For a patient scheduled for sacrocolpopexy who is taking methocarbamol (Robaxin) 750 mg orally every 6 hours, should the medication be continued up to the day of surgery and how should the dosing be adjusted?

Methocarbamol Should Be Held on the Day of Surgery

For a patient taking methocarbamol 750 mg every 6 hours who is scheduled for sacrocolpopexy, discontinue the medication on the day of surgery. The patient may continue taking it up until the night before the procedure, but should not take the morning dose on the day of operation.

Rationale Based on Guidelines

The Society for Perioperative Assessment and Quality Improvement (SPAQI) provides clear consensus guidance on this issue 1. Methocarbamol is a centrally acting skeletal muscle relaxant with significant perioperative concerns:

Key Safety Concerns

• Cardiovascular effects: Methocarbamol causes bradycardia and hypotension, which can be problematic during anesthesia 1
• Central nervous system depression: The medication causes drowsiness and dizziness that can potentiate anesthetic agents 1
• Drug interactions: Methocarbamol interferes with pyridostigmine bromide (used to reverse neuromuscular blockade) and should not be used in patients with myasthenia gravis 1
• Impaired elimination: Clearance is significantly reduced in patients with liver or kidney disease 1

Dosing Instructions

Preoperative management:

• Continue methocarbamol 750 mg every 6 hours up until bedtime the night before surgery
• Hold the morning dose on the day of surgery
• No tapering is required for methocarbamol, as it does not cause clinically significant withdrawal symptoms (unlike carisoprodol or baclofen)

Postoperative resumption:

• Restart methocarbamol once the patient is hemodynamically stable and no longer requires close cardiovascular monitoring
• Typically can resume 24-48 hours postoperatively, or when oral intake is tolerated and anesthesia effects have resolved

Important Caveats

Renal and Hepatic Function

Verify kidney and liver function before surgery. If the patient has significant renal or hepatic dysfunction, consider whether methocarbamol should be continued postoperatively at all, as elimination is significantly impaired in these conditions 1.

Anesthesia Team Communication

Inform the anesthesia team that the patient takes methocarbamol regularly, even though it's being held on the day of surgery. This is important because:

• The drug may still have residual effects
• It may influence the choice of neuromuscular blocking agents and reversal strategies
• The anesthesiologist should be aware of potential interactions with pyridostigmine if reversal is needed 1

Conflicting Evidence on Postoperative Use

While the guideline clearly states to hold methocarbamol on the day of surgery 1, there is conflicting evidence about its postoperative utility:

• Potential benefit: One study showed that preoperative IV methocarbamol reduced opioid consumption and improved physical therapy progress after joint replacement 2
• Potential harm: A more recent 2023 study found that postoperative methocarbamol was associated with higher pain scores and increased opioid requirements 3

This discrepancy likely reflects confounding by indication (sicker patients received methocarbamol) rather than true drug effect. The safest approach is to hold it on the day of surgery as recommended by guidelines, then make individualized decisions about postoperative resumption based on the patient's pain control needs and hemodynamic stability.

No Bridging or Alternative Required

Unlike anticoagulants or medications with withdrawal syndromes, methocarbamol does not require:

• Tapering before discontinuation
• Bridging with alternative agents
• Specific timing beyond holding the day-of-surgery dose

The 750 mg every 6 hours dosing means the patient would typically take doses at 6 AM, 12 PM, 6 PM, and midnight. Simply skip the 6 AM dose on the day of surgery.