Pronunciation:

(BAK loe fen)

U.S. Brand Names:

Generic Available:

Canadian Brand Names:

Use:

Orphan drug: Intrathecal: Treatment of intractable spasticity caused by spinal cord injury, multiple sclerosis, and other spinal disease (spinal ischemia or tumor, transverse myelitis, cervical spondylosis, degenerative myelopathy)

Use - Unlabeled/Investigational:

Pregnancy Risk Factor:

Lactation:

Contraindications:

Warnings/Precautions:

Adverse Reactions:

>10%:

Central nervous system: Drowsiness, vertigo, psychiatric disturbances, insomnia, slurred speech, ataxia, hypotonia

Neuromuscular & skeletal: Weakness

1% to 10%:

Cardiovascular: Hypotension

Central nervous system: Fatigue, confusion, headache

Dermatologic: Rash

Gastrointestinal: Nausea, constipation

Genitourinary: Polyuria

<1%: Palpitations, chest pain, syncope, euphoria, excitement, depression, hallucinations, xerostomia, anorexia, abnormal taste, abdominal pain, vomiting, diarrhea, enuresis, urinary retention, dysuria, impotence, inability to ejaculate, nocturia, paresthesia, hematuria, dyspnea

Withdrawal reactions have occurred with abrupt discontinuation (particularly severe with intrathecal use).

Overdosage/Toxicology:

For toxicity following intrathecal administration: For adults, administer physostigmine 2 mg I.M. or I.V. (not to exceed 1 mg/minute). For pediatric patients, administer physostigmine 0.02 mg/kg I.M. or I.V. (not to exceed 0.5 mg/minute). Consider withdrawal of 30-40 mL of CSF to reduce baclofen concentration. Abrupt withdrawal of intrathecal baclofen has resulted in severe sequelae (hyperpyrexia, obtundation, muscle rigidity, and rhabdomyolysis)

Drug Interactions:

Increased effect: Opiate analgesics, benzodiazepines, hypertensive agents

Increased toxicity: CNS depressants and ethanol (sedation), tricyclic antidepressants (short-term memory loss), clindamycin (neuromuscular blockade), guanabenz (sedation), MAO inhibitors (decrease blood pressure, CNS, and respiratory effects)

Ethanol/Nutrition/Herb Interactions:

Ethanol: Avoid ethanol (may increase CNS depression).

Herb/Nutraceutical: Avoid valerian, St John's wort, kava kava, gotu kola.

Compatibility:

Compatibility when admixed: Compatible: Morphine

Mechanism of Action:

Pharmacodynamics/Kinetics:

Onset of action: 3-4 days

Peak effect: 5-10 days

Absorption (dose dependent): Oral: Rapid

Protein binding: 30%

Metabolism: Hepatic (15% of dose)

Half-life elimination: 3.5 hours

Time to peak, serum: Oral: Within 2-3 hours

Excretion: Urine and feces (85% as unchanged drug)

Dosage:

Oral (avoid abrupt withdrawal of drug):

Children:

2-7 years: Initial: 10-15 mg/24 hours divided every 8 hours; titrate dose every 3 days in increments of 5-15 mg/day to a maximum of 40 mg/day

8 years: Maximum: 60 mg/day in 3 divided doses

Adults: 5 mg 3 times/day, may increase 5 mg/dose every 3 days to a maximum of 80 mg/day

Hiccups: Adults: Usual effective dose: 10-20 mg 2-3 times/day

Intrathecal:

Test dose: 50-100 mcg, doses >50 mcg should be given in 25 mcg increments, separated by 24 hours. A screening dose of 25 mcg may be considered in very small patients. Patients not responding to screening dose of 100 mcg should not be considered for chronic infusion/implanted pump.

Maintenance: After positive response to test dose, a maintenance intrathecal infusion can be administered via an implanted intrathecal pump. Initial dose via pump: Infusion at a 24-hour rate dosed at twice the test dose. Avoid abrupt discontinuation.

Elderly: Oral (the lowest effective dose is recommended): Initial: 5 mg 2-3 times/day, increasing gradually as needed; if benefits are not seen withdraw the drug slowly.

Dosing adjustment in renal impairment: It is necessary to reduce dosage in renal impairment but there are no specific guidelines available

Hemodialysis: Poor water solubility allows for accumulation during chronic hemodialysis. Low-dose therapy is recommended. There have been several case reports of accumulation of baclofen resulting in toxicity symptoms (organic brain syndrome, myoclonia, deceleration and steep potentials in EEG) in patients with renal failure who have received normal doses of baclofen.

Administration:

Test Interactions:

Patient Education:

Intrathecal use: Keep scheduled pump refill visits; abrupt interruption can cause serious withdrawal symptoms. Report increased spasticity, itching, numbness, unresolved insomnia, painful urination, change in urinary patterns, constipation, high fever, or persistent confusion.

Pregnancy precaution: Inform prescriber if you are or intend to become pregnant.

Nursing Implications:

Anesthesia and Critical Care Concerns/Other Considerations:

Dental Health: Effects on Dental Treatment:

Dental Health: Vasoconstrictor/Local Anesthetic Precautions:

Mental Health: Effects on Mental Status:

Mental Health: Effects on Psychiatric Treatment:

Dosage Forms:

Injection, solution, intrathecal [preservative free] (Lioresal®): 50 mcg/mL (1 mL); 500 mcg/mL (20 mL); 2000 mcg/mL (5 mL)

Tablet: 10 mg, 20 mg

Extemporaneously Prepared:

Johnson CE and Hart SM, "Stability of an Extemporaneously Compounded Baclofen Oral Liquid,"Am J Hosp Pharm, 1993, 50:2353-5.

International Brand Names: