Methocarbamol is a muscle relaxant that’s used to treat the pain and discomfort associated with acute muscle spasms. Methocarbamol is commonly sold under the brand name Robaxin. It is considered to have a low addictive potential. Cases of addiction to methocarbamol are rare but are more common among individuals who have a history of substance misuse disorders or who are actively addicted to another drug.
Robaxin may be prescribed for the treatment of lockjaw when individuals are exposed to tetanus. Higher doses, in the range of 24 grams a day, are often required for reducing lockjaw. Lower doses of three to six grams per day are typically prescribed for the treatment of general muscle spasms and associated pain.
General side effects of methocarbamol can include tachycardia (rapid heart rate), bradycardia (slow heart rate), dizziness, blurred vision, nausea, headache, confusion, drowsiness, clumsiness, constipation, memory problems and flushed/itchy skin. Other serious side effects, including fainting, jaundice, persistent vomiting and abdominal pain can occur.
On rare occasions, suicidal thoughts can occur when Robaxin is taken in large quantities. Such symptoms should be reported to the prescribing doctor immediately. Methocarbamol may also cause urine to turn blue, black or green. Discolored urine is not an indicator of something harmful occurring inside the body and should be considered harmless.
Methocarbamol achieves its effects by suppressing the activity of the central nervous system. The exact mechanism of action, however, is unknown. One of the leading theories among researchers is that Robaxin inhibits the activity of the enzyme carbonic anhydrase. Robaxin has no direct effect on the skeletal muscle fibers themselves. Methocarbamol reduces the discomfort associated with persistent muscle twitching by affecting the nerve endings, thereby decreasing muscle spasms.
Robaxin is considered to have a low likelihood of leading to addictive behaviors. Other similar carbamate medications, such as meprobamate, have a significantly higher potential for misuse. Methocarbamol use has been shown to result in sedative effects and dysphoria in higher doses. In most reported cases of methocarbamol misuse, individuals have a history of substance misuse disorders. In general, the misuse profile of Robaxin is like the benzodiazepine lorazepam, although significantly less severe.
Robaxin is safe and effective in a wide range of doses and is not known to have any negative long-term impact. The effects of Robaxin are reversible, meaning they stop along with the cessation of treatment.
Methocarbamol has several potential contraindications to use. The elderly are rarely prescribed methocarbamol due to the increased risk for severe side effects. Robaxin should not be taken during pregnancy. Early research indicates that methocarbamol may lead to an increased likelihood of congenital birth defects in offspring. However, more research needs to be done to investigate this possibility. Studies indicate that methocarbamol is present in the breast milk of lactating mothers. It is unknown as to whether infants fed the breast milk of mothers taking Robaxin results in harmful effects to the child.
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