mephenoxalone

Action and Spectrum

Actions and spectrum: 

mephenoxalone is a muscle relaxant that works by acting on the central nervous system. It is used to relieve muscle spasms and stiffness. Its spectrum of action is primarily on skeletal muscles, where it helps to reduce muscle tension and promote relaxation. mephenoxalone is often used as an adjunct to rest, physical therapy, and other treatments to manage muscle-related conditions. 

Drug Interaction

Adverse Reaction

Frequency not defined 

Drowsiness 

paraesthesia 

headache 

ataxia 

visual disturbances 

hypotension 

blood dyscrasias 

GI disturbances 

Weakness 

paradoxical excitement 

dizziness 

arrhythmias 

hypersensitivity reactions 

Black Box Warning

Black Box Warning: 

There were no specific black box warnings associated with mephenoxalone. 

Contraindication / Caution

Contraindication/Caution: 

Contraindication: 

• Hypersensitivity: Individuals with a known hypersensitivity or allergy to mephenoxalone or any of its components should not use this medication. 
• Renal Impairment: mephenoxalone is primarily eliminated from the body through the kidneys. People with severe renal impairment or kidney disease may need a dosage adjustment or should avoid using mephenoxalone, as it can potentially accumulate in the body. 
• Hepatic Impairment: mephenoxalone is metabolized by the liver. Patients with severe liver impairment or liver disease may also require dosage adjustments or should avoid mephenoxalone use. 
• Alcohol: mephenoxalone may enhance the central nervous system (CNS) depressant effects of alcohol. Therefore, it is advisable to avoid alcohol consumption while taking this medication, as it can increase drowsiness and impair motor skills.

Caution: 

• Drowsiness and Dizziness: mephenoxalone can cause drowsiness and dizziness. Patients should exercise caution when driving, operating machinery, or engaging in activities that requires mental alertness, especially when they are just starting the medication or when the dosage is increased. 
• Elderly Patients: Elderly individuals may be more sensitive to the effects of mephenoxalone, including dizziness and drowsiness. Lower doses or careful monitoring may be necessary in this population. 
• Pregnancy and Lactation: The safety of mephenoxalone during pregnancy and breastfeeding has not been well established. 
• Children: mephenoxalone’s safety and effectiveness in children, especially those under the age of 6, have not been extensively studied. Pediatric dosing and use should be carefully considered under a healthcare provider’s guidance. 
• Drug Interactions: mephenoxalone may interact with other medications, including those that have CNS depressant effects, potentially increasing the risk of drowsiness or respiratory depression.  
• Allergic Reactions: Individuals with known hypersensitivity or allergies to mephenoxalone or any of its components should avoid using this medication.

Comorbidities: 

• Respiratory Conditions: mephenoxalone can cause drowsiness and dizziness, which may be exacerbated in individuals with respiratory conditions like COPD or sleep apnea. Extra caution is needed when using mephenoxalone in individuals with these conditions, as it may further depress respiratory function. 
• Epilepsy or Seizure Disorders: mephenoxalone’s central nervous system depressant effects may lower the seizure threshold. Individuals with a history of epilepsy or seizure disorders should use this medication cautiously and under the supervision of a healthcare provider. 
• Myasthenia Gravis: mephenoxalone’s muscle relaxant properties may affect muscle strength. Patients with myasthenia gravis, a neuromuscular disorder characterized by muscle weakness, should be closely monitored when taking this medication. 
• Psychiatric Disorders: mephenoxalone can cause drowsiness and may affect mood or cognitive function. Patients with depression or anxiety, should use this medication cautiously and report any changes in mood or behaviour to their healthcare provider. 

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: 

mephenoxalone is a centrally acting muscle relaxant that helps alleviate muscle pain and discomfort. Its pharmacological action involves depressing the central nervous system, leading to muscle relaxation. While the precise mechanism of action is not known, it is thought to involve the inhibition of nerve impulses within the spinal cord and brain, reducing muscle spasms and tension.

mephenoxalone’s muscle-relaxing effects contribute to its therapeutic use in various musculoskeletal conditions. However, it can also cause drowsiness and sedation as side effects due to its impact on the central nervous system. As a result, caution should be exercised when operating machinery or performing tasks requiring alertness while taking this medication.  

Pharmacodynamics: 

• Muscle Relaxation: mephenoxalone reduces muscle spasms, stiffness, and tension by affecting nerve signals within the spinal cord and brain. It does so by inhibiting abnormal reflex arcs and reducing the firing of motor neurons that control muscle contraction. 
• Sedation: mephenoxalone has sedative properties, which can result in drowsiness and reduced alertness. This effect can be helpful in reducing muscle-related anxiety or discomfort but also requires caution when performing activities that demand focus and attention, such as driving. 
• Minimal Anticholinergic Activity: Unlike some other muscle relaxants, mephenoxalone has minimal anticholinergic activity, meaning it does not interfere significantly with acetylcholine, a neurotransmitter involved in various bodily functions. 
• Duration of Action: The muscle-relaxing effects of mephenoxalone are short-lived, typically lasting for about 3-4 hours. Multiple doses may be required throughout the day to maintain therapeutic benefits.

Pharmacokinetics: 

Absorption 

mephenoxalone is orally administered and is typically well-absorbed from the gastrointestinal tract. Its absorption can vary among individuals and taking it with food can sometimes improve absorption. 

Distribution 

After absorption, mephenoxalone is distributed throughout the body. It crosses blood-brain barrier, which is why it can exert its muscle relaxant and sedative effects on the central nervous system. 

Metabolism 

mephenoxalone undergoes metabolism in the liver, primarily by cytochrome P450 enzymes, including CYP1A2 and CYP2E1. The exact metabolic pathways are not fully elucidated, but the major metabolites include 5-hydroxymephenoxalone and 3-hydroxy-4-methoxy-mephenoxalone. These metabolites are believed to be pharmacologically inactive. 

Elimination and excretion 

The metabolites of mephenoxalone are primarily excreted through the urine. The elimination half-life of mephenoxalone is short, typically around 1.5 to 2 hours, which means it is rapidly cleared from the body. 

Adminstartion

Administration: 

• Dosage: The recommended dosage of mephenoxalone can vary based on the product and condition being treated.  
• Frequency: mephenoxalone is usually taken three or four times a day, depending on the formulation and the directions given by your healthcare provider. Follow the prescribed dosing schedule. 
• Duration of Treatment: The duration of mephenoxalone treatment is typically short-term, lasting a few weeks to help manage acute muscle spasms or pain.  
• Consistency: Try to take mephenoxalone at the same times each day to maintain consistent blood levels of the medication. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: mephenoxalone 

Pronounced: (meh-feh-NOX-a-lone)  

Why do we use mephenoxalone? 

• Muscle Spasms: mephenoxalone is often prescribed to alleviate muscle spasms, which can be caused by conditions such as muscle strains, sprains, or musculoskeletal injuries. 
• Muscle Pain: It is used to help reduce the pain associated with muscle spasms and tension. 
• Post-Surgical Pain: In some cases, mephenoxalone may be used to manage muscle spasms and pain following surgical procedures. 
• Other Musculoskeletal Conditions: mephenoxalone can be considered for conditions beyond muscle spasms, as deemed appropriate by a healthcare provider.