Tizanidine is an α2-adrenergic agonist that can produce hypotension. Syncope has been reported in the post marketing setting. The chance of significant hypotension
may possibly be minimized by titration of the dose and by focusing attention on signs and symptoms of hypotension prior to dose advancement. In addition, patients
moving from a supine to fixed upright position may be at increased risk for hypotension and orthostatic effects.
Monitor for hypotension when Zanaflex is used in patients receiving concurrent antihypertensive therapy. It is not recommended that Zanaflex be used with other α2-
adrenergic agonists. Clinically significant hypotension (decreases in both systolic and diastolic pressure) has been reported with concomitant administration of either
fluvoxamine or ciprofloxacin and single doses of 4 mg of Zanaflex. Therefore, concomitant use of Zanaflex with fluvoxamine or with ciprofloxacin, potent inhibitors of
CYP1A2, is contraindicated [see Contraindications (4) and Drug Interactions
Risk of Liver Injury
Zanaflex may cause hepatocellular liver injury. Zanaflex should be used with caution in patients with any hepatic impairment.. Monitoring of aminotransferase levels is
recommended for baseline and 1 month after maximum dose is achieved, or if hepatic injury is suspected. [see Dosage and Administration and Use in Specific
Zanaflex can cause sedation, which may interfere with everyday activity. In the multiple dose studies, the prevalence of patients with sedation peaked following the first
week of titration and then remained stable for the duration of the maintenance phase of the study. The CNS depressant effects of Zanaflex with alcohol and other CNS
depressants (e.g., benzodiazepines, opioids, tricyclic antidepressants) may be additive. Monitor patients who take Zanaflex with another CNS depressant for symptoms
of excess sedation.
Zanaflex use has been associated with hallucinations. Formed, visual hallucinations or delusions have been reported in 5 of 170 patients (3%) in two North American
controlled clinical studies. Most of the patients were aware that the events were unreal. One patient developed psychosis in association with the hallucinations.