Is AUVELITY (dextromethorphan/bupropion) safe to use with Robaxin (methocarbamol), hydroxyzine, and gabapentin?

Safety of AUVELITY with Robaxin, Hydroxyzine, and Gabapentin

AUVELITY (dextromethorphan/bupropion) should be used with caution when combined with Robaxin (methocarbamol), hydroxyzine, and gabapentin due to potential additive central nervous system (CNS) depressant effects that could increase the risk of sedation, dizziness, and cognitive impairment.

Drug Interaction Analysis

AUVELITY (Dextromethorphan/Bupropion)

• AUVELITY is a combination medication containing dextromethorphan (an NMDA receptor antagonist and sigma-1 receptor agonist) and bupropion (a CYP2D6 inhibitor that increases dextromethorphan bioavailability) 1, 2
• Common adverse effects include dizziness, nausea, headache, diarrhea, somnolence, dry mouth, anxiety, and insomnia 1
• Carries a boxed warning for increased risk of suicidal thoughts and behaviors, particularly in young adults 1
• Seizures can occur, especially at higher doses 1

Potential Interactions

1. Gabapentin

   • Gabapentin is commonly used for neuropathic pain and has CNS depressant effects 3
   • Common side effects include dizziness (27-46%), somnolence (15-25%), and peripheral edema 3
   • When combined with other CNS depressants, there is potential for additive sedative effects 3
   • No specific pharmacokinetic interaction is expected between gabapentin and AUVELITY

2. Hydroxyzine

   • Hydroxyzine is an antihistamine with significant sedative properties 4
   • Antihistamines have anticholinergic properties that can cause side effects 4
   • Combining with other CNS depressants may increase sedation risk

3. Methocarbamol (Robaxin)

   • Muscle relaxant with CNS depressant effects
   • May have additive sedative effects when combined with other CNS depressants

Risk Assessment

The primary concern with this combination is the potential for additive CNS depression, which could manifest as:

• Increased sedation and somnolence
• Enhanced dizziness
• Cognitive impairment
• Psychomotor impairment affecting daily activities including driving

Guidelines suggest caution when combining multiple CNS depressants, as this can lead to significant functional impairment 4, 3.

Recommendations

1. Dosing Considerations:

   • Consider starting with lower doses of each medication when using this combination
   • For gabapentin, start at 300 mg daily and titrate slowly based on response and tolerability 3
   • Monitor for increased side effects, particularly during the initial combination period

2. Patient Monitoring:

   • Closely monitor for excessive sedation, dizziness, and cognitive impairment
   • Assess for worsening depression or emergence of suicidal thoughts, particularly in the first few weeks of treatment 1
   • Monitor for seizures, which can be a risk with bupropion, especially at higher doses 1

3. Patient Education:

   • Advise against driving or operating heavy machinery until the effects of the combination are known
   • Instruct to avoid alcohol and other CNS depressants, which could further increase sedation
   • Educate about signs of excessive CNS depression requiring medical attention

4. Alternative Considerations:

   • If excessive sedation occurs, consider:
     • Reducing doses of one or more medications
     • Adjusting timing of administration to minimize peak concentration overlap
     • Substituting with alternatives that have less sedative potential

Special Considerations

• Elderly patients are at higher risk for CNS side effects and falls with this combination
• Patients with renal impairment may require dose adjustment of gabapentin as it is primarily eliminated unchanged in urine 3
• Patients with a history of seizures are at increased risk when taking bupropion 1
• Patients with a history of substance use disorders should be monitored closely as the sedative effects may be reinforcing 3

While no absolute contraindication exists for this specific combination, careful monitoring and dose adjustments are essential to minimize the risk of adverse effects from additive CNS depression.