Cocaine

Cocaine is a chemical that has both painkilling properties, similar to novacaine, and stimulant properties like adrenalin. The painkilling effects work by blocking the transmission of pain impulses from the nerves to the brain, allowing it to be used as a local anaesthetic. At higher dosages it can even block nerve impulses from the brain to the lungs, so that breathing stops resulting in coma. In contrast, its stimulant action serves to increase the heart rate, the blood pressure and the breathing rate. It also energises the brain to greater alertness, and intensifies the current mood, anger or fear, or agitation (fight-or-flight) and feelings of well-being, riding high and euphoria.

Fentanyl

Fentanyl, also spelled fentanil, is an opioid used as a pain medication and together with other medications for anesthesia. Fentanyl is also used as a recreational drug, often mixed with heroin or cocaine. It has a rapid onset and its effects generally last less than two hours.