Can I take Adipex (phentermine) and MS Contin (morphine sulfate) together?

Phentermine and MS Contin (Morphine Sulfate) Combination Safety

The combination of Adipex (phentermine) and MS Contin (morphine sulfate) is contraindicated due to significant safety concerns, particularly the risk of severe drug interactions that could lead to increased mortality.

Contraindications and Safety Concerns

Phentermine (Adipex) Considerations:

• Phentermine is a sympathomimetic amine that suppresses appetite through central nervous system effects 1
• It is FDA-approved only for short-term use (12 weeks or less) for weight management 1
• Common side effects include elevated blood pressure, elevated heart rate, insomnia, dry mouth, and anxiety 1

Critical Drug Interaction Concerns:

• Phentermine has documented severe potential drug-drug interactions with opioids like morphine sulfate 2
• Naltrexone/bupropion (another weight loss medication) is specifically contraindicated for use with chronic opioid therapy 3
• The combination may increase the risk of:
  • Central nervous system depression
  • Respiratory depression
  • Cardiovascular complications
  • Serotonin syndrome

Clinical Decision Algorithm

1. Assess medication necessity:

   • Is phentermine essential for weight management? Consider alternatives like orlistat which works through a non-sympathomimetic mechanism 1
   • Is MS Contin essential for pain management? Consider non-opioid alternatives

2. If both medications are deemed necessary:

   • Do not co-administer these medications
   • Consider safer weight management alternatives:
     • Orlistat (non-sympathomimetic mechanism) 3, 1
     • Lorcaserin (safer in patients with cardiovascular disease) 3

3. For patients with chronic pain requiring opioids:

   • Avoid sympathomimetic agents like phentermine 3
   • Consider GLP-1 receptor agonists for weight management in patients requiring opioid therapy 3

Important Monitoring Considerations

If a patient is transitioning from one medication to another:

• Monitor for withdrawal symptoms if discontinuing either medication
• When discontinuing phentermine, gradual tapering is recommended 1:
  • Week 1: Half the regular dose
  • Week 2: Half dose every other day
  • Week 3: Complete discontinuation

Common Pitfalls to Avoid

1. Long-term phentermine use: Despite common practice, phentermine is only FDA-approved for short-term use (≤12 weeks) 1

2. Overlooking cardiovascular risks: Phentermine can increase blood pressure and heart rate, potentially worsening cardiovascular risk when combined with opioids 4

3. Ignoring potential for abuse: Both medications have potential for dependence and abuse, and their combination may increase this risk 2

4. Assuming safety due to separate prescribers: Even if prescribed by different providers, the interaction risk remains significant

The evidence clearly demonstrates that the risks of combining phentermine and morphine sulfate outweigh any potential benefits, and alternative approaches to managing both weight and pain should be pursued.