The active ingredient R-salbutamol sulphate is classed as a beta-agonist and more specifically a beta2 (ß2) adrenergic agonist. Beta-agonists are also referred to as metabolic modifiers or repartitioning agents. R-salbutamol is the pure isomer of salbutamol, which is a 1:1 ratio of the R- and S-isomers.
Salbutamol binds to both ß1 and ß2 receptors on body cells. S-salbutamol has a higher affinity for the ß1 receptor whereas R-salbutamol is selective for the ß2 receptor.
Implication of Receptor Affinity
ß1 receptors are found mainly on the heart muscle and kidneys. Stimulation of the ß1 receptors leads to increased heart rate and possible tachycardia. ß2 receptors are found on the lungs, muscle and most importantly, adipose tissue. The absence of the S-isomer in Salbutamate 10% reduces the negative effect of heart palpitations.
Effect on Fat Metabolism
The binding of R-salbutamol to ß2 receptors on adipose tissue stimulate fat break down (lipolysis). This in turn increases the amount of energy available for muscle growth (protein anabolism).
Effect on Muscle Metabolism
R-salbutamol also binds to ß2 receptors on the muscle, increasing protein deposition, leading to improved carcass dressing percentage.