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Naltrexone hydrochloride and bupropion hydrochloride oral


Oral formulation of naltrexone hydrochloride and bupropion hydrochloride.

Drugs List

  • MYSIMBA 8mg+90mg prolonged release tablet
  • naltrexone hydrochloride 8mg and bupropion hydrochloride 90mg prolonged release tablet
  • Therapeutic Indications


    Weight management in adults with BMI > 30 - adjunct
    Weight management in adults with BMI 27 to < 30 with comorbidity -adjunct



    Initial treatment:
    Week 1
    One tablet to be taken every morning.

    Week 2
    One tablet to be taken every morning and every evening.

    Week 3
    Two tablets to be taken every morning and one tablet to be taken every evening.

    Week 4 to week 16
    Two tablets to be taken every morning and two tablets to be taken every evening.

    After week 16, the patient should be re-assessed. If treatment is to continue the recommended dose of two tablets every morning and two tablets every evening should be administered and the patient should be re-assessed annually.
    Maximum daily dose should not exceed 32mg naltrexone hydrochloride and 360mg bupropion hydrochloride.

    Patients with Renal Impairment

    Moderate or severe renal impairment:
    Reduce maximum dose to 2 tablets daily (1 tablet in the morning, 1 tablet in the evening).


    Children under 18 years
    Patients over 75 years
    Within 2 weeks of discontinuing MAOIs
    Alcohol withdrawal syndrome
    Bipolar disorder
    Bulimia nervosa
    Central nervous system neoplasm
    End stage renal disease
    Epileptic disorder
    History of anorexia nervosa
    History of opioid abuse
    History of seizures
    Severe hepatic impairment
    Uncontrolled hypertension

    Precautions and Warnings

    Females of childbearing potential
    High alcohol intake
    Patients over 65 years
    Predisposition to seizures
    Suicidal ideation
    Cerebrovascular disorder
    Congestive cardiac failure
    Coronary arteriosclerosis
    Diabetes mellitus
    Drug addiction
    Glucose-galactose malabsorption syndrome
    Head trauma
    History of mania
    Lactose intolerance
    Mild hepatic impairment
    Moderate renal impairment
    Recent myocardial infarction

    Patients at risk of suicide should be closely supervised
    Reduce dose in patients with renal impairment
    Advise ability to drive/operate machinery may be affected by side effects
    Advise patient not to drive until they know how the medicine affects them
    Contains lactose
    Monitor blood pressure pre-treatment and periodically thereafter
    Screen for opioid use before treatment
    Diabetic control may need adjustment
    Discontinue treatment if patient develops seizures
    Evaluate treatment efficacy regularly
    Monitor heart rate pre-treatment and periodically thereafter
    Monitor patients for signs and symptoms of Serotonin Syndrome
    Monitor renal function in patients with risk factors for renal impairment
    Potential for drug abuse
    Reassess need for continued treatment at regular intervals
    Advise patient to report symptoms of serum sickness
    Advise patients/carers to seek medical advice if suicidal intent develops
    Consider dose reduction or discontinuation if serotonin syndrome suspected
    May activate mania or hypomania
    May increase risk of seizure
    Discontinue if allergic reaction occurs
    Discontinue if AST or ALT level > 3x ULN and bilirubin > 2x ULN
    Discontinue if heart rate is increased for sustained period
    Discontinue if significant rise in blood pressure occurs
    Stop therapy at 16 weeks if weight loss is less than 5% of initial weight
    Suspend if drug induced liver injury is suspected
    Advise patient against the use of opioids during treatment
    Advise patient not to take St John's wort concurrently
    Advise patient to avoid alcohol during treatment

    Prior to initiating treatment, patients at high risk of renal impairment should have their glomerular filtration rate (eGFR) assessed.

    Do not restart treatment if patient has had a seizure during treatment.

    Temporarily discontinue treatment if patient requires opiate treatment.

    Discontinue treatment if serum sickness is suspected.

    Discontinue treatment if drug-induced liver injury is diagnosed.

    The use of naltrexone hydrochloride and bupropion hydrochloride is not recommended for women attempting to conceive.

    Pregnancy and Lactation


    Naltrexone hydrochloride and bupropion hydrochloride is contraindicated during pregnancy.

    The manufacturer does not recommend using naltrexone hydrochloride and bupropion hydrochloride during pregnancy.

    At the time of writing there is limited published information regarding the use of naltrexone and bupropion in combination during pregnancy. Animal studies using naltrexone during pregnancy have shown teratogenic effects. The molecular weight of naltrexone suggests it does cross the placenta (Briggs et al, 2015) and Schaefer (2015) states that naltrexone is a potent opioid antagonist with a long half life.

    Animal studies have not shown any increased risks of foetal malformations when using bupropion during pregnancy. However some studies have shown cardiovascular defects when bupropion was administered during the first trimester of pregnancy and a strong association of developing attention deficit hyperactivity disorder (ADHD) when used during the second trimester of pregnancy (Schaefer et al, 2015). Briggs (2015) states bupropion should be used during pregnancy if the potential benefits to the mother are necessary.


    Naltrexone hydrochloride and bupropion hydrochloride is contraindicated during breastfeeding.

    The manufacturer does not recommend breastfeeding whilst taking naltrexone hydrochloride and bupropion hydrochloride.

    At the time of writing there is limited published information regarding the use of naltrexone and bupropion in combination during breastfeeding. Naltrexone and bupropion are excreted into breast milk. Briggs (2015) states one case where naltrexone was administered during breastfeeding showed no adverse effects on the infant, however the use of naltrexone during breastfeeding should be evaluated for each individual case. Schaefer (2015) and Hale (2014) also support that no adverse effects have been found when using naltrexone during breastfeeding.

    Studies have shown milk production in breastfeeding women to be suppressed when using bupropion during breastfeeding (Hale et al, 2014). Briggs (2015) states mothers should be advised of the potential risks to the infant if using bupropion during breastfeeding.

    Side Effects

    Blood glucose disturbances
    Blood pressure changes
    Changes in libido
    Chest pain
    Cognitive impairment
    Concentration disturbances
    Decrease in haematocrit
    Delayed hypersensitivity reactions
    Disturbances of appetite
    Dream abnormalities
    Dry mouth
    Ear discomfort
    ECG changes
    Elevation of liver enzymes
    Erectile dysfunction
    Erythema multiforme
    Eye irritation
    Gastrointestinal disorder
    Hepatic disorders
    Hypersensitivity reactions
    Impaired co-ordination
    Impaired memory
    Impaired urination
    Increase in dental caries
    Increased energy
    Increased sputum
    Irregular menstruation
    Lability of affect
    Loss of balance
    Loss of consciousness (transient)
    Mood changes
    Nasal discomfort
    Oral herpes
    Oropharyngeal pain
    Postural hypotension
    Serum creatinine increased
    Serum sickness-like reactions
    Sinus disorder
    Skin disorder
    Stevens-Johnson syndrome
    Suicidal tendencies
    Taste disturbances
    Thrombotic thrombocytopenic purpura
    Tinea pedis
    Tooth ache
    Vestibular disorders
    Visual disturbances
    Weight changes


    It is strongly recommended that the UK National Poisons Information Service be consulted on cases of suspected or actual overdose where there is doubt over the degree of risk or about appropriate management.

    The following number will direct the caller to the relevant local centre (0844) 892 0111

    Information may be obtained if you have access to ToxBase the primary clinical toxicology database of the National Poisons Information Service. This is available via password on the internet ( ) or if this is unavailable at the backup site ( ).

    Further Information

    Last Full Review Date: October 2019

    Reference Sources

    Drugs During Pregnancy and Lactation: Treatment Options and Risk Assessment, 3rd edition (2015) ed. Schaefer, C., Peters, P. and Miller, R. Elsevier, London.

    Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk, 10th edition (2015) ed. Briggs, G., Freeman, R. Wolters Kluwer Health, Philadelphia.

    Medications and Mothers' Milk, Sixteenth Edition (2014) Hale, T and Rowe, H, Hale Publishing, Plano, Texas.

    Summary of Product Characteristics: Mysimba 8mg/90mg prolong-release tablets. Orexigen Therapeutics Ireland Limited. Revised June 2021.

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    Medscape UK | Univadis prescription drug monographs & interactions are based on FDB Multilex Content

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