Below are the general guidelines for dosing tizanidine (Zanaflex). Note that these dosages may be adjusted on a case-by-case basis for individual patients. Always follow your prescribing physician’s instructions for taking tizanidine (Zanaflex).
The following information comes from DailyMed, an FDA label information provider.
What if I miss a dose of tizanidine?
According to Mayo Clinic, if you miss a dose of tizanidine, take it immediately unless you are closer to your next dose. Never double dose.
What if I overdose on tizanidine?
A review of the safety surveillance database revealed cases of intentional and accidental Zanaflex overdose. Some of the cases resulted in fatality and many of the intentional overdoses were with multiple drugs including CNS depressants. The clinical manifestations of tizanidine overdose were consistent with its known pharmacology. In the majority of cases a decrease in sensorium was observed including lethargy, somnolence, confusion and coma. Depressed cardiac function is also observed including most often bradycardia and hypotension. Respiratory depression is another common feature of tizanidine overdose.
Should overdose occur, basic steps to ensure the adequacy of an airway and the monitoring of cardiovascular and respiratory systems should be undertaken. Tizanidine is a lipid-soluble drug, which is only slightly soluble in water and methanol. Therefore, dialysis is not likely to be an efficient method of removing drug from the body. In general, symptoms resolve within one to three days following discontinuation of tizanidine and administration of appropriate therapy. Due to the similar mechanism of action, symptoms and management of tizanidine overdose are similar to that following clonidine overdose. For the most recent information concerning the management of overdose, contact a poison control center.
Note: seek medical help or call 911 immediately if you suspect a tizanidine ovrdose.
Dosage and Administration
Dosing Information
Zanaflex Capsules ® or Zanaflex ® tablets may be prescribed with or without food. Once the formulation has been selected and the decision to take with or without food has been made, this regimen should not be altered.
Food has complex effects on tizanidine pharmacokinetics, which differ with the different formulations. Zanaflex Capsules and Zanaflex tablets are bioequivalent to each other under fasting conditions (more than 3 hours after a meal), but not under fed conditions (within 30 minutes of a meal). These pharmacokinetic differences may result in clinically significant differences when switching administration of tablet and capsules and when switching administration between the fed or fasted state. These changes may result in increased adverse events, or delayed or more rapid onset of activity, depending upon the nature of the switch. For this reason, the prescriber should be thoroughly familiar with the changes in kinetics associated with these different conditions [ see CLINICAL PHARMACOLOGY (12.3)].
The recommended starting dose is 2 mg. Because the effect of Zanaflex peaks at approximately 1 to 2 hours post-dose and dissipates between 3 to 6 hours post-dose, treatment can be repeated at 6 to 8 hour intervals, as needed, to a maximum of three doses in 24 hours.
Dosage can be gradually increased by 2 mg to 4 mg at each dose, with 1 to 4 days between dosage increases, until a satisfactory reduction of muscle tone is achieved. The total daily dose should not exceed 36 mg. Single doses greater than 16 mg have not been studied.
Dosing in Patients with Renal Impairment
Zanaflex should be used with caution in patients with renal insufficiency (creatinine clearance < 25 mL/min), as clearance is reduced by more than 50%. In these patients, during titration, the individual doses should be reduced. If higher doses are required, individual doses rather than dosing frequency should be increased [ see WARNINGS AND PRECAUTIONS (5.7)].
Dosing in Patients with Hepatic Impairment
Zanaflex should be used with caution in patients with any hepatic impairment. In these patients, during titration, the individual doses should be reduced. If higher doses are required, individual doses rather than dosing frequency should be increased. Monitoring of aminotransferase levels is recommended for baseline and 1 month after maximum dose is achieved, or if hepatic injury is suspected. [ see USE IN SPECIFIC POPULATIONS (8.7)]
Drug Discontinuation
If therapy needs to be discontinued, particularly in patients who have been receiving high doses (20 mg to 36 mg daily) for long periods (9 weeks or more) or who may be on concomitant treatment with narcotics, the dose should be decreased slowly (2 mg to 4 mg per day) to minimize the risk of withdrawal and rebound hypertension, tachycardia, and hypertonia [ see DRUG ABUSE AND DEPENDENCE (9.3)].
How is tizanidine supplied?
Zanaflex Capsules®
Zanaflex Capsules ® (tizanidine hydrochloride) capsules are available in three strengths as two-piece hard gelatin capsules containing tizanidine hydrochloride 2.29 mg, 4.58 mg and 6.87 mg, equivalent to 2 mg, 4 mg and 6 mg tizanidine base, respectively.
- The 2 mg capsules have a light blue opaque body with a light blue opaque cap with “2 MG” printed on the cap: bottles of 150 capsules (NDC 10144-602-15)
- The 4 mg capsules have a white opaque body with a blue opaque cap with “4 MG” printed on the cap: bottles of 150 capsules (NDC 10144-604-15)
- The 6 mg capsules have a blue opaque body with a white stripe and blue opaque cap with “6 MG” printed on the capsules: bottles of 150 capsules (NDC 10144-606-15)
Store at 25°C (77°F); excursions permitted to 15-30°C (59-86°F) [see USP Controlled Room Temperature]. Dispense in containers with child resistant closure.
Zanaflex® Tablets
Zanaflex ® (tizanidine hydrochloride) tablets are available as 4 mg white, uncoated tablets containing tizanidine hydrochloride 4.58 mg, equivalent to 4 mg tizanidine base. The tablets have a quadrisecting score on one side and are debossed with “A594” on the other side. Tablets are provided as follows: bottles of 150 tablets (NDC 10144-594-15).
Store at 25°C (77°F); excursions permitted to 15-30°C (59-86°F) [see USP Controlled Room Temperature].
Dispense in containers with child resistant closure .
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