Muslaxin

Muslaxin combines Ibuprofen and Chlorzoxazone to alleviate skeletal muscle pain and spasms. Ibuprofen reduces inflammation, easing pain and swelling while Chlorzoxazone targets muscle spasms, enhancing mobility and further reducing pain.

This combination effectively addresses both inflammation-related discomfort and muscle tension, offering comprehensive relief for these conditions.

Pharmacological class: Muslaxin is a centrally acting muscle relaxant (spasmolytic) with analgesic effect.

Muslaxin is recommended for:

• Relieving low back pain resulting from muscle tension and spasms in adults aged 18 years and older.
• Symptomatic relief by reducing pain and inflammation.

Ibuprofen is a phenylpropionic acid derivative belonging to the NSAID group. It works by reducing the production of prostaglandins in the body. This further leads to a reduction in inflammatory pain, swelling, and fever in humans. It also reversibly inhibits platelet aggregation.

Chlorzoxazone is a centrally acting medication used for treating musculoskeletal pain and improve muscle mobility. It primarily acts in the spinal cord and subcortical areas of the brain to block polysynaptic reflexes responsible for producing skeletal muscle spasms of various origins.

• Muslaxin 200 mg + 250 mg, film-coated tablets: 1 or 2 tablets can be taken orally up to 3 times daily, 4 hours apart.
• Muslaxin 400 mg + 500 mg film-coated tablets: 1 tablet can be taken orally up to 3 times daily, 4 hours apart.
• Maximum single dose: 1 tablet of 400 mg + 500 mg or 2 tablets of the 200 mg + 250 mg composition.
• Maximum daily dose: 3 tablets of 400 mg + 500 mg or 6 tablets of the 200 mg + 250 mg composition.

Additional Considerations:

• No dose adjustment is needed for elderly patients.
• Patients with mild or moderate kidney impairment do not need their dose reduced when using Muslaxin.
• Not for use in children.

Ibuprofen:

Absorption and Distribution:

• It gets absorbed quickly and almost entirely from the gastrointestinal tract.
• On an empty stomach, peak blood plasma concentration (Cmax) is reached in about 45 minutes; with food, it may take 1-2 hours longer.
• It binds strongly to plasma proteins (90%).
• Enters joint spaces slowly, accumulating in synovial fluid at higher concentrations than in plasma.
• Penetrates cerebrospinal fluid at lower concentrations compared to plasma.

Metabolism and Excretion:

• About 60% of the inactive R-form is converted slowly to the active S-form after absorption.
• It primarily gets metabolized in the liver.
• Its half-life (T 1/2) is approximately 2 hours.
• It gets mainly excreted via the kidneys (less than 1% unchanged) and to a lesser extent via bile.
• Studies with limited data suggest that it appears in breast milk at very low levels.

Chlorzoxazone:

Absorption and Distribution:

• It is rapidly absorbed and detected in the blood within 30 minutes’ post-oral administration.
• Peak concentration (Cmax) occurs 1-2 hours after ingestion.
• Metabolized quickly and excreted primarily in urine as glucuronide conjugates.
• Within 24 hours, less than 1% of the dose is passed out unchanged in urine.

• Hypersensitivity to Ibuprofen, Chlorzoxazone, or any other ingredient in the drug
• Liver dysfunction or active liver disease.
• Decompensated heart failure.
• Following after coronary artery bypass surgery.
• History of cerebrovascular or other bleeding.
• Hemophilia or other bleeding disorders.
• Pregnancy or breastfeeding.
• People who have a genetic condition that makes them intolerant to galactose, lack the enzyme lactase, or have difficulty absorbing glucose and galactose.
• History of bronchial asthma, recurrent nasal and sinus polyps, or intolerance to acetylsalicylic acid or other NSAIDs
• Erosive or ulcerative gastrointestinal tract diseases (active or history of peptic ulcer, Crohn's disease or ulcerative bleeding)
• History of gastrointestinal ulcer bleeding caused by NSAIDs
• Serious kidney problems (where creatinine clearance is less than 30 ml/min) or high levels of potassium in the blood.
• Severe heart failure (NYHA class IV) with shortness of breath, swelling and tiredness at rest
• Pregnancy and lactation

Do not use Ibuprofen concomitantly with:

• Acetylsalicylic acid, except in low doses (no more than 75 mg per day) prescribed by the physician
• Other NSAIDs, especially selective cyclooxygenase-2 inhibitors

Muslaxin should be used with caution with the below medications:

• Anticoagulants and thrombolytic drugs (e.g., Alteplase, Tenecteplase)
• Antihypertensive drugs, particularly ACE inhibitors, angiotensin II antagonists and diuretics
• Glucocorticosteroids
• Antiplatelet agents and SSRIs (antidepressants)
• Cardiac glycosides
• Lithium preparations
• Methotrexate
• Immunosuppressants such as cyclosporine and tacrolimus
• Mifepristone (wait 8-12 days after taking before starting Muslaxin)
• Tacrolimus
• Quinolones (e.g., Nalidixic acid, Levofloxacin, Ciprofloxacin)
• Myelotoxic drugs (e.g. Chloramphenicol)
• Certain antibiotics (Cefamandole, Cefoperazone, Cefotetan), Valproic acid, and Plicamycin
• Drugs affecting tubular secretion
• Enzyme inducers (e.g., Phenytoin)
• Enzyme inhibitors
• Oral hypoglycemic drugs, insulin, and sulfonylureas (diabetes medications)
• Antacids (containing Aluminium or Magnesium)
• Cholestyramine (reduces cholesterol absorption)
• Uricosuric drugs
• Estrogens

Common side effects (This might affect 1 out of every 10 people):

• Nausea
• Dry mouth
• Dyspepsia
• Dizziness
• Headache
• Drowsiness
• Abdominal pain
• Severe fatigue (asthenia)
• Elevated blood pressure
• Malaise
• Change in colour of the urine

Uncommon side effects (These may affect 1 in 100 people to 1 in 1000 people):

• Yawning
• Bloating
• Flatulence, Diarrhea, Vomiting, Constipation
• Tachycardia
• Abdominal discomfort, Nausea, Dyspepsia
• Allergic reactions (urticarial, itching)
• Headache
• Skin rashes
• Muscle weakness
• Menstrual irregularities
• Decreased haemoglobin level
• Decreased sensitivity (hypesthesia) in the oral cavity
• Distortion of the sense of taste (dysgeusia)
• Weakening of taste sensations (hypogeusia)
• Elevated levels of transaminases in blood tests
• Disturbance of rhythm and conduction of the heart (1st degree atrioventricular block)

Very rare side effects (affecting less than 1 in 10,000 people):

• Hematopoietic disorders
• Severe hypersensitivity reactions
• Aseptic meningitis
• Peptic ulcers, perforation or gastrointestinal bleeding
• Liver dysfunction
• Exfoliative and bullous dermatoses
• Acute renal failure

• Muslaxin should be used carefully in older patients who have liver, kidney, or heart problems, or who are taking other medications.
• Special care is advised for patients with a history of cardiovascular issues such as hypertension and mild to moderate congestive heart failure, as well as those with gastrointestinal toxicity, Crohn’s disease, peptic ulcers, and systemic lupus erythematosus.

In the most study by Putilina, M. V. (2024), the benefits of combining NSAIDs with a muscle relaxant like Muslaxin were found to be significant:

• Enhanced analgesic and anti-inflammatory effects.
• Simplification of the treatment regimen for conditions involving significant muscle involvement.
• Reduced incidence of side effects, including effects on blood pressure.

It's worth noting that Muslaxin can be used effectively without the need to identify specific patient groups, although its relevance increases when single-drug therapy is insufficient. In conclusion, Muslaxin exemplifies the rationale for using fixed combinations in pain management, highlighting their practical advantages in clinical settings. [1]

In another study by Patel et al. (2019), the combination of Chlorzoxazone and Ibuprofen proved to be an effective therapy for acute low back pain. Both medications were well-tolerated, making them valuable treatment choices for patients with this condition. [2]

1. Putilina, M. V. (2024). Fixed combination of non-steroidal anti-inflammatory drug and muscle relaxant as the basis for rational therapy of pain syndromes: A review. Terapevticheskii Arkhiv, 96(2), 176-180. doi: 10.26442/00403660.2024.02.202583
2. Patel, H.D., Uppin, R.B., Naidu, A.R. et al. Efficacy and Safety of Combination of NSAIDs and Muscle Relaxants in the Management of Acute Low Back Pain. Pain Ther 8, 121–132 (2019). https://doi.org/10.1007/s40122-019-0112-6