<unk>  poses an exceptionally high overdose risk in humans, due to having an extremely unpredictable fatal dosage when mixed with other drugs. In its pure form, overdoses are only moderately unpredictable, with most overdose deaths occurring at serum concentrations of between 150 and 250 ng/mL. But when mixed with other drugs, overdoses can occur with as little as 0.1 ng/mL. Over 85% of overdoses involved at least one other drug, and there was no clear correlation showing at which level the mixtures were fatal. The dosages of fatal mixtures varied by over three magnitudes in some cases. This extremely unpredictable volatility with other drugs makes it especially difficult to avoid fatalities. Naloxone can completely or partially reverse an opioid overdose. In July 2014, the Medicines and Healthcare products Regulatory Agency (MHRA) of the UK issued a warning about the potential for life-threatening harm from accidental exposure to transdermal<unk>  patches, particularly in children, and advised that they should be folded, with the adhesive side in, before being discarded. The patches should be kept away from children, who are most at risk from<unk>  overdose. In the US,<unk>  and<unk>  analogs caused over 29,000 deaths in 2017, a large increase over the previous four years. mcg of<unk> , each Most of the recent increases in<unk>  deaths do not involve prescription<unk>  but are related to illicitly-made<unk>  that is being mixed with or sold as heroin. Death from<unk>  overdose continues to be a public health issue of national concern in Canada since September 2015. In 2016, deaths from<unk>  overdoses in the province of British Columbia averaged two persons per day. In 2017 the death rate rose over 100% with 368 overdose-related deaths in British Columbia between January and April 2017.<unk>  has started to make its way into heroin as well as illicitly-manufactured opioids and benzodiazepines.<unk>  contamination in cocaine, methamphetamine, ketamine, MDMA, and other drugs is common. A kilogram of heroin laced with<unk>  may sell for more than US$100,000, but the<unk>  itself may be produced far more cheaply, for about US$6,000 per kilogram.<unk>  was often produced in China and exported illegally to the U.S. The UK illicit drug market is no longer reliant on China, as domestic<unk>  production is replacing imports. As of 2018,<unk>  was the most commonly listed opioid in overdose drug deaths, surpassing heroin. From 2013 until 2016, overdose deaths involving<unk>  were increasing by 113% per year. In 2021, the Public Health Agency of Canada noted that 87% of accidental apparent opioid toxicity deaths involved<unk> . The intravenous dose causing 50% of opioid-naive experimental subjects to die () is "3 mg/kg in rats, 1 mg/kg in cats, 14 mg/kg in dogs, and 0.03 mg/kg in monkeys." The LD50 in mice has been given as 6.9 mg/kg by intravenous administration, 17.5 mg/kg intraperitoneally, 27.8 mg/kg by oral administration. The LD50 in humans is unknown, but a lethal dose for the average person is estimated to be 2 mg. Contrary to what has been reported in some media outlets, topical (via the skin) and inhalative exposure to<unk>  is extremely unlikely to cause intoxication or overdose (except in cases of prolonged exposure with very large quantities of<unk> , and first responders such as paramedics and police officers are at minimal risk of<unk>  poisoning through accidental contact with intact skin.
Fentanyl
Remifentanil
Ketamine
Alfentanil
Propofol
Etomidate
Sevoflurane
Methoxyflurane