Bioavailability file: Terbutaline

Terbutaline, a synthetic β2-adrenoceptor (β2AR) stimulant, is used mainly in respiratory medicine (bronchial asthma, chronic bronchitis and emphysema) and in obstetrics. It exists as a racemic mixture (+ and - terbutaline). Although (-) terbutaline is responsible for β-agonist activity, (+) terbutaline is devoid of such pharmacological activity. Terbutaline is incompletely absorbed from the gastrointestinal tract. Its bioavailability is low (10-15%) and stereo selective. It is subject to fairly extensive first pass metabolism by sulfate conjugation in the liver and possibly in the gut wall. In this review, physicochemical and pharmacological properties, pharmacokinetics and bioavailability of terbutaline are discussed.