Bupropion SR (Zyban)

1. Health Canada Product Monograph — Bupropion SR

• Bupropion SR (Zyban) is indicated as an aid to smoking cessation treatment, used together with behavioural counselling and support.
• This sustained-release, twice-daily formulation and dosing schedule is specific to the smoking-cessation indication and differs from the once-daily extended-release (XL) formulation used to treat major depressive disorder -- the two are not interchangeable on the same dosing schedule.

• Bupropion has not been thoroughly studied in controlled trials during pregnancy; use only if the anticipated benefit of smoking cessation is judged to outweigh the potential risk to the fetus.

• Bupropion and its metabolites pass into human breast milk. A decision should be made whether to continue breastfeeding or continue bupropion, weighing the importance of smoking cessation to the patient.

• Older adults may have reduced clearance of bupropion and increased sensitivity to its central nervous system effects; use caution and consider the lowest effective dose.

• Not established as safe or effective in patients under 18 years of age for smoking cessation.

• Start 1-2 weeks before the target quit date, while the patient is still smoking.
• Days 1-3: 150 mg PO once daily in the morning.
• Day 4 onward: 150 mg PO twice daily, with doses at least 8 hours apart -- do not exceed a single dose of 150 mg, and do not exceed 300 mg/day.
• Continue for 7-12 weeks; longer maintenance may be considered individually for patients who have quit and are judged to be at high relapse risk.
• If a dose is missed, skip it entirely and resume at the next scheduled time -- do not double up, since this raises seizure risk.
• Tablets must be swallowed whole and never crushed, chewed, or divided, since disrupting the sustained-release coating can cause rapid release and increase seizure/overdose risk.
• In mild-to-moderate hepatic impairment, use with caution and consider a reduced dose/frequency; in severe hepatic impairment, bupropion is not recommended, and if used, the dose should not exceed 150 mg every other day.
• In renal impairment, consider a reduced dose and/or frequency due to the potential for drug accumulation.

If overdose is suspected, seek emergency medical attention immediately or contact your regional Poison Control Centre without delay.

• Overdose can cause seizures (including status epilepticus), hallucinations, loss of consciousness, tachycardia, and ECG changes (QRS/QTc prolongation, arrhythmias); fatalities have been reported, more often with mixed-drug overdose.
• Management is supportive: airway/breathing/circulation support, continuous cardiac monitoring, and EEG monitoring for the first 48 hours after a significant ingestion; activated charcoal may be given; inducing vomiting is not recommended. Seizures are generally managed with intravenous benzodiazepines. There is no specific antidote.

• Insomnia (dosing in the early morning and mid-afternoon, avoiding doses close to bedtime, can reduce this).
• Dry mouth.
• Dizziness.
• Restlessness or agitation.
• Headache.
• Nausea.
• Constipation.
• Tremor.

Serious side effects require immediate discussion with the prescriber or emergency care.

• Seizures -- dose-related; do not exceed the maximum recommended dose or single-dose limit.
• New or worsening depression, agitation, suicidal thoughts, or other mood/behavioural changes -- can occur even without a prior psychiatric history; monitor closely, especially in the first weeks of treatment.
• Severe hypertension, particularly when combined with nicotine replacement therapy -- monitor blood pressure if combination therapy is used.
• Severe allergic reactions (anaphylaxis, angioedema) and severe cutaneous reactions (Stevens-Johnson syndrome, DRESS) have been reported.
• Psychosis, hallucinations, or mania, particularly in patients with a history of bipolar disorder or psychotic illness.
• Seek urgent medical attention for a seizure, signs of a severe allergic reaction, chest pain, or new or worsening suicidal thoughts.

• Use with caution, at a reduced dose, in patients with any factor that lowers the seizure threshold: head trauma, CNS tumour, severe hepatic impairment, heavy alcohol use, or concurrent use of other drugs that lower seizure threshold (antipsychotics, other antidepressants, systemic corticosteroids, quinolone antibiotics, theophylline).
• Use with caution in patients with cardiovascular disease, including recent myocardial infarction or unstable heart disease.
• Use with caution in older adults and in hepatic or renal impairment, starting at a reduced dose.
• Use caution when driving or operating machinery until the effect on alertness and coordination is known.

• Current seizure disorder or any history of seizures.
• Current or past diagnosis of anorexia nervosa or bulimia nervosa (higher seizure risk in this population).
• Abrupt discontinuation of alcohol, benzodiazepines, or other sedative-hypnotics (increases seizure risk).
• Concurrent use of a monoamine oxidase inhibitor (MAOI), or use of an MAOI within the preceding 14 days.
• Concurrent use of any other medication containing bupropion (including bupropion prescribed for depression) -- do not combine.
• Known hypersensitivity to bupropion or any component of the formulation.

• Potent CYP2D6 inhibitor -- may raise levels of drugs metabolized by this pathway and reduce the effectiveness of drugs requiring CYP2D6 activation (e.g., codeine, tamoxifen).
• Do not use with MAOIs (risk of hypertensive crisis, mania, hyperpyrexia); allow a 14-day interval on either side of switching.
• Use with caution alongside other drugs that lower the seizure threshold.
• Combining with nicotine replacement therapy may raise blood pressure -- monitor if used together.

• No clinically significant food interaction; may be taken with or without food.

• Twice daily, at least 8 hours apart, with the first dose in the early morning; avoid a second dose close to bedtime to reduce insomnia risk.

• Store at room temperature, out of reach and sight of children.

• Start this medicine 1-2 weeks before your quit date, while you are still smoking -- it needs time to build up before it helps you quit.
• Take your two daily doses at least 8 hours apart, and never take a dose close to bedtime if you have trouble sleeping.
• Swallow tablets whole -- never crush, chew, or split them.
• Seek urgent care for a seizure, a severe allergic reaction, or new or worsening thoughts of self-harm.
• Avoid alcohol and tell your pharmacist about all your other medicines, since bupropion has a number of important drug interactions.