Usage
Eperisone hydrochloride is a centrally acting muscle relaxant indicated for the relief of muscle stiffness, spasm, and pain associated with various musculoskeletal and neurological conditions. These include:
- Spastic paralysis: Conditions such as cerebrovascular disease, spastic spinal paralysis, cervical spondylosis, and sequelae from trauma (spinal trauma, head injury).
- Myotonic symptoms: Cervical syndrome, periarthritis of the shoulder, lumbago, and tension-type headaches.
- Other conditions with muscle spasticity: Amyotrophic lateral sclerosis, cerebral palsy, spinocerebellar degeneration, spinal vascular diseases, and other encephalomyelopathies.
Pharmacological Classification: Centrally acting muscle relaxant.
Mechanism of Action: Eperisone acts primarily on the central nervous system, inhibiting spinal reflexes and reducing muscle tone. It also exhibits some peripheral vasodilatory effects, improving blood flow to affected muscles.
Alternate Names
Eperisone Hydrochloride.
Brand Names: Myonal, Epry.
How It Works
Pharmacodynamics: Eperisone exerts its muscle relaxant effects through a dual mechanism:
- Central Action: Primarily acts within the spinal cord by suppressing both mono- and polysynaptic reflexes. It is believed to inhibit calcium influx into presynaptic nerve terminals, decreasing the release of excitatory neurotransmitters.
- Peripheral Action: Eperisone also possesses vasodilatory properties, increasing blood flow to skeletal muscles. This enhanced perfusion further aids in reducing muscle spasm and pain.
Pharmacokinetics:
- Absorption: Eperisone is well-absorbed after oral administration, reaching peak plasma concentrations within 1-2 hours. Food intake does not significantly affect absorption.
- Metabolism: Primarily metabolized in the liver.
- Elimination: Excreted mainly through the kidneys.
Mode of Action: Reduces muscle tone by depressing spinal reflexes and improving muscle blood flow.
Receptor Binding/Enzyme Inhibition/Neurotransmitter Modulation: Eperisone is thought to inhibit calcium influx into presynaptic nerve terminals, ultimately reducing the release of excitatory neurotransmitters. The specific receptors or enzymes involved are not fully elucidated.
Elimination Pathways: Primarily renal excretion.
Dosage
Standard Dosage
Adults: 50 mg three times daily after meals. The dose may be adjusted (up to 150mg/day) according to the patient’s age, symptoms, and response.
Children: Eperisone use is not recommended in children due to limited safety and efficacy data.
Special Cases:
- Elderly Patients: Reduced doses are recommended. Close monitoring for adverse effects is crucial.
- Patients with Renal Impairment: Dose adjustment may be necessary depending on the degree of impairment.
- Patients with Hepatic Dysfunction: Caution is advised, and dose adjustments may be needed.
- Patients with Comorbid Conditions: Consider comorbid conditions such as diabetes, cardiovascular disease, and concurrent medication use when determining dosage.
Clinical Use Cases
The standard dosage guidelines apply across various clinical scenarios. There are no specific dosage recommendations for intubation, surgical procedures, mechanical ventilation, ICU use, or emergency situations.
Dosage Adjustments
Dosage adjustments should be made based on patient-specific factors like renal/hepatic function, concurrent medications, and individual response to therapy.
Side Effects
Common Side Effects
- Nausea
- Vomiting
- Stomach discomfort
- Headache
- Weakness
- Drowsiness
- Dizziness
Rare but Serious Side Effects
- Liver dysfunction
- Allergic reactions (e.g., skin rash, itching, swelling)
- Stevens-Johnson syndrome
- Toxic epidermal necrolysis
Long-Term Effects
Long-term effects are not well-established. Regular monitoring for liver function and other potential adverse effects is advised during prolonged use.
Adverse Drug Reactions (ADR)
Serious ADRs like liver damage and severe allergic reactions require immediate medical attention.
Contraindications
- Hypersensitivity to eperisone.
- Myasthenia gravis.
Drug Interactions
Eperisone may interact with other medications, particularly those metabolized by the liver (CYP450 enzymes). Inform your doctor about all medications, including OTC drugs and supplements. Some specific interactions include:
- Metoclopramide: May enhance the muscle relaxant effects of eperisone.
Pregnancy and Breastfeeding
- Pregnancy: Eperisone should be avoided during pregnancy due to limited safety data.
- Breastfeeding: Eperisone is contraindicated during breastfeeding as it is excreted in breast milk.
Drug Profile Summary
- Mechanism of Action: Centrally acting muscle relaxant with vasodilatory effects.
- Side Effects: Nausea, vomiting, drowsiness, dizziness, headache, and rarely, liver dysfunction and allergic reactions.
- Contraindications: Hypersensitivity, myasthenia gravis, breastfeeding.
- Drug Interactions: Metoclopramide, and potentially other drugs metabolized by the liver.
- Pregnancy & Breastfeeding: Contraindicated.
- Dosage: 50 mg three times daily (adults), adjustable up to 150 mg/day.
- Monitoring Parameters: Liver function tests during prolonged therapy.
Popular Combinations
Eperisone is sometimes combined with NSAIDs or other analgesics for enhanced pain relief.
Precautions
- Patients should avoid driving or operating heavy machinery if they experience drowsiness or dizziness.
- Monitor liver function in patients with pre-existing liver disease or during long-term use.
- Use with caution in elderly patients due to increased risk of adverse effects.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Eperisone?
A: The standard adult dose is 50 mg three times a day, adjustable based on patient response and tolerance up to 150mg/day.
Q2: Is Eperisone safe for children?
A: Eperisone is not recommended for use in children due to insufficient safety and efficacy data.
Q3: Can Eperisone be used during pregnancy or breastfeeding?
A: No, Eperisone is contraindicated in both pregnancy and breastfeeding.
Q4: What are the most common side effects of Eperisone?
A: Common side effects include nausea, vomiting, drowsiness, dizziness, and headache.
Q5: Are there any serious side effects associated with Eperisone?
A: Rare but serious side effects include liver dysfunction and severe allergic reactions.
Q6: How does Eperisone interact with other medications?
A: Eperisone may interact with metoclopramide and potentially with other drugs metabolized by the liver.
Q7: What precautions should be taken while using Eperisone?
A: Patients should avoid driving or operating machinery if they experience drowsiness. Liver function should be monitored during long-term use. Elderly patients should be closely monitored for adverse effects.
Q8: How does Eperisone work to relieve muscle spasm and pain?
A: Eperisone acts centrally to suppress spinal reflexes and peripherally to enhance muscle blood flow.
Q9: What conditions is Eperisone used to treat?
A: Eperisone is used to treat muscle stiffness, spasm, and pain associated with various musculoskeletal and neurological conditions like spastic paralysis, myotonic symptoms, and other spasticity-related disorders.
