Ractopamine () is an animal feed additive used to promote leanness and increase food conversion efficiency in farmed animals in several countries, but banned in others. Pharmacologically, it is a phenol-based TAAR1 agonist and β adrenoreceptor agonist that stimulates β and β adrenergic receptors.
It is most commonly administered to animals for meat production as ractopamine hydrochloride. It is the active ingredient in products marketed in the US as Paylean for swine, Optaflexx for cattle, and Topmax for turkeys. It was developed by Elanco Animal Health, a division of Eli Lilly and Company.
As of 2014, the use of ractopamine was banned in 160 countries, including the European Union, China and Russia, while 27 other countries, such as Japan, the United States, South Korea, and New Zealand have deemed meat from livestock fed ractopamine safe for human consumption.
Commercial ractopamine is a mixture of all four possible stereoisomers. It is also a positional isomer of dobutamine, a related drug.