TCA

Tricyclic Antidepressants (TCA)

Tricyclic antidepressants (TCAs) are a class of medications that are primarily used to treat depression. They were first discovered in the early 1950s and were among the first antidepressants to be developed. TCAs are named for their chemical structure, which contains three rings of atoms.

Mechanism of Action

TCAs work by inhibiting the reuptake of neurotransmitters serotonin and norepinephrine in the brain, increasing their levels and prolonging their activity. This helps to improve mood and alleviate symptoms of depression. TCAs also affect other neurotransmitters, which can lead to a range of side effects.

Common TCAs

Some commonly prescribed TCAs include:

• Amitriptyline
• Nortriptyline
• Imipramine
• Desipramine
• Clomipramine

Uses

While primarily used to treat major depressive disorder, TCAs are also prescribed for other conditions, including:

• Anxiety disorders
• Chronic pain
• Migraine prophylaxis
• Obsessive-compulsive disorder (OCD)
• Enuresis (bedwetting) in children

Side Effects

TCAs can cause a variety of side effects due to their broad mechanism of action. Common side effects include:

• Dry mouth
• Constipation
• Urinary retention
• Blurred vision
• Drowsiness
• Weight gain
• Orthostatic hypotension

More serious side effects can include cardiac arrhythmias, especially in overdose situations, which can be life-threatening.

Contraindications

TCAs are contraindicated in patients with certain conditions, such as:

• Recent myocardial infarction
• Arrhythmias
• Severe liver disease
• Narrow-angle glaucoma

Interactions

TCAs can interact with a variety of other medications, including:

• Monoamine oxidase inhibitors (MAOIs)
• Selective serotonin reuptake inhibitors (SSRIs)
• Anticholinergic drugs
• Sympathomimetic drugs

History

The first TCA, imipramine, was discovered in the early 1950s by researchers at the Swiss pharmaceutical company Ciba-Geigy. It was initially developed as an antipsychotic but was found to have significant antidepressant effects. This discovery led to the development of other TCAs and the establishment of a new class of antidepressant medications.

Related Pages

• Selective serotonin reuptake inhibitor
• Monoamine oxidase inhibitor
• Serotonin-norepinephrine reuptake inhibitor
• Depression (mood)
• Anxiety disorder
• Chronic pain
• Migraine
• Obsessive-compulsive disorder
• Enuresis