First high-performance liquid chromatography assay of formoterol concentrations in the low-picogram-per-milliliter range.

A method for the assay of plasma concentrations of the long-acting beta 2-adrenoceptor agonist, formoterol is described. This method, in which high-performance liquid chromotography is used with electrochemical detection, enables, for the first time, pharmacokinetic and pharmacodynamic research with this drug. After column extraction of plasma samples, the eluent is injected on the chromatographic system. Retention times of formoterol and the internal standard, bromo-formoterol, were 5.6 and 10 min, respectively. Our results show that this is a sensitive and reproducible method with a very low limit of detection (20 pg/ml), which creates the possibility of measuring concentrations in a range achievable in humans.