Metaxalone 400mg Tablets
It is used to relax muscles.
Drug Class
Skeletal Muscle Relaxant
Pharmacologic Class
Centrally Acting Skeletal Muscle Relaxant
Pregnancy Category
Category C
FDA Approved
Aug 1962
DEA Schedule
Not Controlled
Overview
What is this medicine?
Metaxalone is a muscle relaxant that works by affecting your brain and nervous system to help relieve muscle spasms and the pain and discomfort associated with them. It's used along with rest and physical therapy.
How to Use This Medicine
Taking Your Medication
To use this medication correctly, follow your doctor's instructions and read all the information provided. You can take this medication with or without food, but be aware that taking it with food may increase sleepiness or dizziness.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry place, avoiding the bathroom. Keep all medications in a safe location, out of the reach of children and pets. When disposing of unused or expired medication, do not flush it down the toilet or pour it down the drain unless instructed to do so. Instead, consult your pharmacist for guidance on the best disposal method or explore local drug take-back programs.
Missing a Dose
If you take this medication regularly, take a missed dose as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your normal dosing schedule. Do not take two doses at the same time or take extra doses. If you take this medication as needed, do not take it more frequently than directed by your doctor.
To use this medication correctly, follow your doctor's instructions and read all the information provided. You can take this medication with or without food, but be aware that taking it with food may increase sleepiness or dizziness.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry place, avoiding the bathroom. Keep all medications in a safe location, out of the reach of children and pets. When disposing of unused or expired medication, do not flush it down the toilet or pour it down the drain unless instructed to do so. Instead, consult your pharmacist for guidance on the best disposal method or explore local drug take-back programs.
Missing a Dose
If you take this medication regularly, take a missed dose as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your normal dosing schedule. Do not take two doses at the same time or take extra doses. If you take this medication as needed, do not take it more frequently than directed by your doctor.
Lifestyle & Tips
- Avoid alcohol and other CNS depressants (e.g., sedatives, tranquilizers, opioids) as they can increase drowsiness and dizziness.
- Do not drive or operate heavy machinery until you know how this medication affects you, as it can cause drowsiness and dizziness.
- Take with food if stomach upset occurs, as food can also increase absorption and potentially reduce stomach upset.
- Do not stop taking this medication suddenly without consulting your doctor, especially if you have been taking it for a long time.
Available Forms & Alternatives
Available Strengths:
Dosing & Administration
Adult Dosing
Standard Dose:
800 mg three to four times a day
Dose Range:
800 - 3200 mg
Condition-Specific Dosing:
acute_pain:
800 mg three to four times a day
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Not established (Not recommended for children under 12 years of age)
Adolescent:
Not established (Not recommended for children under 12 years of age)
Dose Adjustments
Renal Impairment:
Mild:
Use with caution
Moderate:
Use with caution
Severe:
Use with caution; consider lower doses or alternative agents
Dialysis:
Not available; caution advised due to potential accumulation of metabolites
Hepatic Impairment:
Mild:
Use with caution; consider lower doses
Moderate:
Contraindicated
Severe:
Contraindicated
Pharmacology
Mechanism of Action
The precise mechanism of action of metaxalone in humans has not been established, but it is believed to be due to general central nervous system (CNS) depression. It does not directly relax tense skeletal muscles in man.
Pharmacokinetics
Absorption:
Bioavailability:
Not available (variable)
Tmax:
2-4 hours (fasted), 4-5 hours (fed)
FoodEffect:
Increased absorption (up to 3-fold increase in Cmax and AUC) when administered with a high-fat meal.
Distribution:
Vd:
Not available
ProteinBinding:
Not extensively protein bound
CnssPenetration:
Yes
Elimination:
HalfLife:
2.4-4.8 hours
Clearance:
Not available
ExcretionRoute:
Urine (as metabolites)
Unchanged:
<1%
Pharmacodynamics
OnsetOfAction:
Approximately 30-60 minutes
PeakEffect:
2-4 hours
DurationOfAction:
4-6 hours
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical attention immediately:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Fever, chills, or sore throat
Severe stomach pain
Dark urine or yellow skin or eyes
Serotonin syndrome, a rare but life-threatening condition, which may occur with high doses of this medication or when taken with certain other drugs, such as those for depression, migraines, or other conditions. Symptoms of serotonin syndrome include:
+ Agitation
+ Change in balance
+ Confusion
+ Hallucinations
+ Fever
+ Fast or abnormal heartbeat
+ Flushing
+ Muscle twitching or stiffness
+ Seizures
+ Shivering or shaking
+ Excessive sweating
+ Severe diarrhea
+ Upset stomach or vomiting
+ Severe headache
Other Possible Side Effects
Most people taking this medication will not experience side effects, or they may be mild. However, if you notice any of the following side effects, or if they bother you or do not go away, contact your doctor or seek medical attention:
Dizziness or drowsiness
Headache
Feeling nervous or excitable
Irritability
Upset stomach or vomiting
Reporting Side Effects
This is not a comprehensive list of all possible side effects. If you have questions or concerns about side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical attention immediately:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Fever, chills, or sore throat
Severe stomach pain
Dark urine or yellow skin or eyes
Serotonin syndrome, a rare but life-threatening condition, which may occur with high doses of this medication or when taken with certain other drugs, such as those for depression, migraines, or other conditions. Symptoms of serotonin syndrome include:
+ Agitation
+ Change in balance
+ Confusion
+ Hallucinations
+ Fever
+ Fast or abnormal heartbeat
+ Flushing
+ Muscle twitching or stiffness
+ Seizures
+ Shivering or shaking
+ Excessive sweating
+ Severe diarrhea
+ Upset stomach or vomiting
+ Severe headache
Other Possible Side Effects
Most people taking this medication will not experience side effects, or they may be mild. However, if you notice any of the following side effects, or if they bother you or do not go away, contact your doctor or seek medical attention:
Dizziness or drowsiness
Headache
Feeling nervous or excitable
Irritability
Upset stomach or vomiting
Reporting Side Effects
This is not a comprehensive list of all possible side effects. If you have questions or concerns about side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Signs of liver problems: yellowing of the skin or eyes (jaundice), dark urine, unusual tiredness, severe stomach pain, nausea, vomiting.
- Signs of an allergic reaction: rash, itching, swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.
- Excessive drowsiness or dizziness that interferes with daily activities.
- Unusual bleeding or bruising.
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced.
If you have kidney disease or liver disease, as these conditions may affect how your body processes the medication.
If you have anemia or have been informed that you are at risk of developing anemia.
This list is not exhaustive, and it is crucial to discuss all your health problems and medications with your doctor. Please provide your doctor and pharmacist with a comprehensive list of:
All prescription and over-the-counter (OTC) medications you are taking
Any natural products or vitamins you are using
All your health problems, including any medical conditions or concerns
Before starting, stopping, or changing the dose of any medication, including this one, you must consult with your doctor to ensure your safety. It is vital to verify that it is safe to take this medication with all your other medications and health conditions.
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced.
If you have kidney disease or liver disease, as these conditions may affect how your body processes the medication.
If you have anemia or have been informed that you are at risk of developing anemia.
This list is not exhaustive, and it is crucial to discuss all your health problems and medications with your doctor. Please provide your doctor and pharmacist with a comprehensive list of:
All prescription and over-the-counter (OTC) medications you are taking
Any natural products or vitamins you are using
All your health problems, including any medical conditions or concerns
Before starting, stopping, or changing the dose of any medication, including this one, you must consult with your doctor to ensure your safety. It is vital to verify that it is safe to take this medication with all your other medications and health conditions.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. Adhere strictly to the dosage prescribed by your doctor, as taking more than the recommended amount can increase your risk of experiencing severe side effects.
Until you are familiar with how this medication affects you, avoid operating a vehicle or engaging in any activities that require your full attention. Before consuming alcohol, using marijuana or other cannabis products, or taking any prescription or over-the-counter medications that may cause drowsiness, consult with your doctor.
This medication is typically used in conjunction with rest, physical therapy, pain management medications, and other therapeutic interventions. Be aware that it may influence the results of certain laboratory tests, so it is crucial that your doctor and laboratory personnel are informed of your use of this medication.
If you are 65 years of age or older, exercise caution when using this drug, as you may be more susceptible to side effects. If you are pregnant, planning to become pregnant, or are breastfeeding, discuss the potential benefits and risks of this medication with your doctor to ensure the well-being of both you and your baby.
Until you are familiar with how this medication affects you, avoid operating a vehicle or engaging in any activities that require your full attention. Before consuming alcohol, using marijuana or other cannabis products, or taking any prescription or over-the-counter medications that may cause drowsiness, consult with your doctor.
This medication is typically used in conjunction with rest, physical therapy, pain management medications, and other therapeutic interventions. Be aware that it may influence the results of certain laboratory tests, so it is crucial that your doctor and laboratory personnel are informed of your use of this medication.
If you are 65 years of age or older, exercise caution when using this drug, as you may be more susceptible to side effects. If you are pregnant, planning to become pregnant, or are breastfeeding, discuss the potential benefits and risks of this medication with your doctor to ensure the well-being of both you and your baby.
Overdose Information
Overdose Symptoms:
- Nausea
- Vomiting
- Drowsiness
- Dizziness
- Headache
- Loss of muscle control (ataxia)
- Hypotension (low blood pressure)
- Respiratory depression
- Coma
What to Do:
Seek immediate medical attention. Call 911 or Poison Control at 1-800-222-1222. Treatment is generally supportive, including gastric lavage, activated charcoal, and maintenance of vital signs.
Drug Interactions
Major Interactions
Moderate Interactions
- Drugs metabolized by CYP2D6 (e.g., fluoxetine, paroxetine, quinidine)
Monitoring
Baseline Monitoring
Liver Function Tests (LFTs)
Rationale: Metaxalone is extensively metabolized by the liver and has been associated with hepatic dysfunction.
Timing: Prior to initiation, especially in patients with pre-existing hepatic impairment or risk factors.
Routine Monitoring
Liver Function Tests (LFTs)
Frequency: Periodically, especially with prolonged therapy or if symptoms of hepatic dysfunction develop.
Target: Within normal limits
Action Threshold: Discontinue if significant elevation (e.g., >3x ULN) or signs/symptoms of liver injury occur.
Signs and symptoms of CNS depression
Frequency: Regularly during therapy
Target: Minimal or tolerable sedation
Action Threshold: Excessive drowsiness, dizziness, impaired coordination; consider dose reduction or discontinuation.
Symptom Monitoring
- Drowsiness
- Dizziness
- Nausea
- Vomiting
- Stomach upset
- Headache
- Nervousness
- Irritability
- Jaundice (yellowing of skin/eyes)
- Dark urine
- Unusual tiredness
- Abdominal pain
Special Patient Groups
Pregnancy
Category C. Animal studies have shown adverse effects on the fetus, but there are no adequate and well-controlled studies in pregnant women. Use only if the potential benefit justifies the potential risk to the fetus.
Trimester-Specific Risks:
First Trimester:
Potential for fetal harm based on animal data; avoid if possible.
Second Trimester:
Potential for fetal harm based on animal data; avoid if possible.
Third Trimester:
Potential for fetal harm based on animal data; avoid if possible. Risk of neonatal CNS depression if used close to delivery.
Lactation
It is not known whether metaxalone is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants from metaxalone, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
Infant Risk:
L3 - Moderate risk. Potential for sedation in the infant. Monitor for drowsiness, poor feeding, or developmental delay.
Pediatric Use
Safety and effectiveness in pediatric patients under 12 years of age have not been established. Not recommended for this age group.
Geriatric Use
Use with caution in elderly patients. They may be more susceptible to the CNS depressant effects (drowsiness, dizziness) and may require lower doses. Start with the lowest effective dose and titrate slowly.
Clinical Information
Clinical Pearls
- Metaxalone is considered to have a lower potential for abuse and less sedation compared to some other muscle relaxants (e.g., carisoprodol).
- Taking metaxalone with food significantly increases its absorption, which can be beneficial for efficacy but may also increase side effects.
- Contraindicated in patients with known or suspected impaired hepatic function or a history of drug-induced hemolytic or other anemias.
- Patients should be advised about the potential for additive CNS depression when combining metaxalone with alcohol or other CNS depressants.
Alternative Therapies
- Cyclobenzaprine
- Tizanidine
- Methocarbamol
- Baclofen
- Carisoprodol (higher abuse potential)
- Non-pharmacological treatments (rest, physical therapy, heat/cold therapy)
Cost & Coverage
Average Cost:
$15 - $50 per 30 tablets (generic 400mg)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or Tier 2 (for generic)
General Drug Facts
If your symptoms or health issues persist or worsen, it is essential to contact your doctor promptly. To ensure safe and effective treatment, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so it's a good idea to check with your pharmacist for more information. If you have any questions or concerns about your medication, don't hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek emergency medical attention. When reporting the incident, be prepared to provide details about the medication taken, the amount, and the time it occurred.