Dopamine/Noradrenaline Reuptake Inhibitor (DNRI) — Smoking Cessation Pregnancy: §4.6: ZYBAN SHOULD NOT BE USED IN PREGNANCY. Pregnant women should be encouraged to quit smoking without the use of pharmacotherapy. Some epidemiological studies of pregnancy outcomes following maternal exposure in the first trimester have reported an association with increased risk of certain congenital cardiovascular malformations, specifically ventricular septal defects and left outflow tract heart defects, although these findings are not consistent across studies. Animal studies do not indicate direct or indirect harmful effects with respect to reproductive toxicity. Breast-feeding: bupropion and its metabolites are excreted in human breast milk; a decision on whether to abstain from breast-feeding or from therapy should weigh the benefit of each. Fertility: there are no data on the effect of bupropion on human fertility.

Bupropion (Smoking Cessation)

Brand names: Zyban

Bupropion is an oral noradrenaline and dopamine reuptake inhibitor licensed as an aid to smoking cessation. Treatment is started while the person is still smoking, before the planned quit date.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 150 mg daily for six days, increasing on day seven to 150 mg twice daily

Route: Oral (prolonged release tablets swallowed whole — not cut, crushed or chewed, as this may increase the risk of adverse effects including seizures)

Frequency: Once daily for days 1-6, then twice daily from day seven, with an interval of at least 8 hours between successive doses; may be taken with or without food

Max: Maximum single dose must not exceed 150 mg; maximum total daily dose must not exceed 300 mg

Source: UK SPC (eMC) for Zyban 150 mg prolonged release tablets, §4.2 (https://www.medicines.org.uk/emc/product/3827/smpc) — this is the smoking-cessation licence, matching this page's indication. INITIATION: it is recommended that treatment is started while the patient is still smoking, with a 'target stop date' set within the first two weeks of treatment, preferably in the second week. DURATION: patients should be treated for 7-9 weeks; if at seven weeks no effect is seen, treatment should be discontinued. INSOMNIA is a very common adverse event which can be reduced by avoiding bedtime doses (provided there is at least 8 hours between doses). Zyban should be used in accordance with smoking cessation guidelines; prescribers should assess the patient's motivation to quit, as smoking cessation therapies are more likely to succeed in motivated patients who have motivational support. ELDERLY: should be used with caution in older people as greater sensitivity in some individuals cannot be ruled out; the recommended dose in older people is 150 mg once a day. HEPATIC IMPAIRMENT: use with caution; because of increased variability in the pharmacokinetics in patients with mild to moderate impairment, the recommended dose in these patients is 150 mg once a day. Severe hepatic cirrhosis is a contraindication. PAEDIATRIC: use in patients under 18 years of age is NOT RECOMMENDED, as safety and efficacy have not been evaluated in these patients — hence paedDose is null. Verify any under-18 use against a children's formulary. DISCONTINUATION: although discontinuation reactions are not expected, a tapering-off period may be considered. Note: §4.5 was not retrieved in this bundle — the interactions listed below are taken from the US bupropion hydrochloride XL label; verify the full UK §4.5.

Dose adjustments

Renal

Zyban should be used with caution in patients with renal insufficiency. The recommended dose in these patients is 150 mg once a day (§4.2).

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

General: Increase dose gradually to reduce seizure risk. ( 2.1 , 5.3 ) Periodically reassess the dose and need for maintenance treatment. ( 2.2 ) Major Depressive Disorder Starting dose: 150 mg once daily. Usual target dose: 300 mg once daily ( 2.2 ) After 4 days, may increase the dose to 300 mg once daily. ( 2.2 ) Seasonal Affective Disorder Initiate treatment in the autumn prior to onset of seasonal depressive symptoms. ( 2.3 ) Starting dose: 150 mg once daily. Usual target dose: 300 mg once daily. ( 2.3 ) After one week, may increase the dose to 300 mg once daily. ( 2.3 ) Continue treatment through the winter season. ( 2.3 ) Hepatic Impairment Moderate to severe hepatic impairment: 150 …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2025-11-25. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Contraindications

Hypersensitivity to bupropion or any of the excipients
Current seizure disorder or any history of seizures
Known central nervous system (CNS) tumour
Patients who, at any time during treatment, are undergoing abrupt withdrawal from alcohol or any medicinal product known to be associated with risk of seizures on withdrawal (in particular benzodiazepines and benzodiazepine-like agents)
Current or previous diagnosis of bulimia or anorexia nervosa
Severe hepatic cirrhosis
Concomitant use with monoamine oxidase inhibitors (MAOIs) — at least 14 days should elapse between discontinuation of irreversible MAOIs and initiation; for reversible MAOIs a 24 hour period is sufficient
History of bipolar disorder, as it may precipitate a manic episode during the depressed phase
Patients being treated with any other medicinal product containing bupropion (seizure incidence is dose dependent; avoids overdosage)

Side effects

Insomnia (very common) — can be reduced by avoiding bedtime doses
Dry mouth, gastrointestinal disturbance including nausea and vomiting, abdominal pain, constipation (common)
Tremor, concentration disturbance, headache, dizziness, taste disorders (common)
Rash, pruritus, sweating (common); hypersensitivity reactions such as urticaria (common), with more severe reactions including angioedema, dyspnoea/bronchospasm and anaphylactic shock (rare)
Depression, agitation, anxiety (common); confusion (uncommon); suicidal ideation and suicidal behaviour, psychosis, panic attack (not known)
Seizures (rare); increased blood pressure sometimes severe, and flushing (uncommon)

Interactions

CYP2B6 inducers (e.g. ritonavir, lopinavir, efavirenz, carbamazepine, phenobarbital, phenytoin) — a dose increase may be necessary based on clinical exposure, but should not exceed the maximum recommended dose (US label)
Drugs metabolised by CYP2D6 — bupropion inhibits CYP2D6 and can increase concentrations of antidepressants (venlafaxine, nortriptyline, imipramine, desipramine, paroxetine, fluoxetine, sertraline), antipsychotics (haloperidol, risperidone, thioridazine), beta-blockers (metoprolol) and Type 1C antiarrhythmics (propafenone, flecainide); consider dose reduction of these (US label)
Drugs that lower the seizure threshold — dose bupropion with caution (US label)
Dopaminergic drugs (levodopa and amantadine) — CNS toxicity can occur with concomitant use (US label)
MAOIs — increased risk of hypertensive reactions with concomitant use (US label); concomitant use is contraindicated in the UK SPC
Drug-laboratory test interaction: bupropion can cause false-positive urine test results for amphetamines (US label)

Clinical monograph

How it works

It inhibits the reuptake of noradrenaline and dopamine, which is thought to reduce nicotine cravings and withdrawal symptoms, although the precise mechanism in smoking cessation is not fully understood.

Prescribing in practice

It lowers the seizure threshold and is contraindicated in epilepsy or any history of seizures, in eating disorders, and where there is abrupt alcohol or benzodiazepine withdrawal.
It has multiple drug interactions, including with medicines that lower the seizure threshold and those metabolised by CYP2D6.
Insomnia and dry mouth are common; insomnia is reduced by avoiding doses close to bedtime.

Monitoring

Monitor blood pressure, mood and smoking status; review for any seizure risk factors and for interacting medicines before and during treatment.

Counselling the patient

Keep smoking at first and stop on your agreed quit date, usually in the second week of treatment.
Avoid taking it too close to bedtime, as it can disturb sleep, and do not take more than prescribed.
Tell your prescriber if you have ever had a seizure or fit, or an eating disorder, before starting.

Evidence & guidelines

Recommended as an option for smoking cessation by NICE (NG209).

Reference: NICE PH10 Smoking Cessation; Zyban SPC; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways