Naltrexone Dosing for Weight Loss
The recommended dose of naltrexone for weight loss is 32 mg daily (as 8 mg four times daily), administered as part of the FDA-approved combination therapy with bupropion (Contrave). 1
Dosing Protocol for Naltrexone/Bupropion (Contrave)
Naltrexone is not FDA-approved as a standalone medication for weight loss but is used in combination with bupropion. The recommended dosing schedule is:
- Week 1: 8/90 mg (naltrexone/bupropion) once daily in the morning
- Week 2: 8/90 mg twice daily (morning and evening)
- Week 3: 16/180 mg in the morning, 8/90 mg in the evening
- Week 4 and beyond: 16/180 mg twice daily (32 mg naltrexone/360 mg bupropion total daily dose) 1
Efficacy and Monitoring
- Treatment should be discontinued if a patient has not achieved 5% weight loss at 12 weeks on the maximum dosage 1
- Clinical trials show placebo-subtracted weight loss of 4.7% (range 3.2-5.2%) after 1 year of treatment 2
- Patients who achieve ≥5% weight loss by week 16 are likely to maintain clinically significant weight loss at 1 year (average 11.7% weight loss) 3
Patient Selection
Naltrexone/bupropion combination is most appropriate for:
- Patients who describe food cravings or addictive behaviors related to food
- Patients attempting to quit smoking or reduce alcohol intake
- Patients with concomitant depression 1
Contraindications
Do not use naltrexone/bupropion in patients with:
- Uncontrolled hypertension
- Uncontrolled pain
- Recent MAOI use
- History of seizures
- Conditions that predispose to seizures (anorexia/bulimia nervosa, abrupt discontinuation of alcohol, benzodiazepines, barbiturates, or antiepileptic drugs) 1, 4
Common Side Effects
Serious Adverse Effects
- Increased blood pressure and heart rate (requires regular monitoring, especially in first 12 weeks)
- Neuropsychiatric disorders including depression and suicidal ideation
- Seizures (particularly in predisposed individuals) 4, 5
Important Monitoring Parameters
- Blood pressure and heart rate should be monitored regularly, especially during the first 12 weeks of treatment
- Assess weight loss at 12 weeks; discontinue if <5% weight loss achieved
- Monitor for neuropsychiatric symptoms, particularly in patients with history of depression or anxiety 1, 4
Special Considerations
- Naltrexone is an opioid receptor antagonist and will block the effects of opioid pain medications
- The medication is contraindicated in women who are or may become pregnant
- Women of reproductive age must use reliable contraception 1
Remember that naltrexone as monotherapy is not FDA-approved for weight loss, and the evidence supports its use only in combination with bupropion for this indication.