Bioavailability of amiodarone tablets administered with and without food in healthy subjects

The tablet form of amiodarone is indicated for the treatment of recurrent ventricular fibrillation or hemodynamically unstable ventricular tachycardia. It is recommended that the tablet be taken with meals in cases of gastrointestinal intolerance. However, the effect of food on its bioavailability is unknown. The primary objective of this study was to determine the effect of food on the bioavailability of amiodarone. This was a 2-period crossover study conducted in 30 healthy male subjects. Subjects were randomly assigned to 1 of 2 sequences in which the following 2 treatments were administered: (1) a single-dose of amiodarone (three 200-mg Cordarone tablets) after an overnight fast, and (2) the same dose immediately after a standard high-fat breakfast. Plasma concentrations of amiodarone and desethylamiodarone (DEA) were measured for 6 weeks after each dose. Food enhanced the extent of absorption, resulting in a peak concentration (Cmax) and area under the curve (AUCT) 3.8 and 2.4 times the respective values under fasting conditions. Food also significantly increased the rate of absorption, reducing the time (tmax) to Cmax from 7.1 to 4.5 hours. The effect of food on DEA levels was significant but less pronounced. An in vitro dissolution study confirmed a marked difference between amiodarone release under simulated fed and fasting conditions. Thus, food significantly enhances both the rate and extent of absorption of amiodarone, which is attributed partially to the effect of food on drug release from its formulation. Therefore, it is recommended that amiodarone tablets be taken consistently with meals.