Simple determination of cyclosporine in human whole blood by high-performance liquid chromatography

A simple and reproducible high-performance liquid chromatography (HPLC) method was developed for determination of cyclosporine (CyA, also known as cyclosporin A) in human whole blood. The method entailed direct injection of the blood samples after deproteination using acetonitrile. Chromatography was carried out using an ODS column under isocratic elution with acetonitrile–5 mM disodium hydrogen phosphate (75:25, v/v), pH 5.1 at 70 °C and a detector set at 210 nm. The mean absolute recovery of cyclosporine from blood was 97%, and the linearity was assessed in the range of 100–3000 ng/ml blood, with a correlation coefficient of greater than 0.999. The limit of quantification and detection of the present method were 100 and 50 ng/ml, respectively. This method has been used to analyze several hundred human blood samples for bioavailability studies.