required to sedate – or even kill – an elephant, weighing at 6,800kg. Because of its extreme potency, carfentanil is strictly reserved only for use in wildlife science management programmes, research purposes and veterinary practices.

Till date, carfentanil has never been approved for human use in the United States and its potency has allegedly been an interest of the Russian military for use as a chemical weapon. Under no circumstances should carfentanil ever be handled by a civilian with only qualified professionals approved of handling this drug and; even so, only with appropriate precautions and utilisation within the right situation and environment.

Unfortunately, carfentanil has slowly found its way into to the consumer market via the route of illicit drugs, namely in combination with heroin. Because carfentanil is 50 times more potent than heroin, this makes it a suitable addition to heroin which provides a greater effect compared to pure heroin. In addition, carfentanil is a colourless, odourless, water-soluble liquid which makes it undetectable when mixed with heroin. This combination of heroin and carfentanil is particularly popular among regular users who have developed a tolerance towards heroin and are looking for a variant which promises a greater effect.

Problems arise when an inappropriate dose is administered leading to overdose, something that is exceedingly easy with carfentanil owing to its extreme potency. Signs of carfentanil overdose, similar to opioid overdose, are pupillary constriction, respiratory depression and a loss of consciousness. While overdosing is a realistic complication of any opioid administration, carfentanil overdose has been proven to be particularly fatal owing to its narrow therapeutic window. The only treatment for carfentanil overdose is immediate medical attention and the administration of Naloxone, a drug able to reverse the effects of opioids.

It only takes 1mcg of carfentanil to have an effect on humans. The effects of carfentanil include:

• Absent or shallow breathing
• Constricted pupils
• Nausea
• Vomiting
• Lethargy, dizziness or sedation
• Cold, clammy skin
• Loss of consciousness
• Absent or weal pulse

Carfentanil classified as controlled substance in China

As of 1 March 2017, the Chinese government has designated carfentanil (and three other synthetic opioids) as controlled substances. This move comes amidst a surge of opioid related overdoses and deaths over in North America.

Prior to that, China was the largest worldwide exporter of carfentanil with Chinese vendors openly selling the drug online. Further investigation revealed, many of these Chinese businesses even offered international delivery services to countries such as the United States, Canada, Britain, France, Germany, Belgium and Australia for as little as USD2,750/kg. This widespread access to carfentanil resulted in a large number of overdose and death cases over in West – prompting the DEA and US government to request China to blacklist carfentanil.

Aside from the problems associated with addiction, carfentanil also poses a worldwide security threat with terrorism on the rise and carfentanil being a suitable candidate as a chemical weapon for terrorist. Historically, carfentanil has been used several times by military forces to devastating effects most notably by Russian Special Forces in the 2002 Moscow theatre hostage crisis. Since then, carfentanil has been banned from the battlefield under the Chemical Weapons Convention.

All of these factors alluding to this extremely potent drug has ultimately culminated in the aforementioned decision by the Chinese government to make carfentanil a controlled substance – thus, significantly limiting its distribution both regionally and internationally. MIMS

Read more:
US and China’s major moves on opioid crackdown
Three deadly substances to be regulated under Dangerous Drug Ordinance (Cap. 134) in Hong Kong
Tai Po Hospital Chief of Psychiatry Dr Dicky Wai-Sau Chung on the frustrations and challenges of treating psychiatric drug abusers