Determination of the antispasmodic agent ethaverine in human plasma by high-performance liquid chromatography

Ethaverine can be measured in the plasma of human subjects by reversed-phase high-performance liquid chromatography employing UV detection. The limit of detection was 2 ng/ml, and the precision was +/- 14, +/- 6 and +/- 2% at concentrations of 5, 25 and 50 ng/ml respectively. A peak mean plasma drug concentration of 20 ng/ml occurred at 1.5 h after single oral doses of a capsule formulation to human subjects, and declined with a half-life of 2.9 h.