Distribution of amiodarone in heart tissues following intrapericardial administration

The distribution of amiodarone (A) in heart tissues of open chest anestheti zed animals was studied at 20 and 60 min following the insertion of an isot onic solution of the drug into the pericardial sac (PS) in doses from 0.25 to 3 mg per kg body weight (BW) for pigs and after 60 min in doses of 3 to 6 mg for dogs. Most of the A absorbed by the myocardium was found in the su bepicardium part of the left ventricular (LV) wall. For both species the pe rcentage of drug absorbed by the myocardium was largely and inversely relat ed to the dose given, while uptake by the atria was positively related to t he dose and was higher than that in the subepicardial LV wall. Sixty minute s after i.v. administration of A (3.0 mg per kg BW) the drug was evenly dis tributed across the LV wall (16 mu g per g wet tissue), which was significa ntly lower (p < 0.02) than that of subepicardal LV wall (30 mu g) after int rapericardial (IP) administration. This study shows that satisfactory drug concentrations in predicted and specific distribution in the heart tissue w ere derived shortly after intrapericardial administration without measurabl e circulation in the blood.