PLASMA-CONCENTRATIONS OF AMIODARONE, DESE THYLAMIODARONE AND THEIR RATIO IN PATIENTS RECEIVING CHRONIC TREATMENT

We measured plasma concentrations of amiodarone and desethylamiodarone by HPLC in 44 outpatients aged 24 to 67 years old (21 male), receivin g the drug during at least three months. The drug was indicated for su praventricular arrhythmias in 37 patients and ventricular arrhytmias i n seven. Plasma concentrations of amiodarone, desethylamiodarone and t heir ratio were 1.71 +/- 0.82, 0.85 +/- 0.42 mu g/ml and 2.02 respecti vely, for a mean daily dose of 223 +/- 88 mg. In 41 patients, arrtytmi as were successfully treated. These patients received a mean daily dos e of 220 +/- 86 mg and concentrations of amiodarone, desethylamiodaron e and their ratio were 1.75 +/- 0.86, 0.88 +/- 0.45 mu g/ml and 1.99 r espectively. In three patients with treatment failure, receiving a dai ly dose of 257 +/- 115 mg, these figures were 1.2 +/- 0.3, 0.5 +/- 0.1 mu g/ml and 2.4 respectively. We conclude that our patients had lower plasma concentrations of desethylamiodarone and higher amiodarone/des ethylamiodarone ratios than those reported in other countries.