Antidepressants are drugs used to treat depression—and certain other mental disorders such as attention deficit disorder, obsessive-compulsive disorder, narcolepsy, anxiety, and panic disorder--caused by chemical imbalances in the brain. Antidepressants, which work by rebalancing these chemicals called "neurotransmitters," are grouped into three primary categories based on their mechanisms of action: tricyclics (or heterocyclics), monoamine oxidase inhibitors, and selective serotonin re-uptake inhibitors. Three drugs, Wellbutrin, Desyrel, and Effexor, differ in their mechanisms of action from other antidepressants and from each other. Antidepressants are available only by prescription, take from four to six weeks to take full effect, work only on treatable disorders, are non-addictive, and are effective for approximately 80% of individuals treated.
When clinical depression and many other mental illnesses were determined to be primarily biological rather than psychological, development of synthetic drugs revolutionized the treatment of mental disorders. Tricyclics (TCAs), introduced into the marketplace in the 1950s, include imipramine (Tofranil), amitriptyline (Elavil, Limbitrol, Endep), desipramine (Norpramine, Pertofrane), doxepin (Adapin, Sinequan), nortriptyline (Pamelor, Aventyl), and proptriptyline (Vivactil). (The newer Clomipramine (Anafranil) is used specifically to treat obsessive-compulsive disorders.) By blocking specific norepinephrine and dopamine receptors on the neuron, TCAs reduce re-absorption of these neurotransmitters into the cell, increasing their presence in the synapses. This, in turn, enhances the transmission of impulses between the neurons. Side effects of TCAs range from annoying to serious but can often be decreased by changing medications.
Monoamine oxidase inhibitors (MAOIs), considered "second-generation" agents, were developed primarily in the 1980s. These drugs, phenelzine sulfate (Nardil) and tranylcypromine sulfate (Parnate), work by inhibiting production of MAO enzymes which help neurotransmitters like norepinephrine pass through the synapses. Too much MAO actually interferes with this process, however. MAOIs are particularly effective in treating depression accompanied by anxiety, oversleeping, and overeating. While side effects are less troublesome than with TCAs, interaction with certain foods, drinks, and medications can cause rapid and extremely high rise in blood pressure and be fatal. Strict dietary and drug restrictions reduce the popularity of MAOIs; however, some patients respond to MAOIs where other antidepressants fail.
Prozac, the first of the selective serotonin re-uptake inhibitor (SSRIs) was introduced in 1987 and rapidly became the most widely-prescribed antidepressant ever. Taken by over six million Americans, its popularity prompted development of similar drugs, including Zoloft and Paxil. SSRIs block certain receptors on the neuron, preventing "re-uptake" of serotonin--the brain's natural antidepressant--into the cell. Generally favored because of fewer side effects and no dietary restrictions, side effects do occur in some individuals.
Three "other" drugs do not fall into any of the above classes: Wellbutrin, related to amphetamines, enhances norepinephrine function and increases energy level; Desyrel, which works on the serotonin system and has a more tranquilizing effect, is seldom used alone but often in conjunction with Prozac; and Effexor, which inhibits serotonin re-uptake and increases norepinephrine levels, helps many patients who do not respond to other antidepressants.
Plants were undoubtedly used throughout the ages to help treat "melancholy." Although controversial, St. John's wort, a natural herb available over-the- counter and which causes few side effects, gained immense popularity in the 1990s for its effect on mild to moderate depression and seasonal affective disorder.
This is the complete article, containing 520 words
(approx. 2 pages at 300 words per page).
