Methocarbamol vs Cyclobenzaprine (Flexeril) - Comparison of Side Effects & Uses

Methocarbamol

It is a drug that belongs to a group of drugs called muscle relaxants. It can be found under the following brand names – Robaxin, Carbacot, Robaxin-750, or Skelex.

Rather than directly relaxing the muscle, this medication acts on the central nervous system.

It was originally approved by the US Food and Drug Administration in 1957.

Uses

This prescription medication is used together with physical therapy, rest, and other ways to relax muscles and relieve discomfort and pain caused by sprains, strains, and other muscle injuries.

Dosage

The usual recommended dose is 6g a day for the first 4 days in divided doses. Then, the treatment can be continued with 4g a day in divided doses.

The effect of this muscle relaxant can be felt within half an hour of administration of the dose.

Side Effects and Precautions

Common side effects may include:

  • loss of balance or coordination;
  • drowsiness;
  • upset stomach;
  • vomiting;
  • dizziness;
  • memory problems;
  • nausea;
  • confusion;
  • headaches;
  • stuffy nose;
  • eye redness;
  • mild itching or rash;

Rare side effects may include:

  • feeling like you might pass out;
  • chills;
  • flushing (redness, warmth, or tingly feeling);
  • seizure (convulsions);
  • spinning sensation;
  • fever;
  • sleep problems (insomnia);
  • jaundice (yellowing of your skin or eyes);
  • double vision;
  • slow heart rate;
  • blurred vision.

Pregnancy & Breastfeeding

There are no well-done studies to determine the safety of this muscle relaxant during pregnancy, therefore, contact your doctor before using it. Also, it passes into breast milk and may affect the infant in a negative way.

Alcohol

Consumption of alcoholic beverages is not recommended during treatment with this muscle relaxant due to the increased risk of drowsiness, dizziness, and difficulty in concentration.

Overdose

Overdosing happens more frequently when this muscle relaxant is used with another sedative drug or alcohol. Symptoms of an overdose may include:

  • loss of consciousness;
  • nausea;
  • seizure;
  • low blood pressure;
  • blurred vision;
  • severe drowsiness.

Drug Interactions

It may negatively interact with other medications, especially:

  • sleep medicines, like – ramelteon (Rozerem), eszopiclone (Lunesta), or zolpidem (Ambien);
  • drugs used to treat panic attacks and anxiety, like – chlordiazepoxide (Librium), alprazolam (Xanax), clonazepam (Klonopin), clobazam (Onfi), temazepam (Restoril), or lorazepam (Ativan);
  • other medicines which cause sedation;
  • depakote;
  • tricyclic antidepressants, like – amoxapine, amitriptyline, imipramine (Tofranil), doxepin, protriptyline (Vivactil), or nortriptyline (Pamelor);
  • vigamox;
  • opioids (narcotic pain medicines), like – morphine (Avinza, Kadian), hydrocodone (Lortab, Vicodin), or oxycodone (Oxycontin).

Cyclobenzaprine

It is a medication which belongs to a class of medications called muscle relaxants. It can be found under the brand name of Flexeril.

This medication works by preventing muscle spasms without affecting overall muscle control and function.

Uses

It is used to relax muscles and relieve pain and discomfort caused by muscle injuries. Additionally, it is prescribed to reduce symptoms of fibromyalgia.

Symptoms of fibromyalgia include:

  • memory issues;
  • problems with thinking;
  • chronic pain in the body;
  • numbness in hands and feet;
  • painful menstrual periods;
  • headaches;
  • morning stiffness;
  • trouble sleeping (insomnia).

Dosage

The recommended dose is 5 mg taken three times a day. The dosage may be increased to 10 mg taken three times a day.

Side Effects And Precautions

Common side effects may include:

  • constipation;
  • blurred vision;
  • dizziness;
  • dry throat;
  • muscle weakness;
  • nausea;
  • loss of appetite;
  • dry mouth;
  • stomach pain;
  • gas;
  • drowsiness;
  • diarrhea;
  • tired feeling.

Less common side effects may include:

  • feeling light-headed;
  • uneven heartbeats;
  • lack of coordination;
  • sudden numbness, especially on one side of the body;
  • seizure (convulsions);
  • pounding heartbeat;
  • hallucinations (seeing things);
  • fainting;
  • unusual weakness;
  • pain spreading to the shoulder;
  • unusual thoughts;
  • sudden headaches;
  • yellowing of the skin or eyes;
  • problems with vision, speech, or balance;
  • clay-colored stools;
  • easy bruising;
  • loss of appetite;
  • general ill feeling.

Pregnancy & Breastfeeding

As this medication is closely related to the tricyclic antidepressants, you should avoid it if you are pregnant or plant to fall pregnant. Moreover, since it passes into breast milk and may negatively affect the infant, avoid this muscle relaxant if you are breast-feeding a baby.

Drug Interactions

This medication may negatively interact with other drugs. Therefore, tell your healthcare professional if you are using:

  • anticholinergic drugs, such as – ipratropium (Atrovent) or tiotropium (Spiriva);
  • tramadol (a medication used to treat moderate to severe pain in adults);
  • barbiturates (medications that act as central nervous system depressants), such as –  phenobarbital (Donnatal);
  • meperidine (a synthetic opioid pain drug of the phenylpiperidine class);
  • monoamine oxides inhibitors, such as – selegiline (Emsam) and phenelzine (Nardil);
  • guanethidine (an antihypertensive medication which reduces the release of catecholamines);
  • selective serotonin reuptake inhibitors, such as – fluoxetine (Prozac) or sertraline (Zoloft);
  • bupropion (an antidepressant medication that affects chemicals in the brain nerves);
  • serotonin-norepinephrine reuptake inhibitors, such as – venlafaxine (Effexor) or duloxetine (Cymbalta);
  • tricyclic antidepressants, such as –  amitriptyline (Elavil) or clomipramine (Anafranil).

Bottom Line – Methocarbamol vs Cyclobenzaprine (Flexeril)

Methocarbamol (brand names – Robaxin, Carbacot, Robaxin-750, or Skelex) is a muscle relaxant that is used together with physical therapy and rest to treat skeletal muscle conditions, like – pain or injury. This medication works by blocking nerve impulses which are sent to the brain.

Cyclobenzaprine (brand name – Flexeril) is a medication which is used for the relief of muscle spasms associated with acute, painful musculoskeletal conditions. It acts on the locus coeruleus (a nucleus in the pons of the brainstem) where it results in increased norepinephrine release.

References

https://www.sciencedirect.com/topics/neuroscience/methocarbamol
https://www.ncbi.nlm.nih.gov/pubmed/26168743
https://www.ncbi.nlm.nih.gov/pubmed/2703967

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