Description: The tricyclic antidepressants (TCAs) are an older class of chemical compounds used to treat major depressive disorder and related mood disorders. They are thought to act at multiple chemical receptors in the nervous system. These medications may help improve mood, feelings of well-being, relieve tension and anxiety, help you sleep better and may increase your energy level. They have largely been replaced by serotonin-norepinephrine reuptake inhibitors (SNRIs) and selective serotonin reuptake inhibitors (SSRIs) as the preferred pharmacological treatment for depression. Adverse effects have been found to be similar between TCAs and SSRIs. TCAs are still occasionally used for treatment-resistant depression that has not responded to therapy with newer antidepressants (Clinical Therapeutics “Selective serotonin reuptake inhibitors versus tricyclic antidepressants in young patients: a meta-analysis of efficacy and acceptability,” Jul 2014).
Common Side Effects
Side effects from tricyclic antidepressants are relatively common and include: dry mouth, dry nose, blurry vision, lowered gastrointestinal motility, constipation, urinary retention, cognitive or memory impairment, and increased body temperature. Other side effects include: anxiety, drowsiness, confusion, emotional blunting (apathy), restlessness, dizziness, akathisia, changes in appetite and weight, sweating, sexual dysfunction, muscle twitches, weakness, nausea or vomiting, hypotension, tachycardia, and irregular heart rhythms.
Pharmacogenetic testing for these side effects can mitigate the risks by determining what dose is safest based on a patient’s genotype, according to Clinical Pharmacogenetics Implementation Consortium guidelines. (Clinical Pharmacology and Therapeutics “Clinical Pharmacogenetics Implementation Consortium guideline for CYP2D6 and CYP2C19 genotypes and dosing of tricyclic antidepressants,” May 2013).
Understand Your Risks with the Rxight® Genetic Test
Rxight® is a comprehensive CLIA-certified PGx (pharmacogenetic) testing program available. This advanced platform in pharmacogenetics analyzes your ability to metabolize over 200 drugs and over-the-counter products, giving you and your physician advanced warning of potential side effects that may be serious. The test requires a simple cheek swab, available at a participating pharmacy. With the Rxight® test results, which will be reviewed in detail with you, you and your provider can work together in finding the dose that is best for you based on your genes.
How Does Pharmacogenetic Testing Work?
Advances in the medical field of pharmacogenetics have shown that some patients have variability in their genes that encode for enzymes in the liver responsible for breaking down and assimilating drugs into the body. In fact, your drug metabolism genes are responsible for making the enzymes that metabolize drugs. If you have variability in your genome, you could be what are referred to as an “ultra-rapid metabolizer,” “rapid metabolizer,” or a “poor metabolizer” of any given tricyclic antidepressant or any number of other drugs. Slow metabolizers are at risk for medication toxicity and adverse reactions. Conversely, rapid metabolizers require higher levels than normal to achieve therapeutic benefit. Knowing how your genes determine how you metabolize medications is an invaluable tool for your and your prescriber.
Contributors to this Article:
Michael Sapko, MD, PhD; Deborah Kallick, PhD, Medicinal Chemistry
Tricyclic Antidepressants Tested Include:
- Amitriptyline (Elavil, Endep, Vanatrip)
- Amoxapine (Asendin)
- Clomipramine (Anafranil)
- Desipramine (Norpramin)
- Doxepin (Silenor, Sinequan, Adapin)
- Nortriptyline (Pamelor, Aventyl Hydrochloride)
- Protriptyline (Vivactil)
- Trimipramine (Surmontil)
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