[tye-ZAN-ih-deen] Pregnancy Category: C Zanaflex [Rx]
Classification: Skeletal muscle relaxant, centrally-acting
Action/Kinetics: Acts on central a-2 adrenergic receptors; reduces spasticity by increasing presynaptic inhibition of motor neurons. Greatest effects are on polysynaptic pathways. Peak effect: 1-2 hr. Duration: 3-6 hr. Extensive first pass metabolism. tV2: About 2.5 hr. Excreted in urine and feces. Elderly clear drug more slowly.
Uses: Acute and intermittent management of muscle spasticity. Contraindications: Use with a-2-adrenergic agonists. Special Concerns: Use with caution in renal impairment, in elderly and during laction. Use with extreme caution in hepatic insufficiency. Safety and efficacy have not been determined in children. Side Effects: Note: Side effects listed are those with a frequency of 0.1% or greater. Oral: Dry mouth. CV: Hypotension, vasodilation, postural hypotension, syncope, migraine, arrhythmia. GI: Hepatotoxicity, dry mouth, constipation, pharyngitis, vomiting, abdominal pain, diarrhea, dyspepsia, dysphagia, cholelithiasis, fecal impaction, flatulence, GI hemorrhage hepatitis, melena. CNS: Dizziness, dyskinesia, nervousness, somnolence, sedation, hallucinations, psychotic-like symptoms, depression, anxiety, paresthesia, tremor, emotional lability, seizures, paralysis, abnormal thinking, vertigo, abnormal dreams, agitation, depersonalization, euphoria, stupor, dysautonomia, neuralgia. GU: Urinary frequency, UTI, urinary urgency, cystitis, me-norrhagia, pyelonephritis, urinary retention, kidney calculus, enlarged uterine fibroids, vaginal moniliasis, vaginitis. Hematologic: Ecchymosis, anemia, leukopenia, leukocytosis. Musculoskeletal: Myasthenia, back pain, pathological fracture, arthral-gia, arthritis, bursitis. Respiratory: Sinusitis, pneumonia, bronchitis, rhinitis. Dermatologic: Rash, sweating, skin ulcer, pruritus, dry skin, acne, alopecia, urticaria. Body as a whole: Flu syndrome, weight loss, infection, sepsis, cellulitis, death, allergic reaction, moniliasis, malaise, asthenia, fever, abscess, edema. Ophthalmic: Glaucoma, amblyopia, conjunctivitis, eye pain, optic neuritis, retinal hemorrhage, visual field defect. Otic: Ear pain, tinnitus, deafness, otitis media. Miscellaneous: Speech disorder.
Alcohol / T Side effects of tizani-dine; additive CNS depressant effects
Alpha-2-Adrenergic agonists / Additive hypotensive effects Oral contraceptives / l Clearance of tizanidine
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