What are the potential interactions between gabapentin and Cataflam (diclofenac)?

Gabapentin and Diclofenac (Cataflam) Interaction

No clinically significant pharmacokinetic interaction exists between gabapentin and diclofenac (Cataflam), making this combination generally safe to use together when clinically indicated. 1

Key Interaction Information

• Gabapentin is not metabolized by the cytochrome P450 system and is primarily excreted unchanged through the kidneys, minimizing the risk of metabolic drug interactions with diclofenac 1

• Diclofenac (Cataflam) is an NSAID that undergoes hepatic metabolism through the CYP system, but does not significantly affect gabapentin's pharmacokinetics 1

• Unlike some anticonvulsants (such as carbamazepine, phenytoin, or phenobarbital) that interact with many medications, gabapentin has minimal drug interaction potential 1

Safety Considerations When Using This Combination

Renal Function Monitoring

• Both medications can affect renal function, so combined use requires monitoring, especially in:
  • Elderly patients 1
  • Patients with pre-existing renal impairment 1
  • Patients taking other nephrotoxic medications 1

Potential for Enhanced Efficacy

• Some research suggests potential synergistic analgesic effects when combining gabapentinoids with NSAIDs like diclofenac for neuropathic pain 2
• Combined low doses may provide better analgesia with fewer side effects than high doses of either agent alone 2

CNS Effects

• Both medications can cause CNS effects, including:
  • Dizziness and somnolence with gabapentin 1, 3
  • Potential for headache or dizziness with diclofenac 1
  • Combined use may theoretically increase risk of these effects, requiring caution 1

Special Populations

Elderly Patients

• The American Geriatrics Society Beers Criteria recommends caution with NSAIDs like diclofenac in older adults due to increased risk of:
  • GI bleeding
  • Renal impairment
  • Cardiovascular events 1
• Gabapentin requires dose adjustment in elderly patients with reduced renal function 1

Patients with Hepatic Impairment

• Diclofenac can cause hepatic complications and should be used with caution in patients with liver disease 1
• Gabapentin exposure increases in moderate hepatic impairment (2.3-fold) 1

Clinical Recommendations

1. Dosing considerations:

   • Start with lower doses of both medications when using in combination, especially in elderly patients or those with renal impairment 1
   • Consider gabapentin 100-300 mg daily initially with gradual titration 1
   • Use the lowest effective dose of diclofenac for the shortest duration 1

2. Monitoring recommendations:

   • Assess renal function before initiating therapy and periodically during treatment 1
   • Monitor for increased sedation, dizziness, or cognitive effects, especially when initiating therapy 1, 3
   • Watch for signs of GI bleeding or cardiovascular effects from diclofenac 1

3. Patient education:

   • Advise patients about potential additive CNS effects and caution regarding driving or operating machinery 1, 3
   • Instruct patients to report unusual bleeding, edema, or changes in mental status 1

While there are no major pharmacokinetic interactions between gabapentin and diclofenac, careful monitoring for additive side effects and dose adjustments based on patient factors remain important clinical considerations when using these medications together 1, 2.