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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/04/26 17:38:47」(JST)

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Tizanidine (trade names Zanaflex, Sirdalud) is a drug that is used as a muscle relaxant. It is a centrally acting α₂ adrenergic agonist. It is used to treat the spasms, cramping, and tightness of muscles caused by medical problems such as multiple sclerosis, ALS, spastic diplegia, back pain, or certain other injuries to the spine or central nervous system. It is also prescribed off-label for migraine headaches, as a sleep aid, and as an anticonvulsant. It is also prescribed for some symptoms of fibromyalgia.^[1]

Tizanidine has been found to be as effective as other antispasmodic drugs and has superior tolerability to that of baclofen and diazepam.^[2] Tizanidine can be very strong even at the 2 mg dose and may cause hypotension, so caution is advised when it is used in patients who have a history of orthostatic hypotension, or when switching from gel cap to tablet form and vice versa.

Tizanidine can occasionally cause liver damage, generally the hepatocellular type. Clinical trials show that up to 5% of patients treated with tizanidine had elevated liver function test values, though symptoms disappeared upon withdrawal of the drug. Care should be used when first beginning treatment with tizanidine with regular liver tests for the first 6 months of treatment.

Availability

Tizanidine is supplied as 2 and 4 mg tablets for oral administration, and in gel cap form in doses of 2 mg, 4 mg, and 6 mg.

The tablets are composed of the active ingredient, tizanidine hydrochloride (2.288 mg equivalent to 2 mg tizanidine base and 4.576 mg equivalent to 4 mg tizanidine base), and the inactive ingredients, silicon dioxide colloidal, stearic acid, microcrystalline cellulose and anhydrous lactose.

Interactions

Concomitant use of tizanidine and moderate or potent CYP1A2 inhibitors is contraindicated. Concomitant use of tizanidine with fluvoxamine, a potent CYP1A2 inhibitor in man, resulted in a 33-fold increase in the tizanidine AUC (plasma drug concentration-time curve).^{[citation needed]} Flouroquinolone antibiotics such as moxifloxacin, levofloxacin, and ciprofloxacin should also be avoided due to an increased serum concentration of tizanidine when administered concomitantly.^[3] Tizanidine is a potent sedative.^{[citation needed]} It therefore has the potential to interact with other CNS depressants. Alcohol should be avoided, particularly as it can upset the stomach.

It has a volume of distribution of 2.6L (per manufacturers notes).

Side effects

Side effects include dizziness, drowsiness, weakness, nervousness, depression, vomiting, tingling sensation in the arms, legs, hands, and feet, dry mouth, constipation, diarrhea, stomach pain, heartburn, increased muscle spasms, back pain, rash and sweating.^[4]

References

^ Zanaflex for Fibromyalgia
^ Kamen, L.; Henney, HR.; Runyan, JD. (Feb 2008). "A practical overview of tizanidine use for spasticity secondary to multiple sclerosis, stroke, and spinal cord injury.". Curr Med Res Opin 24 (2): 425–39. doi:10.1185/030079908X261113. PMID 18167175.
^ http://www.drugs.com/tizanidine.html
^ Tizanidine - PubMed Health

UpToDate Contents

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2. 成人における緊張型頭痛：予防的治療 tension type headache in adults preventive treatment
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4. 成人における多発性硬化症の症状のマネージメント symptom management of multiple sclerosis in adults
5. クロニジンおよびイミダゾリンによる中毒 clonidine and related imidazoline poisoning

English Journal

Evaluation of tizanidine as a marker of canine CYP1A2 activity.

Locuson CW1, Williams P2, Adcock JM2, Daniels JS1.
Journal of veterinary pharmacology and therapeutics.J Vet Pharmacol Ther.2015 Jul 30. doi: 10.1111/jvp.12256. [Epub ahead of print]
The dog CYP1A2 enzyme is likely an important contributor to the metabolism of veterinary drugs. Dog CYP1A2 is expressed in liver, plus it is inducible and polymorphic, creating the potential for intersubject differences in pharmacokinetics. Hence, the ability to probe dog CYP1A2 activity and inhibit
PMID 26228837

Interventions to Reduce Spasticity and Improve Function in People With Chronic Incomplete Spinal Cord Injury: Distinctions Revealed by Different Analytical Methods.

Duffell LD1, Brown GL2, Mirbagheri MM3.
Neurorehabilitation and neural repair.Neurorehabil Neural Repair.2015 Jul;29(6):566-76. doi: 10.1177/1545968314558601. Epub 2014 Nov 14.
BACKGROUND: Spinal cord injury (SCI) results in impaired function, and ankle joint spasticity is a common secondary complication. Different interventions have been trialed with variable results.OBJECTIVE: We investigated the effects of pharmacological and physical (locomotor training) interventions
PMID 25398727

A severe interaction between Tizanidine and Ciprofloxacin.

Abd-Elsayed A1, Elsharkawy H2, Sakr W2.
Journal of clinical anesthesia.J Clin Anesth.2015 Jun 29. pii: S0952-8180(15)00176-2. doi: 10.1016/j.jclinane.2015.05.016. [Epub ahead of print]
PMID 26138629

Japanese Journal

チザニジンの副作用に関する実態調査 : Cytochrome P450 1A2に影響する薬剤の併用との関連

百賢二,本間真人,松本早矢香 [他],佐々木忠徳,幸田幸直
YAKUGAKU ZASSHI 133(2), 275-281, 2013
… The drug-drug interactions of tizanidine and cytochrome (CYP) P450 1A2 inhibitors, which potentially alter the hepatic metabolism of tizanidine, were investigated by retrospective survey of medical records with regard to prescription. … One thousand five hundred sixty-three patients treated with tizanidine at University of Tsukuba Hospital were investigated. …
NAID 130003361895

Effects of Mexiletine, a CYP1A2 Inhibitor, on Tizanidine Pharmacokinetics and Pharmacodynamics

Momo Kenji,Homma Masato,Osaka Yoshiko,Inomata Shin-ichi,Tanaka Makoto,Kohda Yukinao,本間真人,猪股伸一,田中誠,幸田幸直
Journal of clinical pharmacology 50(3), 331-337, 2010-03
… The aim of this study was to determine whether mexiletine, a CYP1A2 inhibitor, altered the pharmacokinetics and pharmacodynamics of tizanidine. … The pharmacokinetics of tizanidine were examined in an open-label study in 12 healthy participants after a single dose of tizanidine (2 mg) with and without mexiletine coadministration (50 mg, 3 times as a pretreatment for a day and 2 times on the study day). …
NAID 120002836938

Involvement of Supraspinal Imidazoline Receptors and Descending Monoaminergic Pathways in Tizanidine-Induced Inhibition of Rat Spinal Reflexes

Kino Yurika,Tanabe Mitsuo,Honda Motoko [他],ONO Hideki
Journal of pharmacological sciences 99(1), 52-60, 2005-09-20
… The neuronal pathways involved in the muscle relaxant effect of tizanidine were examined by measurement of spinal reflexes in rats. … Tizanidine (i.v. … Depletion of central noradrenaline by 6-hydroxydopamine abolished the depressant effect of tizanidine on the MSR almost completely and attenuated the effect on the DSR. …
NAID 10025730341

Related Pictures

★リンクテーブル★

リンク元	「チザニジン」
拡張検索	「tizanidine hydrochloride」

「チザニジン」

Tizanidine
Systematic (IUPAC) name
	5-chloro-N-(4,5-dihydro-1H-imidazol-2-yl)benzo[c][1,2,5]thiadiazol-4-amine
Clinical data
Trade names	Zanaflex
AHFS/Drugs.com	monograph
MedlinePlus	a601121
Pregnancy cat.	C
Legal status	℞-only (US)
Routes	Oral, Intranasal, Injection
Pharmacokinetic data
Protein binding	30%
Metabolism	CYP 1A2
Half-life	2.54 hours
Identifiers
CAS number	51322-75-9
ATC code	M03BX02
PubChem	CID 5487
DrugBank	DB00697
ChemSpider	5287
UNII	6AI06C00GW
KEGG	D08611
ChEMBL	CHEMBL1079
Synonyms	4-chloro-N-(4,5-dihydro-1H-imidazol-2-yl)-8-thia-7,9-diazabicyclo[4.3.0]nona-2,4,6,9-tetraen-5-amine
Chemical data
Formula	C9H8ClN5S
Mol. mass	253.712 g/mol
	SMILES Clc1ccc3nsnc3c1NC/2=N/CCN\2;
	InChI InChI=1S/C9H8ClN5S/c10-5-1-2-6-8(15-16-14-6)7(5)13-9-11-3-4-12-9/h1-2H,3-4H2,(H2,11,12,13) ; Key:XFYDIVBRZNQMJC-UHFFFAOYSA-N ;
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