The combination of naltrexone 50 mg and bupropion SR 150 mg is a prescription medication used for managing chronic weight in adults. This treatment assists adults who are overweight or obese in achieving and maintaining weight loss. It is typically prescribed alongside a reduced-calorie diet and increased physical activity. The medication addresses certain biological factors that influence appetite and cravings, helping individuals to better control their food intake.
Understanding Naltrexone and Bupropion
Naltrexone, an opioid antagonist, is used for treating opioid and alcohol dependence. It works by blocking the euphoric and sedative effects of these substances and can help reduce cravings. Naltrexone is available in oral form, with common brand names including ReVia and Depade, and an injectable extended-release form called Vivitrol.
Bupropion is an atypical antidepressant prescribed for major depressive disorder, seasonal affective disorder, and as an aid for smoking cessation. It is available under various brand names such as Wellbutrin, Zyban, Wellbutrin SR, and Wellbutrin XL. When combined, naltrexone and bupropion are specifically formulated for weight management, often marketed as Contrave in the United States and Mysimba in Europe.
How This Combination Aids Weight Loss
The combination of naltrexone and bupropion works synergistically within the brain to influence appetite and control cravings. Bupropion, acting as a reuptake inhibitor of norepinephrine and dopamine, and a nicotinic acetylcholine receptor antagonist, stimulates proopiomelanocortin (POMC) neurons in the hypothalamus.
Activation of these POMC neurons leads to a reduction in appetite and an increase in energy output. Endogenous opioids regulate the POMC pathway through a negative feedback loop, which can counteract bupropion’s effect. Naltrexone, a pure opioid antagonist, blocks these opioid receptors, thereby augmenting bupropion’s activation of the POMC neurons and further enhancing its effects. This dual action helps to manage both biological hunger cues and reward-driven eating behaviors.
Who Can Use This Medication and How to Take It
This medication is indicated for adults with an initial body mass index (BMI) of 30 kg/m² or greater (considered obese). It may also be prescribed to individuals with a BMI of 27 kg/m² to less than 30 kg/m² (overweight) who have at least one weight-related comorbidity, such as type 2 diabetes, dyslipidemia, or controlled high blood pressure. This medication is a prescription-only drug and requires medical supervision.
The standard dosage typically involves a gradual increase over several weeks to minimize side effects. A common titration schedule starts with one tablet in the morning for the first week. The dose is then gradually increased to reach the full dosage, which is usually two tablets taken twice daily, providing a total of 32 mg naltrexone and 360 mg bupropion per day. The tablets should be swallowed whole and not cut, crushed, or chewed. It can be taken with or without food, but high-fat meals should be avoided as they may increase the risk of seizures.
Potential Side Effects and Important Warnings
Common side effects associated with this combination medication include nausea, constipation, headache, vomiting, dizziness, insomnia, and dry mouth. These side effects often decrease over time as the body adjusts to the medication.
More serious side effects and warnings exist. The medication carries a boxed warning regarding the potential for suicidal thoughts and behaviors, particularly at the beginning of treatment or when doses are adjusted. Increases in blood pressure and heart rate have also been reported.
Seizures are a known risk, especially with bupropion, and the medication is contraindicated in individuals with a history of seizure disorder or eating disorders like anorexia or bulimia nervosa. It is also not recommended for those with uncontrolled high blood pressure, or who are currently using opioids or have recently stopped alcohol or drug use (including benzodiazepines, barbiturates, or antiepileptics). A 14-day washout period is necessary between discontinuing monoamine oxidase inhibitors (MAOIs) and starting this medication due to the risk of hypertensive reactions. Liver function should be monitored, as liver injury is a possible side effect.
Achieving Results and Long-Term Considerations
Weight loss with this medication varies among individuals, with significant reductions observed in clinical trials. Patients generally achieve results over several months, with average weight loss around 6-7% of body weight in clinical trials over a 56-week period.
This medication is approved for chronic weight management, meaning it can be used long-term under ongoing medical supervision. Regular follow-ups with a healthcare provider are important to monitor progress, manage any side effects, and ensure the medication remains appropriate for the individual’s health needs. The goal is to support sustained weight loss and improve overall health outcomes.