HEMODYNAMIC-EFFECTS OF HYOSCINE-N-BUTYLBROMIDE IN PONIES

The haemodynamic effects of hyoscine-N-butylbromide (0.30 mg/kg, intra venously) were studied in eight adult ponies in a blinded two-period c rossover experiment with repeated measures. Values for heart rate were 63%, 48% and 13% greater than control values at 1, 16 and 46 min, res pectively, after administration of hyoscine-N-butylbromide. Cardiac ou tput increased by 16% at 16 min after drug injection. Mean right atria l pressure was decreased by 79%, 63%, 45% and 52% at 1, 16, 46 and 61 min, respectively, after drug administration. Stroke volume was decrea sed by 32% at 1 min and pulmonary arterial wedge pressure was decrease d by 44% at 16 min. We detected no significant difference in mean syst emic arterial pressure, mean pulmonary arterial pressure, systemic vas cular resistance or pulmonary vascular resistance at any time.