Key result
Magnesium sulfate administered during astemizole overdose increased atrioventricular conduction time and electrical vulnerability, and decreased blood pressure and cardiac output in dogs.
Why the study?
Does magnesium sulfate antagonize the proarrhythmic effects of astemizole overdose in a canine model?
Does magnesium sulfate antagonize the proarrhythmic effects of astemizole overdose in a canine model?
In a canine model of astemizole overdose, magnesium sulfate worsened hemodynamics and did not antagonize proarrhythmic effects, suggesting limited therapeutic utility for this specific toxicity.
Dog model on magnesium in astemizole overdose; leaves open clinical utility and safety.
Polymorphic ventricular arrhythmias induced by astemizole overdose have been reported to be successfully managed with intravenous magnesium sulfate. This study was designed to assess the effects of magnesium sulfate on the cardiovascular system, complicating astemizole overdose, the better to understand the therapeutic utility and undesirable effects of magnesium sulfate. Beagle dogs were anesthetized with halothane inhalation (n = 6). Monophasic action potential of the right ventricle, electrocardiogram, and systemic and left ventricular pressure were continuously monitored. Cardiac output was measured by a thermodilution method. Effective refractory period of the right ventricle was assessed by programmed electrical stimulation. An intentionally high dose of astemizole (3 mg/kg, i.v.) prolonged the repolarization and refractory period, while it decreased the sinus automaticity, ventricular contraction, and conduction. A canine antiarrhythmic dose of magnesium sulfate (100 mg/kg, i.v.) was additionally injected 1 h after i.v. astemizole. Magnesium sulfate increased the atrioventricular conduction time, electrical vulnerability, and preload of the left ventricle, while it decreased the blood pressure and cardiac output, besides the effects similar to those observed after i.v. astemizole. The plasma concentration of astemizole was at least 10 times higher than its therapeutic concentration during the experimental period. Magnesium sulfate could be expected to act as a calcium channel blocker during astemizole overdose; however, it may not antagonize the proarrhythmic effects of astemizole.
No takes yet. Share an insight, caveat, or question.
Sugiyama et al. (1997) studied Astemizole overdose (n=6). Magnesium sulfate vs. Astemizole alone (baseline) was evaluated on Cardiovascular system effects (conduction, pressure, cardiac output, refractory period). Magnesium sulfate administered during astemizole overdose increased atrioventricular conduction time and electrical vulnerability, and decreased blood pressure and cardiac output in dogs.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: