Tricyclic antidepressants (TCA's)

Tricyclic antidepressants (TCA's) were the first medications to come into widespread use for the treatment of depression. Tricyclic antidepressants (TCA's) are now considered older or first generation antidepressants. They are still good medications and work well for many individuals suffering from depression. However, they tent to cause more annoying side effects than the SSRI's. Tricyclic antidepressants (TCA's) they are not generally effective in treating obsessive compulsive disorder and social phobias.

The tricyclic antidepressants work by blocking the reuptake of two neurotransmitters, serotonin and norepinephrine. Both of these chemical messengers are involved in regulating mood in the brain. Blocking reuptake effectively increases their concentration in the synapse, the space between nerve cells. This, in turn, appears to relieve depression my mechanisms which are not fully understood.

The tricyclic antidepressants are so named because most of them have a chemical structure which includes three rings. Some of them in fact have a fourth ring, and so are technically called tetracyclic antidepressants, but they can all be grouped under the category of TCA's for this discussion.

Tricyclic antidepressants (TCA's) were the first medications demonstrated to be effective in treating depression by well-controlled scientific studies. These studies, which have been replicated many times, demonstrated that about two thirds of individuals with a major depressive episode responded to tricyclic antidepressants with a marked reduction in symptoms, as compared to about 1/3 of those on placebo. This response rate has not been exceeded by the newer antidepressants.

Tricyclic antidepressants (TCA's) have some advantages over the newer agents. They are less likely to impair sexual function, especially sexual drive or libido. They may quickly reduce insomnia. They are inexpensive. They have been prescribed longer than the newer agents, increasing our confidence in their safety, especially in long term use. And, as mentioned above, they may be more efficacious in some people who do not respond well to the SSRI's..

As with other antidepressants, the beneficial effects of TCA's often take 2-4 weeks to manifest themselves (as opposed to the side effects, which are seen immediately and may improve with time). The fact that side effects may be prominent during this period (see below) may make getting started on these medications a bit difficult. Therefore, it is often best to start with a low dosage, and work up to a therapeutic dosage over 2 to 4 weeks. Surprisingly, this does not seem to slow their onset of action.

Tricyclic antidepressants (TCA's) are also effective in treating panic disorder. They work primarily by blocking the acute symptoms of panic attacks, and secondarily reducing anticipatory anxiety. They are not used to treat obsessive-compulsive disorder or social phobia, and the SSRI's are more useful for these conditions.

The side effects of the tricyclic antidepressants are more common and often more bothersome than those of the SSRI's and other newer antidepressants.


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