Tizanidin

Tizanidin
ATC Code M03BX02
Formula C9H8ClN5S
Molar Mass (g·mol−1) 253,71
Physical State solid
Melting Point (°C) 221–223
PKS Value 7.48
CAS Number 51322-75-9
PUB Number 5487
Drugbank ID DB00697
Solubility soluble in water

Basics

Tizanidine is a so-called alpha-2-receptor agonist and a representative of the group of centrally acting muscle relaxants. The main areas of application are the treatment of painful muscle tension, for example due to spinal complaints, the treatment after operations (e.g.: after herniated disc) or the symptomatic treatment of multiple sclerosis. Tizanidine requires a prescription and is mainly given in the form of tablets or capsules.

Pharmacology

Pharmacodynamics

Tizanidine binds with high affinity to alpha-2-adrenoreceptors, primarily in the patient's spinal cord. This inhibits the activity of excitatory amino acids, which are responsible for the excessive muscle tone. In addition to its relaxing effect, tizanidine also has moderate analgesic properties.

Pharmacokinetics

Tizanidine is absorbed through the intestine. Oral bioavailability is only 40% which is why the dose should be adjusted accordingly. Tizanidine is bound to plasma proteins at a rate of approximately 30%. The drug is degraded in the liver by the enzyme CYP1A2. The half-life averages about 2.5 hours and final elimination is almost entirely by the kidneys.

Drug interactions

Drugs that inhibit the enzyme CYP1A2 should not be taken concomitantly with tizanidine, as life-threatening elevated plasma levels of the drug may occur. These include: Fluvoxamine, ciprofloxacin, amiodarone, propafenone and mexiletine, cimetidine and some fluoroquinolones. Furthermore, a combination with the following substances is contraindicated: QT interval prolonging substances, antihypertensives, diuretics, beta-blockers, oral contraceptives and alcohol or other centrally depressant substances.

Toxicity

Possible side effects are:

  • Drowsiness, fatigue, dizziness.
  • bradycardia, tachycardia
  • hypotension, rebound hypertension
  • dry mouth, nausea, gastrointestinal disturbances

Use during pregnancy or lactation is not recommended. Tizanidine should be used here only if the benefit clearly outweighs the risk.

Toxicological data

LD50 (rat, oral): 414 mg/kg

Markus Falkenstätter

Markus Falkenstätter
Author

Markus Falkenstätter ist Autor zu pharmazeutischen Themen in der Medizin-Redaktion von Medikamio. Er befindet sich im letzten Semester seines Pharmaziestudiums an der Universität Wien und liebt das wissenschaftliche Arbeiten im Bereich der Naturwissenschaften.

Mag. pharm Stefanie Lehenauer

Mag. pharm Stefanie Lehenauer
Lector

Stefanie Lehenauer ist seit 2020 freie Autorin bei Medikamio und studierte Pharmazie an der Universität Wien. Sie arbeitet als Apothekerin in Wien und ihre Leidenschaft sind pflanzliche Arzneimittel und deren Wirkung.

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The contents shown do not replace the original package insert of the medicinal product, especially with regard to dosage and effect of the individual products. We cannot assume any liability for the correctness of the data, as the data was partly converted automatically. A doctor should always be consulted for diagnoses and other health questions. Further information on this topic can be found here.