Zanaflex  

Tizanidine
Systematic (IUPAC) name
5-chloro-N-(4,5-dihydro-1H-imidazol-2-yl)-2,1,3-benzothiadiazol-4-amine
Identifiers
CAS number	51322-75-9
ATC code	M03BX02
PubChem	5487
DrugBank	APRD00128
ChemSpider	5287
Chemical data
Formula	C9H8ClN5S
Mol. mass	253.712
SMILES	eMolecules & PubChem
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
Pharmacokinetic data
Bioavailability	?
Protein binding	30%
Metabolism	CYP 1A2
Half life	2.54 hours
Excretion	?
Therapeutic considerations
Pregnancy cat.	?
Legal status	Rx-Only, Unscheduled
Routes	Oral, Intranasal, Injection

Tizanidine (brandnames Zanaflex, Sirdalud) is a drug that is used as a muscle relaxant. It is a centrally acting -2 adrenergic agonist. It is used to treat the spasms, cramping, and tightness of muscles caused by medical problems such as multiple sclerosis, 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 may cause hypotension, so caution is advised when it is used in patients who have a history of orthostatic hypotension. Use caution with this drug as it can be very strong even at the 2 mg dose. Also use caution when switching from gel cap to tablet form and vice versa.

Availability

Tizanidine is available in tablets with "cor 138" on one side and 2 scores on the back that create an X, or R179 on one side and a single score through the middle of the back, or a white oval pill with R180 on one side and 2 scores on the back that create an X, or a round white tablet with E 44 on one side, and is double scored on the other side. It is also found as a circular white pill with the number 503 on one side and X-scored on the back^[2].

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.

Side effects

Tizanidine use occasionally causes drug induced liver injury. In controlled clinical studies, approximately 5% of patients treated with Zanaflex had elevations of liver function tests (ALT, AST) to greater than 3 times the upper limit of normal (or 2 times if baseline levels were elevated).^{[citation needed]}

Tizanidine use has been associated with hallucinations. Visual hallucinations and delusions have been reported in 5 of 170 patients (3%) in two North American controlled clinical studies.^{[citation needed]}

If therapy needs to be discontinued, especially in patients who have been receiving high doses for long periods, the dose should be decreased slowly to minimize the risk of withdrawal and rebound hypertension, tachycardia, and hypertonia.

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) by fluvoxamine.

References

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Recent Zanaflex Forums  View All  

What Is It? round pill with a cross on one side and M 724 on the other side. does anyone know what this is? Wednesday, 9/30/2009 8:56:09 PM  1 Reply

Abuse Of Zanaflex I was just wondering if anyone out there has ever abused zanaflex. I am ashamed to admit I did. I was just so desperate to sleep at night. One or two wasn't cutting it so I started going up to 6, 7, or 8 at I time. I would never ever recommend this for anyone. It was just my own desperation and stupidity. I have always had giant tolerances to everything. Anyway, this stuff would put me down hard, it was hard to get up and walk myself to the bathroom and the other thing was the vivid hallucinations, i have never experienced anything like it before. Everything I was seeing was so real it was scary and I would even see people and hold conversations with them. In the morning i would be completely fine. Thankfully i am in treatment for addiction now to various other substances. I just never heard a story about this from anyone else, it was just so crazy. Sunday, 9/13/2009 11:11:15 PM  2 Replies

Zanaflex What side effects has anyone experienced with this drug? Sunday, 8/23/2009 5:09:56 PM  1 Reply

Zanaflex i have recently been prescribed zanaflex. I was told it's a mix of xanax and flexirl. I was just wondering if anyone else has taken the drug and does food really effect it. Tuesday, 4/28/2009 4:19:27 PM  1 Reply

Ri80 Does anyone know what this pill is used for or can it be for numerous things. I found one in my home on the floor and it is not ours. I pray my grandson didn't get it somwhere, but is possible!! Thursday, 2/19/2009 3:50:42 PM  1 Reply

Zanaflex how long does zanaflex stay in ur system? anyone know? Thursday, 2/12/2009 11:36:35 PM  Post a Reply