ZANAFLEX
Zanaflex, dispensed in it's generic form as Tizanidine, is a
skeletal muscle relaxant used to treat muscle spasms associated with multiple
sclerosis or spinal cord injuries. It may also be used to treat other conditions
as determined by your doctor.
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ZANAFLEX!
Brand Name(s):
Zanaflex
Generic Name Tizanidine
Phonetic: (tye zan' i deen)
Who is this for?
Tizanidine, a muscle relaxant, is used to help relax certain muscles in your
body. It relieves the spasms and increased muscle tone caused by medical
problems such as multiple sclerosis or spinal injury. This medication is
sometimes prescribed for other uses; ask your doctor or pharmacist for more
information.
When should I be careful taking it?
Before taking tizanidine,
tell your doctor and pharmacist if you are allergic to tizanidine or any other
drugs.
tell your doctor and pharmacist what prescription and nonprescription
medications you are taking, including other medications that cause drowsiness,
medications for high blood pressure, oral contraceptives, and vitamins.
tell your doctor if you have or have ever had kidney or liver disease.
tell your doctor if you are pregnant, plan to become pregnant, or are
breast-feeding. If you become pregnant while taking tizanidine, call your doctor
immediately.
if you are having surgery, including dental surgery, tell the doctor or dentist
that you are taking tizanidine.
you should know that this drug may make you drowsy. Do not drive a car or
operate machinery until you know how this drug affects you.
remember that alcohol can add to the drowsiness caused by this drug.
What side effects should I watch for?
Side effects from tizanidine can occur. Tell your doctor if any of these
symptoms are severe or do not go away:
dizziness
upset stomach
vomiting
tingling sensation in the arms, legs, hands, and feet
dry mouth
increased muscle spasms
If you experience either of the following symptoms, call your doctor
immediately:
yellowing of the skin or eyes
unexplained flu-like symptoms
How should I take it?
Tizanidine comes as a tablet to take by mouth. It usually is taken two or three
times a day. Follow the directions on your prescription label carefully, and ask
your doctor or pharmacist to explain any part you do not understand. Take
tizanidine exactly as directed. Do not take more or less of it or take it more
often than prescribed by your doctor.
What happens if I miss a dose?
If you take several doses per day, take the missed dose as soon as you remember
it and take any remaining doses for that day at evenly spaced intervals.
However, if you remember a missed dose when it is almost time for your next
scheduled dose, skip the missed dose. Do not take a double dose to make up for a
missed one.
Where should I keep it?
Keep this medication in the container it came in, tightly closed, and out of
reach of children. Store it at room temperature and away from excess heat and
moisture (not in the bathroom). Throw away any medication that is outdated or no
longer needed. Talk to your pharmacist about the proper disposal of your
medication.
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ZANAFLEX!
Zanaflex
Patient Monograph
Description: Tizanidine is an oral agent used to reduce muscle tone associated
with spasticity related to cerebral or spinal cord injury, multiple sclerosis,
or other spastic disorders. The imidazoline chemical structure of tizanidine is
related to that of clonidine and other central-acting alpha2-adrenergic
agonists. Tizanidine significantly reduces muscle tone and frequency of spasms
in patients with spasticity due to spinal cord injury; but does not reduce
muscle strength. Both tizanidine and baclofen (see separate monograph) inhibit
spinal interneuron firing, however, tizanidine's effects are mediated by
alpha2-receptors whereas baclofen acts directly on neuronal membrane
polarization. The efficacy of tizanidine in the treatment of spasticity is
comparable to baclofen. Tizanidine produces more drowsiness and sedation than
baclofen, but tizanidine is not associated with the muscle weakness which may
occur with baclofen therapy. Tizanidine was approved by the FDA on December 3,
1996.
Mechanism of Action: Tizanidine is a central-acting alpha2-adrenergic agonist
which acts at presynaptic receptors. It is structurally and pharmacologically
related to clonidine, but has only 2—10% of clonidine's antihypertensive
potency. The antispasmodic activity of tizanidine results from agonism at
central pre-synaptic alpha2-receptors. The response to agonism at these
receptors is a decrease in the release of excitatory amino acids which in turn
leads to inhibition of spinal motor neurons. In animal models, tizanidine has no
direct effect on skeletal muscle fibers or the neuromuscular junction, and no
major effect on monosynaptic spinal reflexes. The effects of tizanidine are
greatest on polysynaptic pathways. The overall effect of these actions is
thought to reduce facilitation of spinal motor neurons.
Pharmacokinetics: Tizanidine is administered orally. Tizanidine is
well-absorbed, with an absolute oral bioavailability of 40% due to extensive
first pass metabolism in the liver. Following oral administration, peak plasma
concentrations of tizanidine occur in about 1.5 hours. The intrapatient effects
of tizanidine on muscle tone are correlated with plasma concentrations; adverse
effects are dose-related. Food increases the Cmax by about 33% and delays the
time to peak concentration by approximately 40 minutes; but the extent of
tizanidine absorption is not affected. Tizanidine is widely distributed
throughout the body. Tizanidine is approximately 30% bound to plasma proteins.
Approximately 95% of an oral dose of tizanidine is metabolized, presumably to
inactive metabolites with half-lives ranging from 20 to 40 hours. The half-life
of tizanidine is approximately 2.5 hours. Following single and multiple oral
dosing, about 60% and 20% of the tizanidine dose is recovered in the urine and
feces, respectively. Tizanidine clearance is reduced in elderly subjects and in
renally impaired patients, but is not influenced by gender. A cross-study
comparison of pharmacokinetic data following single-dose tizanidine showed that
younger subjects cleared the drug four times faster than elderly subjects.
Tizanidine clearance is reduced by more than 50% in elderly patients with renal
impairment (CrCl < 25 ml/min) compared to healthy elderly subjects. Gender had
no influence on tizanidine pharmacokinetics. It is not known whether tizanidine
is significantly removed by hemodialysis. The effects of race, hepatic disease,
or pediatric age on tizanidine disposition have not been studied.
Drug Form
Tizanidine tablets
What are tizanidine tablets? TIZANIDINE (Zanaflex(R)) is a drug used to relax
certain muscles. It can help to relieve, but not cure muscle spasms (or muscle
tightening) caused by medical problems such as multiple sclerosis or injuries to
the brain or spine. Generic tizanidine tablets are available.
Common Questions
What should my health care professional know before I take tizanidine? They need
to know if you have any of these conditions: -heart or blood vessel disease
-kidney disease -liver disease -low blood pressure -mental disorder -an unusual
or allergic reaction to tizanidine, other medicines, foods, dyes, or
preservatives -pregnant or trying to get pregnant -breast-feeding
How should I take this medicine? Take tizanidine tablets by mouth. Follow the
directions on the prescription label. Swallow the tablets with a drink of water.
Take your doses at regular intervals. Do not take your medicine more often than
directed. Check with your prescriber or health care professional before stopping
your medicine; gradual dosage reduction may be needed. Contact your pediatrician
or health care professional regarding the use of this medicine in children.
Special care may be needed. Older patients (age > 65 years) may have a stronger
reaction to this medicine and may need smaller doses.
What if I miss a dose? If you miss a dose, take it as soon as you can. If it is
almost time for your next dose, take only that dose. Do not take double or extra
doses.
What interactions can occur with tizanidine? -acetaminophen -alcohol
-antihistamine medicines for colds, hay fever, or allergies -baclofen
-benzodiazepine or sedative medicines for treating anxiety or to induce sleep
-barbiturate medicines for inducing sleep or treating seizures (convulsions)
-birth control pills -medicines for high blood pressure -medicines for mental
depression or other mental disorders -medicines for pain such codeine, morphine,
hydrocodone and others -phenytoin or fosphenytoin Tell your prescriber or health
care professional about all other medicines you are taking, including
non-prescription medicines, nutritional supplements, or herbal products. Also
tell your prescriber or health care professional if you are a frequent user of
drinks with caffeine or alcohol, if you smoke, or if you use illegal drugs.
These may affect the way your medicine works. Check with your health care
professional before stopping or starting any of your medicines.
What should I watch for while taking tizanidine? Visit your prescriber or health
care professional for regular checks on your progress. Do not suddenly stop
taking tizanidine. Ask your prescriber or health care professional for advice on
how to gradually reduce the dose of your medicine, before stopping completely.
You may get drowsy or dizzy. Do not drive, use machinery, or do anything that
needs mental alertness until you know how tizanidine affects you. To avoid dizzy
or fainting spells, do not stand or sit up quickly, especially if you are an
older person. Alcohol can make you more drowsy and dizzy. Avoid alcoholic
drinks. Your mouth may get dry. Chewing sugarless gum or sucking hard candy, and
drinking plenty of water will help. Do not treat yourself for coughs, colds or
allergies without asking your prescriber or health care professional for advice.
Some ingredients (antihistamines) can cause drowsiness which may be additive
with tizanidine. If you are going to have surgery tell your prescriber or health
care professional that you are taking tizanidine.
What side effects may I notice from taking tizanidine? Taking too high of a dose
of tizanidine can cause side effects. Ask your prescriber or health care
professional before you reduce your dose, or stop taking tizanidine. Side
effects that you should report to your prescriber or health care professional as
soon as possible: -confusion -dizziness or fainting spells -excitability,
nervousness -low blood pressure -nausea or vomiting -slow or irregular
heartbeat, palpitations, or chest pain -stomach pain -unusual or persistent rash
-unusual tiredness or weakness -yellowing of the skin or eyes Side effects that
usually do not require medical attention (report to your prescriber or health
care professional if they continue or are bothersome): -blurred vision
-constipation -drowsiness -dry mouth -tiredness or weakness
Where can I keep my medicine? Keep out of the reach of children in a container
that small children cannot open. Store at room temperature between 15—30 degrees
C (59—86 degrees F). Protect from light. Keep container tightly closed. Throw
away any unused medicine after the expiration date.