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Methocarbamol, sold under the brand name Robaxin among others, is a medication used for short-term musculoskeletal pain. It may be used together with rest, physical therapy, and pain medication. It has limited use for rheumatoid arthritis and cerebral palsy. Effects generally begin within half an hour. Serious side effects may include anaphylaxis, liver problems, confusion, and seizures. It was approved for medical use in the United States in 1957. It is available as a generic medication. Methocarbamol is available in a fixed-dose combination with ibuprofen as methocarbamol/ibuprofen (sold under the brand name Summit Ultra).
Medical use
Methocarbamol is a muscle relaxant used to treat acute, painful musculoskeletal spasms in a variety of musculoskeletal conditions. However, there is limited and inconsistent published research on the medication's efficacy and safety in treating musculoskeletal conditions, primarily neck and back pain.
- Hypersensitivity reactions and anaphylatic reactions are also reported.
- May cause urine to turn black, blue, or green. Methocarbamol appeared to be less sedating than other muscle relaxants, most notably cyclobenzaprine but had a similarly increased risk of injury.
Pregnancy
Methocarbamol is labeled by the FDA as a pregnancy category C medication.
Interactions
Methocarbamol may inhibit the effects of pyridostigmine bromide.
Pharmacokinetics
In healthy individuals, the plasma clearance of methocarbamol ranges between 0.20 and 0.80 L/h/kg. Small amounts of unchanged methocarbamol are also excreted in the urine. In the United States, low back pain is the fifth most common reason for all physician visits and the second most common symptomatic reason. In 80% of primary care visits for low back pain, at least one medication was prescribed at the initial office visit and more than one third were prescribed two or more medications. The most commonly prescribed drugs for low back pain included skeletal muscle relaxants. Cyclobenzaprine and methocarbamol are on the U.S. Medicare formulary, which may account for the higher use of these products.
Marketing
thumb|Generic methocarbamol 750mg tablet.
Methocarbamol without other ingredients is sold under the brand name Robaxin in the U.K., U.S., Canada and South Africa; it is marketed as Lumirelax in France, Ortoton in Germany and many other names worldwide. In combination with other active ingredients it is sold under other names: with acetaminophen (paracetamol), under trade names Robaxacet and Tylenol Body Pain Night; with ibuprofen as Robax Platinum; with acetylsalicylic acid as Robaxisal in the U.S. and Canada. However, in Spain the tradename Robaxisal is used for the paracetamol combination instead of Robaxacet. These combinations are also available from independent manufacturers under generic names.
Research
Although opioids are typically first-line treatments in severe pain, several trials suggest that methocarbamol may improve recovery and decrease hospital length of stay in those with muscle spasms associated with rib fractures. However, methocarbamol was less useful in the treatment of acute traumatic pain in general.
Long-term studies evaluating the risk of development of cancer in using methocarbamol have not been performed.