Tricyclic Antidepressants (TCAs)

Long used as the treatment of choice for depression, the tricyclic antidepressants have a number of features to recommend them, including the fact that they have been used for over 30 years to successfully treat depression. Certain TCAs have both sedating and antidepressant effects. If a depressed person is sleeping poorly or is anxious - a very common occurrence in depression - this anti-anxiety or anxiolytic effect can be very useful. TCAs all prevent brain cells from pumping a number of neurotransmitters back into transmitting cells to a variable degree.

This leaves more of these neurotransmitters including norepinephrine, serotonin and, to a lesser extent, dopamine in the gaps between cells to be picked up by receiving cells and over time, helps restore normal function. Because the TCAs affect more than one brain chemical, however, they have a number of undesirable side effects - the most common ones being the so-called "anticholinergic" side effects. These side effects include dry mouth, blurred vision, trouble urinating and constipation. TCAs also impair concentration and memory - symptoms which are already present when people are depressed. This means that people taking a TCA are subject to a sort of "double-whammy" effect on concentration and memory. Another side effect of the TCAs is weight gain. With self-esteem again already low in depressed people, people who are sensitive about their weight may be more likely to stop taking their medication because of this particular unwanted effect. There is also the serious issue of deliberate overdosing.

Many depressed people think about killing themselves. Indeed, suicide is a major symptom of depression. Deliberate overdosing with any of the TCAs can be fatal. For this reason, people taking a TCA must be closely monitored if the threat of suicide is real. The TCAs may also not be appropriate for use in the elderly because of their side effect profile. These side effects include a condition called orthostatic hypotension, or dizziness on standing. The TCAs make this tendency to feel dizzy worse and it may be appropriate to treat an elderly depressed patient with a different class of medication to prevent dizziness and subsequent risk of falling.

TCAs include: amitriptyline (Elavil, Levate, Novo-Tryptin, Endep, Enovil, Apo-Amitriptyline/); imipramine (Apo-Imipramine, Impril, Novo-Pramine, PMS-Imipramine, TofranilÆ, Norfranil, Tipramine), desipramine (Alti-Desipramine, Apo-Desipramine, Dom-Desipramine, NorpraminÆ, Novo-Desipramine, Nu-Desipramine, PertofraneÆ, PMS-Desipramine)); nortriptyline (AventylÆ, Pamelor), protriptyline (TriptilÆ, Vivacil), trimipramine (Apo-Trimip, Novo-Tripramine, Nu-Trimipramine, Rhotrimine, SurmontilÆ), doxepin (Alti-Doxepin, Apo-Doxepin, Novo-Doxepin, Rho-Doxepin, SinequanÆ, Triadapin, Zonalon), clomipramine (AnafranilÆ, Apo-Clomipramine, Gen-Clomipramine, Novo-Clopamine), maprotiline (LudiomilÆ, Novo-Maprotiline), amoxapine (AsendinÆ).

How to minimize side effects when taking a TCA   

• Drowsiness and lethargy disappear with time, but when first starting the medication, limit alcohol use and avoid sedatives and antihistamines which can worsen the problem. Also avoid driving a car or operating machinery if drowsiness occurs.
• Report energizing effects including agitation and insomnia to your doctor if they occur. These effects may be reduced by taking the medication in the morning.
• Take the medication with food if nausea or heartburn occur.
• Try reading under a bright light and hold book at a distance, or wear reading glasses if blurred vision occurs. Prescribed eye drops may also help.
• Get up slowly if you are lying or sitting down to minimize dizziness.
• Use talcum powder if sweating occurs.
• Try chewing sugarless gum or sucking on sugarless candy to increase salivation if dry mouth occurs. Frequent tooth-brushing helps too.
• Increase bulk foods, exercise more often and drink lots of fluids if constipation occurs.
• Avoid extreme heat as in a sauna as these agents alter the body's ability to adapt to extreme changes in temperature.
• Don't stop your medication suddenly; otherwise you may experience muscle aches, chills, nausea or vomiting.
• If your prescription is for once a day at bedtime, and you miss one dose, don't take the missed dose the next day and don't double the dose. If you take the medication several times a day, take the missed dose when you remember, then continue with your regular schedule.

Differences between TCAs
As a class of antidepressant agents, the TCAs share many features, including side effects. However, they do vary in side effect intensity and likelihood of these effects occurring. If one medication within this class of antidepressants proves troublesome, a different medication still within the same drug class may be better tolerated. Here's a short list of how the TCAs differ. (From the Clinical Handbook of Psychotropic Drugs. 6th revised edition. Editors Kalyna Z. Bezchlibnyk-Butler, J. Joel Jeffries. Clarke Institute of Psychiatry, Toronto, Canada.)

Anticholinergic effects
(dry mouth, blurred vision, constipation, sweating, problems with urination): Most but not all of the above effects are more likely with amitriptyline, clomipramine, doxepin, amoxapine and maprotiline than with other TCAs.

Central nervous system: (CNS) effects (drowsiness, sedation, insomnia, excitement, confusion, headache): Drowsiness and sedation are more likely with amitriptyline, doxepin and trimipramine than with other TCAs. Insomnia is more likely with clomipramine, imipramine, protriptyline and amoxapine than with other TCAs, while excitement is most likely with imipramine and protriptyline. Confusion is more likely with amitriptyline, nortriptyline and trimipramine than with other TCAs. Headache is most likely with imipramine and is not common with other TCAs.

Tremor: Tremor is more likely with amitriptyline, clomipramine, imipramine, nortriptyline, trimipramine and maprotiline than with other TCAs.

Dizziness: Dizziness is most likely with imipramine and more likely with amitriptyline, clomipramine, doxepin, protriptyline, trimipramine and amoxapine than with other TCAs.

Stomach upset (nausea): Stomach upset is most likely with imipramine and not common with other TCAs.

Weakness/fatigue: Amitriptyline, imipramine, nortriptyline and protriptyline are more likely to cause weakness and fatigue than other TCAs.

Weight gain: Weight gain is most likely with amitriptyline, and is more likely with clomipramine, doxepin, imipramine, trimipramine and maprotiline.

Sexual disturbances: Sexual disturbances are more likely with clomipramine and imipramine than with other TCAs but are common to the class as a whole.

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