Tizanidine - Uses, Dosage, Side Effects, and More

Overview

Tizanidine is used widely in the treatment of muscular spasms. It belongs to the group of alpha-two adrenergic agonists. Neuromuscular disorders like multiple sclerosis can be managed by the drug Tizanidine. The medicine helps treat muscle spasticity, which can be quite painful. Tizanidine helps to relax the affected muscles, thereby alleviating pain. Tizanidine was approved by the FDA (Food and Drug Administration) in 1996 for the treatment of muscle spasms. The article further sheds light on the mechanism of action, pharmacological considerations, and the effectiveness of Tizanidine in specific populations.

What Is Tizanidine Used For?

• Used in the reduction of muscle spasms due to neuromuscular disorders like multiple sclerosis.

• Helps in managing MS-related pain, particularly back pain due to muscle spasticity.

• It does not completely cure the condition but helps increase the effectiveness of physiotherapy in patients with muscle spasms.

• It helps reduce muscle tightness and relax muscles in patients with various injuries, including spinal and acquired brain injuries.

• In cases of stroke and TBI (traumatic brain injury).

Drug Class: Tizanidine belongs to the drug class called muscle relaxants. It is further categorized as a centrally acting muscle relaxant and as an alpha-2 adrenergic agonist.

Doses: The drug Tizanidine is available in two forms:

• Oral Capsules: It is available in doses of 2 mg (milligrams), 4mg, and 6 mg.

• Oral Tablets: It is available in a dosage of 2 mg, 4 mg, and 6 mg.

Warnings and Precautions

The following are warnings and precautions to keep in mind while using Tizanidine.

• Risk of Blurred Vision: Tizanidine may cause drowsiness, unsteadiness, and vision disturbances, so it is advised to avoid any heavy machinery usage and driving when under the drug Tizanidine.

• Risk of Liver Disease: Tizanidine can cause liver disease. Inform the doctor immediately if you experience symptoms like abdominal pain, pale stools, or yellowing of the skin or eyes after starting the drug.

• Risk of Anaphylactic Reactions: The drug Tizanidine carries a risk of severe anaphylactic or hypersensitive reactions, which can be life-threatening. Inform the doctor if any signs of allergy develop after starting the medication.

• Risk of Dry Oral Mucosa: Tizanidine may cause dry mouth. If you experience a dry sensation in the oral mucosa, inform the doctor. The doctor may prescribe sugar-free chewing gum or candies to help manage dry mouth.

For Patients

What Is Tizanidine?

Tizanidine is an alpha-2 receptor agonist that inhibits motor neurons at presynaptic endings. It is a centrally acting drug that inhibits excitatory amino acids, such as aspartate and glutamate, that cause muscle spasms.

When and Why to Take Tizanidine?

The drug Tizanidine should be consumed in the exact doses and scheduled as prescribed by the doctor. It is usually prescribed by the doctor for the management of muscle spasticity and to reduce muscle spasms, after a thorough clinical examination and diagnosis of the underlying causes of muscle stiffness. The doctor usually suggests it in cases of muscle spasms due to neuromuscular disorders like multiple sclerosis, acquired brain injuries, stroke, or spinal cord injuries.

Things to Inform The Doctor Before They Prescribe Tizanidine Medication

• In case of any allergy to any drug or its composition.

• In case of any underlying medical history like diabetes, hypertension, liver disease, etc.

• Inform the doctor if any medications (prescribed or non-prescribed) like Ciprofloxacin, vitamin supplements, antihistamines, or CNS (central nervous system) depressants are ongoing. These drugs may result in drug interactions, which may lead to the worsening of symptoms. The doctor usually stops these drugs or might replace them with an alternate drug regimen before starting Tizanidine.

• Inform the doctor if undergone any surgeries in the past.

• Inform in case of pregnancy or planning for pregnancy.

• Breastfeeding mothers should inform their doctors about their health status.

How To Take Tizanidine?

• Tizanidine tablets or capsules should be taken orally with water, with or without food, at the doses and schedule the doctor recommends, based on the clinical condition and diagnosis. The doctor usually suggests the drug three times daily.

• The tablet or capsule should be taken whole; it is advised not to crush or chew the tablets, and not to open the capsules while taking the medication.

• It is advised not to stop taking the drug suddenly without the doctor's consent.

Things to Do After One Starts Taking Tizanidine:

• Look for any adverse events if present and report them to the doctor immediately.

• Check for symptom improvement and update the doctor on the follow-up visit.

• If symptoms worsen, inform the doctor.

What Are the Side Effects of Tizanidine?

Common Side Effects of Tizanidine are

• Blurred vision.

• Drowsiness.

• Lethargy.

• Hallucination.

• Dry mouth.

• Dizziness.

• Constipation.

• Rhinitis (swelling of the mucous membranes of the nose).

• Asthenia (weakness).

• Abdominal pain.

• Nausea and vomiting.

• Back pain.

• Tingling sensation in the feet and hands.

Serious Side Effects:

• Liver failure.

• Anaphylactic reaction.

• Dermatitis (swelling of the skin).

• Hypotension.

• Severe bradycardia.

• Hypokalemia (low potassium).

• Loss of appetite.

• Yellowish discoloration of skin or eyes.

• Unusual bleeding.

Withdrawal Symptoms:

• Tachycardia (increased heart rate).

• Rebound hypertension.

• Muscle spasticity.

• Other withdrawal symptoms might occur due to the abrupt stopping of drugs.

If any of the above side effects are noticed, the doctor is advised to inform them immediately.

Dietary Alterations: No dietary alterations are needed while on Tizanidine. It is advised to avoid alcohol when under Tizanidine, as the drug can react with alcohol and can result in hallucinations and increased drowsiness.

What Should Be Done if the Dose Is Missed?

Take the missed dose as soon as you remember. One should not take a double dose of the drug to compensate for the missed one. If it is time for the next dose, skip the missed dose and continue with the regular dose of the drug.

What Should Be Done in Case of Overdose?

In case of an overdose of the drug Tizanidine, try calling the poison control helpline immediately.

Overdose of the drug Tizanidine can result in different symptoms, like:

• Lethargy.

• Confusion.

• Shallow breathing.

• Feeling unconscious.

• Reduce heart rate.

Avoid Self-Prescription: The drug is not available over the counter. It should be started only under the doctor's supervision, after a thorough clinical examination of the patient's condition.

For Doctors:

Indications:

• Used in the reduction of muscle spasms.

• Muscle spasticity due to stroke and TBI (traumatic brain injury).

• Management of muscle pain due to spine injury or acquired brain injury.

• Management of headaches and back pain.

Contraindications:

• Hypersensitivity Reactions: Patients allergic to the drug or its composition.

• Patients With Liver Disease: In patients with liver diseases, the drug Tizanidine should be used very cautiously or should be avoided, as multiple research has proved that the drug Tizanidine can result in liver failure and death.

• Patients With Kidney Diseases: In patients with kidney disorders, drug dose adjustment is needed. Tizanidine should be used cautiously in patients with kidney diseases as the renal clearance of the drug is quite low (less than 25 milliliters per minute), which may result in renal toxicity.

What Are the Pharmacological Aspects of Tizanidine?

1. Mechanism of Action:

Tizanidine is an alpha-two receptor agonist that acts by inhibiting motor neurons at the presynaptic terminal, which results in a reduction in the release of glutamate and aspartate (excitatory amino acids). The reduction in the release of these amino acids can lead to reduced muscle spasms and improved management of muscle spasticity by inhibiting motor neurons.

2. Pharmacodynamics:

Tizanidine helps manage muscle spasticity by acting as an agonist on the alpha-two-adrenergic receptor sites.

3. Chemical Taxonomy:

• Kingdom - Organic compound.

• Superclass - Organoheterocyclic compounds.

• Class - Benzothiadiazole.

• Direct Parent - Benzothiadiazole.

Ingredients:

A. Active Ingredients:

The only active ingredient is Tizanidine HCL.

B. Inactive Ingredients:

• Silicon dioxide.

• Stearic acid.

• Microcrystalline cellulose.

• Lactose monohydrate.

• Anhydrous lactose.

4. Pharmacokinetics:

• Absorption: The oral bioavailability of the drug Tizanidine is around 40 percent. According to the research, the food increases the absorption of Tizanidine.

• The Volume of Distribution: The drug Tizanidine has an average steady-state volume of distribution of 2.4 liters per kilogram.

• Protein Binding: Tizanidine is bound to almost 30 percent of the plasma proteins.

• Metabolism: Tizanidine is metabolized by almost 95 percent after consumption by the enzyme CYP1A2 (Cytochrome P450).

• Elimination: The route of elimination of the drug Tizanidine is mainly through the kidneys.

• Half-Life: The average half-life of the drug is approximately two and a half hours.

• Dosage: Tizanidine is available as oral capsules and tablets in doses of 2 mg, 4mg, and 6mg. The dose of both the capsule and tablet starts with 2 mg orally. There should be a minimum 6-hour gap between the two doses. The doctor usually increases the dose gradually from 2 mg to 4 mg based on the symptoms presented by the patient. The maximum dose should not exceed more than 36 mg per day. The doctors usually taper the drug from high to low doses before completely stopping the drug to minimize the withdrawal symptoms.

• Storage: The drug Tizanidine should be stored in an airtight container at room temperature. Keep the drug away from moisture and heat. Keep the medicine out of reach of children and pets. Dispose of the expired medicines carefully.

How Does Tizanidine Work?

As a muscle relaxant, tizanidine has the greatest effect on the body's nervous system. This is because of its properties as an alpha-2 adrenergic agonist, which means it binds to alpha-2 receptors in the brain and spinal cord. The binding slows the release of excitatory neurotransmitters that lead to muscle contraction and also impairs the efficiency of nerve signals. Tizanidine can usually be prescribed for spasticity or muscular spasms resulting from multiple sclerosis or a spinal cord injury, for example. Its sedative properties can also contribute to patients’ comfort and help them feel less stiff and more active overall.

Administration of the Drug:

The drug Tizanidine is prescribed to the patient to be consumed orally in doses of 2 mg, 4 mg, or 6 mg based on the patient's conditions. The doctor usually tapers the drug before stopping the drug.

Toxicity:

The recommended dose of the drug Tizanidine is a maximum of 36 mg per day. Crossing the average maximum dose may be lethal and can result in various toxic symptoms, like:

• Coma.

• Low heart rate.

• Agitation.

• Weakness.

• Hypotension (low blood pressure).

• Altered mental status.

Management of Tizanidine Toxicity: There is no known antidote for Tizanidine toxicity. However, a few measures can be taken to manage the toxicity:

• Continuous airway monitoring in patients with Tizanidine overdose.

• Intravenous fluids and vasopressors should be administered as needed.

• The drug Naloxone, when administered intravenously at a dose of 10 mg, has been shown to be effective in managing Tizanidine toxicity to a certain extent in research; however, Naloxone does not reverse hemodynamic (blood circulation) parameters.

What Other Drugs Will Affect Tizanidine?

The following are the drug interactions of Tizanidine:

• The drug Tizanidine increases the severity of the adverse events if combined with Benzodiazepines and Acetazolamide.

• The drug serum concentration increases when combined with Abemetapir.

• The drug Tizanidine, when combined with Abatacept, increases its metabolism.

• The efficacy of the drug Tizanidine is reduced when combined with Acebutolol.

• The drug Tizanidine can result in increased sedation and cardiac toxicity when combined with alcohol.

• The drug Tizanidine, when given along with Ciprofloxacin, can result in an increased risk of psychomotor impairment.

Use In Specific Populations:

• Tizanidine in Pregnant and Lactating Women: The drug Tizanidine should be used only if indicated by healthcare professionals, based on careful evaluation of the risk-benefit matrix for each patient. It can be used to manage spinal injuries in pregnant females if indicated. The safety and efficacy of the drug's use in breastfeeding mothers have yet to be established, so it should be avoided in lactating women.

• Tizanidine in Patients with Liver Disease: According to numerous research, Tizanidine can result in liver failure and death due to its excessive metabolism in the liver, so it should be avoided or used very cautiously in patients with underlying liver disorders.

• Tizanidine in Patients with Kidney Disease: According to research, the drug has a very low renal clearance rate of approximately 25 mL per minute. It is advised to use the drug safely in patients with underlying kidney disease. Drug dose adjustment is needed in such patients.