GeneralAgitation and Insomnia
A substantial proportion of patients treated with bupropion
experience some degree of increased restlessness, agitation, anxiety, and
insomnia, especially shortly after initiation of treatment. In clinical studies,
these symptoms were sometimes of sufficient magnitude to require treatment with
sedative/hypnotic drugs. In approximately 2% of patients, symptoms were
sufficiently severe to require discontinuation of treatment with
bupropion.
Psychosis, Confusion, and Other Neuropsychiatric
Phenomena
Depressed patients treated with bupropion have been reported to
show a variety of neuropsychiatric signs and symptoms including delusions,
hallucinations, psychosis, concentration disturbance, paranoia and confusion.
Because of the uncontrolled nature of many studies, it is impossible to provide
a precise estimate of the extent of risk imposed by treatment with bupropion. In
several cases, neuropsychiatric phenomena abated upon dose reduction and/or
withdrawal of treatment.
Activation of Psychosis and/or Mania
Antidepressants can precipitate manic episodes in bipolar
disorder patients during the depressed phase of their illness and may activate
latent psychosis in other susceptible patients. Bupropion is expected to pose
similar risks.
Altered Appetite and Weight
A weight loss of greater than 5 lbs occurred in 28% of patients
receiving bupropion. This incidence is approximately double that seen in
comparable patients treated with tricyclics or placebo. Furthermore, while 35%
of patients receiving tricyclic antidepressants gained weight, only 9.4% of
patients treated with bupropion did. Consequently, if weight loss is a major
presenting sign of a patient’s depressive illness, the anorectic and/or weight
reducing potential of bupropion should be considered.
Allergic Reactions
Anaphylactoid/anaphylactic reactions characterized by symptoms
such as pruritus, urticaria, angioedema, and dyspnea requiring medical treatment
have been reported in clinical trials with bupropion. In addition, there have
been rare spontaneous post-marketing reports of erythema multiforme,
Stevens-Johnson Syndrome, and anaphylactic shock associated with bupropion. A
patient should stop taking bupropion and consult a doctor if experiencing
allergic or anaphylactoid/anaphylactic reactions (e.g., skin rash, pruritus,
hives, chest pain, edema, and shortness of breath) during treatment.
Arthralgia, myalgia, and fever with rash and other symptoms suggestive of
delayed hypersensitivity have been reported in association with bupropion. These
symptoms may resemble serum sickness.
Cardiovascular Effects
In clinical practice, hypertension, in some cases severe,
requiring acute treatment, has been reported in patients receiving bupropion
alone and in combination with nicotine replacement therapy. These events have
been observed in both patients with and without evidence of preexisting
hypertension.
Data from a comparative study of the sustained-release formulation of
bupropion (ZYBAN®* Sustained-Release Tablets), nicotine
transdermal system (NTS), the combination of sustained-release bupropion plus
NTS, and placebo as an aid to smoking cessation suggest a higher incidence of
treatment emergent hypertension in patients treated with the combination of
sustained-release bupropion and NTS. In this study, 6.1% of patients treated
with the combination of sustained-release bupropion and NTS had treatment
emergent hypertension compared to 2.5%, 1.6%, and 3.1% of patients treated with
sustained-release bupropion, NTS, and placebo, respectively. The majority of
these patients had evidence of preexisting hypertension. Three patients (1.2%)
treated with the combination of ZYBAN®* and NTS and one
patient (0.4%) treated with NTS had study medication discontinued due to
hypertension compared to none of the patients treated with ZYBAN®* or placebo. Monitoring of blood pressure is recommended in
patients who receive the combination of bupropion and nicotine replacement.
There is no clinical experience establishing the safety of bupropion in
patients with a recent history of myocardial infarction or unstable heart
disease. Therefore, care should be exercised if it is used in these groups.
Bupropion was well tolerated in depressed patients who had previously developed
orthostatic hypotension while receiving tricyclic antidepressants and was also
generally well tolerated in a group of 36 depressed inpatients with stable
congestive heart failure (CHF). However, bupropion was associated with a rise in
supine blood pressure in the study of patients with CHF, resulting in
discontinuation of treatment in two patients for exacerbation of baseline
hypertension.
Hepatic Impairment
Bupropion should be used with extreme caution in patients with
severe hepatic cirrhosis. In these patients, a reduced dose and frequency is
required. Bupropion should be used with caution in patients with hepatic
impairment (including mild to moderate hepatic cirrhosis) and a reduced
frequency and/or dose should be considered in patients with mild to moderate
hepatic cirrhosis.
All patients with hepatic impairment should be closely monitored for possible
adverse effects that could indicate high drug and metabolite levels (see CLINICAL
PHARMACOLOGY, WARNINGS, and
DOSAGE AND
ADMINISTRATION).
Renal Impairment
There is limited information on the pharmacokinetics of bupropion
in patients with renal impairment. An interstudy comparison between normal
subjects and patients with end stage renal failure demonstrated that the parent
drug Cmax and AUC values were comparable in the two
groups, whereas the hydroxybupropion and threohydrobupropion metabolites had a
2.3-fold and 2.8-fold increase, respectively, in AUC for patients with end-stage
renal failure. A second study, comparing normal subjects and patients with
moderate to severe renal impairment (GFR 30.9 ± 10.8 mL/min) showed that
exposure to a single 150 mg dose of sustained-release bupropion was
approximately 2-fold higher in patients with impaired renal function while
levels of the hydroxybupropion and threo/erythrohydrobupropion (combined)
metabolites were similar in the two groups. Bupropion is extensively metabolized
in the liver to active metabolites, which are further metabolized and
subsequently excreted by the kidneys. Bupropion should be used with caution in
patients with renal impairment and a reduced frequency and/or dose should be
considered as bupropion and the metabolites of bupropion may accumulate in such
patients to a greater extent than usual. The patient should be closely monitored
for possible adverse effects that could indicate high drug or metabolite
levels.
Information for Patients
Prescribers or other health professionals should inform patients,
their families, and their caregivers about the benefits and risks associated
with treatment with bupropion and should counsel them in its appropriate use. A
patient Medication Guide about “Antidepressant Medicines, Depression and Other
Serious Mental Illnesses, and Suicidal Thoughts or Actions”, “Quitting Smoking,
Quit-Smoking Medication, Changes in Thinking and Behavior, Depression, and
Suicidal Thoughts or Actions”, and “What Other Important Information Should I
Know About Bupropion Hydrochloride Tablets?” is available for bupropion
hydrochloride tablets. The prescriber or health professional should instruct
patients, their families, and their caregivers to read the Medication Guide and
should assist them in understanding its contents. Patients should be given the
opportunity to discuss the contents of the Medication Guide and to obtain
answers to any questions they may have. The complete text of the Medication
Guide is reprinted at the end of this document.
Patients should be advised of the following issues and asked to alert their
prescriber if these occur while taking bupropion.
Clinical Worsening and Suicide Risk in Treating
Psychiatric Disorders
Patients, their families and their caregivers should be
encouraged to be alert to the emergence of anxiety, agitation, panic attacks,
insomnia, irritability, hostility, aggressiveness, impulsivity, akathisia
(psychomotor restlessness), hypomania, mania, other unusual changes in behavior,
worsening of depression, and suicidal ideation, especially early during
antidepressant treatment and when the dose is adjusted up or down. Families and
caregivers of patients should be advised to look for the emergence of such
symptoms on a day to day basis, since changes may be abrupt. Such symptoms
should be reported to the patient's prescriber or health professional,
especially if they are severe, abrupt in onset, or were not part of the
patient's presenting symptoms. Symptoms such as these may be associated with an
increased risk for suicidal thinking and behavior and indicate a need for very
close monitoring and possibly changes in the medication.
Neuropsychiatric Symptoms and Suicide Risk in Smoking
Cessation Treatment
Although bupropion hydrochloride tablets are not indicated for
smoking cessation treatment, it contains the same active ingredient as
ZYBAN®* which is approved for this use. Patients should
be informed that quitting smoking, with or without ZYBAN®*, may be associated with nicotine withdrawal symptoms
(including depression or agitation), or exacerbation of preexisting psychiatric
illness. Furthermore, some patients have experienced changes in mood (including
depression and mania), psychosis, hallucinations, paranoia, delusions, homicidal
ideation aggression, anxiety and panic, as well as suicidal ideation, suicide
attempt and completed suicide when attempting to quit smoking while taking
ZYBAN®*. If patients develop agitation, hostility,
depressed mood, or changes in thinking or behavior that are not typical for
them, or if patients develop suicidal ideation or behavior, they should be urged
to report these symptoms to their healthcare provider immediately.
Bupropion-Containing Products
Patients should be made aware that bupropion hydrochloride
tablets contain the same active ingredient found in ZYBAN®*, used as an aid to smoking cessation, and that bupropion
hydrochloride tablets should not be used in combination with ZYBAN®* or any other medications that contain bupropion
hydrochloride (such as WELLBUTRIN SR®*, the
sustained-release formulation and WELLBUTRIN XL®*, the
extended-release formulation).
Patients should be instructed to take bupropion in equally divided doses 3 or
4 times a day to minimize the risk of seizure.
Patients should be told that bupropion should be discontinued and not
restarted if they experience a seizure while on treatment.
Patients should be told that any CNS-active drug like bupropion may impair
their ability to perform tasks requiring judgment or motor and cognitive skills.
Consequently, until they are reasonably certain that bupropion does not
adversely affect their performance, they should refrain from driving an
automobile or operating complex, hazardous machinery.
Patients should be told that the excessive use or abrupt discontinuation of
alcohol or sedatives (including benzodiazepines) may alter the seizure
threshold. Some patients have reported lower alcohol tolerance during treatment
with bupropion. Patients should be advised that the consumption of alcohol
should be minimized or avoided.
Patients should be advised to inform their physicians if they are taking or
plan to take any prescription or over-the-counter drugs. Concern is warranted
because bupropion and other drugs may affect each other’s metabolism.
Patients should be advised to notify their physicians if they become pregnant
or intend to become pregnant during therapy.
Laboratory Tests
There are no specific laboratory tests recommended.
Drug Interactions
Few systemic data have been collected on the metabolism of
bupropion following concomitant administration with other drugs or,
alternatively, the effect of concomitant administration of bupropion on the
metabolism of other drugs.
Because bupropion is extensively metabolized, the coadministration of other
drugs may affect its clinical activity. In vitro
studies indicate that bupropion is primarily metabolized to hydroxybupropion by
the CYP2B6 isoenzyme. Therefore, the potential exists for a drug interaction
between bupropion and drugs that are the substrates or inhibitors of the CYP2B6
isoenzyme (e.g., orphenadrine, thiotepa and cyclophosphamide). In addition,
in vitro studies suggest that paroxetine, sertraline,
norfluoxetine, and fluvoxamine as well as nelfinavir, ritonavir, and efavirenz
inhibit the hydroxylation of bupropion. No clinical studies have been performed
to evaluate this finding. The threohydrobupropion metabolite of bupropion does
not appear to be produced by the cytochrome P450 isoenzymes. The effects of
concomitant administration of cimetidine on the pharmacokinetics of bupropion
and its active metabolites were studied in 24 healthy young male volunteers.
Following oral administration of two 150 mg sustained-release tablets with and
without 800 mg of cimetidine, the pharmacokinetics of bupropion and
hydroxybupropion were unaffected. However, there were 16% and 32% increases in
the AUC and Cmax, respectively, of the combined moieties
of threohydrobupropion and erythrohydrobupropion.
While not systematically studied, certain drugs may induce the metabolism of
bupropion (e.g., carbamazepine, phenobarbital, phenytoin).
Multiple oral doses of bupropion had no statistically significant effects on
the single- dose pharmacokinetics of lamotrigine in 12 healthy volunteers.
Animal data indicated that bupropion may be an inducer of drug-metabolizing
enzymes in humans. In one study, following chronic administration of bupropion,
100 mg 3 times daily to eight healthy male volunteers for 14 days, there was no
evidence of induction of its own metabolism. Nevertheless, there may be the
potential for clinically important alterations of blood levels of coadministered
drugs.
Drugs Metabolized by Cytochrome P450IID6
(CYP2D6)
Many drugs, including most antidepressants (SSRIs, many
tricyclics), beta-blockers, antiarrhythmics, and antipsychotics are metabolized
by the CYP2D6 isoenzyme. Although bupropion is not metabolized by this
isoenzyme, bupropion and hydroxybupropion are inhibitors of the CYP2D6 isoenzyme
in vitro. In a study of 15 male subjects (ages 19 to
35 years) who were extensive metabolizers of the CYP2D6 isoenzyme, daily doses
of bupropion given as 150 mg twice daily followed by a single dose of 50 mg
desipramine increased the Cmax, AUC, and t1/2 of desipramine by an average of approximately 2-fold,
5-fold and 2-fold, respectively. The effect was present for at least 7 days
after the last dose of bupropion. Concomitant use of bupropion with other drugs
metabolized by CYP2D6 has not been formally studied.
Therefore, coadministration of bupropion with drugs that are metabolized by
CYP2D6 isoenzyme including certain antidepressants (e.g., nortriptyline,
imipramine, desipramine, paroxetine, fluoxetine, sertraline), antipsychotics
(e.g., haloperidol, risperidone, thioridazine), beta-blockers (e.g.,
metoprolol), and Type 1C antiarrhythmics (e.g., propafenone, flecainide), should
be approached with caution and should be initiated at the lower end of the dose
range of the concomitant medication. If bupropion is added to the treatment
regimen of a patient already receiving a drug metabolized by CYP2D6, the need to
decrease the dose of the original medication should be considered, particularly
for those concomitant medications with a narrow therapeutic index.
MAO Inhibitors
Studies in animals demonstrate that the acute toxicity of
bupropion is enhanced by the MAO inhibitor phenelzine (see CONTRAINDICATIONS).
Levodopa and Amantadine
Limited clinical data suggest a higher incidence of adverse
experiences in patients receiving bupropion concurrently with either levodopa or
amantadine. Administration of bupropion hydrochloride tablets to patients
receiving either levodopa or amantadine concurrently should be undertaken with
caution, using small initial doses and small gradual dose increases.
Drugs that Lower Seizure Threshold
Concurrent administration of bupropion and agents (e.g.,
antipsychotics, other antidepressants, theophylline, systemic steroids, etc.)
that lower seizure threshold should be undertaken only with extreme caution (see
WARNINGS).
Low initial dosing and small gradual dose increases should be employed.
Nicotine Transdermal System
(see PRECAUTIONS:
General: Cardiovascular Effects).
Alcohol
In post-marketing experience, there have been rare reports of
adverse neuropsychiatric events or reduced alcohol tolerance in patients who
were drinking alcohol during treatment with bupropion. The consumption of
alcohol during treatment with bupropion should be minimized or avoided (also see
CONTRAINDICATIONS).
Carcinogenesis, Mutagenesis, Impairment of
Fertility
Lifetime carcinogenicity studies were performed in rats and mice
at doses up to 300 and 150 mg/kg/day, respectively. In the rat study there was
an increase in nodular proliferative lesions of the liver at doses of 100 to 300
mg/kg/day; lower doses were not tested. The question of whether or not such
lesions may be precursors of neoplasms of the liver is currently unresolved.
Similar liver lesions were not seen in the mouse study, and no increase in
malignant tumors of the liver and other organs was seen in either study.
Bupropion produced a borderline positive response (2 to 3 times control
mutation rate) in some strains in the Ames bacterial mutagenicity test, and a
high oral dose (300 mg/kg, but not 100 or 200 mg/kg) produced a low incidence of
chromosomal aberrations in rats. The relevance of these results in estimating
the risk of human exposure to therapeutic doses is unknown.
A fertility study was performed in rats; no evidence of impairment of
fertility was encountered at oral doses up to 300 mg/kg/day.
PregnancyTeratogenic Effects. Pregnancy Category C
In studies conducted in rats and rabbits, bupropion was
administered orally at doses up to 450 and 150 mg/kg/day, respectively
[approximately 11 and 7 times the maximum recommended human dose (MRHD),
respectively, on a mg/m2 basis], during the period of
organogenesis. No clear evidence of teratogenic activity was found in either
species; however, in rabbits, slightly increased incidences of fetal
malformations and skeletal variations were observed at the lowest dose tested
(25 mg/kg/day, approximately equal to the MRHD on a mg/m2
basis) and greater. Decreased fetal weights were seen at 50 mg/kg and greater.
When rats were administered bupropion at oral doses of up to 300 mg/kg/day
(approximately 7 times the MRHD on a mg/m2 basis) prior
to mating and throughout pregnancy and lactation, there were no apparent adverse
effects on offspring development.
One study has been conducted in pregnant women. This retrospective, managed
care database study assessed the risk of congenital malformations overall, and
cardiovascular malformations specifically, following exposure to bupropion in
the first trimester compared to the risk of these malformations following
exposure to other antidepressants in the first trimester and bupropion outside
of the first trimester. This study included 7,005 infants with antidepressant
exposure during pregnancy, 1,213 of whom were exposed to bupropion in the first
trimester. The study showed no greater risk for congenital malformations
overall, or cardiovascular malformations specifically, following first trimester
bupropion exposure compared to exposure to all other antidepressants in the
first trimester, or bupropion outside of the first trimester. The results of
this study have not been corroborated. Bupropion should be used during pregnancy
only if the potential benefit justifies the potential risk to the fetus.
Labor and Delivery
The effect of bupropion on labor and delivery in humans is
unknown.
Nursing Mothers
Like many other drugs, bupropion and its metabolites are secreted
in human milk. Because of the potential for serious adverse reactions in nursing
infants from bupropion, a decision should be made whether to discontinue nursing
or to discontinue the drug, taking into account the importance of the drug to
the mother.
Pediatric Use
Safety and effectiveness in the pediatric population have not
been established (see BOX
WARNING and WARNINGS:
Clinical Worsening and Suicide Risk in Treating Psychiatric Disorders).
Anyone considering the use of bupropion in a child or adolescent must balance
the potential risks with the clinical need.
Geriatric Use
Of the approximately 6,000 patients who participated in clinical
trials with bupropion hydrochloride sustained-release tablets (depression and
smoking cessation studies), 275 were 65 and over and 47 were 75 and over. In
addition, several hundred patients 65 and over participated in clinical trials
using the immediate-release formulation of bupropion (depression studies). No
overall differences in safety or effectiveness were observed between these
subjects and younger subjects, and other reported clinical experience has not
identified differences in responses between the elderly and younger patients,
but greater sensitivity of some older individuals cannot be ruled out.
A single-dose pharmacokinetic study demonstrated that the disposition of
bupropion and its metabolites in elderly subjects was similar to that of younger
subjects; however, another pharmacokinetic study, single and multiple-dose, has
suggested that the elderly are at increased risk for accumulation of bupropion
and its metabolites (see CLINICAL
PHARMACOLOGY).
Bupropion is extensively metabolized in the liver to active metabolites,
which are further metabolized and excreted by the kidneys. The risk of toxic
reaction to this drug may be greater in patients with impaired renal function.
Because elderly patients are more likely to have decreased renal function, care
should be taken in dose selection, and it may be useful to monitor renal
function (see PRECAUTIONS:
General: Renal Impairment and DOSAGE AND
ADMINISTRATION).