Terbutaline is a similar compound to salbutamol, with a tertiary butyl sidechain and a different arrangement of hydroxyl groups on the
benzene ring: this makes it a
1, 3 diol
rather than a 1, 2 diol as in adrenaline.
This arrangement of hydroxyl groups means that the molecule is less susceptible to breakdown by the enzyme catechol-O-methyl transferase, so that it remains active for longer.
Like salbutamol, terbutaline is mostly used as a bronchodilator for the relief of asthma attacks. It has been implicated in producing improved performance in cycling events. Terbutaline and salbutamol may improve sporting performance by altering muscle function and enhancing power production.
Terbutaline is currently on the World Anti-Doping Agency's list of prohibited drugs. However if a Therapeutic Use Exemption (TUE) has been obtained in advance, it may be permitted for use, but only when administered by inhalation. There is some concern that it may be administered orally and remain active in the body without affecting asthma.
Triamcinolone is a corticosteroid with a very different molecular structure, closer to cholesterol but with a fluorine atom.