Anti-obesity (combination)

Naltrexone with bupropion

Brand names: Mysimba

Adult dose

Dose: Titrate over 4 weeks: 1 tab AM week 1 → 1 tab AM + PM week 2 → 2 tabs AM + 1 PM week 3 → 2 tabs AM + 2 PM week 4 onwards

Route: PO

Frequency: BD

Clinical pearls

Adjunct to lifestyle for adults with BMI ≥30 (or ≥27 with comorbidity); NICE TA494
Stop at 16 weeks if <5% weight loss

Contraindications

Uncontrolled hypertension
Seizure history / risk
Bulimia/anorexia history
Severe hepatic impairment
Concurrent opioid use
Concurrent MAOI / within 14 days
Pregnancy

Side effects

Nausea (very common)
Constipation
Headache
Insomnia
Hypertension
Seizures
Suicidal ideation
Hepatotoxicity

Interactions

MAOIs (avoid)
Opioids
CYP2B6 substrates
Drugs lowering seizure threshold
Strong CYP3A4 inhibitors

Monitoring

BP
HR
Mental state
LFTs
Weight

Reference: BNF; NICE TA494; SmPC; https://bnf.nice.org.uk/drugs/naltrexone-with-bupropion/. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways