Simple and sensitive method for monitoring zopiclone in plasma by high-performance liquid chromatography with fluorescence detection

Abstract

A reversed-phase HPLC-fluorescence method has been devised for the assay of the therapeutic plasma concentrations of the non-benzodiazepine hypnotic drug, zopiclone. A structural analogue of zopiclone is utilised as the internal standard. The method is reproducible, and using 2 ml of plasma has a lower detection limit for zopiclone of around 5 ng ml^–1. This procedure was used to follow the plasma level versus time curve of zopiclone for 10 h in a healthy volunteer given a single oral dose of 7.5 mg of zopiclone. A peak level of 86 ng ml^–1 was achieved 1 h after dosing, and the apparent plasma elimination half-life of zopiclone was 4.9 h.