Get advice for managing Multiple Sclerosis: Watch the video.

Baclofen

Pronunciation

Pronunciation: BACK-low-fen
Class: Skeletal muscle relaxant, Centrally acting

Trade Names

Gablofen
- Intrathecal 0.05 mg/mL (50 mcg/mL)
- Intrathecal 10 mg/20 mL (500 mcg/mL)
- Intrathecal 10 mg/5 mL (2,000 mcg/mL)

Lioresal
- Tablets 10 mg
- Tablets 20 mg
- Intrathecal 0.05 mg/mL (50 mcg/mL)
- Intrathecal 10 mg/20 mL (500 mcg/mL)
- Intrathecal 10 mg/5 mL (2,000 mcg/mL)

APO-Baclofen (Canada)
Gen-Baclofen (Canada)
PMS-Baclofen (Canada)
ratio-Baclofen (Canada)

Pharmacology

May inhibit transmission of reflexes at spinal level, possibly by action (hyperpolarization) at primary afferent fiber terminals, resulting in relief of muscle spasticity; has CNS depressant properties.

Slideshow: Living with Your Migraines: Tips for Treatment and Prevention

Pharmacokinetics

Absorption

Rapidly and extensively absorbed. T max is 4 h (intrathecal).

Elimination

Primarily by the kidney in unchanged form.

Onset

0.5 h to 1 h (intrathecal).

Duration

4 to 8 h.

Special Populations

Renal Function Impairment

No data available.

Hepatic Function Impairment

No data available.

Children

The onset, peak response, and duration of action is similar to those in adults.

Indications and Usage

Oral

Treatment of reversible spasticity resulting from multiple sclerosis. May be of some value in patients with spinal cord injuries and other spinal cord diseases.

Intrathecal

Treatment of severe spasticity of spinal cord origin in patients 4 y and older who are unresponsive to or cannot tolerate oral baclofen therapy. Used intrathecally in single bolus test doses; chronic use requires implantable pump.

Unlabeled Uses

Oral

Therapy for trigeminal neuralgia (tic douloureux); tardive dyskinesia; GERD; hiccups; prevention of migraine; Tourette syndrome.

Intrathecal

Cerebral palsy spasticity in children; generalized dystonia associated with cerebral palsy.

Contraindications

Treatment of spasms from rheumatic disorders, stroke, cerebral palsy and Parkinson disease; use of intrathecal form via IV, IM, subcutaneous, or epidural routes.

Dosage and Administration

Spasticity
Adults and Children 12 y and older

PO 5 mg 3 times daily for 3 days. Increase by 5 mg/dose every 3 days as needed up to max 80 mg/day (20 mg 4 times daily).

Severe spasticity
Adults and Children 4 y and older Intrathecal Test dose

Initial bolus containing 50 mcg in a volume of 1 mL intrathecally by barbotage over a period of not less than 1 min. However, for very small patients, a screening dose of 25 mcg may be tried first. Observe patient over 4 to 8 h. If the initial response is less than desired, a second bolus may be administered 24 h after the first. The second bolus dose consists of 75 mcg in 1.5 mL. Again, observe patient for an interval of 4 to 8 h. If the response is still inadequate, a final bolus dose of 100 mcg in 2 mL may be administered 24 h later. Patients who do not respond to a 100 mcg bolus should not be considered candidates for an implanted pump for chronic infusion.

Initial dosage

The screening dose that gave a positive effect should be doubled and administered over a 24-h period, unless the efficacy of the bolus dose was maintained for more than 8 h, in which case the starting daily dose should be the screening dose delivered over a 24-h period. No dose increases should be given in the first 24 h (ie, until steady-state is achieved).

Adults Dosage titration

After the first 24 h, the daily dosage should be increased slowly by 10% to 30% increments for spasticity of spinal cord region, or by 5% to 15% for spasticity of cerebral region, and only once every 24 h until the desired clinical effect is achieved.

Maintenance dosage

12 mcg/day to 2,003 mcg/day in spasticity of spinal cord region, with most patients adequately maintained on 300 to 800 mcg/day. For spasticity of cerebral region, 22 mcg/day to 1,400 mcg/day, with most patients adequately maintained on 90 to 703 mcg/day.

Dosage adjustment

The daily dose may be reduced by 10% to 20% if patients experience side effects.

For spasticity of spinal cord region, the daily dose may be increased by 10% to 40%, but not more than 40%, to maintain adequate symptom control. For spasticity of cerebral region, the daily dose may be increased by 5% to 20%, but not more than 20%, to maintain adequate symptom control.

Children 4 to 11 y of age Dosage titration

After the first 24 h, the daily dose should be increased slowly by 5% to 15% only once every 24 h until the desired clinical effect is achieved.

Maintenance dosage

From 22 mcg/day to 1,400 mcg/day, with most patients adequately maintained on 90 to 703 mcg/day.

Dosage adjustment

The daily dose may be reduced by 10% to 20% if patients experience side effects.

The daily dose may be increased by 5% to 20%, but not more than 20%, to maintain adequate symptom control.

Long-term use

During long-term treatment, approximately 5% of patients become refractory to increasing doses. There is not sufficient experience to make firm recommendations for “tolerance” treatment; however, this tolerance has been treated on occasion, in hospital, by a “drug holiday” consisting of the gradual reduction of baclofen intrathecal over a 2- to 4-wk period and switching to alternative methods of spasticity management. After the “drug holiday,” baclofen intrathecal may be restarted at the initial continuous infusion dose.

General Advice

  • Tablet
  • Administer with milk or food to avoid GI upset.
  • Intrathecal
  • Baclofen intrathecal is most often administered in a continuous infusion mode immediately following implant.
  • Refer to the manufacturer's manual for the implantable pump approved for intrathecal infusion for specific instructions and precautions for programming the pump and refilling the reservoir.
  • The specific concentration that should be used depends on the total daily dose required and the delivery rate of the pump.
  • Baclofen intrathecal may require dilution when used with certain implantable pumps. Please consult manufacturer's manual for specific recommendations.
  • Patients must be monitored closely in a fully equipped and staffed environment during the screening phase and dose-titration period immediately following implant. Resuscitative equipment should be immediately available for use in case of life-threatening or intolerable side effects.
  • Often, the maintenance dose needs to be adjusted during the first few months of therapy while patients adjust to changes in lifestyle because of the alleviation of spasticity.
  • Parenteral drug products should be inspected for particulate matter and discoloration prior to administration, whenever solution and container permit.
  • For patients who require concentrations other than 500 mcg/mL or 2,000 mcg/mL, baclofen intrathecal must be diluted. Baclofen intrathecal must be diluted with sterile preservative-free sodium chloride for injection.
  • If there is not a substantive clinical response to increases in the daily dose, check for proper pump function and catheter patency.
  • The dose should be ordinarily reduced slowly if the drug is discontinued for any reason.
  • Most patients require gradual increases in dose over time to maintain optimal response during chronic therapy. A sudden large requirement for dose escalation suggests a catheter complication (ie, catheter kink or dislodgment).
  • For those patients implanted with programmable pumps who have achieved relatively satisfactory control on continuous infusion, further benefit may be attained using more complex schedules of baclofen intrathecal delivery. For example, patients who have increased spasms at night may require a 20% increase in their hourly infusion rate. Changes in flow rate should be programmed to start 2 h before the time of desired clinical effect.

Storage/Stability

Oral

Do not store above 86°F.

Intrathecal

Do not store above 86°F. Do not freeze. Do not heat sterilize. Discard any unused portion. Do not autoclave.

Drug Interactions

CNS depressants (eg, alcohol)

May cause increased sedative effects.

Morphine (epidural)

May cause hypotension and dyspnea.

Laboratory Test Interactions

May cause false elevation of AST, alkaline phosphatase, or blood glucose.

Adverse Reactions

Cardiovascular

Hypotension (2%); hypertension (1%); chest pain, palpitations.

CNS

Somnolence (21%); headache (11%); convulsions (10%); dizziness (8%); paresthesia (7%); asthenia, coma, confusion, depression, insomnia (2%); abnormal thinking, agitation, anxiety, dysautonomia, hallucinations, tremor (1%); drowsiness, euphoria, lethargy, numbness, seizures, weakness in lower extremities.

Dermatologic

Pruritus (4%); urticaria (1%); rash.

EENT

Amblyopia (2%); diplopia (1%); blurred vision, nasal congestion, taste disorder, tinnitus.

GI

Nausea and vomiting (11%); vomiting (9%); nausea (7%); constipation (5%); dry mouth, increased salivation (3%); diarrhea (2%); anorexia (1%); abdominal pain.

Genitourinary

Urinary retention (8%); impotence, urinary incontinence, urination impaired (2%); urinary frequency (1%); dysuria, enuresis.

Respiratory

Hypoventilation (4%); pneumonia (2%); dyspnea (1%).

Miscellaneous

Hypotonia (35%); hypertonia (6%); accidental injury, pain, speech disorder (4%); peripheral edema (3%); back pain (2%); chills, fever (1%); ankle edema, excessive perspiration, muscle pain, slurred speech, weight gain.

Precautions

Warnings

Intrathecal

Abrupt discontinuation has resulted in high fever, altered mental status, exaggerated rebound spasticity, and muscle rigidity that, in rare cases, advanced to rhabdomyolysis, multiple organ system failure, and death.

Give special attention to patients at apparent risk (eg, spinal cord injuries at T-6 or above, communication difficulties, history of withdrawal symptoms from oral or intrathecal baclofen).


Pregnancy

Category C .

Lactation

Excreted in breast milk.

Children

Safety of oral baclofen in children younger than 12 y and of intrathecal baclofen in children younger than 4 y has not been established.

Renal Function

Administer with caution. Dosage reduction may be necessary.

Central nervous system effects

Use with caution in psychotic disorders, schizophrenia, or confused states; exacerbation of these conditions has been observed.

Dysreflexia

The presence of nociceptive stimuli or abrupt withdrawal may cause an autonomic dysreflexic episode.

Epilepsy and psychotic disorders

Use with caution because of potential exacerbations.

Fatalities

Fatalities occurred in premarketing trials of intrathecal baclofen; baclofen's role in these deaths is unknown.

Infection

Patients should be infection-free before screening trial with baclofen intrathecal.

Intrathecal use

Only specially trained personnel should administer baclofen intrathecally because of potentially life-threatening CNS depression, CV collapse, or respiratory failure. Cases of intrathecal mass at the tip of the implanted catheter have been reported.

Stroke

Baclofen has not significantly benefited patients with stroke; these patients also have poor drug tolerance.

Overdosage

Symptoms

Accommodation disorders, coma, drowsiness, muscle twitching, muscular hypotonia, respiratory depression, seizures, vomiting (oral); dizziness, drowsiness, lightheadedness, seizures, somnolence, respiratory depression, rostral progression of hypotonia and loss of consciousness progressing to coma (intrathecal).

Patient Information

  • Instruct patient to take drug exactly as prescribed. If dose is missed, it should be taken within 1 h. Warn patient not to double up on doses.
  • Explain that full effectiveness of drug may not occur until several wk after initiation of drug therapy.
  • Warn patient not to discontinue medication abruptly. Explain that hallucinations or seizures may occur.
  • Instruct patient to avoid intake of alcoholic beverages or other CNS depressants.
  • Teach patient to avoid sudden position changes to prevent orthostatic hypotension.
  • Caution diabetic patient that false elevation of blood glucose may occur. Instruct patient to monitor blood glucose carefully.
  • Instruct patients to report the following symptoms to their health care provider: dizziness, nausea, hypotension, urinary frequency, retention, painful urination, headache, seizures, weakness.
  • Advise patient that drug may cause drowsiness, and to use caution while driving or performing other tasks requiring mental alertness.

Copyright © 2009 Wolters Kluwer Health.

Hide
(web2)