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Eperisone (formulated as the eperisone hydrochloride salt) is an antispasmodic drug.
Eperisone acts by relaxing both skeletal muscles and vascular smooth muscles, and demonstrates a variety of effects such as reduction of myotonia, improvement of circulation, and suppression of the pain reflex. The drug inhibits the vicious circle of myotonia by decreasing pain, ischaemia, and hypertonia in skeletal muscles, thus alleviating stiffness and spasticity, and facilitating muscle movement
Eperisone has a relatively low incidence of sedation when compared with other antispasmodic drugs; this simplifies the clinical application of the drug and makes it an attractive choice for patients who require antispasmodic therapy without a reduction in alertness.
Eperisone also facilitates voluntary movement of the upper and lower extremities without reducing muscle power; it is therefore useful during the initial stage of rehabilitation and as a supporting drug during subsequent rehabilitative therapy.
- Spastic paralysis in conditions such as cerebrovascular disease
- Spastic spinal paralysis
- Cervical spondylosis
- Postoperative sequelae (including from cerebrospinal tumour)
- Sequelae to trauma (e.g. spinal trauma or head injury)
- Amyotrophic lateral sclerosis
- Cerebral palsy
- Spinocerebellar degeneration
- Spinal vascular diseases and other encephalomyelopathies
- Cervical syndrome, periarthritis of the shoulder, and lumbago.
Eperisone hydrochloride is available as the brand name preparation Myonal as 50 mg sugar coated tablets, or as 10% granules for oral administration. An experimental form of the drug, as a transdermal patch system, has shown promising results in laboratory tests on rodents; however, this product is not currently available for human use. It is also available as the brand name Epry as 50 mg as sugar coated tablets.
Dosage and administration
In adults, the usual dose of eperisone is 50–150 mg per day, in divided doses, after meals. However, the dosage is adjusted by the prescribing clinician depending on factors such as severity of symptoms, patient age and response.
Safety during pregnancy and breast-feeding
Eperisone has not been established to be safe for use by pregnant women; therefore the drug should only be used in pregnant women, or women who may be pregnant, if the expected therapeutic benefits will outweigh the possible risks associated with treatment. The manufacturers of Myonal recommend the drug not be used during lactation (breast-feeding). If eperisone must be used, the patient is advised to stop breast-feeding for the duration of treatment. Eperisone has beed reported to be excreted in breast milk in an animal study (in rats).
- Skeletal muscle relaxation
- Relaxation of hypertonic skeletal muscles
- Improves intramuscular blood flow
- Suppression of spinal reflex potentials
- Reduction of muscle spindle sensitivity via motor neurons
- Vasodilatation and augmentation of blood flow
- Analgesic action and inhibition of the pain reflex in the spinal cord
Eperisone is contraindicated in patients with known hypersensitivity to the drug. Side effects: 'very rare' excessive relaxation, stomachache, nausea, vertigo, anorexia, drowsiness, skin rashes, diarrhoea, vomiting, indigestion, GI disturbances, insomnia, headache, constipation etc.
Eperisone should be administered with care in patients with a history of hypersensitivity to any medication, or with disorders of liver function (it may aggravate hepatic dysfunction).
Weakness, light-headedness, sleepiness or other symptoms may occur. In the event of such symptoms, the dosage should be reduced or treatment discontinued. Patients should be cautioned against engaging in potentially hazardous activities requiring alertness, such as operating machinery or driving a car.
- Shock and anaphylactoid reactions: In the event of symptoms such as redness, itching, urticaria, oedema of the face and other parts of the body, dyspnoea, etc., treatment should be discontinued and appropriate measues taken.
- Other side effects: anaemia, rash, pruritus, sleepiness, insomnia, headache, nausea and vomiting, anorexia, abdominal pain, diarrhoea, constipation, urinary retention or incontinence.
Safety in overdose
Eperisone suffers from a very low bioavailability when taken orally, as a result of high first pass intestinal metabolism; a transdermal patch containing eperisone is currently in development in South Korea. This has shown promise, with the antispasmodic effect lasting over 24 hours, compared to one to two hours following oral administration.
Eperisone is sold in Bangladesh, China, India, Indonesia, Japan, United Arab Emirates, Malaysia, the Philippines, Thailand, Sudan and Pakistan under the brand name Myonal and in Italy under the brand name Expose.
- Yang SI, Park HY, Lee SH et al. (July 2004). "Transdermal eperisone elicits more potent and longer-lasting muscle relaxation than oral eperisone". Pharmacology 71 (3): 150–6. doi:10.1159/000077449. PMID 15161997.
- Bose K (1999). "The efficacy and safety of eperisone in patients with cervical spondylosis: Results of a randomized, double-blind, placebo-controlled trial". Methods Find Exp Clin Pharmacol 21 (3): 209–13. doi:10.1358/mf.19188.8.131.524831. PMID 10389124.
- Yang Sang-In; Park Ha-Young, Lee Sang-Ho, Lee Seung-Jin, Han Ok-Yeun, Lim Sung-Cil, Jang Choon-Gon, Lee Wan-Suk, Shin Young-Hee, Kim Jung-Ju, and Lee Seok-Yong (July 2004). "Transdermal eperisone elicits more potent and longer-lasting muscle relaxation than oral eperisone". Pharmacology 71 (3): 150–6. doi:10.1159/000077449. PMID 15161997.
- Clinical trial number NCT00327730 for "Evaluation of Eperisone HCl in the Treatment of Acute Musculoskeletal Spasm Associated With Low Back Pain" at ClinicalTrials.gov
- Ueno T, Kawana S (July 2007). "[A case of eperisone hydrochloride (myonal)--induced drug eruption leading to erythema and angioedema]". Arerugi (in Japanese) 56 (7): 709–13. PMID 17671415.
- Tanno K, Narimatsu E, Takeyama Y, Asai Y (May 2007). "Infantile case of seizure induced by intoxication after accidental consumption of eperisone hydrochloride, an antispastic agent". Am J Emerg Med 25 (4): 481–2. doi:10.1016/j.ajem.2006.09.002. PMID 17499672.
- EP 0310259 Eperisone as a hypotensive agent
- Fujioka M, Kuriyama H (December 1985). "Eperisone, an antispastic agent, possesses vasodilating actions on the guinea-pig basilar artery". J. Pharmacol. Exp. Ther. 235 (3): 757–63. PMID 3935775.
- Inoue S, Bian K, Okamura T, Okunishi H, Toda N (July 1989). "Mechanisms of action of eperisone on isolated dog saphenous arteries and veins" (– Scholar search). Jpn. J. Pharmacol. 50 (3): 271–82. doi:10.1254/jjp.50.271. PMID 2761129.[dead link]
- Viveksarathi, K., et al. "Dosage form design and evaluation of eperisone hydrochloride matrix film coated extended release tablets." Int J Pharm Pharm Sci 4.2 (2012): 575-581. http://www.ijppsjournal.com/Vol4Issue2/3559.pdf