Effects of 2-camphanone on canine portal vein blood flow and rat smooth muscle

Abstract 2-Camphanone is under clinical evaluation for alleviation of hemorrhoidal bleeding and inflammation. Reduced portal venous blood flow may distend, whereas improved portal venous blood flow may alleviate, hemorrhoidal vein distention. The effects of 2-camphanone on canine portal venous blood flow were investigated using pulsed Doppler flow techniques and on the spontaneous contractions of the isolated rat portal vein. Both intravenous (0.06, 0.2, and 0.6 mg/kg) and transdermal (6 mg/dog on the thigh) administration of 2-camphanone to dogs anesthetized with pentobarbital sodium increased portal venous flow velocity by 20%–30% without affecting femoral arterial blood flow, heart rate, or arterial blood pressure compared with vehicle-treated animals. Transdermal administration of 0.6, 2, and 6 mg of 2-camphanone, in a volume of 0.1 mL, to rats decreased the spontaneous contractions of the isolated rat portal vein in vitro. The data suggest that 2-camphanone exhibits a relatively selective effect on portal venous smooth muscle to reduce venous congestion and increase blood flow velocity. 2-Camphanone may be useful in the treatment not only of hemorrhoids, but also of esophageal reflux and portal hypertension.