Tizanidine
Encyclopedia
Tizanidine is a drug
that is used as a muscle relaxant
. It is a centrally acting α2 adrenergic agonist. It is used to treat the spasm
s, cramp
ing, and tightness of muscle
s caused by medical problems such as multiple sclerosis
, spastic diplegia
, back pain
, or certain other injuries to the spine
or central nervous system
. It is also prescribed off-label for migraine
headache
s, as a sleep aid, and as an anticonvulsant
. It is also prescribed for some symptoms of fibromyalgia
.
Tizanidine has been found to be as effective as other antispasmodic drugs and have superior tolerability than baclofen
and diazepam
. Tizanidine may cause hypotension
, so caution is advised when it is used in patients who have a history of orthostatic hypotension. Use caution with this drug as it can be very strong even at the 2 mg dose. Also use caution when switching from gel cap to tablet form and vice versa.
Tizanidine can occasionally cause liver damage, generally the hepatocellular type. Clinical trials show that up to 5% of patients treated with tizanidine had elevated liver function test values, though symptoms disappeared upon withdrawal of the drug. Care should be used when first beginning treatment with tizanidine with regular liver tests for the first 6 months of treatment.
It is also found as a round white tablet with 2 scores on the back which create an X and the letters R L on the other side. This is certainly a 4mg tablet and could also be a 2mg.
Tizanidine is supplied as 2 and 4 mg tablets for oral administration, and in gel cap form in doses of 2 mg, 4 mg, and 6 mg.
The tablets are composed of the active ingredient, tizanidine hydrochloride (2.288 mg equivalent to 2 mg tizanidine base and 4.576 mg equivalent to 4 mg tizanidine base), and the inactive ingredients, silicon dioxide colloidal, stearic acid, microcrystalline cellulose and anhydrous lactose.
inhibitors is contraindicated. Concomitant use of tizanidine with fluvoxamine
, a potent CYP1A2 inhibitor in man, resulted in a 33-fold increase in the tizanidine AUC (plasma drug concentration-time curve) by fluvoxamine.
Tizanidine is a potent sedative. It therefore has the potential, to interact with other CNS depressants. Alcohol should obviously be avoided, particularly as it can cause stomach upset.
It has a Volume of Distribution of 2.6L/Kg (Manufacturers notes).
Drug
A drug, broadly speaking, is any substance that, when absorbed into the body of a living organism, alters normal bodily function. There is no single, precise definition, as there are different meanings in drug control law, government regulations, medicine, and colloquial usage.In pharmacology, a...
that is used as a muscle relaxant
Muscle relaxant
A muscle relaxant is a drug which affects skeletal muscle function and decreases the muscle tone. It may be used to alleviate symptoms such as muscle spasms, pain, and hyperreflexia. The term "muscle relaxant" is used to refer to two major therapeutic groups: neuromuscular blockers and spasmolytics...
. It is a centrally acting α2 adrenergic agonist. It is used to treat the spasm
Spasm
In medicine a spasm is a sudden, involuntary contraction of a muscle, a group of muscles, or a hollow organ, or a similarly sudden contraction of an orifice. It is sometimes accompanied by a sudden burst of pain, but is usually harmless and ceases after a few minutes...
s, cramp
Cramp
Cramps are unpleasant, often painful sensations caused by muscle contraction or over shortening. Common causes of skeletal muscle cramps include muscle fatigue, low sodium, and low potassium...
ing, and tightness of muscle
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
s caused by medical problems such as multiple sclerosis
Multiple sclerosis
Multiple sclerosis is an inflammatory disease in which the fatty myelin sheaths around the axons of the brain and spinal cord are damaged, leading to demyelination and scarring as well as a broad spectrum of signs and symptoms...
, spastic diplegia
Spastic diplegia
Spastic diplegia, historically known as Little's Disease, is a form of cerebral palsy that is a neuromuscular condition of hypertonia and spasticity in the muscles of the lower extremities of the human body, usually those of the legs, hips and pelvis...
, back pain
Back pain
Back pain is pain felt in the back that usually originates from the muscles, nerves, bones, joints or other structures in the spine.The pain can often be divided into neck pain, upper back pain, lower back pain or tailbone pain...
, or certain other injuries to the spine
Vertebral column
In human anatomy, the vertebral column is a column usually consisting of 24 articulating vertebrae, and 9 fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs...
or central nervous system
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
. It is also prescribed off-label for migraine
Migraine
Migraine is a chronic neurological disorder characterized by moderate to severe headaches, and nausea...
headache
Headache
A headache or cephalalgia is pain anywhere in the region of the head or neck. It can be a symptom of a number of different conditions of the head and neck. The brain tissue itself is not sensitive to pain because it lacks pain receptors. Rather, the pain is caused by disturbance of the...
s, as a sleep aid, and as an anticonvulsant
Anticonvulsant
The anticonvulsants are a diverse group of pharmaceuticals used in the treatment of epileptic seizures. Anticonvulsants are also increasingly being used in the treatment of bipolar disorder, since many seem to act as mood stabilizers, and in the treatment of neuropathic pain. The goal of an...
. It is also prescribed for some symptoms of fibromyalgia
Fibromyalgia
Fibromyalgia is a medical disorder characterized by chronic widespread pain and allodynia, a heightened and painful response to pressure. It is an example of a diagnosis of exclusion...
.
Tizanidine has been found to be as effective as other antispasmodic drugs and have superior tolerability than baclofen
Baclofen
Baclofen is a derivative of gamma-aminobutyric acid . It is primarily used to treat spasticity and is under investigation for the treatment of alcoholism....
and diazepam
Diazepam
Diazepam , first marketed as Valium by Hoffmann-La Roche is a benzodiazepine drug. Diazepam is also marketed in Australia as Antenex. It is commonly used for treating anxiety, insomnia, seizures including status epilepticus, muscle spasms , restless legs syndrome, alcohol withdrawal,...
. Tizanidine may cause hypotension
Hypotension
In physiology and medicine, hypotension is abnormally low blood pressure, especially in the arteries of the systemic circulation. It is best understood as a physiologic state, rather than a disease. It is often associated with shock, though not necessarily indicative of it. Hypotension is the...
, so caution is advised when it is used in patients who have a history of orthostatic hypotension. Use caution with this drug as it can be very strong even at the 2 mg dose. Also use caution when switching from gel cap to tablet form and vice versa.
Tizanidine can occasionally cause liver damage, generally the hepatocellular type. Clinical trials show that up to 5% of patients treated with tizanidine had elevated liver function test values, though symptoms disappeared upon withdrawal of the drug. Care should be used when first beginning treatment with tizanidine with regular liver tests for the first 6 months of treatment.
Availability
Tizanidine is available in tablets with "cor 138" on one side and 2 scores on the back that create an X, or R179 on one side and a single score through the middle of the back, or a white oval pill with R180 on one side and 2 scores on the back that create an X, or a round white tablet with E 44 on one side, and is double scored on the other side. It is also found as a circular white pill with the number 503 on one side and X-scored on the back. Also somewhat common is a white round tablet that is X-scored with what appears to be, on the opposite side, an uppercase "A" with a horizontal line through the right half of the letter, somewhat like a "G" and the numbers 594.It is also found as a round white tablet with 2 scores on the back which create an X and the letters R L on the other side. This is certainly a 4mg tablet and could also be a 2mg.
Tizanidine is supplied as 2 and 4 mg tablets for oral administration, and in gel cap form in doses of 2 mg, 4 mg, and 6 mg.
The tablets are composed of the active ingredient, tizanidine hydrochloride (2.288 mg equivalent to 2 mg tizanidine base and 4.576 mg equivalent to 4 mg tizanidine base), and the inactive ingredients, silicon dioxide colloidal, stearic acid, microcrystalline cellulose and anhydrous lactose.
Interactions
Concomitant use of tizanidine and moderate or potent CYP1A2CYP1A2
Cytochrome P450 1A2 , a member of the cytochrome P450 mixed-function oxidase system, is involved in the metabolism of xenobiotics in the body...
inhibitors is contraindicated. Concomitant use of tizanidine with fluvoxamine
Fluvoxamine
Fluvoxamine is an antidepressant which functions as a selective serotonin reuptake inhibitor . Fluvoxamine was first approved by the U.S. Food and Drug Administration in 1993 for the treatment of obsessive compulsive disorder . Fluvoxamine CR is approved to treat social anxiety disorder...
, a potent CYP1A2 inhibitor in man, resulted in a 33-fold increase in the tizanidine AUC (plasma drug concentration-time curve) by fluvoxamine.
Tizanidine is a potent sedative. It therefore has the potential, to interact with other CNS depressants. Alcohol should obviously be avoided, particularly as it can cause stomach upset.
It has a Volume of Distribution of 2.6L/Kg (Manufacturers notes).