mephenesin

Action and Spectrum

Actions and Spectrum: 

Action: 

mephenesin primarily exerts its therapeutic effects by depressing the CNS, specifically the spinal cord, leading to muscle relaxation. It is believed to act by inhibiting the reflex arcs within the spinal cord that are responsible for causing muscle spasms. mephenesin does not directly affect skeletal muscles but instead targets the nervous system to alleviate muscle tension and spasticity indirectly. 

Spectrum: 

Muscle Spasms: mephenesin was prescribed to reduce involuntary muscle contractions or spasms, which conditions like muscle strain, injury, or neurological disorders could cause. 

Muscle Pain: It alleviated pain associated with muscle tension, mainly when the pain was due to muscle spasms. 

Drug Interaction

Adverse Reaction

Frequency not defined  

Hypersensitivity reactions 

Vomiting 

Nausea 

loss of appetite 

weakness 

drowsiness 

Lassitude 

Black Box Warning

Black Box Warning:  

None

Contraindication / Caution

Contraindication/Caution:  

Hypersensitivity: Individuals with a known hypersensitivity or allergic reaction to mephenesin or related medications should avoid its use. 

Severe Respiratory Conditions: mephenesin might cause respiratory depression in some cases. Individuals with severe respiratory conditions such as chronic obstructive pulmonary disease (COPD), severe asthma, or other breathing issues could be more susceptible to respiratory depression when exposed to mephenesin.  

Liver or Kidney Dysfunction: mephenesin is metabolized in the liver and excreted by the kidneys. Patients with severe liver or kidney dysfunction may not be able to effectively process and eliminate the medication, which could lead to potential adverse effects. 

Central Nervous System (CNS) Depression: mephenesin has the potential to cause CNS depression, which could lead to drowsiness, impaired coordination, and reduced cognitive function. Individuals already taking medications that depress the CNS (such as opioids, benzodiazepines, or alcohol) should avoid mephenesin to prevent additive effects. 

Pregnancy and Breastfeeding: There might be limited data on the safety of mephenesin use during pregnancy or breastfeeding. Due to the lack of sufficient information, it’s generally recommended to avoid its use in these situations unless specifically advised by a healthcare professional. 

Children and Elderly: mephenesin’s safety and efficacy in children and elderly individuals might not be well-established. Caution should be exercised if considering its use in these populations. 

Pregnancy / Lactation

Pregnancy warnings:     

Pregnancy category: N/A 

Lactation: Excreted into human milk is unknown 

Pregnancy Categories:         

Category A: Studies that were well-controlled and met expectations revealed no risk to the fetus in either the first or second trimester. 

Category B: There were a lack of studies on pregnant women and no evidence of risk to the fetus in animal experiments.   

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:  

mephenesin is a centrally-acting muscle relaxant utilized to manage musculoskeletal conditions. 

Pharmacodynamics: 

mephenesin’s pharmacological profile centers on its influence over the CNS, particularly the spinal cord. mephenesin exerts its muscle relaxant effects by acting as a gamma-aminobutyric acid (GABA) receptor agonist. GABA, an inhibitory neurotransmitter, plays a pivotal role in modulating neuronal excitability. By enhancing GABAergic transmission, mephenesin suppresses motor neuron activity, ultimately culminating in muscle relaxation.  

Pharmacokinetics:  

Absorption 

mephenesin’s absorption is primarily mediated through oral administration. Following ingestion, the drug undergoes dissolution in the gastrointestinal tract, subsequently permitting its passage through the intestinal epithelial barrier. The absorption process of mephenesin is relatively rapid, with peak plasma concentrations attained within a notable timeframe. 

Distribution 

Upon entering the systemic circulation, mephenesin demonstrates a moderate volume of distribution. The drug exhibits a propensity to accumulate within well-vascularized tissues, particularly skeletal muscle. Furthermore, mephenesin’s lipophilic nature contributes to its capacity to traverse cell membranes, allowing for widespread distribution. 

Metabolism 

mephenesin undergoes hepatic metabolism primarily via enzymatic biotransformation. The cytochrome P450 enzyme system, notably CYP2C9, has been identified as a critical element in the metabolic transformation of mephenesin. The resultant metabolites are hydroxylated derivatives, which subsequently undergo conjugation with glucuronic acid to facilitate their elimination. 

Excretion and Elimination 

Renal excretion serves as the predominant route of elimination for mephenesin and its metabolites. The conjugated metabolites are excreted via urine, contributing significantly to the elimination process. A minor portion of the drug and its metabolites may also undergo biliary excretion into the feces. 

Adminstartion

Administration:  

mephenesin is primarily administered orally and topically. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: mephenesin 

Why do we use mephenesin?  

Skeletal Muscle Spasms: mephenesin finds its primary clinical utility in managing skeletal muscle spasms and associated discomfort. Targeting the central nervous system acts as an effective skeletal muscle relaxant, relieving muscle spasms resulting from various etiologies such as musculoskeletal injuries, strains, and neurological disorders. 

Musculoskeletal Conditions: Utilizing mephenesin alleviates musculoskeletal conditions characterized by muscle rigidity and tension. It is particularly beneficial in conditions such as torticollis, fibromyalgia, and myofascial pain syndrome, where excessive muscle contractions contribute to discomfort and limited range of motion.