14. Etorphine
It is a synthetic drug that is at least 5,000 times more powerful than heroin, and it is 1000 to 80,000 times more potent than morphine. 1/100th of a gram could knock out an elephant. Even if it touches the skin, it is enough to put someone in danger. The drug is bought legally by veterinarians, but it is regulated under strict laws. It can be used in immobilizing the elephants or other big animals. Naloxone can be used as an antidote in humans, and it has to be given at once when a person is exposed to etorphine.