The tricyclic antidepressants represent an older class of antidepressants that were once widely used in the treatment of depression. The tricyclic antidepressants refer to their three-ring chemical structures. For convenience, this blogshall refer to the tricyclic antidepressants as TCAs.



Tricyclic Antidepressant. Tri means three, cylic means a cycle or structure, and antidepressant means a cure or treatment for depression. Therefore, TCAs contain a 3-ring molecular structure (see image above). They one of the classes of antidepressants. The picture below shows the chemical structure of the the “Big Five” with their 3 ring structure.


(Pictured from Henry’s Clinical Diagnosis and Management by Laboratory Methods)

TCAs does not only treat depression alone but also the following:

For children:

  • Enuresis (you can’t control to urinate)
  • Obsessive-compulsive disorder
  • Attention deficit hyperactivity disorder
  • School phobia
  • Separation anxiety

For adults:

  • Neuralgic pain
  • Chronic pain
  • Migraine

TCA and its Beginnings

Between the late 1950s and the late 1980s, tricyclic antidepressants (TCAs) were used extensively in the management of depression and other psychiatric disorders. Although there are many other antidepressants out there, TCAs are first line therapy in the management of depression. However, side effects are one of the reasons why they are being replaced by other antidepressants with fewer side effects.

Consequently, TCA toxicity, which can be life-threatening, remains a significant clinical issue. The first report of the adverse effects of tricyclic overdose came within 2 years of their clinical use. (Read more: http://www.uptodate.com/contents/tricyclic-antidepressant-poisoning and http://www.mayoclinic.org/diseases-conditions/depression/in-depth/antidepressants/art-20046983?pg=1)

How tricyclic and tetracyclic antidepressants work

 Basically, all antidepressants play the same role in keeping your mind in a state of happiness. Although antidepressants do not necessarily make sad people happy. The word ‘depressed’ is often used when people really mean sad, fed up, or unhappy. True depression is different to unhappiness and has persistent symptoms (which often include persistent sadness). 
A closer look of our brain cells chemicals are being transmitted. There are so many chemicals that are being communicated with each brain cells every single time depending on the mood of the person. In depression chemicals in the brain called serotonin and norepinephrine are being absorbed thus there are low levels of these chemicals. TCAs act by blocking the absorption of these chemicals thus increasing there levels in the brain. So the more serotonin and epinephrine, the merrier. 
TCAs can also affect other chemical messengers, which triggers the side effects.

Side effects and cautions



Side effects of cyclic antidepressants vary somewhat from medication to medication and usually don’t last long. The most common side effects of cyclic antidepressants include:

  • Dry mouth
  • Blurred vision
  • Constipation
  • Urinary retention
  • Drowsiness
  • Increased appetite leading to weight gain
  • Drop in blood pressure when moving from sitting to standing, which can cause lightheadedness
  • Increased sweating

Other side effects may include:

  • Disorientation or confusion, particularly in older people when the dosage is too high
  • Tremor
  • Increased or irregular heart rate
  • More-frequent seizures in people who have seizures
  • Difficulty achieving an erection, delayed orgasm or low sex drive

(Lifted from: http://www.mayoclinic.org/diseases-conditions/depression/in-depth/antidepressants/art-20046983?pg=1)


The “Big Five’s” Sting



(Read more: http://www.medscape.org/viewarticle/508718_2)



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