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Metaxalone 400 mg. Metaxalone 400mg: Comprehensive Guide to Uses, Side Effects, and Dosage

What are the primary uses of Metaxalone 400mg. How should Metaxalone be taken for optimal results. What are the potential side effects and interactions of Metaxalone. How does Metaxalone work as a muscle relaxant. What precautions should be taken when using Metaxalone.

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Understanding Metaxalone: A Powerful Muscle Relaxant

Metaxalone, commonly prescribed in 400mg doses, is a potent muscle relaxant used to alleviate discomfort associated with acute musculoskeletal conditions. This medication works by affecting the central nervous system to produce muscle relaxation, providing relief from pain and stiffness.

How does Metaxalone differ from other muscle relaxants? Unlike some alternatives, Metaxalone doesn’t directly act on the muscles or nerves. Instead, it works within the brain and spinal cord to reduce pain sensations and promote relaxation. This unique mechanism of action makes it an effective choice for many patients suffering from muscle-related discomfort.

Key Benefits of Metaxalone

  • Effective pain relief for acute musculoskeletal conditions
  • Promotes muscle relaxation without directly affecting muscle tissue
  • Can be used in combination with physical therapy and rest for optimal results
  • Generally well-tolerated with fewer side effects compared to some other muscle relaxants

Proper Usage and Dosage Guidelines for Metaxalone 400mg

Adhering to proper dosage instructions is crucial for maximizing the benefits of Metaxalone while minimizing potential risks. The typical recommended dose is 800mg (two 400mg tablets) taken three to four times daily. However, dosage may vary based on individual patient needs and medical conditions.

Should Metaxalone be taken with food? It’s generally recommended to take Metaxalone with food to enhance its absorption and potentially reduce the risk of gastrointestinal side effects. Some studies suggest that taking it with a high-fat meal can significantly increase its bioavailability.

Important Dosage Considerations

  1. Always follow your healthcare provider’s instructions
  2. Do not exceed the prescribed dose
  3. Take with food for optimal absorption
  4. If you miss a dose, take it as soon as you remember, unless it’s close to the next scheduled dose
  5. Avoid doubling up on doses to make up for a missed one

Potential Side Effects and Precautions of Metaxalone

While Metaxalone is generally well-tolerated, it’s essential to be aware of potential side effects. Common side effects may include drowsiness, dizziness, headache, and nausea. In rare cases, more severe side effects can occur.

Can Metaxalone cause allergic reactions? Although rare, some individuals may experience allergic reactions to Metaxalone. Symptoms of an allergic reaction may include rash, itching, swelling, severe dizziness, or difficulty breathing. If you experience any of these symptoms, seek immediate medical attention.

Less Common but Serious Side Effects

  • Severe dizziness or fainting
  • Unusual weakness or fatigue
  • Yellowing of the eyes or skin (jaundice)
  • Dark urine or pale stools
  • Persistent nausea or vomiting

If you experience any of these serious side effects, contact your healthcare provider immediately.

Drug Interactions and Contraindications

Metaxalone can interact with various medications and substances, potentially altering its effectiveness or increasing the risk of side effects. It’s crucial to inform your healthcare provider about all medications, supplements, and herbal products you’re taking.

Is it safe to consume alcohol while taking Metaxalone? Combining Metaxalone with alcohol can intensify its sedative effects, leading to increased drowsiness and impaired coordination. It’s strongly advised to avoid alcohol consumption while taking this medication.

Notable Drug Interactions

  • MAO inhibitors (e.g., isocarboxazid, phenelzine)
  • Certain antidepressants (e.g., fluoxetine, paroxetine)
  • Opioid pain medications
  • Other central nervous system depressants
  • Some antihistamines

Always consult with your healthcare provider or pharmacist before starting any new medication or supplement while taking Metaxalone.

Metaxalone in Pregnancy and Breastfeeding

The safety of Metaxalone during pregnancy and breastfeeding has not been thoroughly established. Limited data is available on its effects on fetal development or its presence in breast milk.

Can Metaxalone be used during pregnancy? The use of Metaxalone during pregnancy should be carefully considered and only under the guidance of a healthcare provider. The potential benefits must be weighed against possible risks to the developing fetus.

Considerations for Pregnant and Breastfeeding Women

  • Inform your healthcare provider if you are pregnant or planning to become pregnant
  • Discuss the potential risks and benefits of Metaxalone use during pregnancy
  • If breastfeeding, consult your doctor before taking Metaxalone
  • Consider alternative treatments if advised by your healthcare provider

Long-term Use and Potential for Dependence

While Metaxalone is not considered habit-forming in the same way as some other medications, long-term use should be monitored closely by a healthcare provider. Prolonged use may lead to tolerance, where higher doses are needed to achieve the same effect.

Does Metaxalone cause withdrawal symptoms? Unlike some other muscle relaxants, Metaxalone is not associated with significant withdrawal symptoms when discontinued. However, abrupt discontinuation after long-term use may result in a return of muscle pain or spasms.

Guidelines for Long-term Use

  1. Regular follow-ups with your healthcare provider
  2. Periodic reassessment of the need for continued use
  3. Gradual tapering of the dose if discontinuation is recommended
  4. Exploration of alternative treatments or therapies
  5. Monitoring for any signs of dependence or misuse

Metaxalone and Its Impact on Daily Activities

As a muscle relaxant with potential sedative effects, Metaxalone can impact an individual’s ability to perform certain daily activities. It’s crucial to understand these effects to ensure safety and optimal functioning while taking the medication.

How does Metaxalone affect driving ability? Metaxalone can cause drowsiness and dizziness, which may impair your ability to drive or operate machinery. It’s advisable to avoid these activities until you know how the medication affects you personally.

Precautions for Daily Activities

  • Avoid driving or operating heavy machinery until you know how Metaxalone affects you
  • Be cautious when performing tasks that require alertness
  • Avoid alcohol and other substances that can enhance drowsiness
  • Plan activities around your dosing schedule if possible
  • Inform your employer if your job involves potentially dangerous tasks

Comparing Metaxalone to Other Muscle Relaxants

Metaxalone is one of several muscle relaxants available for treating musculoskeletal conditions. Understanding how it compares to other options can help patients and healthcare providers make informed decisions about treatment.

What makes Metaxalone unique among muscle relaxants? Metaxalone’s mechanism of action, which focuses on the central nervous system rather than directly on muscle tissue, sets it apart from some other muscle relaxants. This can result in fewer peripheral side effects for some patients.

Comparison with Common Muscle Relaxants

MedicationMechanism of ActionCommon Side EffectsTypical Dosing
MetaxaloneCentral nervous system effectsDrowsiness, dizziness, headache800mg 3-4 times daily
CyclobenzaprineSimilar to tricyclic antidepressantsDry mouth, drowsiness, dizziness5-10mg 3 times daily
BaclofenGABA-B receptor agonistDrowsiness, dizziness, weakness5-20mg 3-4 times daily
TizanidineAlpha-2 adrenergic agonistDry mouth, drowsiness, dizziness2-4mg up to 3 times daily

Metaxalone in Combination Therapies

While Metaxalone can be effective on its own, it’s often used as part of a comprehensive treatment plan for musculoskeletal conditions. Combining Metaxalone with other therapies can enhance its effectiveness and promote faster recovery.

How does physical therapy complement Metaxalone treatment? Physical therapy can help strengthen muscles, improve flexibility, and correct posture issues that may contribute to muscle pain. When combined with Metaxalone, physical therapy can lead to more significant improvements in pain relief and function.

Common Combination Therapies

  • Physical therapy exercises
  • Heat or cold therapy
  • Massage therapy
  • Non-steroidal anti-inflammatory drugs (NSAIDs)
  • Lifestyle modifications (e.g., ergonomic adjustments, stress reduction techniques)

It’s important to note that any combination therapy should be discussed with and approved by your healthcare provider to ensure safety and effectiveness.

Managing Potential Drug Interactions with Metaxalone

As with many medications, Metaxalone can interact with other drugs, potentially altering their effectiveness or increasing the risk of side effects. Understanding and managing these interactions is crucial for safe and effective treatment.

Why is it important to inform healthcare providers about all medications and supplements? Some interactions can be serious or even life-threatening. By providing a complete list of all substances you’re taking, your healthcare provider can assess potential risks and adjust your treatment plan accordingly.

Steps to Manage Drug Interactions

  1. Maintain an up-to-date list of all medications, supplements, and herbal products you’re taking
  2. Inform all healthcare providers about your current medications, including Metaxalone
  3. Ask about potential interactions before starting any new medication or supplement
  4. Be aware of the signs of potential drug interactions and report any unusual symptoms to your healthcare provider
  5. Consider using a single pharmacy for all prescriptions to help track potential interactions

Metaxalone and Its Impact on Laboratory Tests

Metaxalone can potentially interfere with certain laboratory tests, leading to inaccurate results. This interference is particularly notable with urine glucose tests, where Metaxalone may cause false-positive results.

How can patients ensure accurate test results while taking Metaxalone? Informing laboratory personnel and healthcare providers about your Metaxalone use is crucial. This allows them to interpret results accurately or choose alternative testing methods if necessary.

Laboratory Tests Potentially Affected by Metaxalone

  • Urine glucose tests
  • Certain liver function tests
  • Some drug screening tests

Always inform healthcare providers and laboratory personnel about your Metaxalone use before undergoing any tests to ensure accurate interpretation of results.

Storage and Disposal of Metaxalone

Proper storage and disposal of Metaxalone are essential for maintaining its effectiveness and preventing accidental ingestion or misuse. Following guidelines for medication storage and disposal helps ensure safety and environmental protection.

What are the best practices for storing Metaxalone? Store Metaxalone at room temperature, away from moisture and direct light. Keep it in its original container, tightly closed, and out of reach of children and pets.

Storage and Disposal Guidelines

  • Store at room temperature (20-25°C or 68-77°F)
  • Keep away from heat, moisture, and direct light
  • Do not store in the bathroom
  • Keep out of reach of children and pets
  • Do not use expired medication
  • Dispose of unused medication through proper channels (e.g., drug take-back programs)

Recognizing and Managing Metaxalone Overdose

While Metaxalone is generally safe when used as prescribed, overdose is possible and can be dangerous. Recognizing the signs of overdose and knowing how to respond can be life-saving.

What are the symptoms of Metaxalone overdose? Symptoms may include severe drowsiness, confusion, slowed breathing, loss of consciousness, and in severe cases, coma. If you suspect an overdose, seek emergency medical attention immediately.

Steps to Take in Case of Suspected Overdose

  1. Call emergency services or poison control immediately
  2. Provide information about the amount ingested and time of ingestion if known
  3. Do not induce vomiting unless instructed by a medical professional
  4. If the person is unconscious, turn them on their side to prevent choking
  5. Have the medication container or label available for reference

Metaxalone’s Role in Managing Chronic Pain Conditions

While Metaxalone is primarily prescribed for acute musculoskeletal conditions, its use in managing chronic pain conditions is an area of ongoing research and clinical interest. Understanding its potential role in long-term pain management can help patients and healthcare providers make informed decisions about treatment options.

Can Metaxalone be effective for chronic pain conditions? While primarily used for short-term relief, some patients with chronic musculoskeletal pain may benefit from carefully monitored, intermittent use of Metaxalone as part of a comprehensive pain management plan.

Considerations for Chronic Pain Management

  • Regular assessment of efficacy and side effects
  • Combination with other pain management strategies (e.g., physical therapy, cognitive behavioral therapy)
  • Monitoring for potential tolerance or dependence
  • Exploration of alternative or complementary treatments
  • Periodic medication holidays to assess ongoing need and effectiveness

It’s crucial to work closely with a healthcare provider to develop a personalized approach to chronic pain management that may or may not include Metaxalone, depending on individual circumstances and response to treatment.

Metaxalone Oral: Uses, Side Effects, Interactions, Pictures, Warnings & Dosing

See also How to Use section.

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor’s approval.

Some products that may interact with this drug include: diet pills/appetite suppressants (such as diethylpropion), drugs for attention deficit disorder (such as atomoxetine, methylphenidate), apraclonidine, bupropion, buspirone, carbamazepine, cyclobenzaprine, deutetrabenazine, a certain combination product (dextromethorphan/quinidine), levodopa, maprotiline, methyldopa, metoclopramide, certain opioid pain relievers (such as fentanyl, meperidine, methadone, tapentadol), certain drugs for Parkinson’s disease (such as entacapone, tolcapone), certain supplements (such as tryptophan, tyramine), tetrabenazine, tricyclic antidepressants (such as amitriptyline, doxepin), valbenazine.

The risk of serotonin syndrome/toxicity increases if you are also taking other drugs that increase serotonin. Examples include street drugs such as MDMA/”ecstasy,” St. John’s wort, certain antidepressants (including mirtazapine, SSRIs such as fluoxetine/paroxetine, SNRIs such as duloxetine/venlafaxine), tramadol, certain “triptans” used to treat migraine headaches (such as rizatriptan, sumatriptan, zolmitriptan), among others. The risk of serotonin syndrome/toxicity may be more likely when you start or increase the dose of these drugs.

Some products can interact with metaxalone if you take them together, or even if you take them weeks before or after taking metaxalone. Tell your doctor or pharmacist if you take anything in the list of products that may interact with this drug, or any of the products that increase serotonin, within 2 weeks before or after taking metaxalone. Also tell them if you have taken fluoxetine within 5 weeks before starting metaxalone. Ask your doctor how much time to wait between starting or stopping any of these drugs and starting metaxalone.

Taking other MAO inhibitors with this medication may cause a serious (possibly fatal) drug interaction. Do not take any other MAO inhibitors (isocarboxazid, linezolid, methylene blue, moclobemide, phenelzine, procarbazine, rasagiline, safinamide, selegiline, tranylcypromine) during treatment with this medication. Most MAO inhibitors should also not be taken for two weeks before and after treatment with this medication. Ask your doctor when to start or stop taking this medication.

Before using metaxalone, report the use of drugs that may increase the risk of extremely high blood pressure (hypertensive crisis) when combined with metaxalone, including herbal products (such as ephedra/ma huang), nasal decongestants (such as phenylephrine, pseudoephedrine), and stimulants (such as amphetamines, ephedrine, epinephrine, phenylalanine). Metaxalone should not be used with any of these medications. Talk to your doctor or pharmacist for more details.

Tell your doctor or pharmacist if you are taking other products that cause drowsiness such as opioid pain or cough relievers (such as codeine, hydrocodone), alcohol, marijuana (cannabis), drugs for sleep or anxiety (such as alprazolam, lorazepam, zolpidem), other muscle relaxants (such as carisoprodol, cyclobenzaprine), or antihistamines (such as cetirizine, diphenhydramine).

Check the labels on all your medicines (such as allergy or cough-and-cold products) because they may contain ingredients that cause drowsiness. Ask your pharmacist about using those products safely.

This medication may interfere with certain lab tests (such as certain urine glucose tests), possibly causing false test results. Make sure lab personnel and all your doctors know you use this drug.

Does Metaxalone interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Metaxalone: MedlinePlus Drug Information


pronounced as (me tax’ a lone)

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  • Why is this medication prescribed?
  • How should this medicine be used?
  • Other uses for this medicine
  • What special precautions should I follow?
  • What should I do if I forget a dose?
  • What side effects can this medication cause?
  • What should I know about storage and disposal of this medication?
  • In case of emergency/overdose
  • What other information should I know?
  • Brand names

Metaxalone, a muscle relaxant, is used with rest, physical therapy, and other measures to relax muscles and relieve pain and discomfort caused by strains, sprains, and other muscle injuries.

Metaxalone comes as a tablet to take by mouth. It usually is taken three or four times a day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take metaxalone exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.

Before taking metaxalone,

  • tell your doctor and pharmacist if you are allergic to metaxalone, any other medications, or any of the ingredients in metaxalone tablets. Ask your pharmacist for a list of the ingredients.
  • tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take while taking metaxolone. Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
  • tell your doctor if you have or have ever had kidney disease, liver disease, seizures, or a blood disorder.
  • tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. If you become pregnant while taking metaxalone, call your doctor immediately.
  • talk to your doctor about the risks and benefits of taking metaxalone if you are 65 years of age or older. Older adults should not usually take metaxalone because it is not as safe or effective as other medications that can be used to treat the same condition.
  • you should know that this drug may make you drowsy. Do not drive a car or operate machinery until you know how metaxalone affects you.
  • remember that alcohol can add to the drowsiness caused by this drug.

Take the missed dose as soon as you remember it. However, if it is almost time for your next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

Metaxalone may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

  • drowsiness
  • dizziness
  • headache
  • nervousness

If you experience any of the following symptoms, call your doctor immediately:

  • agitation, hallucinations, coma
  • fast heart rate, high body temperature
  • muscle twitching, loss of muscle control
  • nausea, vomiting, diarrhea
  • severe skin rash
  • difficulty breathing
  • yellowing of the skin or eyes
  • unusual bruising or bleeding
  • unusual tiredness or weakness
  • seizures

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration’s (FDA) MedWatch Adverse Event Reporting program online (http://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature, away from excess heat and moisture (not in the bathroom).

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. http://www.upandaway.org

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA’s Safe Disposal of Medicines website (http://goo. gl/c4Rm4p) for more information if you do not have access to a take-back program.

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at https://www.poisonhelp.org/help. If the victim has collapsed, had a seizure, has trouble breathing, or can’t be awakened, immediately call emergency services at 911.

  • Skelaxin®

Last Revised – 07/15/2022

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instructions for use, dosage, composition, analogues, side effects / Pillintrip

and PATIENT INFORMATION ).

Carcinogenesis, mutagenesis, impaired fertility

The carcinogenic potential of metaxalone has not been determined.

Pregnancy

Reproduction studies in rats showed no evidence of impaired fertility or fetal harm due to metaxalone. Post-marketing experience has not shown any evidence of fetal injury, but such experience cannot rule out the possibility of rare or subtle injury to the human fetus. The safe use of metaxalone has not been demonstrated in relation to possible adverse effects on fetal development. Therefore, metaxalone tablets should not be used in women who are or may be pregnant, especially during early pregnancy, unless the physician considers that the potential benefits outweigh the potential hazards.

Nursing mothers

It is not known if this drug is excreted in breast milk. As a general rule, caution should not be exercised when taking medications, as many medications are excreted in breast milk.

Pediatric use

Safety and efficacy in children over 12 years of age have not been established.

Overdose and Contraindications

Intentional or accidental overdose deaths have occurred with metaxalone, especially when combined with antidepressants, and this class of drug has been reported in combination with alcohol.

Serotonin syndrome has been reported when metaxalone was used at doses above the recommended dose layers (see WARNINGS ).

When determining LD 50 progressive sedation, hypnosis and finally respiratory failure were found in rats and mice with increasing dosage. No LD can be found in dogs 50 is determined because higher doses were emetic after 15-30 minutes.

Treatment

Gastric lavage and supportive care. It is recommended that you consult with your regional gift management center.

PRICE

Hypersensitivity to components of this product is known.

Known tendency to drug-induced, hemolytic or other anemia.

Significantly impaired renal or hepatic function.

Clinical pharmacology

CLINICAL PHARMACOLOGY

Mechanism of action

The mechanism of action of metaxalone in humans has not been established, but it can be attributed to a general depression of the central nervous system.

Metaxalone has no direct effect on the contractile mechanism of the striated muscle, motor end plate or nerve fiber.

Pharmacokinetics

The pharmacokinetics of metaxalone was studied in healthy adult volunteers after a single dose of metaxalone in sober and well-fed conditions at doses ranging from 400 to 800 mg.

Absorption

Peak plasma concentrations of metaxalone occur approximately 3 hours after an oral dose of 400 mg under sober conditions. The logarithmic concentrations of metaxalone then decrease with a finite half-life of 9.0 ± 4.8 hours. Doubling the dose of Metaxalone from 400 mg to 800 mg results in an approximately proportional increase in Metaxalone exposure as evidenced by peak plasma concentrations (Cmax) and area under the curve (AUC). Dose proportionality at doses above 800 mg has not been studied. The absolute bioavailability of metaxalone is not known.

Pharmacokinetic parameters of single dose metaxalone in two groups of healthy volunteers are shown in Table 1.

Table 1: Mean (% CV) pharmacokinetic parameters of Metaxalone

Dose (mg) Cmax (ng/ml) Tmax (h) AUC∞ (ng & ml; h/ml) t½ (h) CL / F ( L / h)
400 1 983 (53) 3. 3 (35) 7479 (51) 9, 0 (53) 68 (50)
800 2 1816 (43) 3.0 (39) 15044 (46) 8.0 (58) 66 (51)
1 Subjects received 1x400mg tablet sober (N = 42)
2 Subjects received 2x400mg tablets sober conditions (N = 59)
Food Effects

A randomized, bi-directional, crossover study was conducted in 42 healthy volunteers (31 males, 11 females) who administered a Metaxalone 400 mg tablet while sober and after a standard high-fat breakfast. Subjects ranged from 18 to 48 years (mean age = 23.5 ± 5.7 years). Compared to sober states, the presence of a high-fat meal increased by 177.5% during drug C administration and increased AUC (AUC0-t, AUC∞) by 123.5% and 115.4%, respectively. Time to peak concentration (Tmax) was also delayed (4.3 hours vs. 3.3 hours) and the terminal half-life was reduced (2. 4 hours vs. 9.0 hours) under feeding conditions compared with fasting.

In a second study with a similar effect, healthy volunteers (N = 59, 37 males, 22 females) were given two tablets of metaxalone 400 mg (800 mg) aged 18-50 years (mean age = 25). 6 ± 8.7 years). Compared to sober states, the presence of a high-fat meal increased by 193.6% during drug C administration and increased AUC (AUC0-t, AUC, ∞) by 146.4% and 142.2%, respectively. Time to Peak concentration (Tmax) was also delayed (4.9h versus 3.0 h), and the terminal half-life was shortened (4.2 h compared to 8.0 h) under fed versus fasting conditions. Similar nutritional effects were observed in the aforementioned study when a Metaxalone tablet was administered instead of two 400 mg Metaxalone tablets. An increase in metaxalone exposure, which coincides with a decrease in half-life, may be due to more complete absorption of metaxalone in the presence of a high-fat meal (Figure 1).

Figure 1: Mean (SD) concentrations of metaxalone after a dose of 800 mg under fasting and feeding conditions

Distribution, metabolism and elimination

Although plasma protein binding and absolute bioavailability of metaxalone are unknown, the apparent volume of distribution (V/F 800 L) and lipophilia (log P = 2. 42) of metaxalone indicate that the drug is mainly distributed in tissues. Metaxalone is metabolized in the liver and excreted in the urine as unidentified metabolites. Hepatic cytochrome P450 enzymes play a role in the metabolism of metaxalone. In particular, CYP1A2, CYP2D6, CYP2E1 and CYP3A4 and to a lesser extent CYP2C8, CYP2C9and CYP2C19 metabolize metaxalone.

Metaxalone does not significantly inhibit major CYP enzymes such as CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP3A4. Metaxalone does not cause significant induction of important CYP enzymes such as CYP1A2, CYP2B6 and CYP3A4 in vitro .

Pharmacokinetics in special populations
Age

The effect of age on the pharmacokinetics of metaxalone was determined after a single administration of two 400 mg (800 mg) tablets under fasting and feeding conditions. The results were evaluated separately, as well as in combination with the results of three other studies. Using the combined data, the results show that the pharmacokinetics of metaxalone under sober conditions is significantly more dependent on age than under feeding, with bioavailability increasing with age under sober conditions.

The fasting and feeding bioavailability of metaxalone in three groups of healthy volunteers of different ages is shown in Table 2.

Table 2: Mean pharmacokinetic parameters (% CV) feeding

Age (years) Junior volunteers Elderly volunteers
25.6 ± 8.7 9007 9

39.3 ± 10.8 71.5 ± 5.0
N

Food Tasty Fed Tasty Fed Delicious Fed
Cmax (ng/ml) 1816 (43) 3510 (41) 2719 (4 6) 2915 (55) 3168 (43) 3680 ( 59)
TMAX (h) 3.0 (39) 4.9 (48) 3.0 (40) 8.7 (91) 2 ,6 (30) 6.5 (67)
AUC0-t (ng·h/ml) 14531 (47) 20683 (41) 19836 (40) 20482 (37) 23797 (45) 24340 (48)
AUC∞ (ng·h/mL) 15045 (46) 20833 (41) 9) 20815 (37) 24194 (44) 24704 (47)
Gender

in which 48 healthy adult subjects (24 men, 24 women) were administered, two tablets of metaxalone 400 mg (800 mg) in sober conditions. The bioavailability of metaxalone was significantly higher in women than in men than Cmax (2115 ng/ml vs 1335 ng/ml) and AUC∞ (17884 ng h/ml vs 10328 ng h/ml). The mean half-life was 11.1 hours for women and 7.6 hours for men. The apparent volume of distribution of metaxalone was approximately 22% higher in men than in women, but the difference was not significant when adjusted for body weight. Similar results were also seen when the previously described combined data set was used in the analysis.

Liver/renal failure

The effect of liver and kidney disease on the pharmacokinetics of metaxalone has not been determined. In the absence of such information, Metaxalone should be used with caution in patients with hepatic and/or renal insufficiency.

Skelaxin (Metaxalone): Uses, Dosage, Side Effects, Interactions, Warning0294 Product Description

  • Indications and Dosage
  • Adverse Effects and Drug Interactions
  • Warnings and Precautions
  • Overdose and Contraindications
  • Clinical Pharmacology
  • Medication Guide 9 0289

    Product description

    What is skelaxin and how is it used?

    Skelaxin is a prescription medicine used to treat the symptoms of musculoskeletal pain. Skelaxin can be used alone or with other medicines.

    Skelaxin belongs to a class of drugs called skeletal muscle relaxants.

    It is not known whether Skelaxin is safe and effective in children under 12 years of age.

    What are the possible side effects of Skelaxin?

    Skelaxin can cause serious side effects, including:

    • weak or shallow breathing,
    • lightheadedness,
    • pale or yellow skin,
    • dark urine0289
    • high fever,
    • confusion,
    • weak spot,
    • upper stomach pain,
    • loss of appetite and
    • yellowing of the skin or eyes (jaundice)

    900 08 Seek immediate medical attention if you have any – any of the above symptoms.

    The most common side effects of Skelaxin include:

    • dizziness,
    • drowsiness,
    • nausea,0289
    • upset stomach,
    • headache, and
    • feeling nervous or irritable

    Tell your doctor if you have any side effects that bother you or that don’t go away.

    These are not all possible side effects of Skelaxin. For more information, contact your doctor or pharmacist.

    Ask your doctor about side effects. You can report side effects to the FDA at 1-800-FDA-1088.

    DESCRIPTION

    SKELAXIN (metaxalone) is available in the form of pink oval tablets with a score of 800 mg.

    Chemically, metaxalone is 5-[(3,5-dimethylphenoxy)methyl]-2-oxazolidinone. Empirical formula: C 12 H fifteen HE 3 , which corresponds to a molecular weight of 221.25. Structural formula:

    Metaxalone is a white or almost white odorless crystalline powder, easily soluble in chloroform, soluble in methanol and6% ethanol, but practically insoluble in ether or water.

    Each tablet contains 800 mg of metaxalone and the following inactive ingredients: alginic acid, ammonium calcium alginate, B-Rose liquid, corn starch and magnesium stearate.

    INDICATIONS AND DOSAGE

    INDICATIONS

    SKELAXIN (metaxalone) is indicated as an adjunct to rest, physical therapy and other measures to relieve discomfort associated with acute, painful musculoskeletal problems. The mechanism of action of this drug has not been precisely established, but may be related to its sedative properties. Metaxalone does not directly relax tense human skeletal muscles.

    DOSAGE AND ADMINISTRATION

    The recommended dose for adults and children over 12 years of age is one 800 mg tablet three to four times daily.

    HOW SUPPLIED

    SKELAXIN (Metaxalone) Available as an 800 mg scored oval pink tablet, debossed with 8667 on the grooved side and an ‘S’ on the other side. Available in vials of 100 ( NDC 60793-136-01) and in vials of 500 ( NDC 60793-136-05).

    Store at controlled room temperature between 15°C and 30°C (59°F and 86 °F).

    SKELAXIN is a registered trademark of King Pharmaceuticals Research and Development, Inc.

    Distributed by: Pfizer Inc., New York, NY 10017 Revised: November 2015

    Side effects and drug interactions

    SIDE EFFECTS

    The most common reactions to metaxalone include:

    9 0008 CNS: drowsiness, dizziness headache and nervousness or “irritability”;

    Digestive: nausea, vomiting, gastrointestinal upset.

    Other adverse reactions:

    Immune system: hypersensitivity reaction, rash with or without itching;

    Hematological: leukopenia; hemolytic anemia;

    Hepatobiliary: jaundice.

    side effects of Kenalog 40 injection

    Anaphylactoid reactions have been reported with metaxalone, although rare.

    DRUG INTERACTIONS

    No information provided.

    Warnings and Precautions

    WARNINGS

    Potentially life-threatening serotonin syndrome (SS) has been reported with the use of metaxalone. These reports have usually occurred when metaxalone was used concomitantly with serotonergic drugs (such as tramadol or selective serotonin reuptake inhibitors (SSRIs)) or when metaxalone was used at higher than recommended doses (see DRUG INTERACTIONS and OVERDOSE ). Signs of SS may include clonus, agitation, sweating, tremors, hyperreflexia, hypertonicity, and fever.

    SKELAXIN may potentiate the effects of alcohol and other CNS depressants.

    PRECAUTIONS

    Metaxalone should be used with great caution in patients with pre-existing liver disease. In such patients, serial liver function tests should be performed.

    Benedict’s false positive tests have been noted due to an unknown reducing agent. A specific glucose test will differentiate the results.

    Dietary intake of SKELaxin may increase overall CNS depression; Elderly patients may be particularly sensitive to such CNS effects. (See CLINICAL PHARMACOLOGY : Pharmacokinetics and PATIENT INFORMATION ).

    Carcinogenesis, mutagenesis, impaired fertility

    The carcinogenic potential of metaxalone has not been determined.

    Pregnancy

    Reproduction studies in rats showed no evidence of impaired fertility or harm to the fetus due to metaxalone. Post-marketing experience has not shown evidence of fetal injury, but such experience cannot rule out the possibility of infrequent or minor injury to the human fetus. The safe use of metaxalone has not been established with regard to possible adverse effects on fetal development. Therefore, metaxalone tablets should not be used by women who are pregnant or planning pregnancy, especially in early pregnancy, unless, in the opinion of the physician, the potential benefits outweigh the possible risks.

    Nursing mothers

    It is not known if this drug is secreted in breast milk. As a general rule, breastfeeding should not be done while the patient is taking medication, as many medications are excreted in breast milk.

    Pediatric use

    Safety and efficacy in children under 12 years of age have not been established.

    Overdose and contraindications

    OVERDOSAGE

    Deaths due to intentional or accidental overdose have occurred with the use of metaxalone, especially in combination with antidepressants, and cases of this class of drugs in combination with alcohol have been reported.

    Serotonin syndrome has been reported when higher than recommended doses of metaxalone have been reported (see WARNINGS ).

    When determining the LD 50 in rats and mice with increasing dosage, progressive sedation, hypnosis and, finally, respiratory failure were noted. In dogs no LD 50 could be determined because higher doses caused emesis after 15-30 minutes.

    Care

    Gastric lavage and supportive care. It is recommended to consult with the regional poison control center.

    CONTRAINDICATIONS

    Known hypersensitivity to any component of this product.

    Known tendency to drug-induced, hemolytic or other anemia.

    Significant impairment of kidney or liver function.

    Clinical pharmacology

    CLINICAL PHARMACOLOGY

    Mechanism of action

    The mechanism of action of metaxalone in humans has not been established, but it may be associated with general depression of the central nervous system.

    Metaxalone has no direct action on the contractile mechanism of the striated muscle, motor end plate or nerve fiber.

    Pharmacokinetics.

    The pharmacokinetics of metaxalone was evaluated in healthy adult volunteers after administration of a single dose of SCELaxin on an empty stomach and after meals at doses of 400 to 800 mg.

    Absorption

    Peak plasma concentrations of metaxalone occur approximately 3 hours after oral administration of 400 mg on an empty stomach. Thereafter, metaxalone concentrations decrease logarithmically with a terminal half-life of 9.0 ± 4.8 hours. Doubling the dose of SKELaxin from 400 mg to 800 mg results in an approximately proportional increase in metaxalone exposure, as evidenced by peak plasma concentrations (Cmax) and area under the curve (AUC). Dose proportionality at doses above 800 mg has not been studied. The absolute bioavailability of metaxalone is unknown.

    Pharmacokinetic parameters of a single dose of metaxalone in two groups of healthy volunteers are presented in Table 1.

    Table 1: Mean (% CV) pharmacokinetic parameters of metaxalone

    Dose (mg) Cmax (ng/ml) Tmax (h) AUC & infin; (ng & bull; h / ml) t & frac12; CL / F (51) 9.0 (53) 68 (50)
    800 two0079

    8.0 (58) 66 (51)
    one Subjects received 1 tablet of 400 mg on an empty stomach (N = 42).
    two Subjects received 2 x 400 mg tablets on an empty stomach (N = 59).
    Nutritional effects

    A randomized, two-way crossover study was conducted in 42 healthy volunteers (31 males, 11 females) who were administered one tablet of SKELAXIN 400 mg on an empty stomach and after a standard high-fat breakfast. The age of the subjects ranged from 18 to 48 years (mean age = 23. 5 ± 5.7 years). Compared to fasting conditions, the presence of a high-fat meal during drug administration increased Cmax by 177.5% and increased AUC (AUC0-t, AUC.infin.) by 123.5% and 115.4%, respectively. The time to reach maximum concentration (Tmax) was also delayed (4.3 hours compared to 3.3 hours) and the terminal half-life was reduced (2.4 hours compared to 90 hours) under eating conditions compared with fasting.

    In a similarly designed food impact study, two 400 mg (800 mg) SKELAXIN tablets were administered to healthy volunteers (N = 59, 37 males, 22 females) aged 18 to 50 years (mean age = 25.6 ± 8.7 years). Compared to fasting conditions, the presence of a high-fat meal during drug administration increased Cmax by 193.6% and increased AUC (AUC0-t, AUC & infin;) by 146.4% and 142.2%, respectively. The time to reach maximum concentration (Tmax) was also delayed (4.9hours compared to 3.0 hours), and the terminal elimination half-life decreased (4.2 hours compared to 8.0 hours) under conditions of food intake compared with conditions on an empty stomach. Similar nutritional effects results were observed in the aforementioned study when one SKELAXIN 800 mg tablet was administered instead of two SKELAXIN 400 mg tablets. An increase in metaxalone exposure, coinciding with a decrease in half-life, may be due to more complete absorption of metaxalone in the presence of a high-fat meal (Fig. 1).

    Figure 1: Mean (SD) concentrations of metaxalone after a dose of 800 mg under fasting and feeding conditions

    Distribution, metabolism and excretion

    Although plasma protein binding and absolute bioavailability of metaxalone are unknown, it appears the volume of distribution (V/F ~ 800 L) and lipophilicity (log P = 2.42) of metaxalone suggest that the drug is widely distributed in tissues. Metaxalone is metabolized in the liver and excreted in the urine as unidentified metabolites. Liver cytochrome P450 enzymes play a role in the metabolism of metaxalone. In particular, CYP1A2, CYP2D6, CYP2E1 and CYP3A4 and, to a lesser extent, CYP2C8, CYP2C9and CYP2C19 appear to metabolize metaxalone.

    Metaxalone slightly inhibits major CYP enzymes such as CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP3A4. Metaxalone slightly induces major CYP enzymes such as CYP1A2, CYP2B6 and CYP3A4. in vitro .

    Pharmacokinetics in special populations
    Age

    The effect of age on the pharmacokinetics of metaxalone was determined after a single dose of two 400 mg (800 mg) tablets on an empty stomach and after a meal. The results were analyzed separately and also in combination with the results of three other studies. Using the pooled data, the results show that the pharmacokinetics of metaxalone are significantly more dependent on age under fasted conditions than under food conditions, with fasting bioavailability increasing with age.

    The fasting and postprandial bioavailability of metaxalone in three groups of healthy volunteers of different ages is shown in Table 2. feeding

    9 0660 39.3 ± 10.8

    9057 5 2915 (55)

    9 0575 23797 (45)

    Age (years) Young volunteers Older volunteers
    25.6 ± 8.7 71.5 ± 5.0
    N 59 21 2. 3
    Food Hungry fed Hungry fed Hungry fed
    Cmax (ng/mL) 1816 (43) 3510 (41) 2719 (46) 3168 (43) 3680 (59)
    Tmax (h) 3.0 (39) 4.9 (48) 3.0 (40) 8.7 (91) 2.6 (30) 6.5 (67) 90 079
    AUC0-t (ng and steer / ml) 14531 (47) 20683 (41) 19836 (40) 20482 (37) 24340 (48)
    AUC & infin; (ng & bull; h / ml) 15045 (46) 20833 (41) 20490 (39) 20815 (37) 24194 (44) 24704 (47)
    Gender women) were administered two SKELAXIN 400 mg tablets ( 800 mg) on ​​an empty stomach.

    Bioavailability of metaxalone was significantly higher in women compared to men as evidenced by Cmax (2115 ng/mL vs 1335 ng/mL) and AUC∞ (17884 ng-middot; h/ml compared to 10328 ng-middot; h/ml). The mean elimination half-life was 11.1 hours in women and 7.6 hours in men. The apparent volume of distribution of metaxalone was approximately 22% higher in men than in women, but differed slightly when adjusted for body weight. Similar results were also obtained when the previously described combined dataset was used in the analysis.

    Hepatic / renal failure

    The effect of liver and kidney disease on the pharmacokinetics of metaxalone has not been determined. In the absence of such information, SKELaxin should be used with caution in patients with hepatic and/or renal impairment.

    Medication Guide

    PATIENT INFORMATION

    SKELAXIN may impair the mental and/or physical abilities required to perform hazardous tasks such as operating machinery or driving a car, especially when used with alcohol or other CNS depressants.