Abstract
Summary 16-Acetyl-gitoxin, the cardioactive metabolite of pengitoxin, was estimated by the86Rb uptake technique. In 70 consecutive patients taking an oral maintenance dose of pengitoxin 0.4 mg (Pentagit®), the mean plasma concentration was 20.8±6.7 ng/ml. Toxic signs were not observed up to plasma levels of 40 ng per ml.