Acorda Therapeutics and the FDA have informed healthcare professionals of changes to the CONTRAINDICATIONS and WARNINGS Sections of the product labeling for Zanaflex (tizanidine), a medication used for a variety of purposes including the relief of spasticity related to neurological disorders, as a treatment of restless legs syndrome associated with these diseases, by patients with fibromyalgia, and as a chronic headache and migraine preventive.

In pharmacokinetic studies where tizanidine was coadministered with
either fluvoxamine (the antidepressant Luvox) or ciprofloxacin (the
antibiotic Cipro) (CYP1A2 inhibitors), the serum concentration of
tizanidine was significantly increased and potentiated its hypotensive
and sedative effects. Although there are no clinical studies evaluating
the effects of other CYP1A2 inhibitors on tizanidine, coadministration
of tizanidine with other CYP1A2 inhibitors [zileuton (for asthma), other
fluroquinolones, antiarrythmics, cimetidine (Tagamet), famotidine
(pepcid), oral contraceptives, acyclovir (Zovirax) and ticlopidine
(Ticlid)] should be avoided. If their use is clinically necessary, they
should be used with caution.

If you're taking Zanaflex (tizanidine) with any of the medications
listed in the MedWatch warning, you may wish to consult your doctor
about this issue. Do not discontinue your medications without consulting
your physician.

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Resources:

MedWatch Safety Information. "Zanaflex (tizanidine hydrochloride)
Tablets and Capsules." April
11, 2007.

Healthcare Professional Letter. Acorda Therapeutics and the FDA.
"Updated Safety Informaiton: Contraindications to the use of Tizanidine."