Experiments on the pharmacology of hydroxydione sodium succinate

The actions of hydroxydione sodium succinate ("Viadril") have been studied in chloralose or decerebrate cats, or cats otherwise untreated. It is virtually devoid of action at the neuromuscular, ganglionic, or peripheral adrenergic synapse. After rapid intravenous injection, hydroxydione produced a transient hypotension with little bradycardia and stimulated the respiration. These effects were over in 1 to 2 min. and were reduced if injection was slow or the hydroxydione diluted. Vagotomy did not alter the depressor response, but reduced the respiratory stimulation. In the untreated or the decerebrate animal, as much as five times the anaesthetic dose of hydroxydione was required to depress the respiration or blood pressure. Chloralose potentiated these depressant actions 5 to 10 fold. Both the circulatory and the respiratory depression appeared to be mediated centrally. Decerebrate rigidity was readily lessened by hydroxydione, but the pinna reflex and conjunctival reflex were relatively resistant to its action, and the knee jerk outstandingly so.