Cardiopulmonary effects of clenbuterol in the horse

Abstract

Clenbuterol, a bronchospasmolytic agent (beta 2 agonist) was studied in terms of its hemodynamic and airflow response in eight, healthy horses. Four animals were instrumented to record intrapleural pressure and air flow, these were used to compute pulmonary resistance, peak flow rates, and tidal volumes. Four animals were instrumented to record pulmonary arterial pressure, carotid arterial pressure, cardiac output, and arterial gas tensions. After control values were recorded, clenbuterol (0.8 microgram/kg) was intravenously administered to each horse in each experiment group. Following clenbuterol administration, non-elastic resistance of the lung or pulmonary resistance significantly decreased, 33.6% reduction at 10 min post-clenbuterol. Pulmonary resistance remained lowered during the entire procedure and showed no tendency of returning toward control values by 3 h post-clenbuterol. Within 30 sec following clenbuterol injection carotid arterial pressure decreased (mean pressure decrease 28.2%). Accompanying the change in arterial pressure, the heart rate drastically increased, 99.0%. Both changes were transient and returned to control ranges within 2 min. Clenbuterol appears to be effective in reducing non-elastic resistance of the lung, however intravenous administration to an animal with pre-existing cardiovascular or cardiopulmonary disease should be avoided.

Some cardiopulmonary effects of midazolam premedication in clenbuterol-treated bitches during surgical endoscopic examination of the uterus and ovariohysterectomy

“…The decrease in the arterial blood pressure observed in this investigation after clenbuterol administration (26 %), was similar to the decrease observed in halothane-anaesthetised horses (28 %) treated with clenbuterol 5,15 . In addition, isoflurane also causes peripheral vasodilation 6 , and could potentiate the hypotensive effects of midazolam and clenbuterol.…”

“…It may also have minimal $1-adrenergic activity that can cause tachycardia and ventricular arrhythmias 1,13 . Its administration during anaesthesia in horses 5,7,12,15 has been reported previously, but not its intravenous administration during anaesthesia in dogs. Intra-operative duodenal administration in dogs resulted in a 15 % decrease in arterial blood pressure 11 , and a decrease of 31 % in horses anaesthetised with intravenous agents 5 .…”

Albuterol and Exercise Effects on Ankle Extensor Strength during 40 Days of Unloading

“…Data were compared with a 2 (gender) 3 2 (treatment) 3 4 (time) MANCOVA, with day 0 AEXT strength measurements and a drug/body mass ratio as covariates. Results: [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40], as well as CAP and EAP days 11-20 and 21-30 showed the following signifi cant results: ALB-W . ALB-M, PLA-M .…”

Temporal Strength Changes From Resistance Exercise and Albuterol on Unloaded Muscle

“…However, 7.4 mgÁkg -1 of albuterol, far in excess of human dosages, failed to do the same (13). Side effects from clenbuterol are preceded by significant changes in blood pressure and heart rate (37), yet no such changes occurred with albuterol given to unloaded humans (9). Differences among the partial b 2 agonists may be due to clenbuterol's longer half-life and albuterol's rapid sulfation, as low plasma levels occur, despite quick serum absorption (13,30).…”

“…Doses in excess of those recommended for human use promote skeletal muscle mass and strength gains as well as several adverse side effects in animals (18,34,37). Therapeutic oral b 2 agonist doses produced mixed changes in muscle strength without side effects (11,24,27,28).…”