Tizanidine 4mg Tablets
It is used to relax muscles.It may be given to you for other reasons. Talk with the doctor.
Drug Class
Skeletal muscle relaxant
Pharmacologic Class
Alpha-2 adrenergic agonist
Pregnancy Category
Category C
FDA Approved
Dec 1996
DEA Schedule
Not Controlled
Overview
What is this medicine?
Tizanidine is a medication used to relax muscles and relieve muscle spasms caused by conditions like multiple sclerosis or spinal cord injury. It works by acting on the brain and spinal cord to reduce muscle stiffness and tightness.
How to Use This Medicine
Taking Your Medication Correctly
To use this medication safely and effectively, follow your doctor's instructions and read all the information provided. Take your medication with or without food, but be consistent in how you take it each time. If you take it with food, always take it with food. If you take it on an empty stomach, always take it on an empty stomach.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry place, avoiding the bathroom. Keep all medications in a safe location, out of the reach of children and pets. Dispose of unused or expired medications properly. Do not flush them down the toilet or pour them down the drain unless instructed to do so. If you have questions about disposing of your medication, consult your pharmacist. You may also want to check if there are drug take-back programs in your area.
What to Do If You Miss a Dose
If you take this medication regularly, take a missed dose as soon as you remember. However, if it's close to the time for your next dose, skip the missed dose and resume your regular schedule. Do not take two doses at the same time or take extra doses. If you take this medication as needed, do not take it more frequently than directed by your doctor.
To use this medication safely and effectively, follow your doctor's instructions and read all the information provided. Take your medication with or without food, but be consistent in how you take it each time. If you take it with food, always take it with food. If you take it on an empty stomach, always take it on an empty stomach.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry place, avoiding the bathroom. Keep all medications in a safe location, out of the reach of children and pets. Dispose of unused or expired medications properly. Do not flush them down the toilet or pour them down the drain unless instructed to do so. If you have questions about disposing of your medication, consult your pharmacist. You may also want to check if there are drug take-back programs in your area.
What to Do If You Miss a Dose
If you take this medication regularly, take a missed dose as soon as you remember. However, if it's close to the time for your next dose, skip the missed dose and resume your regular schedule. Do not take two doses at the same time or take extra doses. If you take this medication as needed, do not take it more frequently than directed by your doctor.
Lifestyle & Tips
- Avoid driving or operating heavy machinery until you know how tizanidine affects you, as it can cause drowsiness and dizziness.
- Avoid alcohol consumption while taking tizanidine, as it can increase drowsiness and other side effects.
- Do not stop taking tizanidine suddenly, especially if you have been on it for a long time or at high doses, as this can lead to withdrawal symptoms like high blood pressure, fast heart rate, and muscle spasms. Your doctor will guide you on how to slowly reduce the dose.
- Take tizanidine consistently with or without food. Do not switch between taking it with food and without food, as this can change how much medication your body absorbs and lead to unpredictable effects.
- Rise slowly from a sitting or lying position to avoid dizziness or fainting due to a drop in blood pressure.
Available Forms & Alternatives
Dosing & Administration
Adult Dosing
Standard Dose:
Initial 2 mg orally, may increase by 2-4 mg every 1-4 days. Usual therapeutic dose 8-24 mg/day in 3-4 divided doses. Max single dose 16 mg. Max daily dose 36 mg.
Dose Range:
2 - 36 mg
Condition-Specific Dosing:
spasticity:
Initial 2 mg, titrate slowly based on response and tolerability. Administer in 3 divided doses.
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Not established
Adolescent:
Not established
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment, but monitor for adverse effects.
Moderate:
No specific adjustment, but monitor for adverse effects.
Severe:
For CrCl < 25 mL/min, reduce initial dose to 2 mg once daily and titrate slowly based on response and tolerability. Monitor for adverse effects.
Dialysis:
Not well studied. Use with caution and monitor closely.
Hepatic Impairment:
Mild:
Use with caution, monitor LFTs.
Moderate:
Use with caution, monitor LFTs. Consider lower doses.
Severe:
Not recommended due to increased systemic exposure and potential for hepatotoxicity.
Pharmacology
Mechanism of Action
Tizanidine is an alpha-2 adrenergic agonist that acts centrally. It reduces spasticity by increasing presynaptic inhibition of motor neurons at the alpha-2 adrenergic receptor sites, primarily within the spinal cord. This leads to a reduction in the release of excitatory amino acids, which in turn inhibits polysynaptic reflexes.
Pharmacokinetics
Absorption:
Bioavailability:
Approximately 40%
Tmax:
1-2 hours
FoodEffect:
Food increases Cmax by approximately 33% and AUC by 20%. Tizanidine should be taken consistently with or without food to minimize variability in plasma concentrations.
Distribution:
Vd:
2.4 L/kg
ProteinBinding:
Approximately 30%
CnssPenetration:
Yes
Elimination:
HalfLife:
Approximately 2.5 hours (range 1.5-4 hours)
Clearance:
Not available (highly variable)
ExcretionRoute:
Renal (approximately 60% of dose)
Unchanged:
Approximately 60% (as metabolites), 20% (unchanged drug)
Pharmacodynamics
OnsetOfAction:
Within 1 hour
PeakEffect:
1-2 hours
DurationOfAction:
3-6 hours
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
While rare, some people may experience severe and potentially life-threatening side effects when taking this medication. If you notice any of the following symptoms, contact your doctor or seek immediate medical attention:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of liver problems, including:
+ Dark urine
+ Tiredness
+ Decreased appetite
+ Upset stomach or stomach pain
+ Light-colored stools
+ Vomiting
+ Yellow skin or eyes
Signs of a urinary tract infection (UTI), such as:
+ Blood in the urine
+ Burning or pain when passing urine
+ Frequent or urgent need to urinate
+ Fever
+ Lower stomach pain
+ Pelvic pain
Severe dizziness or fainting
Confusion
Hallucinations (seeing or hearing things that are not there)
Mood changes or changes in behavior
Slow heartbeat
Fever, chills, or sore throat
Other Possible Side Effects
Like all medications, this drug can cause side effects. Many people experience no side effects or only mild ones. If you notice any of the following side effects or any other unusual symptoms, contact your doctor for advice:
Dry mouth
Dizziness
Drowsiness
Fatigue
Weakness
Not all possible side effects are listed here. If you have questions or concerns about side effects, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
While rare, some people may experience severe and potentially life-threatening side effects when taking this medication. If you notice any of the following symptoms, contact your doctor or seek immediate medical attention:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of liver problems, including:
+ Dark urine
+ Tiredness
+ Decreased appetite
+ Upset stomach or stomach pain
+ Light-colored stools
+ Vomiting
+ Yellow skin or eyes
Signs of a urinary tract infection (UTI), such as:
+ Blood in the urine
+ Burning or pain when passing urine
+ Frequent or urgent need to urinate
+ Fever
+ Lower stomach pain
+ Pelvic pain
Severe dizziness or fainting
Confusion
Hallucinations (seeing or hearing things that are not there)
Mood changes or changes in behavior
Slow heartbeat
Fever, chills, or sore throat
Other Possible Side Effects
Like all medications, this drug can cause side effects. Many people experience no side effects or only mild ones. If you notice any of the following side effects or any other unusual symptoms, contact your doctor for advice:
Dry mouth
Dizziness
Drowsiness
Fatigue
Weakness
Not all possible side effects are listed here. If you have questions or concerns about side effects, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Severe drowsiness or sedation
- Dizziness or lightheadedness, especially when standing up
- Fainting
- Signs of liver problems (e.g., yellowing of skin or eyes, dark urine, persistent nausea or vomiting, unusual tiredness, stomach pain)
- Slowed heart rate
- Difficulty breathing
- Hallucinations
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the allergic reaction you experienced, including any symptoms that occurred.
If you are currently taking ciprofloxacin or fluvoxamine, as these medications may interact with this drug.
Please note that this is not an exhaustive list of all potential drug interactions or health concerns that may affect your use of this medication. Therefore, it is crucial to discuss all of your:
Prescription and over-the-counter (OTC) medications
Natural products
Vitamins
Health problems
with your doctor and pharmacist to ensure safe use. Do not initiate, discontinue, or modify the dosage of any medication without first consulting your doctor to confirm that it is safe to do so in conjunction with this medication.
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the allergic reaction you experienced, including any symptoms that occurred.
If you are currently taking ciprofloxacin or fluvoxamine, as these medications may interact with this drug.
Please note that this is not an exhaustive list of all potential drug interactions or health concerns that may affect your use of this medication. Therefore, it is crucial to discuss all of your:
Prescription and over-the-counter (OTC) medications
Natural products
Vitamins
Health problems
with your doctor and pharmacist to ensure safe use. Do not initiate, discontinue, or modify the dosage of any medication without first consulting your doctor to confirm that it is safe to do so in conjunction with this medication.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication.
To ensure your safety, avoid driving and other activities that require alertness until you understand how this medication affects you. When getting up from a sitting or lying down position, rise slowly to minimize the risk of dizziness or fainting. Be cautious when using stairs.
Before consuming alcohol, marijuana, or other forms of cannabis, or taking prescription or over-the-counter medications that may impair your reactions, consult with your doctor.
If you have been taking a high dose of this medication or using it regularly, do not stop taking it abruptly without first discussing it with your doctor. Stopping the medication suddenly may increase your risk of side effects. If you need to discontinue use, your doctor will guide you on how to gradually stop taking it.
As directed by your doctor, have your blood work checked regularly and discuss the results with them.
Do not switch between the capsule and tablet forms of this medication without consulting your doctor. If your doctor changes your medication form (e.g., from capsules to tablets), the new form may interact differently with food. Your doctor may monitor you closely after switching to the new form to check for any differences in how it works or potential side effects.
Animal studies have shown that this medication can cause fertility problems. Although it is unclear if this medication affects human fertility, discuss any concerns with your doctor.
If you are 65 years or older, use this medication with caution, as you may be more susceptible to side effects.
If you are pregnant, plan to become pregnant, or are breastfeeding, inform your doctor. You and your doctor will need to discuss the potential benefits and risks of this medication to you and your baby.
To ensure your safety, avoid driving and other activities that require alertness until you understand how this medication affects you. When getting up from a sitting or lying down position, rise slowly to minimize the risk of dizziness or fainting. Be cautious when using stairs.
Before consuming alcohol, marijuana, or other forms of cannabis, or taking prescription or over-the-counter medications that may impair your reactions, consult with your doctor.
If you have been taking a high dose of this medication or using it regularly, do not stop taking it abruptly without first discussing it with your doctor. Stopping the medication suddenly may increase your risk of side effects. If you need to discontinue use, your doctor will guide you on how to gradually stop taking it.
As directed by your doctor, have your blood work checked regularly and discuss the results with them.
Do not switch between the capsule and tablet forms of this medication without consulting your doctor. If your doctor changes your medication form (e.g., from capsules to tablets), the new form may interact differently with food. Your doctor may monitor you closely after switching to the new form to check for any differences in how it works or potential side effects.
Animal studies have shown that this medication can cause fertility problems. Although it is unclear if this medication affects human fertility, discuss any concerns with your doctor.
If you are 65 years or older, use this medication with caution, as you may be more susceptible to side effects.
If you are pregnant, plan to become pregnant, or are breastfeeding, inform your doctor. You and your doctor will need to discuss the potential benefits and risks of this medication to you and your baby.
Overdose Information
Overdose Symptoms:
- Hypotension (low blood pressure)
- Bradycardia (slow heart rate)
- Drowsiness
- Dizziness
- Respiratory depression (slowed breathing)
- Coma
What to Do:
Seek immediate medical attention. Call 911 or Poison Control at 1-800-222-1222. Treatment is supportive and symptomatic; there is no specific antidote. Gastric lavage may be considered if performed soon after ingestion.
Drug Interactions
Contraindicated Interactions
- Strong CYP1A2 inhibitors (e.g., fluvoxamine, ciprofloxacin)
Major Interactions
- Moderate CYP1A2 inhibitors (e.g., oral contraceptives, zileuton, mexiletine, acyclovir, ticagrelor)
- Other CNS depressants (e.g., alcohol, benzodiazepines, opioids, tricyclic antidepressants, sedating antihistamines)
- Antihypertensives (e.g., alpha-2 agonists like clonidine, beta-blockers, diuretics, ACE inhibitors, ARBs)
- QT-prolonging drugs (theoretical risk)
Moderate Interactions
- Alpha-1 blockers (e.g., prazosin, terazosin)
- Muscle relaxants (additive sedation)
- Baclofen (additive sedation, hypotension)
Minor Interactions
- Not specifically identified, but caution with any drug affecting blood pressure or CNS.
Monitoring
Baseline Monitoring
Liver function tests (ALT, AST)
Rationale: To establish baseline and identify pre-existing hepatic impairment, as tizanidine can cause liver injury.
Timing: Prior to initiation of therapy
Blood pressure
Rationale: To establish baseline and monitor for hypotensive effects.
Timing: Prior to initiation of therapy
Routine Monitoring
Liver function tests (ALT, AST)
Frequency: At 1, 3, and 6 months after initiation, then periodically as clinically indicated or if symptoms of liver injury occur.
Target: Within normal limits
Action Threshold: Discontinue if ALT or AST are persistently >3 times the upper limit of normal (ULN) or if accompanied by clinical symptoms of liver injury.
Blood pressure
Frequency: Regularly, especially during dose titration and if symptoms of hypotension occur.
Target: Maintain within patient's normal range, avoid symptomatic hypotension.
Action Threshold: If symptomatic hypotension occurs, reduce dose or discontinue.
Heart rate
Frequency: Periodically, especially during dose titration.
Target: Within normal limits
Action Threshold: If symptomatic bradycardia occurs, reduce dose or discontinue.
Symptom Monitoring
- Drowsiness
- Dizziness
- Lightheadedness
- Hypotension (e.g., orthostatic hypotension)
- Dry mouth
- Weakness
- Fatigue
- Nausea
- Signs of liver injury (e.g., unexplained nausea, anorexia, fatigue, dark urine, jaundice, right upper quadrant tenderness)
Special Patient Groups
Pregnancy
Category C. Use only if the potential benefit justifies the potential risk to the fetus. Animal studies have shown adverse effects, but there are no adequate and well-controlled studies in pregnant women.
Trimester-Specific Risks:
First Trimester:
Potential for developmental toxicity based on animal data; human data lacking.
Second Trimester:
Human data lacking; potential for adverse effects.
Third Trimester:
Human data lacking; potential for adverse effects, including withdrawal symptoms in neonate if used near term.
Lactation
Tizanidine is excreted in human milk. Due to the potential for serious adverse reactions in breastfed infants, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
Infant Risk:
Risk unknown, use with caution. Potential for sedation, hypotonia, and other CNS effects in the infant. Limited human data suggest low levels in milk, but caution is advised.
Pediatric Use
Safety and effectiveness in pediatric patients have not been established. Not recommended for use in this population.
Geriatric Use
Use with caution in elderly patients due to increased sensitivity to adverse effects (e.g., hypotension, sedation, dry mouth, hallucinations). Start with lower doses and titrate slowly. Renal function should be monitored.
Clinical Information
Clinical Pearls
- Tizanidine's effect on spasticity is relatively short-acting, requiring multiple daily doses. Patients should be advised to take doses at times when relief of spasticity is most important (e.g., before activities or at bedtime).
- Abrupt discontinuation of tizanidine, especially after prolonged use or high doses, can lead to rebound hypertension, tachycardia, and hypertonia. Taper the dose slowly over 2-4 weeks.
- The hypotensive effect of tizanidine can be significant, particularly with the first dose or during dose escalation. Advise patients about orthostatic hypotension and to rise slowly.
- Liver function tests are crucial due to the risk of hepatotoxicity. Adherence to the monitoring schedule is important.
- Food significantly impacts tizanidine's pharmacokinetics. Instruct patients to take it consistently either with food or without food to maintain stable drug levels and minimize variability in response and side effects.
Alternative Therapies
- Baclofen (oral, intrathecal)
- Diazepam
- Dantrolene
- Botulinum toxin injections (for focal spasticity)
- Gabapentin (off-label for spasticity)
- Pregabalin (off-label for spasticity)
Cost & Coverage
Average Cost:
Varies widely, typically $10-$50 per 30 tablets (4mg)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or Tier 2 (generic)
General Drug Facts
If your symptoms or health issues persist or worsen, it's essential to contact your doctor for further guidance. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so be sure to check with your pharmacist for more information. If you have any questions or concerns about this medication, don't hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek emergency medical attention. When reporting the incident, be prepared to provide details about the medication taken, the amount, and the time it occurred.