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Clinician’s Corner: Tricyclic Antidepressants (TCA)

Although there are 9 different tricyclic antidepressants (TCA) approved in the United States I have only 5 on my shelf at Thompson Pharmacy, Broad Avenue where I practice.

With 9 different TCA’s when do we use them?

• MOST likely to cause drowsiness: Amitriptyline, doxepin and imipramine
• MOST likely to cause weight gain: Amitriptyline, doxepin and imipramine
• CLEANEST: Nortriptyline and desipramine are less likely to cause sedation and weight gain.
• BED WETTING: imipramine is most used
• OBSESSIVE COMPULSIVE DISORDER: Clomipramine was the first drug that was approved for Obsessive-Compulsive disorder.

The most common TCA’s I see in my practice are amitriptyline and nortriptyline. The following is from my St. Francis lecture notes to delineate the differences between the two:
DIFFERENCES BETWEEN Amitriptyline (Elavil®) and Nortriptyline (Pamelor®)
• Nortriptyline is generally better tolerated than amitriptyline. It has much less sedation and anticholinergic side effects.
• The mortality from nortriptyline in overdose is similar to that from SSRIs
• Nortriptyline is the least problematic of the tricyclic antidepressants in terms of drug interactions. It is relatively safe to combine it with certain SSRIs (sertraline and citalopram).
• Nortriptyline is better choice for elderly.
• Maximum dose for Nortriptyline should never exceed 150mg.

MOST TCA’s
• Common side effects: blurry vision, dry mouth, urinary retention, sexual dysfunction, daytime drowsiness
• Cardiac effects: may alter rate, rhythm, & contractility. May cause dizziness.
• Central Nervous System- seizures, respiratory depression, disorientation & coma
• COMMON USES: diabetic neuropathy, phantom leg pain, cancer pain, pain from shingles
• COST: ALL are available generically, and relatively inexpensive.
• CAUTION must be exercised with TCA in patients with suicidal thoughts due to high lethality risks with overdose. The lethal dose is only EIGHT times the therapeutic dose, so if TCA’s are ingested in an overdose, they may block the sinoatrial node in the heart. TCA are more dangerous than SSRI (Prozac, Zoloft and others) in overdose. Therefore, a seven-day supply of a maximally dosed tricyclic antidepressant could be lethal. Here are the brand and generic names of the most common tricyclic antidepressants.

GENERIC BRAND YEAR
Imipramine Tofranil® 1959
Amitriptyline Elavil® 1961
Desipramine Norpramin® 1964
Nortriptyline Pamelor® 1964
Protriptyline Vivactil 1967
Doxepin Sinequan® 1969
Clomipramine Anafranil® 1989

Tricyclic antidepressants are older drugs, and in most cases older than your Thompson Pharmacist (except for two of us!). These drugs are still used frequently today, and in spite of their side effects provide a lot of benefits to our patients. If you have any concern about any of your medications feel free to ask your Thompson Pharmacist. Go Ahead and ASK…at Thompson Pharmacy it’s ALL for YOU!!