Mysimba is a prescription-only medication indicated as an adjunct to a reduced-calorie diet and increased physical activity for chronic weight management in adults. It is specifically designed for patients with an initial Body Mass Index (BMI) of 30 kg/m² or greater (obesity), or 27 kg/m² or greater (overweight) in the presence of at least one weight-related comorbidity, such as hypertension, type 2 diabetes, or dyslipidaemia. Its unique dual-mechanism action targets key areas of the brain involved in hunger and reward, helping to control appetite and reduce food cravings. This comprehensive approach supports sustainable weight loss as part of a long-term treatment strategy under medical supervision.

Features

• Active Ingredients: A fixed-dose combination of Naltrexone Hydrochloride and Bupropion Hydrochloride.
• Mechanism of Action: Naltrexone is an opioid antagonist, and Bupropion is a dopamine and norepinephrine reuptake inhibitor. Their combined action on hypothalamic and mesolimbic pathways regulates appetite and energy balance.
• Dosage Form: Extended-release (ER) tablets for oral administration.
• Dosing Schedule: A specific titration schedule over four weeks is required to reach the maintenance dose and minimize initial side effects.
• Prescription Status: Available only under medical supervision with a valid prescription.

Benefits

• Sustained Weight Loss: Clinical trials demonstrated significant weight loss compared to placebo, with many patients achieving a 5% or greater reduction in body weight.
• Appetite Suppression: Works on the hunger centres in the brain to help reduce feelings of hunger and increase feelings of fullness (satiety).
• Reduced Food Cravings: Targets the reward system to help diminish cravings for high-calorie and palatable foods.
• Improvement in Weight-Related Comorbidities: Weight loss achieved with Mysimba can lead to improvements in parameters such as waist circumference, HDL cholesterol, and triglycerides.
• Adjunct to Lifestyle Modification: Provides pharmacological support to enhance the effects of diet and exercise, making it easier for patients to adhere to a healthier lifestyle.

Common use

Mysimba is used for the chronic management of weight in adults who meet specific BMI criteria. It is not intended for use as a monotherapy but is always prescribed as part of a comprehensive weight management plan that includes ongoing nutritional counselling and a program of regular physical activity. Treatment is typically long-term, provided that the patient is responding to therapy (e.g., has lost at least 5% of their initial body weight after 16 weeks of treatment at the maintenance dose) and tolerating the medication well. It is not indicated for the treatment of depression or for smoking cessation, although its component Bupropion is approved for the latter.

Dosage and direction

Must be taken exactly as prescribed by a healthcare professional.

• Week 1: One 8 mg/90 mg tablet taken orally in the morning.
• Week 2: One tablet in the morning and one tablet in the evening.
• Week 3: Two tablets in the morning and one tablet in the evening.
• Week 4 (Maintenance Dose): Two tablets in the morning and two tablets in the evening.
• The total daily dose is two tablets twice daily (32 mg naltrexone/360 mg bupropion per day).
• Tablets must be swallowed whole and must not be crushed, divided, or chewed, as this can alter the release profile and increase the risk of adverse effects, including seizures.
• To minimize the risk of insomnia, the evening dose should not be taken too close to bedtime.
• The medication can be taken with or without food. If taken with food, it may reduce the risk of nausea.

Precautions

• Medical Supervision: Treatment must be initiated and monitored by a clinician experienced in the treatment of obesity.
• Blood Pressure and Heart Rate Monitoring: Mysimba can cause an increase in blood pressure and/or heart rate. Regular monitoring is required, especially in patients with controlled hypertension.
• Seizure Risk: Bupropion is associated with a dose-dependent risk of seizure. Mysimba is contraindicated in patients with a seizure disorder or other conditions that predispose to seizures.
• Hepatic Impairment: Use with caution in patients with hepatic impairment. Dosage adjustment is recommended in patients with moderate to severe hepatic impairment.
• Renal Impairment: Use is not recommended in patients with end-stage renal disease.
• Allergic Reactions: Discontinue at first sign of rash, hives, or other allergic reaction.
• Pregnancy and Lactation: Not recommended for use during pregnancy or while breastfeeding.

Contraindications

Mysimba must not be used in patients with:

• Uncontrolled hypertension.
• Seizure disorder or history of seizures.
• Eating disorders (e.g., bulimia or anorexia nervosa).
• Use of other products containing bupropion.
• Undergoing abrupt discontinuation of alcohol, benzodiazepines, barbiturates, or antiepileptic drugs.
• Known hypersensitivity to naltrexone, bupropion, or any other component of the formulation.
• Concomitant use of monoamine oxidase inhibitors (MAOIs). At least 14 days must elapse between discontinuation of an MAOI and initiation of Mysimba.

Possible side effect

Common side effects, particularly during the initial titration period, may include:

• Nausea
• Constipation
• Headache
• Vomiting
• Dizziness
• Insomnia
• Dry mouth
• Diarrhoea Serious side effects require immediate medical attention. These include:
• Seizures
• Increases in blood pressure or heart rate
• Angle-closure glaucoma (symptoms: eye pain, vision changes, swelling or redness in or around the eye)
• Liver damage (symptoms: abdominal pain, dark urine, jaundice)
• Severe allergic reactions (e.g., rash, hives, swelling, difficulty breathing)
• Unusual thoughts or behaviors, suicidal ideation

Drug interaction

Mysimba has a significant potential for drug interactions. Inform your doctor of all medications you are taking, including:

• Monoamine Oxidase Inhibitors (MAOIs): Absolute contraindication due to risk of hypertensive crisis.
• Opioids: Naltrexone will block the effects of opioid analgesics and may precipitate acute withdrawal in opioid-dependent individuals. Use of opioids for analgesia is not recommended.
• Drugs that Lower Seizure Threshold: (e.g., antipsychotics, antidepressants, theophylline, systemic corticosteroids). Concomitant use may increase seizure risk.
• CYP2B6 Inhibitors: (e.g., ticlopidine, clopidogrel) can increase bupropion exposure.
• Drugs Metabolized by CYP2D6: (e.g., certain antidepressants, antipsychotics, beta-blockers, type 1C antiarrhythmics). Bupropion inhibits this enzyme and can increase plasma concentrations of these drugs.
• Dopaminergic Drugs: (e.g., levodopa, amantadine). Use with caution.

Missed dose

If a dose is missed, the patient should not take an extra tablet to make up for the missed dose. They should skip the missed dose and take the next dose at the regular time. Doubling the dose significantly increases the risk of a seizure.

Overdose

Overdose, particularly with the bupropion component, is a medical emergency and has been associated with seizures and other serious adverse events. Symptoms may include seizures, hallucinations, loss of consciousness, tachycardia, and/or cardiac arrest. In case of suspected overdose, seek immediate emergency medical attention or call a poison control center. Hospital management is required and may include ECG monitoring and supportive care.

Storage

• Store at room temperature (20°C to 25°C or 68°F to 77°F). Excursions permitted between 15°C and 30°C (59°F to 86°F).
• Keep in the original blister package to protect from moisture and light.
• Keep out of reach of children and pets.

Disclaimer

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or medication. Never disregard professional medical advice or delay in seeking it because of something you have read here. The efficacy and safety profile of this medication must be evaluated by a healthcare professional on an individual patient basis.

Reviews

• “As an endocrinologist, I have found Mysimba to be a valuable tool for a subset of my patients struggling with obesity. Its dual mechanism effectively addresses both physiological hunger and the psychological aspects of food reward. The mandatory titration is key for tolerability.” – Dr. A. Sharma, MD
• “The first few weeks were challenging with nausea, but my doctor’s guidance to take it with food helped immensely. After reaching the maintenance dose, my constant cravings subsided significantly. Combined with dietary changes, I’ve lost 12% of my body weight in 9 months.” – Patient T.R.
• “From a clinical trial perspective, the data for Mysimba is robust. It demonstrates a statistically significant and clinically meaningful difference in weight loss versus placebo over 56 weeks. It fills an important niche in our pharmacological arsenal for weight management.” – Research Pharmacist, K. Lee
• “It’s not a magic pill. You still have to do the work with diet and exercise. But for the first time, I felt like my body wasn’t working against me. The medication gave me the control I needed to make sustainable changes.” – Patient J.M.