Tricyclic Antidepressants

Tricyclic antidepressants are named for the chemical structure of many of the drugs in the class -- three rings. The first of the tricyclic antidepressants, imipramine (later brand-named Tofranil), was discovered in the late 1950s. Although many other antidepressants have come along since then, the tricyclics still have a place in the treatment of bipolar disorder, and some are also used to treat other conditions.

How Do Tricyclic Antidepressants Work?

Most tricyclic antidepressants are thought to act by blocking reuptake of two critical brain hormones, the neurotransmitters serotonin and norepinephrine -- some block one, some the other, and some are "dual action." (See Messengers of the Brain for more information on how neurotransmitters work.)

Tricyclic Antidepressants and Drug Allergies

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.

Pregnancy / Breastfeeding

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.

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 may be prescribed for insomnia)
• Dizziness
• Increased appetite
• Weight gain (may be significant)
• Blurry vision
• Changes in sexual functioning

See our Side Effects Library or the specific listings below for the side effects of individual tricyclic antidepressants.

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:

• other 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 MAO inhibitors, another type of antidepressants, or switching from one to the other. Taking them 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:

• Amitriptyline (Elavil, Endep and many others)
• Amoxapine (Asendin)
• Clomipramine (Anafranil)
• Desipramine (Norpramin, Pertofrane)
• Doxepin (Adapin, Sinequan)
• Imipramine (Tofranil)
• Nortriptyline (Pamelor, Aventyl)
• Protriptyline (Vivactil)
• Trimipramine (Surmontil)

Disclaimer: This is not intended to be all-inclusive or to replace information provided by your doctor or with prescriptions from drug manufacturers.

_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. 9/8/06.