1. Clinical Overview
A fixed-dose combination (FDC) of a centrally-acting muscle relaxant (Eperisone) and a centrally-acting analgesic/antipyretic (Paracetamol). Eperisone acts by suppressing the myotatic reflex and improving muscle tone, while Paracetamol elevates the pain threshold. This combination is primarily indicated for the symptomatic relief of painful muscle spasms associated with musculoskeletal conditions, offering both muscle relaxation and pain relief. It is widely used in the Indian market for conditions like cervical spondylosis, low back pain, and fibromyalgia.
| Onset | Duration | Bioavailability |
|---|---|---|
| Paracetamol: 30-60 minutes. Eperisone: 1-2 hours. | Paracetamol: 4-6 hours. Eperisone: 6-8 hours. | Paracetamol: ~85% (oral). Eperisone: ~90% (oral). |
2. Mechanism of Action
Eperisone acts centrally by suppressing the myotatic reflex (monosynaptic and polysynaptic reflexes) at the level of the spinal cord and brainstem. It also has a peripheral vasodilatory effect, improving blood flow to muscles. Paracetamol's exact mechanism is not fully elucidated but is believed to act centrally by inhibiting cyclooxygenase (COX), particularly the COX-2 variant, and modulating the endogenous cannabinoid and serotonergic pathways, leading to analgesia and antipyresis with minimal peripheral anti-inflammatory effect.
3. Indications & Uses
- Symptomatic relief of painful muscle spasms associated with musculoskeletal disorders
- Cervical spondylosis with radiculopathy/myopathy
- Low back pain (lumbago) with muscle spasm
- Tension headache associated with neck muscle spasm
4. Dosage & Administration
Adult Dosage: One tablet (Eperisone 50mg + Paracetamol 325mg) three times daily, after meals. Maximum: 3 tablets per day.
Administration: Administer orally with or after food to minimize gastrointestinal discomfort. Swallow whole with a glass of water. Do not crush or chew. Maintain adequate hydration.
5. Side Effects
Common side effects may include:
- Drowsiness/Sedation
- Dizziness/Lightheadedness
- Nausea
- Gastric discomfort/Heartburn
- Headache
- Dry mouth
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Alcohol (Chronic/Heavy Use) | Potentiates CNS depression with Eperisone; significantly increases risk of paracetamol-induced hepatotoxicity. | Major |
| Other CNS Depressants (e.g., Benzodiazepines, Opioids, Antipsychotics) | Additive sedation, dizziness, and impaired motor skills. | Major |
| Antihypertensives, Vasodilators | Enhanced hypotensive effect with Eperisone. | Moderate |
| Enzyme Inducers (e.g., Rifampicin, Carbamazepine, Phenytoin) | Increase metabolism of paracetamol, potentially increasing toxic metabolite (NAPQI) formation. | Moderate |
| Warfarin | Paracetamol may potentiate anticoagulant effect with prolonged high-dose use (>4g/day for several days). | Moderate |
| Metoclopramide, Domperidone | May increase absorption rate of paracetamol. | Minor |
| Cholestyramine | Reduces absorption of paracetamol if taken within 1 hour. | Moderate |
| CYP3A4 Inhibitors (e.g., Ketoconazole, Clarithromycin) | May increase Eperisone plasma levels, increasing risk of side effects. | Moderate |
7. Patient Counselling
- DO take after food to avoid stomach upset.
- DO inform your doctor about all other medicines, including OTC painkillers and herbal supplements.
- DO maintain adequate fluid intake.
- DO NOT consume alcohol while on this medication.
- DO NOT exceed the prescribed dose or duration.
- DO NOT take for fever for more than 3 days without consulting a doctor.
- DO NOT use with other paracetamol-containing products (cold & flu remedies).
8. Toxicology & Storage
Overdose: Stage 1 (0-24h): Nausea, vomiting, anorexia, malaise, pallor, diaphoresis. Stage 2 (24-72h): Right upper quadrant pain, elevated LFTs, oliguria. Stage 3 (72-96h): Peak hepatotoxicity (jaundice, coagulopathy, encephalopathy), renal failure, myocardial injury. Eperisone overdose: Enhanced CNS depression (coma, respiratory depression), severe hypotension, bradycardia.
Storage: Store below 30°C, in a cool, dry place. Protect from light and moisture. Keep out of reach of children. Do not use after the expiry date printed on the pack.