From the FDA Drug Label
For the severest cases or in postoperative conditions in which oral administration is not feasible, additional doses of 1 gram may be repeated every 8 hours up to a maximum of 3 g/day for no more than 3 consecutive days. ROBAXIN Injectable may be administered undiluted directly into the vein at a maximum rate of three mL per minute It may also be added to an intravenous drip of Sodium Chloride Injection (Sterile Isotonic Sodium Chloride Solution for Parenteral Use) or five percent Dextrose Injection (Sterile 5 percent Dextrose Solution); one vial given as a single dose should not be diluted to more than 250 mL for I.V. infusion.
The recommended dose of Robaxin IV for spasm is 1 gram (one 10 mL vial), which may be repeated every 8 hours up to a maximum of 3 g/day for no more than 3 consecutive days. The maximum rate of administration is 3 mL per minute. 1
From the Research
Intravenous Robaxin (methocarbamol) for muscle spasms is not recommended due to lack of efficacy compared to placebo, as shown in the most recent study 2. Instead, other treatment options should be considered. The study published in 2022 2 found that among patients with acute low back pain treated with a nonsteroidal anti-inflammatory drug, skeletal muscle relaxants, including methocarbamol, do not improve outcomes more than placebo. Key points to consider:
- The efficacy of methocarbamol is not significantly different from placebo in treating muscle spasms 2.
- The medication should be used with caution in patients with renal or hepatic impairment, and dose adjustments may be necessary.
- Patients should be monitored for potential side effects, particularly hypotension, during administration.
- Other treatment options, such as nonsteroidal anti-inflammatory drugs, physical therapy, or alternative muscle relaxants, may be more effective in managing muscle spasms.
- The most recent study 2 provides the highest quality evidence, and its findings should be prioritized in clinical decision-making.