Zanaflex


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tizanidine hydrochloride

Apo-Tizanidine, Gen-Tizanidine, Zanaflex

Pharmacologic class: Alpha-adrenergic agonist (centrally acting)

Therapeutic class: Skeletal muscle relaxant

Pregnancy risk category C

Action

Stimulates alpha2-adrenergic agonist receptor sites and reduces spasticity by inhibiting presynaptic motor neurons

Availability

Tablets: 2 mg, 4 mg

Indications and dosages

Increased muscle tone associated with spasticity

Adults: Initially, 4 mg P.O. q 6 to 8 hours (no more than three doses in 24 hours). Increase in increments of 2 to 4 mg, up to 8 mg/dose or 24 mg/day (not to exceed 36 mg/day), as needed.

Contraindications

• Hypersensitivity to drug or its components

Precautions

Use cautiously in:
• renal or hepatic impairment
• elderly patients
• pregnant or breastfeeding patients
• children (safety not established).

Administration

• Give with or without food.

Adverse reactions

CNS: drowsiness, asthenia, dizziness, speech disorder, dyskinesia, nervousness, anxiety, depression, hallucinations, sedation, paresthesia

CV: hypotension, bradycardia

EENT: blurred vision, pharyngitis, rhinitis

GI: vomiting, diarrhea, constipation, abdominal pain, dyspepsia, dry mouth

GU: urinary frequency, urinary tract infection

Hepatic: hepatitis

Musculoskeletal: back pain, myasthenia

Skin: rash, skin ulcers, sweating

Other: fever, infection, flulike symptoms

Interactions

Drug-drug. Alpha2-adrenergic agonist antihypertensives: increased risk of hypotension

CNS depressants (such as antihistamines, opioids, sedative-hypnotics): additive CNS depression

Hormonal contraceptives: increased tizanidine blood level, greater risk of adverse reactions

Drug-diagnostic tests. Alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase, glucose: increased levels

Drug-food. Any food: increased drug bioavailability, shorter time to peak concentration (with no effect on absorption)

Drug-behaviors. Alcohol use: additive CNS depression

Patient monitoring

• Monitor temperature and vital signs. Watch for orthostatic hypotension, bradycardia, and fever or other signs and symptoms of infection.
• Assess liver function tests.

Patient teaching

• Advise patient he may take with or without food.
• Tell patient to report signs or symptoms of infection or depression.
• Instruct patient to move slowly when sitting up or standing, to avoid dizziness from sudden blood pressure decrease.

Tell patient to immediately report unusual tiredness or yellowing of skin or eyes.
• Caution patient not to drink alcohol.
• Instruct patient to avoid driving and other hazardous activities until he knows how drug affects concentration and alertness.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, foods, and behaviors mentioned above.

tiZANidine

(tye-zan-i-deen) ,

Zanaflex

(trade name)

Classification

Therapeutic: antispasticity agents
Pharmacologic: adrenergics
Pregnancy Category: C

Indications

Increased muscle tone associated with spasticity due to multiple sclerosis or spinal cord injury.

Action

Acts as an agonist at central alpha-adrenergic receptor sites.
Reduces spasticity by increasing presynaptic inhibition of motor neurons.

Therapeutic effects

Decreased spasticity, allowing better function.

Pharmacokinetics

Absorption: Completely absorbed after oral administration but rapidly metabolized, resulting in 40% bioavailability.
Distribution: Widely distributed.
Metabolism and Excretion: 95% metabolized by the liver.
Half-life: 2.5 hr.

Time/action profile (reduced muscle tone)

ROUTEONSETPEAKDURATION
POunknown1–2 hr3–6 hr

Contraindications/Precautions

Contraindicated in: Hypersensitivity.
Use Cautiously in: Renal impairment;Concurrent antihypertensive therapy; Obstetric / Lactation / Pediatric: Safety not established; Geriatric: Dose ↓ may be necessary due to ↓ clearance.
Exercise Extreme Caution in: Impaired hepatic function.

Adverse Reactions/Side Effects

Central nervous system

  • anxiety (most frequent)
  • depression (most frequent)
  • dizziness (most frequent)
  • sedation (most frequent)
  • weakness (most frequent)
  • dyskinesia
  • hallucinations
  • nervousness

Ear, Eye, Nose, Throat

  • blurred vision
  • pharyngitis
  • rhinitis

Cardiovascular

  • hypotension (most frequent)
  • bradycardia

Gastrointestinal

  • abdominal pain (most frequent)
  • diarrhea (most frequent)
  • dry mouth (most frequent)
  • dyspepsia (most frequent)
  • constipation
  • hepatocellular injury
  • ↑ liver enzymes
  • vomiting

Genitourinary

  • urinary frequency

Dermatologic

  • rash (most frequent)
  • skin ulcers (most frequent)
  • sweating (most frequent)

Musculoskeletal

  • back pain (most frequent)
  • myasthenia (most frequent)
  • paresthesia (most frequent)

Miscellaneous

  • fever (most frequent)
  • speech disorder

Interactions

Drug-Drug interaction

Levels and effects ↑ by concurrent use of hormonal contraceptives or alcohol.↑ risk of hypotension with alpha2-adrenergic agonist antihypertensives (avoid concurrent use).↑ CNS depression may occur with alcohol or other CNS depressants including some antidepressants, sedative/hypnotics, antihistamines, and opioid analgesics.Concurrent CYP1A2 inhibitors (ciprofloxacin, fluvoxamine and others) may ↑ levels and risk of hypotension and excessive sedation.

Route/Dosage

Tablets are not interchangeable with capsules
Oral (Adults) 4 mg q 6–8 hr initially (no more than 3 doses/24 hr); ↑ by 2–4 mg/dose up to 8 mg/dose or 24 mg/day (not to exceed 36 mg/day). Some patients may tolerate twice-daily dosing.

Availability (generic available)

Tablets: 2 mg, 4 mg Cost: Generic — 2 mg $35.39 / 100, 4 mg $47.93 / 100
Capsules: 2 mg, 4 mg, 6 mg Cost: Generic — 2 mg $406.72 / 150, 4 mg $515.53 / 150, 6 mg $773.24 / 150

Nursing implications

Nursing assessment

  • Assess muscle spasticity before and periodically during therapy.
    • Monitor BP and pulse, especially during dose titration. May cause orthostatic hypotension, bradycardia, dizziness, and, rarely, syncope. Effects are usually dose related.
    • Observe patient for drowsiness, dizziness, and asthenia. A change in dose may alleviate these problems.
  • Lab Test Considerations: Monitor liver function tests before and at 1, 3, and 6 mo of therapy. May cause ↑ in serum glucose, alkaline phosphatase, AST, and ALT levels.

Potential Nursing Diagnoses

Impaired physical mobility (Indications)
Risk for injury (Adverse Reactions)

Implementation

  • Do not confuse tizanidine with tiagabine.
    • Doses should be titrated carefully to prevent side effects.
  • Oral: May be taken without regard to meals.

Patient/Family Teaching

  • Instruct patient to take tizanidine as directed. Tizanidine may need to be discontinued gradually.
  • May cause dizziness and drowsiness. Advise patient to avoid driving or other activities requiring alertness until response to drug is known.
  • Instruct patient to change positions slowly to minimize orthostatic hypotension.
  • Advise patient to avoid concurrent use of alcohol or other CNS depressants while taking this medication.

Evaluation/Desired Outcomes

  • Decrease in muscle spasticity with an increased ability to perform activities of daily living.

Zanaflex®

Tizanidine Neurology An agent used to manage ↑ muscle tone in spasticity–eg, in spinal cord injury, multiple sclerosis. See Spasticity.

Zanaflex

A brand name for the muscle relaxing drug TIZANIDINE.
References in periodicals archive ?
and our dependence on our collaboration partner Biogen Idec in connection therewith; competition, including the impact of generic competition on Zanaflex Capsules revenues; failure to protect our intellectual property, to defend against the intellectual property claims of others or to obtain third party intellectual property licenses needed for the commercialization of our products; failure to comply with regulatory requirements could result in adverse action by regulatory agencies; and the ability to obtain additional financing to support our operations.
The company said that tizanidine hydrochloride capsules are an authorised generic version of ZANAFLEX CAPSULES (tizanidine hydrochloride).
The company's letter also pointed out that Zanaflex capsules and tablets are not bioequivalent taken after eating.
Net sales of Zanaflex Capsules and Zanaflex tablets reached USD23.
Zanaflex, the new drug, is marketed by Athena Neurosciences, a subsidiary of the Elan Corporation.
ZANAFLEX CAPSULES([R]) (tizanidine hydrochloride), ZANAFLEX([R]) (tizanidine hydrochloride) tablets and authorized generic capsules net revenue and royalties - For the quarter ended December 31, 2012, the Company reported combined net revenue from ZANAFLEX CAPSULES and ZANAFLEX tablets sales of $1.
For the full year ended December 31, 2012, the Company reported combined net revenue from ZANAFLEX CAPSULES and ZANAFLEX tablets sales of $13.
5 million relating to ZANAFLEX CAPSULES due to the patent infringement trial decision.
Non-GAAP net income in the same quarter of 2011, before share-based compensation charges, net milestone revenue and accounting adjustments relating to ZANAFLEX CAPSULES due to the Apotex patent infringement trial court decision, was $16.
ZANAFLEX CAPSULES([R]) (tizanidine hydrochloride), ZANAFLEX([R]) (tizanidine hydrochloride) tablets and authorized generic tablets net revenue and royalties - For the quarter ended June 30, 2012, the Company reported combined net revenue from ZANAFLEX CAPSULES and ZANAFLEX tablets sales of $2.
The Company also markets ZANAFLEX CAPSULES([R]) (tizanidine hydrochloride) and ZANAFLEX([R]) (tizanidine hydrochloride) tablets, a short-acting drug for the management of spasticity.
Combined First Quarter ZANAFLEX Franchise and ex-U.