DrugLib.com — Drug Information Portal

Rx drug information, pharmaceutical research, clinical trials, news, and more

Zanaflex (Tizanidine Hydrochloride) - Side Effects and Adverse Reactions

 
 



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



See index of all Zanaflex side effect reports >>

Drug label data at the top of this Page last updated: 2011-04-25

-- advertisement -- The American Red Cross
 
Home | About Us | Contact Us | Site usage policy | Privacy policy

All Rights reserved - Copyright DrugLib.com, 2006-2017