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Bupropion / Naltrexone

Mysimba · ATC code A08AA

Key facts
Active substance
Bupropion / Naltrexone
Drug class
Anorectic
ATC code
A08AA
Authorisation
centrally authorised across the EU (EMA)
Dosage forms
Mysimba 8 mg/90 mg prolonged-release tablets
Marketing authorisation holder
Orexigen Therapeutics Ireland Limited
Information as of
2026-10-27

Key facts

Bupropion/naltrexone is a fixed-dose combination for weight management in adults with obesity or overweight with comorbidities, as an adjunct to a reduced-calorie diet and increased physical activity.

What it is used for

  • Adults with initial BMI ≥30 kg/m² (obese)
  • Adults with BMI ≥27 kg/m² to <30 kg/m² and at least one weight-related comorbidity (e.g. type 2 diabetes, dyslipidaemia, controlled hypertension)
  • Discontinue after 16 weeks if at least 5% of initial body weight has not been lost

Dosing

  • Escalation over 4 weeks: week 1 one tablet in the morning; week 2 one morning and one evening; week 3 two morning, one evening; week 4 onwards two morning and two evening.
  • Maximum: two tablets twice daily (32 mg naltrexone hydrochloride and 360 mg bupropion hydrochloride).
  • Moderate or severe renal impairment: maximum two tablets daily (one morning, one evening).
  • Caution over 65 years; not recommended over 75 years.
  • Evaluate after 16 weeks and annually; do not take an extra dose for a missed dose.

Contraindications

  • Uncontrolled hypertension; current or past seizures; known CNS tumour
  • Acute alcohol or benzodiazepine withdrawal; history of bipolar disorder; bulimia or anorexia nervosa
  • Opioid dependence, opioid agonist treatment (e.g. methadone, buprenorphine) or acute opioid withdrawal
  • Concomitant bupropion- or naltrexone-containing products or MAOIs
  • End-stage renal failure and severe hepatic impairment

Important warnings

  • Suicidal thoughts and behaviour; close supervision, especially early in treatment and after dose changes
  • Dose-related seizure risk from bupropion
  • Blood pressure may increase; discontinue if there are concerns
  • Cardiovascular risks beyond one year not fully determined

Side effects

  • Very common: nausea, constipation, vomiting, headache
  • Common: dizziness, dry mouth
  • In studies 23.8% discontinued due to an adverse reaction (placebo 11.9%)
  • Seizure in about 0.06% of subjects in trials

Interactions

  • MAOIs: must not be used together
  • Opioid-containing medicines (analgesics, cough and antidiarrhoeal remedies) may not fully work due to naltrexone
  • CYP-mediated interactions are in the full text

Pregnancy and breastfeeding

  • Should not be used during pregnancy or when attempting to become pregnant.
  • Naltrexone, bupropion and metabolites are excreted in breast milk; a risk to infants cannot be excluded.

Summary of the official product information, written with AI (Claude, Anthropic) on 2026-10-28. Every number was checked automatically against the original text. Not reviewed by a physician – the full official text is authoritative.

Full official text →

Common questions – ask Medelix

For patients

Package leaflet, verbatim

Package leaflet for patients →

Authorisation and brand names by country

Medicines with exactly this active-substance composition, as listed in the national registers – alphabetical and without ranking. Whether a product is currently available is not shown here.

EU – centrally authorised (all member states)

  • MysimbaOrexigen Therapeutics Ireland Limited · EMEA/H/C/003687

Source: European Medicines Agency (EMA), product information

Brand names in 3 more European countries
Iceland
Mysimba
Liechtenstein
Mysimba
Norway
Mysimba

EMA – Article 57 product data (EU/EEA), 2026-10-28

Medelix receives no money from pharmaceutical companies. Brand names are listed alphabetically and without ranking.

Another question about this substance?

Medelix answers clinical questions from guidelines, studies and product information – every claim with its source.

Sources

  1. European Medicines Agency. Mysimba – EPAR, Product Information (OF THE TEXT Detailed information on this medicinal product i). 2026-10-27. https://www.ema.europa.eu/en/documents/product-information/mysimba-epar-product-information_en.pdf
  2. Wikidata (CC0): ATC A08AA.

Editorial: Medelix editorial team · last updated 2026-10-27 · How these pages are made · Report an error

Source: European Medicines Agency (EMA), product information. Not advertising, not a treatment recommendation. For questions about your own treatment, ask your doctor or pharmacist.