Facts on File Encyclopedia of Health and Medicine

ferent mechanism from subsequent classes in that
it blocks the function of an enzyme (monoamine
oxidase, or MAO) to indirectly extend the avail-
ability of the neurotransmitters DOPAMINE, NOREPI-
NEPHRINE, and serotonin. Unfortunately, the body
requires MAO to metabolize tyramines, proteins
that occur naturally in certain foods. Unmetabo-
lized tyramines affect cardiovascular function and
can cause rapid, extreme elevations in BLOOD PRES-
SURE, which presents a significant risk for STROKE.
People taking MAOIs must avoid eating foods high
in tyramines, such as smoked meats, cheeses,
wines, and fermented or pickled foods. Because
the risk for potentially fatal HYPERTENSION (high
blood pressure) is so high, doctors prescribe
MAOIs primarily as a final treatment option when
other antidepressant medications do not improve
symptoms.

MONOAMINE OXIDASE
INHIBITOR (MAOI) ANTIDEPRESSANTS
isocarboxazid phenelzine
tranylcypromine

Tricyclics The tricyclic class of antidepressants,
so-called because of their three-ringed molecular
structure, entered the market in the early 1960s as
a welcome alternative to MAOIs. This second gen-
eration of antidepressants became the most widely
prescribed antidepressant medications for 30
years, leading treatment protocols until selective
serotonin reuptake inhibitors (SSRIs) supplanted
them in the 1980s. Tricyclics, also called TCAs,
appear to selectively suppress serotonin and nor-
epinephrine reuptake, though the precise mecha-
nisms by which they do so remain unknown.
Doctors may prescribe tricyclic antidepressants
to treat other health conditions, notably ENURESIS
(bedwetting), OBSESSIVE–COMPULSIVE DISORDER(OCD),
CHRONIC FATIGUE SYNDROME, and some CHRONIC PAIN
syndromes such as FIBROMYALGIA and chronic
regional PAINsyndrome. Though an improvement
over MAOIs, with their multitude of side effects,
the tricyclic antidepressants have some significant
side effects of their own, most bothersome among
them being drowsiness, dry MOUTH, CONSTIPATION,
and SEXUAL DYSFUNCTION. Doctors now tend to pre-
scribe tricyclics as second-line treatment for
depression that does not improve with SSRIs.

TRICYCLIC ANTIDEPRESSANTS

amitriptyline clomipramine

desipramine doxepin

imipramine nortriptyline

protriptyline trimipramine

Selective serotonin reuptake inhibitors (SSRIs)

The SSRIs block reuptake of only serotonin, elimi-

nating or diminishing many of the side effects

attributable to inhibited reuptake of norepineph-

rine, which is a feature of MAOIs and tricyclics.

Doctors now prescribe SSRIs as the first line of

medication treatment to treat moderate depres-

sion in most people. SSRIs are also effective in

treating the EATING DISORDERSanorexia nervosa and

bulimia. At lower doses than doctors typically pre-

scribe to treat depression, SSRIs have moved to

the front line of therapeutic options for treating

discomforts related to MENOPAUSE such as HOT

FLASHES, replacing hormone replacement therapy

(HRT).

SELECTIVE SEROTONIN REUPTAKE INHIBITORS (SSRIS)

citalopram duloxetine

escitalopram fluoxetine

fluvoxamine paroxetine

sertraline

Tetracyclics The tetracyclic class of antidepres-

sants (a four-ringed molecular structure) debuted

in the late 1990s as an alternative to the tricyclics.

Like tricyclics, the tetracyclics extend the presence

of serotonin and norepinephrine by delaying their

reuptake. However, tetracyclics have fewer as well

as milder side effects than tricyclics.

TETRACYCLIC ANTIDEPRESSANTS

amoxapine maprotiline

mirtazapine

Other antidepressants Several new antidepres-

sants came into use in the late 1990s and early

2000s that do not fit within conventional classifi-

cations. These drugs selectively affect specific neu-

rotransmitters or neuroreceptors through different

mechanisms from those of other antidepressants.

Bupropion has US Food and Drug Administration

(FDA) approval for use in SMOKING CESSATION

efforts.

antidepressant medications 361