Dopamine and isoproterenol in imipramine intoxication in the dog

Poisoning by sodium channel blocking agents

Poisoning by drugs that block voltage-gated sodium channels produces intraventricular conduction defects, myocardial depression, bradycardia, and ventricular arrhythmias. Human and animal reports suggest that hypertonic sodium bicarbonate may be effective therapy for numerous agents possessing sodium channel blocking properties, including cocaine, quinidine, procainamide, flecainide, mexiletine, bupivacaine, and others.

Modelling of non-linear pharmacokinetics in sheep after short-term infusion of cardiotoxic doses of imipramine

Imipramine was administered to sheep (n = 10) by intravenous infusion in high doses (450 mg-900 mg) to elicit cardiovascular shock. A cardiac assist device was then employed to manage the acute overdose situation. The concentration-time course of imipramine and its metabolite desmethylimipramine in plasma was measured by HPLC. As an indicator of imipramine's cardiotoxic effect, cardiac output was monitored. The aim of the study was to evaluate the pharmacokinetics under these conditions and to assess the efficiency of a cardiac assist device with (n = 5) and without (n = 5) an integrated haemoperfusion unit in removing drug from the circulation. The kinetics of imipramine could be described by a three compartment body model with concentration-dependent clearance resulting in non-linear kinetics. The changes in cardiac output with time could be linked to the pharmacokinetic model by a linear relationship. The cardiac assist device was found to contribute to the overall elimination of imipramine whereas the haemoperfusion unit had no clinically relevant impact.

Epinephrine and sodium bicarbonate independently and additively increase survival in experimental amitriptyline poisoning

OBJECTIVES

Cardiac depression is the main adverse effect of severe tricyclic antidepressant poisoning. The aim of this study was to investigate whether treatment with epinephrine or norepinephrine increases survival as compared with standard treatment with sodium bicarbonate in experimental amitriptyline poisoning.

DESIGN

Nonrandomized, controlled intervention trial.

SETTING

University laboratory.

SUBJECTS

Male, anesthetized, paralyzed, and mechanically ventilated Sprague-Dawley rats (n = 91).

INTERVENTIONS

Rats subjected to a 60-min infusion of amitriptyline (2 mg/kg/min) were treated with a continuous infusion of either epinephrine, norepinephrine, sodium bicarbonate, epinephrine plus sodium bicarbonate, norepinephrine plus sodium bicarbonate, or placebo.

MEASUREMENTS AND MAIN RESULTS

Inotropic drug treatment was associated with an increased survival rate as compared with treatment with sodium bicarbonate and treatment with placebo. Epinephrine treatment was superior to norepinephrine. Additional treatment with sodium bicarbonate increased survival rate for each inotropic drug. Sodium bicarbonate and inotropic drug treatment independently increased the survival rate (p < .001 for both effects). No interaction between these two treatment effects was observed.

CONCLUSIONS

Both epinephrine and norepinephrine increased the survival rate in tricyclic antidepressant poisoning in rats. Sodium bicarbonate increased the survival rate independent of inotropic drug treatment. Furthermore, epinephrine was superior to norepinephrine when used both with and without sodium bicarbonate, and the most effective treatment was epinephrine plus sodium bicarbonate.