Tizanidine

What it is and how it works

Mechanism of Action Tizanidine is a central alpha-2-adrenergic receptor agonist and presumably reduces spasticity by increasing presynaptic inhibition of motor neurons. The effects of tizanidine are greatest on polysynaptic pathways. The effect of these actions is thought to reduce facilitation of spinal motor neurons.

Indications

Tizanidine Tablets, USP is a central alpha-2-adrenergic agonist indicated for the management of spasticity. Because of the short duration of therapeutic effect, treatment with Tizanidine Tablets, USP should be reserved for those daily activities and times when relief of spasticity is most important . Tizanidine Tablets, USP is a central alpha-2-adrenergic agonist indicated for the management of spasticity. Because of the short duration of therapeutic effect, treatment with Tizanidine Tablets, USP should be reserved for those daily activities and times when relief of spasticity is most important [ see Dosage and Administration ].

Dosage and administration (summary)

• Recommended starting dose: 2 mg; dose can be repeated at 6 to 8 hour intervals, up to a maximum of 3 doses in 24 hours • Dosage can be increased by 2 mg to 4 mg per dose, with 1 to 4 days between increases; total daily dose should not exceed 36 mg • Tizanidine pharmacokinetics differs between tablets and capsules, and when taken with or without food. These differences could result in a change in tolerability and control of symptoms ( 2.1 , 12.3 ) • To discontinue Tizanidine Tablets, USP, decrease dose slowly to minimize the risk of withdrawal and rebound hypertension, tachycardia, and hypertonia Dosing Information Tizanidine Tablets, USP tablets may be prescribed with or without food.

Contraindications

Tizanidine Tablets, USP is contraindicated in patientstaking potent inhibitors of CYP1A2, such as fluvoxamine or ciprofloxacin [ see Drug Interactions (7.1 , 7.2 ) ]. Concomitant use with potent inhibitors of CYP1A2, such as fluvoxamine or ciprofloxacin ( 4 , 5.5 , 7.1 , 7.2 )

Warnings and precautions

• Hypotension: monitor for signs and symptoms of hypotension, in particular in patients receiving concurrent antihypertensives; Tizanidine Tablets, USP should not be used with other α 2 -adrenergic agonists ( 5.1 , 7.7 ) • Risk of liver injury: monitor ALTs; discontinue Tizanidine Tablets, USP if liver injury occurs • Sedation: Tizanidine Tablets, USP may interfere with everyday activities.

Pregnancy

Pregnancy Pregnancy Category C Tizanidine Tablets, USP has not been studied in pregnant women. Tizanidine Tablets, USP should be given to pregnant women only if the benefit outweighs the risk to the unborn fetus.

Storage and supply

Tizanidine Tablets, USP 4 mg are available as; white to off-white, round, flat beveled, uncoated tablets debossed with product code “503” on one side, and quadrisecting score on the other.

Source: Tizanidine (Tizanidine) — US FDA prescribing information, 2023-11-09, DailyMed. Summarised and shortened; the full label governs. Iranian registration, indications and labelling may differ.