diclofenac and metaxalone

Action and Spectrum

Actions and spectrum: 

diclofenac: 

• Action: diclofenac is a nonsteroidal anti-inflammatory drug (NSAID) that works by inhibiting the enzymes responsible for producing prostaglandins. Prostaglandins are chemical messengers in the body that promote inflammation, pain, and fever. By reducing prostaglandin production, diclofenac has anti-inflammatory, analgesic (pain-relieving), and antipyretic (fever-reducing) effects. 
• Spectrum of Use: diclofenac is primarily used to relieve pain and inflammation in various conditions, including arthritis (rheumatoid arthritis, osteoarthritis), gout, ankylosing spondylitis, and musculoskeletal disorders. It is available in various formulations, including oral tablets, topical gels or creams, and ophthalmic solutions. 

metaxalone: 

• Action: metaxalone is a muscle relaxant that works by depressing central nervous system and reducing nerve impulses or signals that cause muscle spasms or stiffness. It is thought to work through its sedative properties without directly affecting muscle function. 
• Spectrum of Use: metaxalone is used for the relief associated with acute, painful musculoskeletal conditions, such as muscle spasms and pain. It is typically prescribed as part of a broader treatment plan that includes rest, physical therapy, and other measures to address the underlying musculoskeletal issue. 

Drug Interaction

Adverse Reaction

Frequency not defined 

Nausea 

Stomach pain 

Diarrhea 

Loss of appetite 

Vomiting 

Heartburn 

Sleepiness 

Black Box Warning

Black Box Warning: 

There is no specific black box warning associated with the combination of diclofenac and metaxalone. 

Contraindication / Caution

Contraindication/Caution: 

Contraindication: 

• Allergy or Hypersensitivity: If an individual has a known allergy to diclofenac, metaxalone, or related medications, using this combination is contraindicated. 
• Asthma, Urticaria, or Allergic Reactions: diclofenac can exacerbate asthma or induce allergic reactions. If an individual has a history of asthma, urticaria, or allergic reactions triggered by NSAIDs, diclofenac should be avoided. 
• Severe Liver or Kidney Impairment: Both diclofenac and metaxalone may affect liver and kidney function. In individuals with severe impairment of these organs, the use of this combination may be contraindicated. 
• Severe Cardiovascular Conditions: diclofenac can increase the risk of cardiovascular events, making its use contraindicated in individuals with severe heart conditions, recent heart surgery, or cerebrovascular disease. 
• Pregnancy and Breastfeeding: Use during pregnancy or breastfeeding should be carefully considered, as both medications have potential risks. The combination may be contraindicated in certain circumstances.

Caution: 

• Gastrointestinal Effects: diclofenac can increase the risk of gastrointestinal side effects such as bleeding, ulcers, and stomach pain. Patients should be cautious and report any symptoms of gastrointestinal distress to their healthcare provider. 
• Cardiovascular Risks: diclofenac is associated with an increased risk of cardiovascular events. Patients with a history of heart disease, high blood pressure, or other cardiovascular risk factors should use this combination with caution and under the supervision of a healthcare provider. 
• Asthma and Allergies: diclofenac may exacerbate asthma or cause allergic reactions. Patients with a history of asthma or allergies should be cautious and report any worsening of symptoms. 
• Substance Abuse History: metaxalone has the potential for misuse, and patients with a history of substance abuse or addiction should use this combination with caution. 

Comorbidities: 

• Cardiovascular Disease: Patients with comorbid cardiovascular conditions such as hypertension, heart disease, or a history of heart attacks may be at increased risk of adverse cardiovascular effects associated with diclofenac.  
• Gastrointestinal Conditions: Patients with a history of gastrointestinal conditions like peptic ulcers, gastritis, or inflammatory bowel disease may be at higher risk for gastrointestinal side effects caused by diclofenac. Caution is advised, and alternative medications with a lower risk of gastrointestinal effects may be considered. 
• Renal Impairment: Patients with comorbid kidney disease or impaired renal function should be cautious when using both diclofenac and metaxalone. These medications can affect renal function, and dose adjustments may be required. 
• Liver Disease: Patients with liver conditions, including cirrhosis or hepatitis, may require dose adjustments or avoidance of metaxalone, which is metabolized in the liver. diclofenac should also be used cautiously in patients with liver impairment. 
• Elderly Patients: Elderly individuals may be at increased risk of side effects and may have multiple comorbidities that can interact with these medications. Careful assessment and monitoring are essential. 

Pregnancy / Lactation

Pregnancy consideration: pregnancy category: not assigned 

Lactation: excreted into human milk: unknown  

Pregnancy category: 

• Category A: well-controlled and Satisfactory studies show no risk to the fetus in the first or later trimester. 
• Category B: there was no evidence of risk to the fetus in animal studies, and there were not enough studies on pregnant women. 
• Category C: there was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.   
• Category D: adequate data with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits. 
• Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women. 
• Category N: There is no data available for the drug under this category. 

Pharmacology

Pharmacology: 

diclofenac is a nonsteroidal anti-inflammatory drug which inhibits prostaglandin production, reducing inflammation, pain, and fever. metaxalone, on the other hand, is a muscle relaxant that depresses the central nervous system, relieving muscle spasms. When used together, diclofenac can alleviate inflammatory pain, while metaxalone targets the muscle-related component of discomfort.

Their combined pharmacology aims to provide comprehensive relief in musculoskeletal conditions marked by both inflammation and muscle spasm. Patients should use this combination under the guidance of a healthcare provider, considering potential side effects and interactions.  

Pharmacodynamics: 

diclofenac is a nonsteroidal anti-inflammatory drug that acts by inhibiting cyclooxygenase (COX) enzymes, specifically COX-1 and COX-2. By doing so, diclofenac reduces the production of prostaglandins, which are mediators of inflammation, pain, and fever. This action leads to anti-inflammatory, analgesic, and antipyretic effects. 

metaxalone is a muscle relaxant that acts by exerting its effects within the central nervous system. It acts as a central nervous system depressant, affecting interneurons in the spinal cord and brain, resulting in a reduction of muscle spasms or tension. 

When used in combination, diclofenac addresses the inflammatory component of pain, while metaxalone targets muscle-related discomfort. The synergistic effect aims to relieve pain, reduce inflammation, and ease muscle spasms, making this combination useful in treating conditions characterized by both inflammatory pain and muscle tension.  

Pharmacokinetics: 

Absorption 

• diclofenac: diclofenac is well-absorbed from the gastrointestinal tract when taken orally. It is available in various oral formulations, including immediate-release and extended-release tablets. Topical diclofenac formulations are also available for local application. 
• metaxalone: metaxalone is well-absorbed after oral administration, with peak plasma concentrations reached within 3-4 hours. 

Distribution 

• diclofenac: diclofenac is highly protein-bound (over 99%) in the plasma and has a small volume of distribution. It can cross the blood-brain barrier. 
• metaxalone: metaxalone has a moderate volume of distribution and is distributed to skeletal muscles. 

Metabolism 

• diclofenac: diclofenac undergoes extensive hepatic metabolism. It is metabolized by cytochrome P450 enzymes, primarily CYP2C9 and CYP3A4, into several metabolites, including the pharmacologically active one, 4′-hydroxydiclofenac. 
• metaxalone: metaxalone undergoes hepatic metabolism but is primarily excreted unchanged in the urine. 

Elimination and excretion 

• diclofenac: diclofenac and its metabolites are primarily excreted in the urine. A small portion is eliminated in the feces. The elimination half-life varies between 1 and 2 hours for the initial compound and up to 2-3 hours for some metabolites. 
• metaxalone: metaxalone is primarily excreted in the urine. The elimination half-life is 9-11 hours. 

Adminstartion

Administration: 

• Dosage: The appropriate dosage of diclofenac and metaxalone will depend on the patient’s condition, age, weight, and other individual factors. Follow the prescribed dosage carefully. 
• Route of Administration: Both diclofenac and metaxalone are typically administered orally in the tablets or capsule form. They should be taken with a full glass of water. It is essential to swallow them whole and not crush or chew the tablets unless directed otherwise. 
• Frequency: The frequency of dosing will depend on the specific regimen prescribed by the healthcare provider. It may be taken once daily or divided into multiple doses throughout the day. 
• Duration of Treatment: It is determined by the healthcare provider and may vary based on the patient’s condition. It is essential to complete the full course of treatment as prescribed. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: diclofenac and metaxalone 

Pronounced: (dye-kloe-fen-ak / meh-TAX-a-lone)  

Why do we use diclofenac and metaxalone? 

The combination is often used to relieve pain and discomfort with musculoskeletal conditions, including muscle spasms, strains, and sprains. Patients with inflammatory joint conditions like gout, osteoarthritis or rheumatoid arthritis may benefit from this combination to reduce pain and inflammation. It can be used to manage pain following traumatic injuries or accidents, which may involve muscle strain and inflammation.