Drug
Therapy
There
are several "classes" of medications available to
treat depression. Medications are categorized by the way they
interact with a variety of neurotransmitters. Even within a
class, medications may affect individuals differently. All of
these medications take time to become effective with several
weeks to months required to see a full therapeutic effect. Again,
medication should be prescribed in conjunction with counseling
or psychotherapy.
Tricyclic Antidepressants (TCA's):
TCA's
are named for the presence of three rings in their chemical
structure such as amitriptyline and imipramine. The primary
effect of most tricyclic antidepressants is to block the reuptake
of both norepinephrine and serotonin. They are effective antidepressants,
but they also affect many other receptor systems, which may
cause a wide range of side effects, as well as toxicity in overdose.
Tricyclic antidepressants have been around for many decades
and have shown effectiveness in certain individuals. Potential
side effects include dry mouth, constipation, weight gain and
sexual dysfunction.
Serotonin
Specific Reuptake Inhibitor's (SSRI's)
are
the main classification of antidepressant drugs used today.
SSRI's such as fluoxetine, paroxetine and sertraline involve
the use of the neurotransmitter serotonin, which is used by
certain nerve cells in the brain to communicate with other brain
cells. Under the right conditions, these nerve cells release
serotonin, which then affects neighboring cells. After serotonin
is released, it is taken back up into the cell so that it can
be used again. SSRI's interfere with the serotonin being recycled
once it has been released in the neuronal synapse, thus allowing
more free-floating serotonin outside the cell. Potential side
effects include nausea, headache, nervousness, insomnia and
sexual dysfunction.
Serotonin
and Norepinephrine Reuptake Inhibitors (SNRI's):
SNRI's
such as venlafaxine were, in theory, designed to combine the
actions of neurotransmitters serotonin, norepinephrine and to
a small extent, dopamine. In practice, however, SNRIs' primary
effect is on serotonin. This is because norepinehprine and dopamine
effect appears only when the drug is taken in higher doses.
The problem with higher doses is the potential for side effects
or toxicity.
note:
Specific Serotonin Receptor sites
1.
Serotonin-1 Receptor (5-HT1) Activity
a. Anti-depressant effect
2.
Serotonin-2 Receptor (5-HT2) Activity
a. Inhibits 5-HT-1 Receptor
b. Causes sexual dysfunction
c. Causes insomnia
d. Causes anxiety
3.
Serotonin-3 Receptor (5-HT3) Activity
a. Causes Gastrointestinal symptoms
b. Causes headache
Noradrenergic
and Specific Serotonergic Antidepressants (NaSSA's):
NaSSA's
such as mirtazapine (Remeron®) do not work by inhibiting
neurotransmitter reuptake, although the net effect is increasing
brain levels of norepinephrine and serotonin. They are effective
antidepressants because they block certain subreceptors such
as alpha-2 adrenergic receptors, which increase nor-epinephrine,
and both 5-HT2 and 5-HT3 serotonin receptor sites. One good
aspect of this particular drug is that they do not share the
SSRI-type effects on sexual function because they block 5-HT2
receptor sites specifically, yet do not block 5-HT1 receptor
sites. Commonly reported side effects include drowsiness, excess
sedation, weight gain and dry mouth.
Monoamine
Oxidase Inhibitors (MAOI's):
MAOI's
are usually indicated only when other antidepressants prove
ineffective. Naturally occurring monoamine oxidase metabolizes
serotonin, norepinephrine and dopamine. MAOI's inhibit this
process, thus increasing levels of these neurotransmitters.
MAOI's
include phenelzine (Nardil), isocarboxazid (Marplan), and tranylcypromine
(Parnate) and newly released, moclobemide (Aurorex). MAOI's
commonly cause orthostatic hypotension (a sudden drop in blood
pressure upon standing), drowsiness, dizziness, sexual dysfunction,
and insomnia. MAOI's can have serious interactions with a number
of
drugs; including some common over-the-counter cough medications,
decongestants and SSRI's. MAOI's also have a potential for hypertensive
crisis when taken with foods containing tyramine. Tyramine is
an amino acid which is normally metabolized by MAO in the gut.
With the addition of a MAOI, an increase of tyramine levels
will occur and prevent further metabolism of serotonin, dopamine
and more specifically norepinephrine which would cause a substantial
rise in blood pressure. Tyramine is found in cheese, wines,
and anything aged or fermented.
note: Foods High in Tyramine:
-
All aged/mature cheese (exception: cottage cheese, cream cheese)
- Dry and fermented sausage (bologna, salami, pepperoni, corned
beef,
and liver)
- Pickled herring and salted dried fish
- Broad beans and pods (lima, fava beans, lentils, snow peas,
and soy
beans)
- Meat extracts
- Yeast extracts/brewer's yeast
- Beer and Ale
- Red wine (chianti, burgundy, sherry, vermouth)
- Sauerkraut
- Banana Peel
