Tricyclic antidepressant overdose

Tricyclic antidepressant overdose is poisoning caused by excessive medication of the tricyclic antidepressant (TCA) type. Symptoms may include elevated body temperature, blurred vision, dilated pupils, sleepiness, confusion, seizures, rapid heart rate, and cardiac arrest. If symptoms have not occurred within six hours of exposure they are unlikely to occur. TCA overdose may occur by accident or purposefully in an attempt to cause death. The toxic dose depends on the specific TCA. Most are non-toxic at less than 5 mg/kg except for desipramine, nortriptyline, and trimipramine, which are generally non-toxic at less than 2.5 mg/kg. In small children one or two pills can be fatal. An electrocardiogram (ECG) should be included in the assessment when there is concern of an overdose. In overdose activated charcoal is often recommended. People should not be forced to vomit. In those who have a wide QRS complex (> 100 ms) sodium bicarbonate is recommended. If seizures occur benzodiazepines should be given. In those with low blood pressure intravenous fluids and norepinephrine may be used. The use of intravenous lipid emulsion may also be tried. In the early 2000s TCAs were one of the most common cause of poisoning. In the United States in 2004 there were more than 12,000 cases. In the United Kingdom they resulted in about 270 deaths a year. An overdose from TCAs was first reported in 1959. The peripheral autonomic nervous system, central nervous system and the heart are the main systems that are affected following overdose. Initial or mild symptoms typically develop within 2 hours and include tachycardia, drowsiness, a dry mouth, nausea and vomiting, urinary retention, confusion, agitation, and headache. More severe complications include hypotension, cardiac rhythm disturbances, hallucinations, and seizures. Electrocardiogram (ECG) abnormalities are frequent and a wide variety of cardiac dysrhythmias can occur, the most common being sinus tachycardia and intraventricular conduction delay resulting in prolongation of the QRS complex and the PR/QT intervals.