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ADVERSE REACTIONS
In multiple dose, placebo-controlled clinical studies, 264 patients were treated
with tizanidine and 261 with placebo. Adverse events, including severe adverse
events, were more frequently reported with tizanidine than with placebo.
COMMON ADVERSE EVENTS LEADING TO DISCONTINUATION
Forty-five of 264 (17%) patients receiving tizanidine and 13 of 261 (5%) of
patients receiving placebo in three multiple dose, placebo-controlled clinical
studies, discontinued treatment for adverse events. When patients withdrew from
the study, they frequently had more than one reason for discontinuing. The
adverse events most frequently leading to withdrawal of tizanidine treated
patients in the controlled clinical studies were asthenia (weakness, fatigue
and/or tiredness) (3%), somnolence (3%), dry mouth (3%), increased spasm or tone
(2%), and dizziness (2%).
MOST FREQUENT ADVERSE CLINICAL EVENTS SEEN IN ASSOCIATION WITH THE USE OF TIZANIDINE
In multiple dose, placebo-controlled clinical studies involving 264 patients
with spasticity, the most frequent adverse effects were dry mouth,
somnolence/sedation, asthenia (weakness, fatigue and/or tiredness) and
dizziness. Three-quarters of the patients rated the events as mild to moderate
and one-quarter of the patients rated the events as being severe. These events
appeared to be dose related.
ADVERSE EVENTS REPORTED IN CONTROLLED STUDIES
The events cited reflect experience gained under closely monitored conditions of
clinical studies in a highly selected patient population. In actual clinical
practice or in other clinical studies, these frequency estimates may not apply,
as the conditions of use, reporting behavior, and the kinds of patients treated
may differ. Table 1 lists treatment emergent signs and symptoms that were
reported in greater than 2% of patients in three multiple dose,
placebo-controlled studies who received tizanidine where the frequency in the
tizanidine group was at least as common as in the placebo group. These events
are not necessarily related to tizanidine treatment. For comparison purposes,
the corresponding frequency of the event (per 100 patients) among placebo
treated patients is also provided.
Table 1: Multiple Dose, Placebo-Controlled Studies—Frequent (> 2%) Adverse
Events Reported for Which Tizanidine Tablets Incidence is Greater than Placebo
Event
|
Placebo
N = 261 % |
Zanaflex
Tablet
N = 264 % |
|
|
|
Dry Mouth |
10 |
49 |
Somnolence |
10 |
48 |
Asthenia * |
16 |
41 |
Dissiness |
4 |
16 |
UTI
|
7 |
10 |
Infection |
5 |
6 |
Constipation |
1 |
4 |
Liver function test
abnormal
|
less than 1 |
3 |
Vomiting |
0 |
3 |
Speech Disorder |
0 |
3 |
Amblyopia (blurred vision) |
less than 1 |
3 |
Urinary frequency |
2 |
3 |
Flu syndrome |
2 |
3 |
SGPT/ALT increased |
less than 1 |
3 |
Dyskinesia |
0 |
3 |
Nervousness |
less than 1 |
3 |
Pharyngitis |
1 |
3 |
Rhinitis |
2 |
3 |
* (weakness, fatigue, and/or tiredness)
In the single dose, placebo-controlled study involving 142 patients with
spasticity, the patients were specifically asked if they had experienced any of
the four most common adverse events: dry mouth, somnolence (drowsiness),
asthenia (weakness, fatigue and/or tiredness) and dizziness. In addition,
hypotension and bradycardia were observed. The occurrence of these adverse
effects is summarized in Table 2. Other events were, in general, reported at a
rate of 2% or less.
Table 2: Single Dose, Placebo-Controlled Study—Common Adverse Events Reported
Event
|
Placebo
N = 48 % |
Tizanidine Tablet
8mg,
N = 45 |
Tizanidine Tablet 16mg, N = 49 |
Somnolence |
31 |
78 |
92 |
Dry Mouth |
35 |
76 |
88 |
Asthenia * |
40 |
67 |
78 |
Dissiness |
4 |
22 |
45 |
Hypotension |
0 |
16 |
33 |
Bradycardia
|
0 |
2 |
10 |
*(weakness, fatigue, and/or tiredness)
OTHER ADVERSE EVENTS OBSERVED DURING THE EVALUATION OF TIZANIDINE
Tizanidine was administered to 1385 patients in additional
clinical studies where adverse event information was available. The conditions
and duration of exposure varied greatly, and included (in overlapping
categories) double-blind and open-label studies, uncontrolled and controlled
studies, inpatient and outpatient studies, and titration studies. Untoward
events associated with this exposure were recorded by clinical investigators
using terminology of their own choosing. Consequently, it is not possible to
provide a meaningful estimate of the proportion of individuals experiencing
adverse events without first grouping similar types of untoward events into a
smaller number of standardized event categories.
In the tabulations that follow, reported adverse events were classified using
a standard COSTART-based dictionary terminology. The frequencies presented,
therefore, represent the proportion of the 1385 patients exposed to tizanidine
who experienced an event of the type cited on at least one occasion while
receiving tizanidine. All reported events are included except those already
listed in Table 1. If the COSTART term for an event was so general as to be
uninformative, it was replaced by a more informative term. It is important to
emphasize that, although the events reported occurred during treatment with
tizanidine, they were not necessarily caused by it.
Events are further categorized by body system and listed in order of
decreasing frequency according to the following definitions: frequent adverse
events are those occurring on one or more occasions in at least 1/100 patients
(only those not already listed in the tabulated results from placebo-controlled
studies appear in this listing); infrequent adverse events are those occurring
in 1/100 to 1/1000 patients; rare adverse events are those occurring in fewer
than 1/1000 patients.
BODY AS A
WHOLE
|
Frequent: |
Fever |
Infrequent: |
Allergic reaction, moniliasis, malaise, abscess, neck pain,
sepsis, cellulites, death, overdose |
Rare: |
Carcinoma, congenital anomaly, suicide
attempt |
CARDIOVASCULAR
SYSTEM
|
Infrequent: |
Vasodilatation, postural hypotension, syncope, migraine,
arrhythmia |
Rare: |
Angina pectoris, coronary artery disorder, heart
failure, myocardial infarct, phlebitis, pulmonary embolus, ventricular
extrasystoles, ventricular tachycardia |
DIGESTIVE
SYSTEM
|
Frequent: |
Abdomen pain, diarrhea, dyspepsia |
Infrequent: |
Dysphagia, cholelithiasis, fecal impaction, flatulence,
gastrointestinal hemorrhage, hepatitis, melena, |
Rare: |
Gastroenteritis, hematemesis, hepatoma, intestinal obstruction,
liver damage |
HEMIC AND LYMPHATIC
SYSTEM
|
Infrequent: |
Ecchymosis, hypercholesteremia, anemia, hyperlipemia, leukopenia,
leukocytosis, sepsis |
Rare: |
Petechia, purpura, thrombocythemia,
thrombocytopenia |
METABOLIC AND NUTRITIONAL
SYSTEM
|
Infrequent: |
Edema, hypothyroidism, weight loss |
Rare: |
Adrenal cortex insufficiency, hyperglycemia, hypokalemia,
hyponatremia, hypoproteinemia, respiratory acidosis |
MUSCULOSKELETAL
SYSTEM
|
Frequent: |
Myasthenia, back pain |
Infrequent: |
Pathological fracture, arthralgia, arthritis,
bursitis |
NERVOUS
SYSTEM
|
Frequent: |
Depression, anxiety, paresthesia |
Infrequent: |
Tremor, emotional lability, convulsion, paralysis, thinking
abnormal, vertigo, abnormal dreams, agitation, depersonalization, euphoria,
migraine, stupor, dysautonomia, neuralgia |
Rare: |
Dementia, hemiplegia, neuropathy |
RESPIRATORY
SYSTEM
|
Infrequent: |
Sinusitis, pneumonia, bronchitis |
Rare: |
Asthma |
SKIN AND
APPENDAGES
|
Frequent: |
Rash, sweating, skin ulcer |
Infrequent: |
Pruritus, dry skin, acne, alopecia, urticaria |
Rare: |
Exfoliative dermatitis, herpes simplex, herpes zoster, skin
carcinoma |
SPECIAL
SENSES
|
Infrequent: |
Ear pain, tinnitus, deafness, glaucoma, conjunctivitis, eye pain,
optic neuritis, otitis media, retinal hemorrhage, visual field defect |
Rare: |
Iritis, keratitis, optic atrophy |
UROGENITAL
SYSTEM
|
Infrequent: |
Urinary urgency, cystitis, menorrhagia, pyelonephritis, urinary
retention, kidney calculus, uterine fibroids enlarged, vaginal moniliasis,
vaginitis |
Rare: |
Albuminuria, glycosuria, hematuria, metrorrhagia |
|
REPORTS OF SUSPECTED ZANAFLEX SIDE EFFECTS / ADVERSE REACTIONS
Below is a sample of reports where side effects / adverse reactions may be related to Zanaflex. The information is not vetted and should not be considered as verified clinical evidence.
Possible Zanaflex side effects / adverse reactions in 65 year old male
Reported by a individual with unspecified qualification from Ireland on 2011-10-11
Patient: 65 year old male
Reactions: Drug Ineffective, Quality of Life Decreased, Drug Interaction, Muscle Spasticity
Suspect drug(s):
Aminopyridine (Fampridine)
Dosage: 1 df, bid
Start date: 2011-06-23
Zanaflex
Dosage: 8 mg bid oral
Administration route: Oral
Indication: Muscle Spasticity
Start date: 2005-03-21
Other drugs received by patient: Acetaminophen; Copaxone
Possible Zanaflex side effects / adverse reactions in 55 year old female
Reported by a consumer/non-health professional from United States on 2011-10-12
Patient: 55 year old female
Reactions: Memory Impairment, Cardiac Disorder
Suspect drug(s):
Valsartan
Dosage: 160 mg , 1 d, oral
Administration route: Oral
Indication: Hypertension
Start date: 2002-01-01
Bupropion HCL
Dosage: 300 mg, 1 d, oral
Administration route: Oral
Indication: Depression
Ventolin
Dosage: 90 mcg, 2 hr
Indication: Asthma
Gabapentin
Dosage: 6 dosage forms (2 dosage forms, 3 in 1 d), oral
Administration route: Oral
Indication: Fibromyalgia
Start date: 2004-01-01
Gabapentin
Dosage: 6 dosage forms (2 dosage forms, 3 in 1 d), oral
Administration route: Oral
Indication: Diabetic Neuropathy
Start date: 2004-01-01
Vicodin
Dosage: 4 hr, oral
Administration route: Oral
Indication: Arthralgia
Start date: 2006-01-01
Metformin Hydrodchloride/sitagliptin (Metformin and Sitagliptin)
Dosage: 1 d, oral
Administration route: Oral
Indication: Diabetes Mellitus
Klonopin
Dosage: 1 mg (0.5 mg, 2 in 1 d),oral
Administration route: Oral
Indication: Anxiety
Klonopin
Dosage: 1 mg (0.5 mg, 2 in 1 d),oral
Administration route: Oral
Indication: Panic Attack
Prilosec
Dosage: 40 mg (20 mg, 2 in d, oral
Administration route: Oral
Indication: Gastrooesophageal Reflux Disease
Epipen
Dosage: transdermal
Indication: Hypersensitivity
Imiprex (Imipraminoxide Hydrochloride)
Dosage: 100 mg, as required, oral
Administration route: Oral
Indication: Migraine
Nitroglycerin
Dosage: 0.4 mg, as required, other
Indication: Chest Pain
Flovent
Dosage: 220 mcg (110 mcg, 2 in 1 d)
Indication: Asthma
Simvastatin
Dosage: oral
Administration route: Oral
Indication: Product Used FOR Unknown Indication
Zyrtec
Dosage: 10 mg (10 mg, 1 in 1 d),oral
Administration route: Oral
Indication: Hypersensitivity
Start date: 2009-01-01
Lozol
Dosage: 1.25 mg, 1 d, oral
Administration route: Oral
Indication: Fluid Retention
Start date: 2002-01-01
Carafate
Dosage: 2 gm (1 gm, 2 in 1 d),oral
Administration route: Oral
Indication: Gastrooesophageal Reflux Disease
Flonase
Dosage: 500 mcg, 1 d), nasal
Indication: Hypersensitivity
Multivitamin
Dosage: oral
Administration route: Oral
Indication: Product Used FOR Unknown Indication
Zanaflex
Dosage: 4 mg (2 mg, 2 in 1 d), oral
Administration route: Oral
Indication: Muscle Spasms
Start date: 2009-01-01
Lortab
Dosage: oral
Administration route: Oral
Indication: Product Used FOR Unknown Indication
Metofrmin (Metformin)
Dosage: 500 mg, 1 in d, oral
Administration route: Oral
Indication: Diabetes Mellitus
Aggrenox
Dosage: 2 in 1 d, oral
Administration route: Oral
Indication: Product Used FOR Unknown Indication
Start date: 2009-12-01
Possible Zanaflex side effects / adverse reactions in 50 year old female
Reported by a consumer/non-health professional from United States on 2011-11-03
Patient: 50 year old female weighing 89.4 kg (196.6 pounds)
Reactions: Stomatitis, Mouth Ulceration, Genital Ulceration, Lichenoid Keratosis, Rash
Suspect drug(s):
Zanaflex
Other drugs received by patient: Robaxin
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Drug label data at the top of this Page last updated: 2011-04-25
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