Drug Database - Zanaflex

Generic Name: tizanidine (tye-ZAN-i-deen)

Brand Names: Zanaflex®

Classification: Muscle Relaxant

Issue Date: 1996

Zanaflex is a short-acting muscle relaxant. It works by blocking nerve impulses (pain sensations) that are sent to your brain. Zanaflex is used to treat spasticity by temporarily relaxing muscle tone.

Zanaflex is a short-acting medication that should be taken only for daily activities that require relief from muscle spasticity.

Do not use Zanaflex at a time when muscle tone is needed to assure safe balance and movement for certain activities. In some situations, it may endanger your physical safety to be in a state of reduced muscle tone.

Switching between Zanaflex tablets and capsules, or changing the way you take it with regard to eating, can cause an increase in side effects or a decrease in therapeutic effect. Follow your doctor's instructions carefully. After making any changes in how you take Zanaflex, contact your doctor if you notice any change in how well the medicine works or if it causes increased side effects.

Do not take more than three doses (36 mg) of Zanaflex in a 24-hour period. Too much of this medication can damage your liver.

Zanaflex can cause side effects that may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be awake and alert.

Dizziness is most likely to occur when you rise from a sitting or lying position. Get up slowly to prevent dizziness and a possible fall.

Avoid using other medicines that make you sleepy such as:

• cold medicine
• pain medication
• muscle relaxer
• medicine for seizures, depression or anxiety

They can add to sleepiness caused by Zanaflex. Avoid drinking alcohol. It can increase some of the side effects of Zanaflex.

Take this medication exactly as it was prescribed for you. Do not take the medication in larger amounts, or take it for longer than recommended by your doctor. Follow the directions on your prescription label.

Your doctor may occasionally change your dose to make sure you get the best results from this medication.

Take this medication with a full glass of water. Zanaflex is a short-acting medication, and its effects will be most noticeable between 1 and 6 hours after you take it. This medication should be taken only for daily activities that require relief from muscle spasticity.

In most cases, you may take up to three doses in one day if needed. Allow 6 to 8 hours to pass between doses.

Carefully follow your doctor's instructions about taking this medication with or without food. Taking Zanaflex tablets with food can increase the levels of Zanaflex in your blood stream, but taking Zanaflex capsules with food can decrease the levels.

Switching between Zanaflex tablets and capsules, or changing the way you take it with regard to eating, can cause an increase in side effects or a decrease in therapeutic effect. Follow your doctor's instructions carefully. After making any changes in how you take Zanaflex, contact your doctor if you notice any change in how well the medicine works or if it causes increased side effects.

Do not take more than three doses (36 mg) in a 24-hour period. Too much of this medication can damage your liver.

To be sure this medication is not causing harmful effects, your liver function will need to be tested on a regular basis. Do not miss any scheduled visits to your doctor.

You may have withdrawal symptoms such as dizziness, fast heart rate, tremors, anxiety, and increased spasticity when you stop using Zanaflex after using it over a long period of time. Do not stop using this medication suddenly without first talking to your doctor. You may need to use less and less before you stop the medication completely. Store Zanaflex at room temperature away from moisture and heat.

Do not use this medication if you are allergic to Zanaflex, or if you are also taking the antidepressant fluvoxamine (Luvox®) or the antibiotic ciprofloxacin (Cipro®).

Before using Zanaflex, tell your doctor if you are allergic to any drugs, or if you have:

• liver disease
• kidney disease
• high or low blood pressure
• history of "Long QT syndrome"

If you have any of these conditions, you may not be able to use Zanaflex, or you may need a dosage adjustment or special tests during treatment.

This medication may be harmful to an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment. It is not known whether Zanaflex passes into breast milk or if it could harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.

In older adults, Zanaflex may take much longer to clear from the body. Follow your doctor's instructions about your specific dosage and medication schedule.

Seek emergency medical attention if you think you have used too much of this medicine. Symptoms of a Zanaflex overdose may include:

• drowsiness
• confusion
• slow heart rate
• shallow breathing
• feeling light-headed
• severe drowsiness
• fainting
• coma

Side Effects

Get emergency medical help if you have any of these signs of an allergic reaction:

• hives
• difficulty breathing
• swelling of your face, lips, tongue, or throat

Call your doctor at once if you have any of these serious side effects:

• feeling light-headed
• fainting
• slow heart rate
• hallucinations
• confusion
• unusual thoughts or behavior
• nausea
• stomach pain
• low fever
• loss of appetite
• dark urine
• clay-colored stools
• jaundice (yellowing of the skin or eyes)
• burning or pain when you urinate

Less serious side effects may be more likely to occur, such as:

• drowsiness
• dizziness
• feeling anxious or nervous
• numbness or tingling
• stomach pain
• diarrhea
• constipation
• vomiting
• fever
• dry mouth
• muscle weakness
• back pain
• increased muscle tone or spasms
• sweating or skin rash

Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome.

Before taking Zanaflex, tell your doctor if you are using any of the following drugs:

• acyclovir (Zovirax®)
• cimetidine (Tagamet®)
• famotidine (Pepcid®)
• ticlopidine (Ticlid®)
• zileuton (Zyflo®)
• birth control pills
• enoxacin (Penetrex®)
• gatifloxacin (Tequin®)
• levofloxacin (Levaquin®)
• lomefloxacin (Maxaquin®)
• moxifloxacin (Avelox®)
• ofloxacin (Floxin®)
• sparfloxacin (Zagam®)
• trovafloxacin (Trovan®)
• norfloxacin (Noroxin®)
• clonidine (Catapres®)
• guanabenz (Wytensin®)
• guanfacine (Tenex®)
• methyldopa (Aldomet®)
• amiodarone (Cordarone®, Pacerone®)
• mexiletine (Mexitil®)
• propafenone (Rhythmol®)
• verapamil (Calan®, Covera®, Isoptin®)

If you are using any of these drugs, you may not be able to use Zanaflex, or you may need dosage adjustments or special tests during treatment.

There may be other drugs not listed that can affect Zanaflex. Tell your doctor about all the prescription and over-the-counter medications you use. This includes vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start using a new medication without telling your doctor.