Zanaflex 2mg 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 muscle relaxant used to treat muscle spasms and tightness (spasticity) caused by conditions like multiple sclerosis or spinal cord injury. It works by calming overactive nerves in the brain and spinal cord that control muscle movement.
How to Use This Medicine
Taking Your Medication Correctly
To get the most benefit from your medication, follow your doctor's instructions carefully. Read all the information provided with your prescription and follow the instructions closely. You can take this medication with or without food, but it's essential to take it the same way each time. Choose to take it either always with food or always on an empty stomach to maintain consistency.
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. When disposing of unused or expired medications, do not flush them down the toilet or pour them down the drain unless instructed to do so by your pharmacist. Instead, check with your pharmacist for guidance on the best disposal method or look into local drug take-back programs.
What to Do If You Miss a Dose
If you take this medication regularly, take the missed dose as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses. If you take this medication as needed, follow your doctor's instructions and do not take it more frequently than recommended.
To get the most benefit from your medication, follow your doctor's instructions carefully. Read all the information provided with your prescription and follow the instructions closely. You can take this medication with or without food, but it's essential to take it the same way each time. Choose to take it either always with food or always on an empty stomach to maintain consistency.
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. When disposing of unused or expired medications, do not flush them down the toilet or pour them down the drain unless instructed to do so by your pharmacist. Instead, check with your pharmacist for guidance on the best disposal method or look into local drug take-back programs.
What to Do If You Miss a Dose
If you take this medication regularly, take the missed dose as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses. If you take this medication as needed, follow your doctor's instructions and do not take it more frequently than recommended.
Lifestyle & Tips
- Avoid driving or operating heavy machinery until you know how this medication affects you, as it can cause drowsiness and dizziness.
- Avoid alcohol consumption while taking tizanidine, as it can increase drowsiness and dizziness.
- Avoid sudden changes in position (e.g., standing up quickly from sitting or lying down) to prevent dizziness or fainting due to low blood pressure.
- Inform your doctor about all other medications you are taking, especially other sedatives, pain medications, or blood pressure medications.
- 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 (e.g., rebound spasticity, high blood pressure, fast heart rate, anxiety). Your doctor will guide you on how to slowly reduce the dose.
- Take tizanidine consistently with or without food, but try to stick to the same way each time to avoid changes in how much medicine your body absorbs.
Available Forms & Alternatives
Available Strengths:
Generic Alternatives:
Dosing & Administration
Adult Dosing
Standard Dose:
Initial 2 mg orally once daily, titrated gradually. Usual therapeutic dose is 8 mg to 24 mg daily in 3 divided doses.
Dose Range:
2 - 36 mg
Condition-Specific Dosing:
spasticity:
Initial 2 mg, increased by 2 mg to 4 mg every 1 to 4 days based on response and tolerability. Maximum single dose 16 mg. Maximum daily dose 36 mg.
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 increased adverse effects.
Moderate:
For CrCl < 25 mL/min, initiate with 2 mg once daily and titrate slowly based on response and tolerability. Monitor for adverse effects.
Severe:
For CrCl < 25 mL/min, initiate with 2 mg once daily and titrate slowly based on response and tolerability. Monitor for adverse effects.
Dialysis:
Tizanidine is not significantly removed by hemodialysis. Dose adjustment as per severe renal impairment.
Hepatic Impairment:
Mild:
Use with caution. Monitor liver function tests (LFTs).
Moderate:
Use with caution. Monitor LFTs closely. Consider lower initial doses and slower titration.
Severe:
Not recommended due to increased systemic exposure and potential for liver injury. If used, extreme caution and close monitoring of LFTs are required.
Pharmacology
Mechanism of Action
Tizanidine is an alpha-2 adrenergic agonist. It reduces spasticity by increasing presynaptic inhibition of motor neurons at the spinal cord level, likely by inhibiting the release of excitatory amino acids. It has a greater affinity for alpha-2 receptors than alpha-1 receptors.
Pharmacokinetics
Absorption:
Bioavailability:
Approximately 40%
Tmax:
1 to 2 hours
FoodEffect:
Food increases Cmax by approximately 30% and AUC by approximately 20%, and prolongs Tmax by approximately 1 hour. This can lead to increased side effects. Consistent administration (with or without food) is recommended.
Distribution:
Vd:
2.4 L/kg
ProteinBinding:
Approximately 30%
CnssPenetration:
Yes
Elimination:
HalfLife:
2.5 hours (range 1.5 to 4 hours)
Clearance:
Not available (systemic clearance is approximately 2.4 L/hr/kg)
ExcretionRoute:
Renal (approximately 60% of dose), Fecal (approximately 20% of dose)
Unchanged:
Approximately 60% of the dose is excreted in urine as metabolites, with only about 5% as unchanged drug.
Pharmacodynamics
OnsetOfAction:
Within 1 hour
PeakEffect:
1 to 2 hours
DurationOfAction:
3 to 6 hours
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical attention immediately:
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
Changes in behavior
Slow heartbeat
Fever, chills, or sore throat
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other unusual symptoms that bother you or do not go away, contact your doctor:
Dry mouth
Dizziness
Drowsiness
Fatigue
* Weakness
This is not an exhaustive list of possible side effects. 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.
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical attention immediately:
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
Changes in behavior
Slow heartbeat
Fever, chills, or sore throat
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other unusual symptoms that bother you or do not go away, contact your doctor:
Dry mouth
Dizziness
Drowsiness
Fatigue
* Weakness
This is not an exhaustive list of possible side effects. 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 dizziness or fainting (signs of low blood pressure)
- Unusual tiredness or weakness
- Yellowing of the skin or eyes (jaundice)
- Dark urine
- Persistent nausea, vomiting, or stomach pain (signs of liver problems)
- Hallucinations or unusual thoughts/behavior
- Difficulty breathing or swallowing
- Rash or itching
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 potential interactions. To ensure your safety, it is crucial to disclose all of your medications, including:
Prescription and over-the-counter (OTC) drugs
Natural products
* Vitamins
Additionally, inform your doctor about any existing health problems. This information will help your doctor determine whether it is safe for you to take this medication in conjunction with your other medications and health conditions.
Remember, do not start, stop, or change the dosage of any medication without first consulting your doctor. It is vital to verify that it is safe to take this medication with all of your other medications and health problems to minimize potential risks and interactions.
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 potential interactions. To ensure your safety, it is crucial to disclose all of your medications, including:
Prescription and over-the-counter (OTC) drugs
Natural products
* Vitamins
Additionally, inform your doctor about any existing health problems. This information will help your doctor determine whether it is safe for you to take this medication in conjunction with your other medications and health conditions.
Remember, do not start, stop, or change the dosage of any medication without first consulting your doctor. It is vital to verify that it is safe to take this medication with all of your other medications and health problems to minimize potential risks and interactions.
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 climbing 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.
Follow your doctor's instructions for regular blood tests 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.
Inform your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. 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 climbing 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.
Follow your doctor's instructions for regular blood tests 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.
Inform your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. 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:
- Drowsiness
- Dizziness
- Lightheadedness
- Bradycardia (slow heart rate)
- Hypotension (low blood pressure)
- Respiratory depression (slow, shallow breathing)
- Coma
What to Do:
Seek immediate medical attention. Call 911 or Poison Control at 1-800-222-1222. Treatment is supportive, including maintaining airway, breathing, and circulation, and managing hypotension and bradycardia. There is no specific antidote.
Drug Interactions
Contraindicated Interactions
- Strong CYP1A2 inhibitors (e.g., fluvoxamine, ciprofloxacin)
Major Interactions
- Other CYP1A2 inhibitors (e.g., oral contraceptives, zileuton, mexiletine, propafenone, verapamil, amiodarone, cimetidine, acyclovir, famotidine, ticagrelor)
- Alcohol (increased CNS depression and hypotension)
- Other CNS depressants (e.g., benzodiazepines, opioids, tricyclic antidepressants, antihistamines, other muscle relaxants) - increased sedation and hypotension
- Antihypertensives (e.g., alpha-2 agonists like clonidine, diuretics, beta-blockers, ACE inhibitors) - increased risk of hypotension and bradycardia
Moderate Interactions
- Oral contraceptives (may increase tizanidine exposure)
- Drugs that prolong QT interval (theoretical risk, monitor ECG)
- Hepatotoxic drugs (increased risk of liver injury)
Minor Interactions
- Not specifically identified as minor, 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 identify pre-existing hypotension, as tizanidine can cause significant hypotension.
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 greater than 3 times the upper limit of normal (ULN) or if accompanied by signs/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 if patient is on other bradycardia-inducing drugs.
Target: Within normal limits
Action Threshold: If symptomatic bradycardia occurs, reduce dose or discontinue.
Efficacy (Spasticity reduction)
Frequency: Regularly during dose titration and maintenance.
Target: Improved muscle tone, reduced spasms, improved function.
Action Threshold: If inadequate response, consider dose increase or alternative therapy. If excessive weakness, reduce dose.
Adverse Effects (e.g., sedation, dizziness, dry mouth)
Frequency: Regularly, especially during dose titration.
Target: Tolerable level of side effects.
Action Threshold: If intolerable, reduce dose or discontinue.
Symptom Monitoring
- Drowsiness
- Dizziness
- Dry mouth
- Hypotension (lightheadedness, fainting)
- Bradycardia
- Weakness
- Fatigue
- Nausea
- Constipation
- Blurred vision
- Hallucinations
- Psychosis
- Symptoms of liver injury (e.g., unexplained nausea, anorexia, fatigue, right upper quadrant pain, dark urine, jaundice)
Special Patient Groups
Pregnancy
Category C. Animal studies have shown adverse effects on the fetus. Tizanidine should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Trimester-Specific Risks:
First Trimester:
Potential for developmental toxicity observed in animal studies (e.g., skeletal abnormalities).
Second Trimester:
Potential for developmental toxicity observed in animal studies.
Third Trimester:
Potential for developmental toxicity observed in animal studies. Risk of neonatal withdrawal symptoms if used near term is unknown but possible with alpha-2 agonists.
Lactation
Tizanidine is excreted in human milk. Due to the potential for serious adverse reactions in breastfed infants (e.g., sedation, hypotonia, bradycardia), 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:
Possible sedation, hypotonia, bradycardia, and other CNS effects. Monitor infant for drowsiness, poor feeding, and changes in heart rate.
Pediatric Use
Safety and effectiveness in pediatric patients have not been established. Use is generally not recommended.
Geriatric Use
Use with caution in elderly patients due to increased sensitivity to adverse effects (e.g., hypotension, sedation, dry mouth) and potential for age-related decreases in renal and hepatic function. Start with lower doses and titrate slowly. Monitor closely for adverse effects.
Clinical Information
Clinical Pearls
- Tizanidine is most effective for spasticity that interferes with daily activities or causes pain, rather than for general muscle soreness.
- Dose titration is crucial to minimize side effects. Start low and go slow.
- Consistency in administration (with or without food) is important to maintain stable drug levels and avoid fluctuations in side effects.
- Warn patients about the potential for sudden withdrawal symptoms if the drug is stopped abruptly.
- Monitor liver function tests regularly, especially during the first 6 months of therapy.
- Educate patients about orthostatic hypotension and advise them to rise slowly from a sitting or lying position.
- Avoid concomitant use with strong CYP1A2 inhibitors (e.g., fluvoxamine, ciprofloxacin) due to significantly increased tizanidine levels and risk of severe hypotension and sedation.
Alternative Therapies
- Baclofen (GABA-B agonist)
- Cyclobenzaprine (centrally acting muscle relaxant)
- Dantrolene (direct-acting skeletal muscle relaxant)
- Carisoprodol (centrally acting muscle relaxant)
- Metaxalone (centrally acting muscle relaxant)
- Methocarbamol (centrally acting muscle relaxant)
- Botulinum toxin injections (for localized spasticity)
- Physical therapy
- Occupational therapy
Cost & Coverage
Average Cost:
$10 - $30 per 30 tablets (generic 2mg)
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.