Food Safety

β₂-Adrenergic agonists, also known as β₂-adrenergic receptor agonists or β-agonists, are a class of drugs used to treat asthma and other pulmonary disease states. They act on the β₂-adrenergic receptor, thereby causing smooth muscle relaxation, resulting in dilation of bronchial passages, vasodilation in muscle and liver, relaxation of uterine muscle and release of insulin.

Beta-agonists are illegally used as growth promoters in animal production. Pharmacologically active residues in edible tissues have led to intoxication outbreaks in several countries. Council Directive 96/22/EC prohibits the use of β-agonists in livestock farming.

Clenbuterol is an authorized β-agonist for specific therapeutic uses in the EU (horses and cows), the USA (horses), and Canada. In Australia, some β-agonists, including clenbuterol, are authorized and their MRLs have been established.

Ractopamine hydrochloride is pharmacologically classified as a phenethanolamine β-adrenoceptor agonist. The use of the substance as a feed additive is authorised in different countries (USA, Canada, Japan and Mexico) for growth promotion of fattening pigs and cattle. Ractopamine has not yet been authorized for use in the EU.