A classification of medications taken to relieve the symptoms of depression, though they are also useful for treating chronic (particularly neuropathic) pain. They work primarily by extending the availability of certain neurotransmitters in the brain. Each tricyclic drug does this in a somewhat different way; most have the strongest influence on suppressing the reuptake of serotonin and norepi-nephrine and do not affect monoamine oxidase (MAO) or dopamine directly. The tricyclic antide-pressants have been on the market since the 1950s. Once therapy with tricyclics begins, it can require up to eight weeks, and sometimes longer, for the full antidepressant effect to become established. Stopping a tricyclic antidepressant should be done gradually over about two weeks.
Depression is four to six times as common in people with Parkinson’s as in the general public, affecting 40 percent or more of those with Parkinson’s at some stage of the disease. Depression is often one of the earliest symptoms of Parkinson’s; however, the disease is not recognized until other symptoms begin to appear. The dopamine depletion that characterizes Parkinson’s upsets the balance of neurotransmitters in the brain, altering the functions of them all. Antidepressant medications help to restore balance to the neurotransmitters that are most involved with mood and emotion.
Tricyclic antidepressants interact with numerous other medications including many anti-parkin-son’s medications. In particular, tricyclic antidepressants can decrease the amount of levodopa that enters the bloodstream from the intestines.
Commonly prescribed tricyclic antidepressants include
• amitriptyline (Elavil, Endep)
• Desipramine (Norpramine)
• Imipramine (Tofranil)
• Nortriptyline (Pamelor)
Tricyclic antidepressants have a variety of side effects that vary somewhat by drug. Common among them are drowsiness, constipation, dry mouth, and cardiac arrhythmias (a key factor in their lethality even if just several days’ worth of medication is taken as an intentional overdose). Tricyclics also rarely can worsen the symptoms of Parkinson’s or cause other extrapyramidal symptoms such as dystonia and choreic dyskinesias. They cannot be used at the same time as MONOAMINE OXIDASE INHIBITOR (MAOI) MEDICATIONS (including selegiline) or selective serotonin reuptake inhibitor (ssri) medications. The SSRIs have become the antidepressants of choice for people with Parkinson’s disease, as they have the fewest drug interactions and side effects.