How Long Does Robaxin Stay In Your System?

While the time Robaxin stays in your system depends on many factors, most methocarbamol metabolites are excreted in the urine within five hours of ingesting the drug.

Robaxin is a brand name of the generic medication methocarbamol. Methocarbamol is a central nervous system depressant that is used to treat involuntary muscle spasms. Robaxin has a relatively short half-life. In healthy individuals, nearly all methocarbamol metabolites are excreted in the urine within five hours of ingesting the drug.

How Long Does It Take for Robaxin (Methocarbamol) To Work?

Robaxin (methocarbamol) works quickly. Those who take the medication may feel the effects in about 30 minutes. The drug typically reaches peak levels in the body two hours after an oral dose. Repeat doses of methocarbamol may be taken every six hours as directed by a healthcare provider.

How Long Does Robaxin (Methocarbamol) Stay In Your System?

Robaxin is a brand name for the generic medication methocarbamol. Methocarbamol is a central nervous system depressant used to treat involuntary muscle spasms. Robaxin has a relatively short half-life. In healthy individuals, nearly all methocarbamol metabolites are excreted in urine within five hours of ingesting the drug.

Robaxin (Methocarbamol) Prescription Facts

Pregnant mothers should avoid taking Robaxin due to an increased likelihood of the infant being born with congenital disabilities. Methocarbamol is present in the milk of lactating mothers receiving treatment with the drug. It is unknown whether this may damage the development of nursing infants. Methocarbamol should be avoided when driving an automobile or operating heavy machinery due to the potential for impaired motor skills.

Robaxin (Methocarbamol) Regulations

Methocarbamol is unsafe for many elderly patients due to the increased risk of serious side effects. Common side effects of Robaxin may include upset stomach, skin flushing, poor coordination (ataxia), dizziness, blurred vision and drowsiness. Cases of rapid heart rate (tachycardia) and slow heart rate (bradycardia) have been reported on rare occasions. These are serious conditions and should be reported to the prescribing doctor immediately. Other side effects indicative of a poor reaction to the drug include itching, jaundice (yellow skin and eyes), fainting, nausea, vomiting, difficulty urinating, mood swings and abdominal pain. Incidences of increased suicidal thoughts are uncommon but are more likely to occur in young patients taking high doses of methocarbamol.

Most Commonly Abused Drugs Containing Robaxin (Methocarbamol)

Robaxin is considered low risk for developing a dependence on the drug. Abruptly stopping treatment can lead to an increased likelihood of side effects. Methocarbamol is potentially addictive like the benzodiazepine lorazepam, although the addictive qualities of methocarbamol are considerably weaker. Occurrences of addiction to methocarbamol alone are rare. Typical habits evolve in individuals with a history of addiction to other substances.

How Robaxin (Methocarbamol) Affects the Brain and Body

Robaxin has a high therapeutic index, meaning it tends to be effective and safe at a wide range of doses. Taking 500–750 mg daily of methocarbamol is common for treating persistent involuntary muscle spasms. Significantly higher doses may be necessary for treating lockjaw associated with tetanus. Severe side effects are more likely to occur at higher doses. The exact mechanism of action of methocarbamol is unknown. Robaxin does not act directly on striatal muscle fibers but inhibits the functioning of neurons that trigger muscle twitching and pain. Symptoms can be reduced by depressing the activity of these neurons.

Half-life of Robaxin (Methocarbamol)

The plasma elimination half-life of methocarbamol ranges between one and two hours before excreted in the urine. Nearly all of methocarbamol’s metabolites are excreted in the urine. However, only a minuscule amount of methocarbamol itself is eliminated in the urine. The plasma protein binding of methocarbamol ranges from 46–50% in healthy individuals.

Does Robaxin Show Up on a Drug Test?

Standard five-panel drug tests are the most common pre-employment drug screening. Five-panel drug tests check for amphetamines, cocaine, oxycodone and tetrahydrocannabinol (THC). Methocarbamol, a skeletal muscle relaxant, doesn’t fall into these categories and shouldn’t affect a standard drug test. 

Factors That Influence How Long Robaxin (Methocarbamol) Stays in Your System

The patient’s age and kidney and liver health influence the body’s metabolism of Robaxin. Elderly patients take slightly longer to eliminate methocarbamol in the urine. This means methocarbamol levels will be higher in older patients than in younger patients taking the same dose. Patients on hemodialysis due to poorly functioning kidneys and individuals with liver cirrhosis due to alcohol misuse may also have higher levels of Robaxin in their system because of the increased time to eliminate the drug and the lower amount of drug bound to protein in the blood.

How Long Does Robaxin (Methocarbamol) Stay In Your Urine, Hair and Blood?

Standard drug tests do not routinely check for methocarbamol or its metabolites. Testable levels of methocarbamol metabolites may be present in the urine beginning one to two hours following ingestion. Methocarbamol can remain in urine for about four to five hours after consumption. These ranges can differ depending on the patient’s age and health. For most individuals, only 2% of absorbed methocarbamol will remain in the blood for 24 hours following the final drug dose. Most substances may be tested via a hair sample within 90 days of the last dose.

Editor – Theresa Valenzky

Theresa Valenzky graduated from the University of Akron with a Bachelor of Arts in News/Mass Media Communication and a certificate in psychology. She is passionate about providing genuine information to encourage and guide healing in all aspects of life. Read more

Medically Reviewed By – Elizabeth Cambria

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