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GENERIC
NAME: bupropion
BRAND NAME:
Wellbutrin, Wellbutrin SR, Wellbutrin XL,
Zyban
DRUG CLASS AND MECHANISM:
Bupropion is an antidepressant medication that
affects chemicals within the brain that nerves
use to send messages to each other. These
chemical messengers are called
neurotransmitters. The neurotransmitters that
are released by nerves are taken up again by the
nerves that release them for reuse. (This is
referred to as reuptake.) Many experts believe
that depression is caused by an imbalance among
the amounts of neurotransmitters that are
released. Bupropion is unrelated to other
antidepressants. It works by inhibiting the
reuptake of dopamine, serotonin, and
norepinephrine, an action which results in more
dopamine, serotonin, and norepinephrine to
transmit messages to other nerves. Bupropion is
unique in that its major effect is on dopamine,
an effect which is not shared by the selective
serotonin reuptake inhibitors or SSRIs (e.g.
paroxetine, Paxil; fluoxetine, Prozac;
sertraline, Zoloft) or the tricyclic
antidepressants or TCAs (e.g. amitriptyline,
Elavil; imipramine, Tofranil; desipramine,
Norpramin).
PRESCRIPTION:
Yes
GENERIC AVAILABLE:
Yes
PREPARATIONS: Wellbutrin,
round tablets: 75 mg (orange), 100mg (red).
Zyban, round tablets: 100 mg (blue), 150 mg
(purple). Wellbutrin SR, round tablets: 100 mg
(blue), 150 mg (purple). Wellbutrin XL, tablets:
150 and 300 mg.
STORAGE: Tablets should be
kept at room temperature, 15- 25°C
(59-77°F).
PRESCRIBED FOR: Wellbutrin,
Wellbutrin SR, and Wellbutrin XL are used for
the management of major depression and seasonal
affective disorder (depression that occurs
primarily during the fall and winter). Zyban has
been approved as an aid to patients who want to
quit smoking.
DOSING: Bupropion usually
is given in two or three daily doses. When used
for smoking cessation, bupropion usually is
started as 150 mg once daily for three days, and
then the dose is increased if the patient
tolerates the starting dose. Smoking is
discontinued two weeks after starting bupropion
therapy. Wellbutrin SR is given as two daily
doses. Wellbutrin XL is given as one dose
daily.
DRUG INTERACTIONS: Although
no systematic studies have been done to assess
the potential of bupropion to interact with
other drugs, bupropion should be used cautiously
in patients receiving drugs that reduce the
threshold for seizures. Such drugs include
prochlorperazine (Compazine), chlorpromazine
(Thorazine), and other antipsychotic medications
of the phenothiazine class. Additionally,
persons who are withdrawing from benzodiazepines
(e.g. diazepam, Valium; alprazolam, Xanax) are
at increased risk for
seizures.
PREGNANCY: Although there
are no adequate studies of bupropion in pregnant
women, studies in pregnant animals using doses
much higher than those used in humans, have
demonstrated that bupropion is safe. Bupropion,
therefore, can be used in pregnancy if the
physician feels that it is
necessary.
NURSING MOTHERS: It is not
known if bupropion is secreted in breast
milk.
SIDE EFFECTS: The most
commonly noted side effects associated with
bupropion are agitation, dry mouth, insomnia,
headache, nausea, constipation, and tremor. In
some people, the agitation or insomnia is most
marked shortly after starting therapy. Some
patients may experience weight loss. Uncommonly,
patients may experience manic episodes or
hallucinations. Four of every 1000 persons who
receive bupropion in doses less than 450 mg/day
experience seizures. When doses exceed 450
mg/day, the risk increases ten-fold. Other risk
factors for seizures include past injury to the
head and medications which can lower the
threshold for seizures. (See drug interactions.)
"If
antidepressants are discontinued abruptly,
symptoms may occur such as dizziness, headache,
nausea, changes in mood, or changes in the sense
of smell, taste, etc. (Such symptoms even may
occur when even a few doses of antidepressant
are missed.) Therefore, it is recommended that
the dose of antidepressant be reduced gradually
when therapy is discontinued."
It has been
suggested that bupropion and SSRIs may cause
depression to worsen and even lead to suicide in
a small number of patients. These potential side
effects are difficult to evaluate in depressed
patients because depression can progress with or
without treatment, and suicide is itself a
consequence of depression. Moreover, the
evidence supporting these potential side effects
is weak. Therefore, no conclusions can yet be
drawn about the relationship between bupropion
and SSRIs and worsening depression and suicide.
Until better information is available, patients
receiving bupropion or SSRIs should be monitored
for worsening depression and suicidal
tendencies. |
