Mysimba UK

Mysimba UK is a prescription medicine used as part of a comprehensive weight-management programme for certain adults. It contains two active ingredients, naltrexone hydrochloride and bupropion hydrochloride, formulated as prolonged-release tablets. The medicine is intended to be used alongside a reduced-calorie diet and increased physical activity rather than as a standalone approach to weight management.

Mysimba works through two active components that affect pathways involved in appetite regulation and food-reward signalling. Naltrexone is an opioid receptor antagonist, while bupropion affects neuronal dopamine and norepinephrine reuptake. The combined action of these ingredients is thought to influence pathways involved in appetite and energy-balance regulation.

What is Mysimba?

Mysimba contains 8 mg of naltrexone hydrochloride and 90 mg of bupropion hydrochloride per prolonged-release tablet. It belongs to the centrally acting anti-obesity medicines category and is intended for use in adults when prescribed appropriately.

According to the current UK Summary of Product Characteristics, Mysimba may be prescribed for adults with an initial BMI of 30 kg/m² or greater, or adults with a BMI from 27 kg/m² to below 30 kg/m² when one or more weight-related health conditions are present. These can include conditions such as type 2 diabetes, dyslipidaemia or controlled hypertension.

Eligibility must be assessed by an appropriate healthcare professional. A prescription should not be based on BMI alone without considering the patient’s medical history, current medicines, contraindications and other relevant clinical factors.

How Mysimba is used

The UK product information specifies that Mysimba treatment is introduced gradually over a four-week period. The dose is increased progressively during the first weeks of treatment, with the maximum recommended daily dose being two tablets in the morning and two tablets in the evening. Tablets should be swallowed whole with water and should not be cut, chewed or crushed.

Patients should follow the dosage prescribed by their healthcare professional rather than changing the dose themselves.

The need for continued treatment should be assessed after 16 weeks. According to the UK prescribing information, treatment should be discontinued if the patient has not achieved at least 5% loss of their initial body weight after 16 weeks. Continued treatment should also be reviewed regularly.

Mysimba and weight management

Mysimba is intended to form part of a wider weight-management programme. The UK product information specifically describes its use alongside a reduced-calorie diet and increased physical activity.

Individual responses can vary, and treatment suitability depends on factors such as medical history, existing conditions, other medicines and potential contraindications. A qualified prescriber should determine whether Mysimba is appropriate.

Mysimba prescription information

Mysimba is a prescription-only medicine. A healthcare professional should review the patient’s circumstances before treatment is supplied.

Mysimba should not be treated as a general-purpose weight-loss supplement. It contains pharmacologically active ingredients and has important contraindications and potential medicine interactions.

Before prescribing, the healthcare professional should consider the patient’s blood pressure, seizure history, psychiatric history, alcohol use, opioid use, current medicines and kidney or liver function where appropriate.

Important Mysimba warnings

Mysimba must not be used by people with certain conditions or circumstances. The UK product information lists contraindications including uncontrolled hypertension, current or previous seizures, certain central nervous system tumours, bipolar disorder, certain eating disorders, acute alcohol or benzodiazepine withdrawal, chronic opioid dependence or acute opioid withdrawal, and concomitant treatment containing naltrexone or bupropion. It is also contraindicated with monoamine oxidase inhibitors.

Mysimba can interact with opioid-containing medicines. This is particularly important because naltrexone blocks opioid receptors. Patients taking opioid medicines should tell their prescriber before treatment. The official UK product information also advises that alcohol consumption should be minimised or avoided during treatment.

Mysimba can also be associated with dizziness and sleepiness and may affect the ability to drive or operate machinery. Patients should understand how the medicine affects them before undertaking activities requiring full alertness.

Mysimba side effects

Like all medicines, Mysimba can cause side effects. The patient information leaflet provides the complete list and should be read before treatment.

Potential adverse effects include gastrointestinal symptoms and effects involving the nervous system. More serious reactions are possible, including seizures and liver-related adverse reactions, which is why appropriate clinical assessment and monitoring are important.

Patients experiencing concerning or severe symptoms should seek appropriate medical advice.

Who should not take Mysimba?

Mysimba is not suitable for everyone. In particular, the UK product information states that it should not be used by people with uncontrolled hypertension, a current seizure disorder or history of seizures, certain psychiatric or neurological conditions, current opioid dependence or acute opioid withdrawal, or certain eating disorders.

People taking other medicines containing bupropion or naltrexone should not take Mysimba. Certain antidepressants and other medicines may also require particular consideration because bupropion can affect CYP2D6-mediated drug metabolism.

Mysimba and other medicines

Always provide the prescriber with a complete list of medicines, supplements and other treatments currently being used.

Particular attention is required with opioid-containing medicines, monoamine oxidase inhibitors, medicines metabolised by CYP2D6 and medicines that may lower the seizure threshold. The official product information contains detailed interaction information for healthcare professionals.

Research and further information

For authoritative product information, healthcare professionals and patients should consult the current UK product information rather than relying solely on commercial product descriptions.

The Electronic Medicines Compendium (emc) provides the current UK Summary of Product Characteristics and Patient Information Leaflet for Mysimba.

Product Features

• Mysimba prolonged-release tablets
• Contains naltrexone hydrochloride and bupropion hydrochloride
• 8 mg/90 mg per tablet
• Prescription medicine
• Intended for eligible adults
• Used as part of a comprehensive weight-management programme
• Used alongside a reduced-calorie diet and increased physical activity
• Requires clinical assessment before prescribing
• Treatment response should be reviewed by the prescriber
• Full UK prescribing and safety information available through the official product documentation

Important Warnings

Prescription only: Mysimba should only be supplied and used following appropriate clinical assessment and prescription.

Do not use if contraindicated: Important contraindications include uncontrolled hypertension, seizure disorders or history of seizures, certain psychiatric and neurological conditions, certain eating disorders, chronic opioid dependence or acute opioid withdrawal, and use of MAOIs.

Opioids: Tell your prescriber if you use opioid-containing medicines because naltrexone can interfere with opioid medicines and treatment.

Alcohol: Alcohol consumption should be minimised or avoided during treatment.

Driving: Mysimba may cause dizziness or sleepiness. Do not drive or operate machinery until you know how the medicine affects you.

Pregnancy: Mysimba should not be used during pregnancy because weight loss offers no potential benefit during pregnancy and may cause harm to the unborn child. Discuss pregnancy, planned pregnancy or breastfeeding with a healthcare professional before treatment.

Children: Mysimba is not indicated for children or adolescents below 18 years of age.

Frequently Asked Questions

1. What is Mysimba?

Mysimba is a prescription weight-management medicine containing naltrexone hydrochloride and bupropion hydrochloride. It is used alongside dietary and physical-activity measures in eligible adults.

2. Is Mysimba available in the UK?

Yes. Mysimba has UK product information and is a prescription medicine. A qualified healthcare professional must determine whether it is appropriate for an individual patient.

3. What does Mysimba contain?

Each prolonged-release tablet contains 8 mg of naltrexone hydrochloride and 90 mg of bupropion hydrochloride.

4. Who may be prescribed Mysimba?

The UK prescribing information specifies adults with an initial BMI of at least 30 kg/m², or adults with a BMI of 27 kg/m² to below 30 kg/m² who also have one or more specified weight-related comorbidities. Clinical suitability must be assessed by the prescriber.

5. Is Mysimba a prescription medicine?

Yes. Mysimba requires appropriate clinical assessment and prescription.

6. Can Mysimba be taken with opioid medicines?

Mysimba is contraindicated in people currently dependent on chronic opioids or experiencing acute opioid withdrawal. Naltrexone can also interfere with opioid-containing medicines. Patients should tell their healthcare professional about any opioid medicine they use.

7. How long is Mysimba treatment?

The need for continued treatment should be assessed after 16 weeks. The UK product information states that treatment should be stopped if the patient has not lost at least 5% of their initial body weight after 16 weeks. Continued treatment should be reviewed regularly.

8. Can Mysimba cause side effects?

Yes. Like other prescription medicines, Mysimba can cause side effects. Patients should read the Patient Information Leaflet and discuss potential risks with their healthcare professional.

9. Can Mysimba affect driving?

It can. Mysimba may cause dizziness or sleepiness and has been associated with loss of consciousness and seizures. Patients should avoid driving or operating machinery if affected.

10. Where can I find the official Mysimba information?

The UK Electronic Medicines Compendium provides the current Mysimba Summary of Product Characteristics and Patient Information Leaflet.