TCA’s: Tricyclic Anti-depressants

Tricyclic antidepressants are one of the oldest anti-depressants available (along with MAOIs).  They work by inhibiting the reuptake of norepinephrine and serotonin by pre-synaptic neurons in the Central Nervous System.

Huh?

Okay, let’s put this in plain English. Neurons communicate with each other by sending out messages using neurotransmitters like norepinephrine and serotonin.  But not all of these messengers will make it to their destination in a timely fashion!  So after the message has been sent, the body starts to “clean up” any unused neurotransmitters.  One way to clean-up is by recycling the norepinephrine and serotonin back into the original neuron to be reused later.

Got that so far?  Because that’s how the body works normally.  But if the client is taking a Tricyclic medication, such as Elavil (amitriptyline), Trofanil (Imipramine), or Pamelor (Nortriptyline HCl), then something a little different happens.

Basically, Tricyclic medications work by stopping the first neuron from recycling the norepinephrine and serotonin.  This means that the extra norepinephrine and serotonin hang out a lot longer in between the neurons, which increases the chance that more of them will manage to continue sending the message.  With more norepinephrine and serotonin available, a depressed mood often improves.

Of course, like any drug, there are many common side effects that can cause clients a lot of discomfort but aren’t inherently dangerous.  First off, tricyclics have anti-cholinergic effects:  they dry out everything!  Dry eyes, dry mouth, decreased urine output, and constipation are the primary symptoms related to anti-cholinergic effects.  Some clients also experience orthostatic hypotension, sedation, or restlessness and muscle twitches.

But the most well-known side effect of tricyclics is probably weight gain.  This is possibly also one of the biggest reasons for non-compliance as well!  After all, would you want to keep taking a medication if it made you gain weight and turn into a puffy marshmallow?  How do you think that side effect would influence your mood?

Here’s some other odds and ends that you should know about tricyclic anti-depressants.  They can take up to 2-4 weeks to relieve symptoms, so you’ll have to educate your clients that they shouldn’t expect their depression to improve immediately.  Also, tricyclics are contraindicated in clients with narrow-angle glaucoma because it can increase eye pressure, which will worsen damage done to the eye.

Finally, it is easy for patients to overdose using tricyclics.  That’s a dangerous prospect when working with a depressed client!  So make sure that you do a suicide assessment on every patient taking (or being prescribed) tricyclics.  If you suspect the patient might be at risk for a suicide attempt, then the initial prescription might only be filled for a couple days or a week at a time to prevent the client from having too much of the tricyclic available all at once.

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