The different types of medication used to treat depression
Medication choices include many
medication within the following classes:
-
Tricyclic
antidepressants (TCAs)
-
Monoamine
oxidase inhibitors (MAOIs)
-
Selective
serotonin reuptake inhibitors (SSRIs)
-
Others
TCAs and
MAOIs
TCAs and MAOIs
are the oldest antidepressants. They are effective treatments but have
many problematic side effects. In addition, they can be unsafe to use in
patients with certain medical conditions and in older persons. MAOIs
require strict adherence to a dietary plan that is free of tyramine.
Although these medications are effective for treatment of depression,
they are now typically reserved for use after a person's symptoms have
not improved on one of the newer medications available. The most commonly
prescribed TCAs are desipramine and nortriptyline because of their better
tolerated side effect profiles.
SSRIs
The first SSRI to enter the market was fluoxetine (Prozac) in the late
1980s. Because of its low side-effect profile relative to the TCAs and
MAOIs, fluoxetine quickly became the most popular antidepressant. Several
SSRIs have come on the market since. Because SSRIs as a group are the
most commonly prescribed antidepressants, the decision as to choice of
medication is often in deciding between the SSRIs available. There is no
good evidence that any SSRI is better than another in the treatment of
depression or any of the anxiety disorders. The choice of SSRI has more
to do with side profiles and potential drug interactions. Discontinuation
syndromes are least likely from fluoxetine and are more likely from
paroxetine. Fluoxetine may be a better choice for someone who tends to
miss doses of medication. On the other hand, because of its long
half-life, adverse effects will take longer to dissipate after
discontinuation of the drug. In terms of potential interactions with
other medications, fluoxetine, paroxetine, and fluvoxamine have the
highest potential for such interactions. Sertraline, citalopram, and
escitalopram have a lower risk for interactions. Cost may be a factor in
medication choice as well, with fluoxetine and paroxetine being available
in generic forms.
Other Medications
Medications classified under "others" have various mechanisms of action.
Bupropion blocks the reuptake of dopamine and norepinephrine. Bupropion
does not have significant drug–drug interactions and is not associated
with sexual dysfunction. Venlafaxine and duloxetine are dual reuptake
inhibitors of both norepinephrine and serotonin (and to a lesser extent,
dopamine). They have similar side effect profiles to the SSRIs but have
the advantage of working through two neurotransmitter systems.
Mirtazapine causes increased levels of serotonin and norepinephrine by
blocking the inhibition of their release (both serotonin and
norepinephrine act to turn off their own release by interacting with
receptors on the sending neuron). Trazodone and nefazodone are chemically
similar (trazodone is an older antidepressant), blocking serotonin
reuptake as well as blocking some types of serotonin receptors directly.
Trazodone is very sedating and is mainly used for insomnia, and
nefazodone is not first-line because of its association with some cases
of liver failure.
Typically, the first decision regarding antidepressant choice is between
the newer classes. All antidepressants are effective for depression, but
the choice of type will likely depend on side-effect profiles, patient
characteristics, physician preference, and cost. Some insurance plans
have formularies restricting use to a specific medication. In these
circumstances, the physician would need to explain the rationale for
choosing a non-formulary medicine over a formulary one.
In addition to antidepressants, many other medications are used in the
treatment of depression: anticonvulsants, antipsychotic, and
benzodiazepines. Typically, these medications are used to address
specific co-morbid conditions or symptoms that are not addressed by the
antidepressant. In cases of partial response to an antidepressant, there
may be medications prescribed for augmentation, including buspirone,
thyroid hormone, or even a stimulant such as methylphenidate.
