Effects of single-dose and short-term oral nifedipine on indocyanine green clearance as assessed by spectrophotometry and high performance liquid chromatography.

The effects of single-dose (10 mg) and short-term (10 mg tid) nifedipine treatment on apparent hepatic blood flow, as assessed by indocyanine green (ICG) clearance, were studied in ten healthy male subjects. ICG was measured by both spectrophotometric and high performance liquid chromatography (HPLC) assay methods. Blood clearance of ICG and apparent hepatic blood flow were increased by 30 and 50%, respectively, after single-dose nifedipine, whereas after 4 days' treatment these values were 12 and 30%. The spectrophotometric assay significantly overestimated ICG plasma concentrations from 7 minutes onwards. Although the spectrophotometric and HPLC assay showed marked differences in calculated half-lives and volume of distribution of ICG, the ICG clearance values were similar for the two assay methods.