Zanaflex Indications… Dosage
- multiple sclerosis
- spasticity
- spinal cord trauma
Zanaflex (Tizanidine) Indications… Dosage
For the acute and intermittent management of increased muscle tone associated with spasticity (including spasticity related to multiple sclerosis or spinal cord trauma):
NOTE: Because of its short duration, tizanidine should be reserved for activities and times when spasticity control is most important. Use tizanidine with caution when spasticity is beneficial to obtain increased function or to sustain posture and balance during movement.
Oral dosage:
Adults: A single dose of 8 mg PO reduces muscle tone in patients with spasticity for a period of several hours. Peak effects occur in 1-2 hours and lasts between 3-6 hours. The effects are dose-related. Because of dose-related adverse reactions, treatment should be initiated with single 4 mg PO dose and increased gradually in 2- 4 mg increments to optimum effect (satisfactory reduction of muscle tone at a tolerated dose). The dose can be repeated at 6-8 hour intervals, as needed, to a maximum of three doses in 24 hours. Experience with daily doses exceeding 24 mg or single doses exceeding 12 mg is limited. Maximum daily dosage is 36 mg/day. In one study by the manufacturer, the maximum dosage was given in three unequal doses to spinal cord injury patients (e.g., 10 mg in the morning and afternoon and 16 mg at night). Long-term experience with doses >= 8 mg or daily doses >= 24 mg is limited. Due to the potential for hepatotoxicity, monitoring of aminotransferase levels is recommended during the first 6 months of tizanidine therapy (e.g., baseline, 1, 3 and 6 months) and periodically thereafter, based on clinical status. Although there are no specific recommendations regarding discontinuation of therapy, increased spasticity may occur which may require increased tizanidine dosage or alternative therapy. It would be prudent to gradually reduce the dosage, while monitoring spasticity.
Elderly: Use the lower end of the adult dosage range. Use tizanidine cautiously in elderly patients; drug clearance may be decreased four-fold.
Children: Safe and effective use has not been established.
Maximum Dosage Limits:
- Adults: 36 mg/day PO.
- Elderly: 36 mg/day PO. Maximum doses of tizanidine should be used cautiously in elderly patients; drug clearance may be substantially decreased.
- Adolescents: Safe and effective use has not been established.
- Children: Safe and effective use has not been established.
Patients with hepatic impairment:
Because of potential hepatoxicity due to tizanidine, the drug should be avoided or used with extreme caution in patients with hepatic impairment. Tizanidine has not been studied in patients with hepatic disease.
Patients with renal impairment:
CrCl < 25 ml/min: Use lower doses (e.g., 2-4 mg PO) initially during the dose titration. Increase the dose cautiously if needed to control spasticity. Monitor closely for side effects; tizanidine clearance is reduced > 50% in renally impaired patients.
Intermittent hemodialysis:
It is not known whether tizanidine is removed by hemodialysis; it appears that no supplemental dosage is needed following hemodialysis.
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