Tizanidine 4mg Capsules
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
C
FDA Approved
Dec 1996
DEA Schedule
Not Controlled
Overview
What is this medicine?
Tizanidine is a medication used to relax muscles and reduce muscle stiffness and spasms (spasticity) caused by conditions like multiple sclerosis or spinal cord injury. It works by affecting nerve signals in the brain and spinal cord.
How to Use This Medicine
Taking Your Medication Correctly
To ensure you get the most out of 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.
Missing a Dose
If you take this medication regularly and miss a dose, take it 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 ensure you get the most out of 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.
Missing a Dose
If you take this medication regularly and miss a dose, take it 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 alcohol and other CNS depressants (e.g., sedatives, tranquilizers) as they can increase drowsiness and dizziness.
- Avoid driving or operating heavy machinery until you know how this medication affects you, as it can cause drowsiness and dizziness.
- Do not stop taking this medication suddenly, especially if you have been on it for a long time or at high doses, as this can lead to withdrawal symptoms like rebound hypertension, tachycardia, and increased spasticity. Your doctor will guide you on how to slowly reduce the dose.
- Take capsules consistently with or without food. Do not switch between capsules and tablets without consulting your doctor, as they are not interchangeable.
- Rise slowly from a sitting or lying position to avoid dizziness or fainting due to low blood pressure.
Available Forms & Alternatives
Dosing & Administration
Adult Dosing
Standard Dose:
Initial 2 mg orally once daily, titrate gradually. Usual therapeutic dose is 8 mg to 36 mg daily in 3 to 4 divided doses.
Dose Range:
2 - 36 mg
Condition-Specific Dosing:
spasticity:
Initial 2 mg, increased by 2 mg to 4 mg at 1 to 4 day intervals until satisfactory reduction of tone is achieved. Max single dose 16 mg. Max total 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 adverse effects.
Moderate:
CrCl < 25 mL/min: Initiate with 2 mg once daily, then titrate slowly based on response and tolerability.
Severe:
CrCl < 25 mL/min: Initiate with 2 mg once daily, then titrate slowly based on response and tolerability.
Dialysis:
Not well studied, use with caution and monitor closely. Tizanidine is minimally removed by hemodialysis.
Hepatic Impairment:
Mild:
Use with caution, monitor LFTs.
Moderate:
Use with caution, monitor LFTs. Consider lower starting dose and slower titration.
Severe:
Use with caution, monitor LFTs. Consider lower starting dose and slower titration. Contraindicated in severe hepatic impairment if LFTs are persistently elevated.
Pharmacology
Mechanism of Action
Tizanidine is an alpha-2 adrenergic agonist. It reduces spasticity by increasing presynaptic inhibition of motor neurons at the alpha-2 adrenergic receptor sites within the spinal cord, leading to a reduction in the release of excitatory amino acids.
Pharmacokinetics
Absorption:
Bioavailability:
Approximately 40% (capsules)
Tmax:
1-2 hours
FoodEffect:
Capsules: Food increases Cmax by approximately 30% and AUC by 20%. Tablets: Food significantly increases Cmax and AUC. Capsules and tablets are not bioequivalent and should not be interchanged without re-titration.
Distribution:
Vd:
2.4 L/kg
ProteinBinding:
Approximately 30%
CnssPenetration:
Yes
Elimination:
HalfLife:
Approximately 2.5 hours
Clearance:
Not available (highly variable)
ExcretionRoute:
Renal (approximately 60% of dose), Fecal (approximately 20%)
Unchanged:
Approximately 60% (renal)
Pharmacodynamics
OnsetOfAction:
Within 1 hour
PeakEffect:
1-2 hours
DurationOfAction:
3-6 hours
Safety & Warnings
Side Effects
Serious Side Effects: Seek Medical Help Immediately
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 right away:
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 have mild ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other 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, 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 right away:
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 have mild ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other 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, 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 lightheadedness, especially when standing up
- Fainting spells
- Yellowing of the skin or eyes (jaundice)
- Dark urine or pale stools
- Persistent nausea, vomiting, or abdominal pain (signs of liver problems)
- Unusual weakness or fatigue
- Hallucinations (seeing or hearing things that are not there)
- Sudden increase in muscle spasms or stiffness after stopping the medication
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 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 the form of the medication you are taking (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 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 the form of the medication you are taking (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)
- Somnolence (extreme drowsiness)
- Dizziness
- Miosis (pinpoint pupils)
- Respiratory depression
- Coma
What to Do:
Seek immediate medical attention or call a poison control center (e.g., 1-800-222-1222). Management is supportive, including maintaining airway, monitoring vital signs, and administering IV fluids for hypotension.
Drug Interactions
Contraindicated Interactions
- Fluvoxamine (strong CYP1A2 inhibitor)
- Ciprofloxacin (strong CYP1A2 inhibitor)
Major Interactions
- Other strong or moderate CYP1A2 inhibitors (e.g., amiodarone, mexiletine, propafenone, verapamil, oral contraceptives)
- CNS depressants (e.g., alcohol, benzodiazepines, opioids, tricyclic antidepressants, sedating antihistamines) - increased sedation and hypotension
- Antihypertensives (e.g., diuretics, ACE inhibitors, beta-blockers) - additive hypotensive effects
Moderate Interactions
- Alpha-2 adrenergic agonists (e.g., clonidine) - additive hypotensive effects
- QT prolonging drugs (theoretical risk of additive QT prolongation)
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 hepatotoxicity.
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 or dose increase, then periodically as clinically indicated.
Target: Within normal limits (WNL)
Action Threshold: Discontinue if ALT or AST are persistently >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: Patient's normal range, avoiding symptomatic hypotension.
Action Threshold: If symptomatic hypotension or significant drop in BP occurs, consider dose reduction or discontinuation.
Heart Rate
Frequency: Periodically, especially during dose titration.
Target: WNL
Action Threshold: If significant bradycardia occurs, consider dose reduction or discontinuation.
Symptom Monitoring
- Dizziness
- Somnolence
- Dry mouth
- Asthenia (weakness)
- Hypotension (lightheadedness, fainting)
- Bradycardia
- Hallucinations
- Signs of liver injury (e.g., nausea, vomiting, dark urine, jaundice, abdominal pain)
Special Patient Groups
Pregnancy
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 observed in animal studies.
Second Trimester:
Risk not well-established, but generally avoided unless clearly needed.
Third Trimester:
Risk not well-established, but generally avoided unless clearly needed.
Lactation
It is not known whether tizanidine is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing 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, caution advised. Potential for sedation or other adverse effects in the infant.
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, asthenia). Start with lower doses and titrate slowly, monitoring closely for adverse reactions.
Clinical Information
Clinical Pearls
- Tizanidine capsules and tablets are not bioequivalent; do not interchange without re-titration due to significant differences in pharmacokinetic profiles.
- Abrupt discontinuation of tizanidine, especially after prolonged use or high doses, can lead to rebound hypertension, tachycardia, and increased spasticity. Taper the dose slowly.
- Monitor liver function tests (ALT, AST) at baseline, 1, 3, and 6 months, and periodically thereafter, as tizanidine can cause dose-related hepatotoxicity.
- Be aware of significant drug interactions, particularly with strong CYP1A2 inhibitors (e.g., fluvoxamine, ciprofloxacin), which are contraindicated.
- Educate patients about potential for drowsiness, dizziness, and hypotension, and advise caution with activities requiring mental alertness.
Alternative Therapies
- Baclofen (Lioresal)
- Dantrolene (Dantrium)
- Diazepam (Valium)
- Botulinum toxin injections (e.g., Botox, Myobloc) for focal spasticity
Cost & Coverage
Average Cost:
$10 - $50 per 30 capsules (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 medical attention. When seeking help, be prepared to provide details about the medication taken, the amount, and the time it happened.