What is Skelaxin used for. How does metaxalone work as a muscle relaxant. What are the common side effects of Skelaxin. How should Skelaxin be taken for maximum effectiveness. What are the potential drug interactions with metaxalone. Who should not take Skelaxin. How long does it take for Skelaxin to start working.

Understanding Skelaxin: A Powerful Muscle Relaxant

Skelaxin, known generically as metaxalone, is a prescription medication primarily used as a muscle relaxant. It belongs to a class of drugs called centrally acting skeletal muscle relaxants. Healthcare providers often prescribe Skelaxin to alleviate pain and discomfort associated with acute musculoskeletal conditions, such as strains and sprains.

How does Skelaxin work? Metaxalone acts on the central nervous system to produce its muscle-relaxing effects. While the exact mechanism of action is not fully understood, it is believed to depress the central nervous system, particularly at the level of the spinal cord and subcortical areas of the brain. This action helps to reduce muscle spasms and associated pain without causing complete paralysis.

Key Facts About Skelaxin

• Generic Name: Metaxalone
• Brand Name: Skelaxin
• Drug Class: Centrally acting skeletal muscle relaxant
• Available Forms: Oral tablets (usually 800 mg)
• Prescription Required: Yes

Medical Uses and Indications for Skelaxin

The primary use of Skelaxin is for the relief of discomfort associated with acute, painful musculoskeletal conditions. It is often prescribed as part of a comprehensive treatment plan that includes rest, physical therapy, and other measures to promote healing and reduce pain.

What conditions is Skelaxin typically prescribed for? Healthcare providers may recommend Skelaxin for:

• Muscle strains
• Sprains
• Back pain
• Neck pain
• Other acute musculoskeletal disorders

It’s important to note that Skelaxin is generally prescribed for short-term use, typically no longer than two to three weeks. This is because prolonged use may lead to dependence and other potential side effects.

Proper Administration and Dosage of Skelaxin

The appropriate dosage of Skelaxin can vary depending on the individual patient, the condition being treated, and the patient’s response to the medication. However, there are general guidelines for its use.

Standard Dosage Instructions

• Usual Adult Dose: 800 mg (1 tablet) 3 to 4 times daily
• Maximum Daily Dose: 3200 mg (4 tablets)
• Duration of Treatment: Typically 2-3 weeks or as directed by a healthcare provider

How should Skelaxin be taken for maximum effectiveness? For optimal results, follow these guidelines:

1. Take Skelaxin with food to increase its absorption and effectiveness.
2. Swallow the tablet whole with a full glass of water.
3. Do not crush, chew, or break the tablet unless instructed by your healthcare provider.
4. Space doses evenly throughout the day, typically every 6-8 hours.
5. Avoid alcohol while taking Skelaxin, as it can increase the risk of side effects.

Always follow your healthcare provider’s instructions and never adjust your dosage without consulting them first.

Potential Side Effects and Adverse Reactions

Like all medications, Skelaxin can cause side effects. While not everyone experiences these side effects, it’s important to be aware of them and report any unusual symptoms to your healthcare provider.

Common Side Effects

What are the most frequently reported side effects of Skelaxin? The following side effects are generally mild and may resolve on their own:

• Drowsiness or dizziness
• Headache
• Nausea or vomiting
• Irritability
• Nervousness
• Dry mouth

Serious Side Effects

While rare, some side effects of Skelaxin can be serious and require immediate medical attention. These include:

• Severe allergic reactions (rash, itching, swelling, severe dizziness, difficulty breathing)
• Unusual changes in mood or behavior
• Confusion or disorientation
• Yellowing of the skin or eyes (jaundice)
• Dark urine
• Persistent nausea or vomiting

If you experience any of these serious side effects, seek medical help immediately.

Drug Interactions and Precautions

Skelaxin 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.

Notable Drug Interactions

What are the potential drug interactions with metaxalone? Some significant interactions include:

• MAO Inhibitors: Combining Skelaxin with MAOIs can lead to serious, potentially fatal interactions.
• Central Nervous System Depressants: Alcohol, benzodiazepines, and opioids can enhance the sedative effects of Skelaxin.
• Serotonergic Drugs: SSRIs, SNRIs, and certain other medications can increase the risk of serotonin syndrome when combined with Skelaxin.
• Certain Antidepressants: Tricyclic antidepressants and bupropion may interact with Skelaxin.
• Certain Parkinson’s Disease Medications: Drugs like levodopa and entacapone may interact with metaxalone.

This list is not exhaustive, and it’s essential to consult with a healthcare provider or pharmacist about all potential drug interactions.

Precautions and Contraindications

Who should not take Skelaxin? The following groups should exercise caution or avoid using metaxalone:

• Individuals with liver disease or impaired liver function
• Those with a history of drug abuse or addiction
• Pregnant women or those planning to become pregnant
• Breastfeeding mothers
• Individuals with known hypersensitivity to metaxalone or any components of the formulation

Always consult with a healthcare provider before starting or stopping any medication, including Skelaxin.

Pharmacokinetics and Metabolism of Skelaxin

Understanding how Skelaxin is processed in the body can provide insights into its effectiveness and potential side effects.

Absorption and Distribution

How is Skelaxin absorbed and distributed in the body? Metaxalone is rapidly absorbed from the gastrointestinal tract, with peak plasma concentrations occurring approximately 3 hours after oral administration. Taking the medication with food, particularly a high-fat meal, can significantly increase its bioavailability.

Metabolism and Elimination

Skelaxin is primarily metabolized in the liver through various pathways, including oxidation and demethylation. The drug and its metabolites are primarily excreted in the urine, with a small amount eliminated in feces. The elimination half-life of metaxalone is approximately 9 hours, meaning it takes about 45 hours (5 half-lives) for the drug to be completely eliminated from the body.

Long-Term Use and Potential for Dependence

While Skelaxin is generally prescribed for short-term use, some patients may require longer treatment periods. It’s crucial to understand the potential risks associated with prolonged use of this medication.

Risk of Dependence

Can long-term use of Skelaxin lead to dependence? While Skelaxin is not classified as a controlled substance, there is a potential for psychological dependence with long-term use. Patients may become accustomed to the muscle-relaxing effects and find it difficult to function without the medication. Physical dependence is less common but can occur in some cases.

Tolerance Development

With prolonged use, some patients may develop tolerance to Skelaxin, requiring higher doses to achieve the same therapeutic effect. This can increase the risk of side effects and potential for dependence. Healthcare providers typically monitor patients closely when long-term use is necessary and may consider alternative treatments or periodic drug holidays to mitigate these risks.

Skelaxin in Special Populations

The use of Skelaxin may require special considerations in certain patient populations. Understanding these nuances is crucial for safe and effective use of the medication.

Elderly Patients

How should Skelaxin be used in elderly patients? Older adults may be more sensitive to the effects of Skelaxin, particularly its sedating properties. Healthcare providers may start with lower doses and adjust gradually based on individual response and tolerability. Close monitoring for side effects, especially those affecting balance and cognitive function, is essential in this population.

Patients with Liver Impairment

Skelaxin is primarily metabolized in the liver, so patients with liver disease or impaired liver function require special attention. Dosage adjustments may be necessary, and in some cases, alternative medications might be considered. Regular liver function tests may be recommended for patients on long-term therapy.

Pregnancy and Breastfeeding

Is Skelaxin safe during pregnancy and breastfeeding? The safety of metaxalone during pregnancy has not been definitively established. It is classified as FDA Pregnancy Category C, meaning that animal studies have shown an adverse effect on the fetus, but there are no adequate studies in humans. The drug should only be used during pregnancy if the potential benefit justifies the potential risk to the fetus.

Regarding breastfeeding, it is not known whether metaxalone is excreted in human milk. Given the potential for serious adverse reactions in nursing infants, 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.

Comparing Skelaxin to Other Muscle Relaxants

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

Skelaxin vs. Cyclobenzaprine

How does Skelaxin compare to cyclobenzaprine (Flexeril)? Both medications are used to treat muscle spasms, but they have different mechanisms of action and side effect profiles:

• Mechanism: Skelaxin acts primarily on the central nervous system, while cyclobenzaprine is structurally similar to tricyclic antidepressants and works by affecting both the brain and spinal cord.
• Side Effects: Cyclobenzaprine tends to cause more drowsiness and anticholinergic side effects (dry mouth, constipation) compared to Skelaxin.
• Duration: Cyclobenzaprine has a longer half-life and may provide longer-lasting relief, but also increases the risk of next-day drowsiness.

Skelaxin vs. Carisoprodol

Another common muscle relaxant is carisoprodol (Soma). Key differences include:

• Controlled Substance: Carisoprodol is a controlled substance due to its potential for abuse and dependence, while Skelaxin is not.
• Onset of Action: Carisoprodol may have a faster onset of action compared to Skelaxin.
• Side Effects: Carisoprodol may cause more significant central nervous system depression and has a higher risk of abuse.

The choice between these medications depends on individual patient factors, including the specific condition being treated, potential for drug interactions, and patient history.

Skelaxin 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 Skelaxin 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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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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Skelaxin Tablet English – Product

Skelaxin Tablet English – Product – TabletWise.com

About Us

• About Us
• Privacy Policy
• Terms of use

• Overview
• Benefits
• Side effects
• Precautions
• Interactions
• Contraindications

Overview

Skelaxin Tablet is used for Relieving muscle spasms, Used in conjunction with rest and physical therapy, Muscle relaxation and other conditions.

Skelaxin Tablet contains Metaxalone as an active ingredient. Available in tablet form.

Detailed information regarding the use, composition, dosage, side effects of Skelaxin Tablet, as well as user reviews are provided below:

Uses

Skelaxin Tablet is used for the treatment, control, prevention, & improvement of the following diseases, conditions and symptoms:

• Relieve muscle spasms
• Used in conjunction with rest and physical therapy
• Muscle relaxation

Learn more : Benefits

Side effects

The following is a list of possible side-effects that may occur from all constituents of Skelaxin Tablet. This list is not final. These side effects have been recorded previously, but are not always recorded when using the drug. Some of these side effects may be extremely rare, but have incredibly severe consequences. If you notice any side effects, contact your doctor immediately. Especially in the case of observing side effects for a long time.

• Nausea
• Jaundice
• Acute and severe allergic reactions
• Vomiting
• Drowsiness
• Hemolytic anemia
• Indigestion
• Allergic rejection
• Dizziness
• Nervousness or irritability
• Less white blood cells with or without itching
• Headache
• Blurred vision
• Dry mouth
• Constipation

If you experience side effects not listed above, contact your healthcare provider for advice. In addition, you can report side effects to your local Food and Drug Administration.

Precautions

Before starting this drug, tell your doctor about any medications you are taking, dietary supplements (such as vitamins, natural supplements, etc.), allergies, existing medical conditions, and current health conditions (such as pregnancy, upcoming surgery, and etc. ). The side effects of the drug may be more pronounced depending on the state of your body. Take this medicine as directed by your doctor, or follow the directions for use that come with your medicine. The dosage of the drug depends on your condition. Tell your doctor if there is no change or if your condition worsens. Important points to discuss with your healthcare provider are listed below.

• Do not take with food
• Pre-existing liver damage

If you use other drugs or over the counter products at the same time, the effects of Skelaxin Tablet may change. Tell your healthcare provider about all medications, vitamins, and supplements you use. Your doctor will be able to make the right plan for taking the drug, which will avoid negative interactions. Skelaxin Tablet may interact with the following drugs and products:

• Acetaminophen
• Aspirin
• Buprenorphine
• Caffeine
• Juxtapid
• Kynamro
• Leflunomide 90 008
• Lomitapide
• Mipomersen
• Naloxone

Hypersensitivity to Skelaxin Tablet is a contraindication. In addition, Skelaxin Tablet should not be used if you have the following conditions:

• Drug-induced hemolytic anemia or other
• Impaired renal and hepatic function
• hypersensitivity

Composition and active ingredients

Skelaxin Tablet contains the following active ingredients (salts)

90 005

Please note attention to the fact that this drug is available with different strengths of intensity for each of the active ingredients listed above.

Packing options and strengths

Skelaxin Tablet is available in the following pack sizes and strengths

Skelaxin Tablet packs are available: 400MG, 800MG

FAQ

900 06

Can Skelaxin tablets / Skelaxin Tablet is used to relieve muscle spasms and is used along with rest and physical therapy?

Yes, relieve muscle spasms and used along with rest and physical therapy are among the most common reported uses for Skelaxin Tablet. Please do not use Skelaxin Tablet to relieve muscle spasms and is used along with other and physical therapy without consulting first with your doctor. Click here and view survey results to find out what other patients report as common uses of Skelaxin Tablet.

• Is it safe to drive or operate heavy machinery while using this product?

  If you experience drowsiness, dizziness, hypotension or a headache as side-effects when using Skelaxin Tablet medicine then it may not be safe to drive a vehicle or operate heavy machinery. You should stop driving if taking this medicine makes you drowsy, dizzy, or hypotensive. Doctors recommend that you stop drinking alcohol with such drugs, because. alcohol greatly increases the side effects and drowsiness. Please check for these effects on your body when using Skelaxin Tablet. Be sure to consult your doctor for advice based on the characteristics of your body and general health.

• Is this drug (product) addictive or addictive?

  Most drugs are not habit-forming or addictive. In most cases, the state classifies drugs that can be addictive as controlled dispensing drugs. For example, schedule H or X in India and schedule II-V in the USA. Please check the information on the drug packaging to make sure that this drug is not in the controlled category. Also, do not self-medicate or accustom your body to medications without consulting your doctor.

• Can I stop using this product immediately or do I need to slowly stop using it?

  Some medications need to be stopped gradually due to a rebound effect. Be sure to check with your healthcare provider for advice based on your body, general health, and other medications you may be taking.

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Skelaxin (Metaxalone): Uses, Dosage, Side Effects, Interactions, Prevention

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 colored urine,
• confusion,
• weak point
• upper stomach pain,
• loss of appetite and
• yellowing of the skin or eyes (jaundice)

Get medical help right away if you have any of the above symptoms.

The most common side effects of Skelaxin include:

• dizziness,
• drowsiness,
• nausea,
• vomiting,
• upset stomach,

9000 6 headache and

• feeling of nervousness or irritability

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 as oval pink 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 corresponding to a molecular weight of 221.25. Structural formula:

Metaxalone is an odorless white or almost white crystalline powder, easily soluble in chloroform, soluble in methanol and 96% 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 0003 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 from 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 whether 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 as 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 SKELaxin on an empty stomach and after meals at doses ranging from 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 two0366	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 men, 11 women) 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 second food impact study with a similar design, 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 0635 39.3 ± 10.8

9055 0 2915 (55)

9 0550 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) 90 366
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.

DRUG INTERACTIONS

The sedative effect of SCELaxin and other CNS depressants (eg, alcohol, benzodiazepines, opioids, tricyclic antidepressants) can be complex.