Beta-Agonists

β-Agonistic drugs are used in human healthcare for the treatment of for instance asthma. A number of β-agonistic drugs have repartitioning effects in meat producing animals. The flow of nutrients is shifted from adipose tissue towards muscle tissue. The result is an improved lean meat deposition and higher production efficiency. The use of β-agonists as feed additives is not permitted in the EU. Nevertheless, there have been reported several incidences of the use of β-agonist drugs in sports as well as in agriculture. Clenbuterol is the only β-agonist for which Community MRLs have been established, i.e. for bovine and equidae muscle (0.1 ng/g), liver and kidney (0.5 ng/g) and bovine milk (0.05 ng/g). The other β-agonists are banned.

Urine is still the most frequently analysed sample material, however, other sample materials are used for different reasons. In farmhouses, urine, faeces, hair and feed can be sampled. Sampling of faeces is much easier and faster than sampling of urine, and the residue levels for β-agonists are comparable. At slaughter, edible tissues (liver, kidney and muscle) can be sampled next to body fluids (plasma, urine and bile) and eye samples. Bile is one of the most suitable sample material for the control on misuse of anabolic steroids and can be preferred for the control of both steroids and β-agonists.

We have six β-agonists kits in our program. The 5071BAGC kit is a specific clenbuterol ELISA, when there is no demand for detecting other β-agonists. Kit 5061BAG and 5061BAFS use a combination of two antibodies, anti-clenbuterol and anti-salbutamol. In the 5061BAFS kit the antibodies are direct coated on the plate, which results in the highest sensitivity.

In the BAGF kit we use one antibody, resulting in a slight difference in cross reactivity. With this kit results are available in only 45 minutes, whereas the sensitivity is slightly better than in the 5061BAG kit. The β-agonist tube test can be used on site, with a sensitivity down to 1 ppb for urine. The Ractopamine kit, 5061RACT, completes the panel of β-agonists.