Opioids are a class of drugs that derive from, or mimic, natural substances found in the opium poppy plant. Opioids work in the brain to produce a variety of effects, including pain relief. As a class of substances, they act on opioid receptors to produce morphine-like effects.
A sample of raw opium
Prescription opioid pain reliever overdose deaths in the United States over years
Carfentanil or carfentanyl, sold under the brand name Wildnil, is an extremely potent opioid analgesic used in veterinary medicine to anesthetize large animals such as elephants and rhinoceroses. It is typically administered in this context by tranquilizer dart. Carfentanil has also been used in humans to image opioid receptors. It has additionally been used as a recreational drug, typically by injection, insufflation, or inhalation. Deaths have been reported in association with carfentanil.
2 milligrams of fentanyl, a lethal dose for most people. The lethal dose of carfentanil is uncertain, but is predicted to be much smaller. Diameter of a US penny is 19.05 mm, or 0.75 inches.