Studies comparing it to the benzodiazepine lorazepam and the antihistamine diphenhydramine, along with placebo, find that methocarbamol produces increased "liking" responses and some sedative-like effects; however, at higher doses dysphoria is reported. It is considered to have an abuse profile similar to, but weaker than, lorazepam. Interactions
Methocarbamol may inhibit the effects of pyridostigmine bromide. Therefore, methocarbamol should be used with caution in those with myasthenia gravis taking anticholinesterase medications.Methocarbamol may disrupt certain screening tests as it can cause color interference in laboratory tests for 5-hydroxy-indoleacetic acid (5-HIAA) and in urinary testing for vanillylmandelic acid (VMA) using the Gitlow method. Pharmacology
Mechanism of action
The mechanism of action of methocarbamol has not currently been established. Its effect is thought to be localized to the central nervous system rather than a direct effect on skeletal muscles. It has no effect on the motor end plate or the peripheral nerve fiber. The efficacy of the medication is likely related to its sedative effect. Alternatively, methocarbamol may act via inhibition of acetylcholinesterase, similarly to carbamate. Pharmacokinetics
In healthy individuals, the plasma clearance of methocarbamol ranges between 0.20 and 0.80 L/h/kg. The mean plasma elimination half-life ranges between 1 and 2 hours, and the plasma protein binding ranges between 46% and 50%. The elimination half-life was longer in the elderly, those with kidney problems, and those with liver problems.
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 is less preferred in low back pain. It has limited use for rheumatoid arthritis and cerebral palsy. Effects generally begin within half an hour. It is taken by mouth or injection into a vein.Common side effect include headaches, sleepiness, and dizziness. Serious side effects may include anaphylaxis, liver problems, confusion, and seizures. Use is not recommended in pregnancy and breastfeeding. Because of risk of injury, skeletal muscle relaxants should generally be avoided in geriatric patients. Methocarbamol is a centrally acting muscle relaxant. How it works is unclear, but it does not appear to affect muscles directly.Methocarbamol was approved for medical use in the United States in 1957. It is available as a generic medication. It is relatively inexpensive as of 2016. In 2019, it was the 136th most commonly prescribed medication in the United States, with more than 4 million prescriptions. 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 medications efficacy and safety in treating musculoskeletal conditions, primarily neck and back pain.Methocarbamol injection may have a beneficial effect in the control of the neuromuscular spasms of tetanus.