Drug treatment for mood disorders. Part 2: Tricyclic antidepressants (TCAs) Pharmacological profile

Tricyclic antidepressants (TCAs) Pharmacological profile is unique. Although this group of drugs is very effective in treating major depressive disorders, they are a second choice and only used when the first-choice antidepressants fail. This is because TCAs block many receptors and ion channels that would result in many side effects, some of them so dangerous that they are contraindications. TCAs can block the reuptake of monoamines (MA), increasing the availability of MA at the synapse and producing antidepressant action. They block muscarinic receptors producing atropine-like side effects and contraindications. They block histamine type 1 receptors, producing sedation. They also block adrenergic receptors type alpha 1 producing orthostatic hypotension. Furthermore, TCAs may block sodium channels in the myocardium producing prolongation of the QRS complex resulting in ventricular arrhythmias. They also block potassium channels in the myocardium resulting in the prolongation of the QT wave producing Torsade De point. TCAs have many approved and off-label clinical applications. Mainly as an antidepressant in major depression. They are also effective in certain forms of neurotic illnesses like panic attacks and obsessive-compulsive behavior. Other uses include insomnia, attention-deficit hyperactivity, and adjuvants with other analgesics in the treatment of neuropathic and chronic pain. TCAs have a small therapeutic index, and an overdose is fatal and should be treated immediately in the ICU. This presentation presented all these facts in a simple flow-catching sequence. I hope you will enjoy it as I did. Best regards.