Tricyclic

The tricyclic antidepressants are all derived from the same molecule, imipramine. Their name reflects the features of their molecular structure which consists of three rings of atoms. Other antidepressants with similar effects are called tetracyclines and have four rings.

How do the tricyclic antidepressants work?

The tricyclic antidepressants block the pumps involved in re-uptake of serotoninergic and noradrenergic neurotransmitters from synapses. They therefore allow larger amounts of serotonin and noradrenaline to be released and as the patients with depression have abnormally low levels of these neurotransmitters they reduce their symptoms.

Do they have contraindications or precautions?

Tricyclic antidepressants increase the risk of suicidal thoughts. The side effects of the tricyclics include dry mouth, constipation, urinary retention, concentration difficulties, appetite problems, cardiac dysrhythmias, excessive sweating, weight gain, nausea, tremor and headaches. Finally, like all of the antidepressants, tricyclics must be taken strictly according to the doctor's prescription. Follow the doses, do not use in combination with other medicines unless specifically instructed, do not take with alcohol.

Sources:

• Vidal 2010, Le Dictionnaire
• Mc Gill University website, accessed on 25 May 2011