Effect of blood sample tubes on amiodarone and desethylamiodarone concentrations

We have investigated the change in amiodarone and desethylamiodarone concentrations in blood sampled from three different Vacutainer tubes: (a) sodium heparin, (b) gel separator (SST), and (c) no additive (plain tube). Amiodarone and desethylamiodarone concentrations were determined by a reverse-phase high pressure liquid chromatography technique in samples from 12 subjects on chronic amiodarone therapy. Amiodarone concentrations were significantly lower in plasma compared with serum from either gel separator (11.5%, p = 0.05) or no additive (13.5%, p = 0.01) tubes. Desethylamiodarone concentrations were significantly lower in plasma compared with serum from gel separator tubes (8.5%, p = 0.04) and were slightly lower compared with no additive tubes (4.4%, p = 0.41). Serum amiodarone and desethylamiodarone concentrations from either no additive or gel separator tubes yielded similar results. We conclude that significant amiodarone and desethylamiodarone concentration differences occur between serum and plasma, and that no binding of amiodarone and desethylamiodarone to the separator gel occurs.