Tricyclic antidepressants, or TCAs, are used to treat several conditions, including depression, pain from peripheral neuropathy, migraines and bedwetting in children. TCA's include amitriptyline, imipramine and nortriptyline. Tricyclic antidepressants affect a number of receptor types, including those for histamine and acetylcholine. As a result, they affect many different systems in the body, and can cause a wide variety of side effects.
Suicidality
Antidepressants, including TCAs, can increase thoughts of suicide and suicidal acts. The FDA issued a special warning about this side effect. Suicidality increases in particular in children, adolescents and young adults. The risk of suicide can appear in patients treated for any condition, including patients who were not depressed prior to starting the medication.
Side Effects from Blocking Acetylcholine and Histamine
Cholinergic receptors are spread throughout the autonomic nervous system, which controls the automatic functions of the body. By blocking these receptors, TCAs cause side effects such as blurry vision, dry mouth and confusion, in particular in elderly patients. As explained in "Harrison's Principles of Internal Medicine," urinary retention may occur, especially in men with enlarged prostates. Red, dry skin is another possible side effects. Pressure in the eye may increase, which can be dangerous in patients who have a certain type of glaucoma.
TCA's antihistamine effect can lead to sedation and weight gain. As explained in "Kaplan and Sadock's Comprehensive Textbook of Psychiatry," sedation can be severe, limiting the ability to function normally throughout the day.
Cardiac Side Effects
Tricyclics can increase the heart rate. They can also cause a change in the EKG that indicates an increased risk for a fatal disturbance in the heart rhythm, called Torsades de Pointes. As explained in an article published in "Heart" in 2003, the risk of an arrhythmia grows if TCAs are combined with other medications that cause the same effect. Risk is also increased in patients with heart disease.
References
- FDA.Gov: Suicidality and Antidepressant Drugs
- "Kaplan and Sadock's Comprehensive Textbook of Psychiatry"; Virginia Sadock and Pedro Ruiz; 2009
- "Harrison's Principles of Internal Medicine, 17th Edition"; Antoni Fauci (ed); 2008
- "Heart"; Drug Induced QT Prolongation and Torsades de Pointes; Nov 2003
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