Cardiovascular effects of romifidine in dogs

Objective-To characterize the cardiovascular effects of romifidine at doses ranging from 5 to 100 mug/kg of body weight, IV. Animals-25 clinically normal male Beagles. Procedure-Romifidine was administered IV at a dose of 5, 10, 25, 50, or 100 mug/kg (n = 5/group). Heart rate, arterial pressure, central venous pressu re, mean pulmonary arterial pressure, pulmonary capillary wedge pressure, b ody temperature, cardiac output, and PCV were measured immediately prior to and at selected times after romifidine administration, Cardiac index, stro ke index, rate-pressure product, systemic and pulmonary vascular resistance indices, and left and right ventricular stroke work indices were calculate d, Degree of sedation was assessed by an observer who was blinded to the do se administered. Results-Romifidine induced a decrease in heart rate, pulmonary arterial pre ssure, rate-pressure product, cardiac index, and right ventricular stroke w ork index and an increase in central venous pressure, pulmonary capillary w edge pressure, and systemic vascular resistance index. In dogs given romifi dine at a dose of 25, 50, or 100 mug/kg, an initial increase followed by a prolonged decrease in arterial pressure was observed. Arterial pressure imm ediately decreased in dogs given romifidine at a dose of 5 or 10 mug/kg. Conclusions and Clinical Relevance-Results suggest that IV administration o f romifidine induces dose-dependent cardiovascular changes in dogs. However , the 2 lowest doses (5 and 10 mug/kg) induced less cardiovascular depressi on, and doses greater than or equal to 25 mug/kg induced similar cardiovasc ular changes, suggesting that there may be a ceiling on the cardiovascular effects of romifidine.