Tricyclic antidepressantswere the first line of treatment for major depression from the 1960s through the 1980s. We now know that these medications affected two chemical neurotransmitters, norepinephrine and serotonin. Tricyclics are as effective in treating depression as the newer antidepressants, but their side effects are somewhat more unpleasant. They are no longer the first medication tried for most depressed patients.
Tricyclic antidepressants such as imipramine, amitriptyline, nortriptyline, and desipramine are used when newer medications are not effective. They may also be used at night to improve sleep. Some of these medications are also used to treat neuropathic (nerve-related) pain.
Monoamine oxidase inhibitors are older antidepressants that are effective for some people with major depression who do not respond to other antidepressants. They are also effective for the treatment of panic disorder and bipolar depression. MAOIs approved for the treatment of depression are phenelzine (Nardil), tranylcypromine (Parnate), and isocarboxazid (Marplan). These medications can have severe side-effects in some situations, so patients must follow directions very carefully. Because substances in certain foods, beverages, and medications can cause dangerous interactions when combined with MAOIs, people on these agents must adhere to dietary restrictions.
Newer antidepressants have been introduced beginning in the early 1990s. The first of these medications were the selective serotonin reuptake inhibitors (SSRIs). It has been thought that these medications work by increasing serotonin (a neurotransmitter) between nerve cells. Neurotransmitters are chemicals that pass a nerve impulse from one cell to another. Research has shown that these medications may also help people grow new brain cells. SSRIs include fluoxetine (Prozac), sertraline (Zoloft), fluvoxamine (Luvox), paroxetine (Paxil ), citalopram (Celexa), and escitalopram (Lexapro). While these medications did not cause some of the bothersome side-effects of older medications, many people noticed a loss of sex drive when taking SSRIs.
The late 1990s saw additional medications that, like the tricyclics, affect both norepinephrine and serotonin but have fewer side effects. These new medications included venlafaxine (Effexor) and nefazadone (Serzone). Nefazadone was later taken off the market in the U.S. because cases of life-threatening hepatic failure were reported in patients.
Newer medications chemically include mirtazepine (Remeron) - which can be sedating, and bupropion (Wellbutrin) - which tends to be more activating. Wellbutrin has not been associated with weight gain or sexual dysfunction but it can't be used with anyone at risk for a seizure disorder.
