How should fibromyalgia medications, such as pregabalin, duloxetine, and milnacipran, be managed in patients undergoing surgery with general anesthesia?

Management of Fibromyalgia Medications During General Anesthesia

Fibromyalgia medications such as pregabalin, duloxetine, and milnacipran should be continued through the perioperative period to prevent withdrawal symptoms and maintain pain control, with specific precautions for each medication.

Medication-Specific Recommendations

Pregabalin

• Continue through surgery: Pregabalin should be maintained at the current dose throughout the perioperative period 1
• Abrupt discontinuation can lead to withdrawal symptoms including insomnia, nausea, headache, and diarrhea 2
• When discontinuing pregabalin (if necessary), taper gradually over a minimum of 1 week 2
• Pregabalin may have beneficial effects on postoperative pain management, with studies showing decreased postoperative pain scores up to 24 hours after surgery 3
• Dosage adjustment required in patients with renal insufficiency 2

Duloxetine

• Continue through surgery: Maintain duloxetine therapy to prevent discontinuation syndrome 1
• Abrupt discontinuation can cause dizziness, nausea, headache, paresthesia, and irritability
• Monitor for potential interactions with other medications that affect serotonin levels to prevent serotonin syndrome
• Use with caution in elderly patients who are more susceptible to CNS effects and falls 1
• Monitor patients with cardiac disease for cardiovascular effects 1

Milnacipran

• Continue through surgery: Similar to duloxetine, maintain therapy to prevent discontinuation syndrome 1
• Monitor blood pressure as SNRIs can cause modest increases in blood pressure
• Be aware of potential drug interactions with other serotonergic medications

Anesthetic Considerations

1. Preoperative Assessment:

   • Document current fibromyalgia medication regimen and dosages
   • Assess for potential drug interactions with anesthetic agents
   • Evaluate baseline pain levels and functional status

2. Intraoperative Management:

   • Be aware that patients on pregabalin may require less anesthetic agents due to its CNS depressant effects
   • Monitor for hemodynamic changes, particularly in patients taking SNRIs (duloxetine, milnacipran)
   • Consider multimodal analgesia approaches to optimize pain control

3. Postoperative Management:

   • Resume oral medications as soon as possible
   • Consider IV formulations if oral intake is delayed
   • Maintain consistent dosing schedule to prevent withdrawal symptoms

Special Considerations

• Pregabalin: May enhance the effects of other CNS depressants used during anesthesia, potentially requiring dose adjustments of anesthetic agents 3, 2
• Duloxetine/Milnacipran: Monitor for serotonin syndrome if used with other serotonergic medications (e.g., certain opioids like tramadol) 4
• Pain Management: Patients with fibromyalgia may have altered pain perception and may require individualized postoperative pain management strategies 3

Potential Pitfalls and How to Avoid Them

1. Withdrawal Syndrome: Avoid abrupt discontinuation of any fibromyalgia medications. If oral intake is not possible postoperatively, consult with pain management or psychiatry for alternative administration routes 1

2. Drug Interactions: Be vigilant about potential interactions between fibromyalgia medications and anesthetic agents. Specifically:

   • Gabapentinoids (pregabalin) may potentiate CNS depression 3
   • SNRIs (duloxetine, milnacipran) may interact with vasopressors and certain analgesics 3

3. Inadequate Pain Control: Patients with fibromyalgia may have baseline hyperalgesia and central sensitization. Consider multimodal analgesia including regional anesthesia techniques when appropriate 3, 1

4. Renal Impairment: Adjust pregabalin dosing in patients with renal insufficiency, as it is primarily eliminated by renal excretion 2

The most recent evidence suggests that combination therapy with pregabalin and duloxetine may be more effective than monotherapy for fibromyalgia symptoms 5, but this should not alter the perioperative management approach of continuing these medications through surgery.