What Are Tricyclic Antidepressants and How Are They Used?

Clomipramine (Anafranil) tricyclic antidepressant
Clomipramine (Anafranil) tricyclic antidepressant molecule. Getty Images/MOLEKUUL/SCIENCE PHOTO LIBRARY

Tricyclic antidepressants are older medications that first were developed in the late 1950s. Although many clinicians now prefer newer forms of antidepressants, tricyclics still have a place in the treatment of bipolar disorder, and some also are used to treat other conditions.

The first of the tricyclic antidepressants, Tofranil (generic name: imipramine) was an important discovery and actually helped psychiatrists to formulate their ideas about how depression occurs.

Tricyclic antidepressants are named for the chemical structure of many of the drugs in the class — the drugs are made up of three rings of atoms.

How Do Tricyclic Antidepressants Work?

When you're depressed, it's thought that you don't have enough of two chemicals your brain uses to transmit signals: serotonin and norepinephrine.

Tricyclic antidepressants work by preventing your body from breaking down those chemicals, known as neurotransmitters. Some tricyclic antidepressants block the breakdown of one, some the other, and some are considered "dual action" because they block the breakdown of both serotonin and norepinephrine.

When your body is blocked from breaking down these neurotransmitters, more of them is available for your brain to use. This, in turn, is thought to elevate your mood.

Common Side Effects of Tricyclic Antidepressants

Although each of the tricyclic antidepressants is slightly different from the others, they share similar side effects.

Common ones may include:

  • dry mouth
  • constipation
  • drowsiness (some drugs may be prescribed for insomnia)
  • dizziness
  • increased appetite
  • weight gain (may be significant)
  • blurry vision
  • changes in sexual functioning

If you have had a bad reaction to carbamazepine (Tegretol), or any previous psychiatric medication, make sure you tell this to your doctor if he suggests you take a tricyclic antidepressant.

In addition, there are reports of babies having problems when their mothers took tricyclic antidepressants at the end of the pregnancy. Tricyclics do pass into breast milk. If you are pregnant, nursing or plan to become pregnant, discuss use of tricyclics with your doctor.

Drug Interaction Information

Some of the side effects of tricyclic antidepressants can be intensified by other drugs. Your doctor should know what other drugs you are taking, including prescription medications, over-the-counter drugs and street drugs. For example:

  • Tricyclics can cause cardiac arrhythmia — a fast, pounding or irregular heartbeat. Drugs that can make this worse include amphetamines, diet pills, decongestants, allergy medications, and asthma medications.
  • Sleeping pills, antipsychotic medications, muscle relaxants, antihistamines, tranquilizers and alcoholic beverages can increase the sedating properties of tricyclics.

Other drugs that can cause problems when taken with tricyclic antidepressants include, but are not limited to:

  • psychiatric medications
  • blood-thinning drugs
  • medications for overactive thyroid
  • Tagamet (cimetidine)
  • certain blood pressure medications

Finally, serious, even fatal complications can occur when combining tricyclic antidepressants with another type of antidepressants known as MAO inhibitors, or when switching from one to the other. Taking these two types of drugs together or within two weeks of each other may cause sudden high body temperature, extremely high blood pressure, severe convulsions, and death. Your doctor may prescribe them together, but this situation should be under the doctor's close supervision.

Information on Individual Tricyclic Antidepressants

The tricyclic antidepressants are most often sold under their generic names, so they are listed by those names here, with the most common brand names following:

Sources:

Susic, P. (2006, January 19). Antidepressants: The tricyclics. St.Louis Psychologist and Counseling Information and Referral. 9-28-06.

Trujillo, K.A., and Chinn, A.C. (1996). Antidepressants.

Continue Reading