Chemicals extracted from the skin of Epipedobates tricolor may be shown to have medicinal value. Scientists use this poison to make a painkiller.[27] One such chemical is a painkiller 200 times as potent as morphine, called epibatidine; however, the therapeutic dose is very close to the fatal dose.[28] A derivative ABT-594 developed by Abbott Laboratories, called Tebanicline got as far as Phase II trials in humans,[29] but was dropped from further development due to unacceptable incidence of gastrointestinal side effects.[30] Secretions from dendrobatids are also showing promise as muscle relaxants, heart stimulants and appetite suppressants.[31] The most poisonous of these frogs, the golden poison frog (Phyllobates terribilis), has enough toxin on average to kill ten to twenty men or about ten thousand mice.