No

Skeletal Muscle Relaxant

Treatment of reversible spasticity associated with multiple sclerosis or spinal cord lesions

C

Hypersensitivity to baclofen or any component

Use with caution in patients with seizure disorder, impaired renal function; avoid abrupt withdrawal of the drug; elderly are more sensitive to the effects of baclofen and are more likely to experience adverse CNS effects at higher doses.

>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

Symptoms of overdose include vomiting, muscle hypotonia, salivation, drowsiness, coma, seizures, respiratory depression

Atropine has been used to improve ventilation, heart rate, blood pressure, and core body temperature. Following initiation of essential overdose management, symptomatic and supportive treatment should be instituted.

Increased effect: Opiate analgesics, benzodiazepines, hypertensive agents

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

Inhibits the transmission of both monosynaptic and polysynaptic reflexes at the spinal cord level, possibly by hyperpolarization of primary afferent fiber terminals, with resultant relief of muscle spasticity

Onset of action: Muscle relaxation effect requires 3-4 days

Peak effect: Maximal clinical effect is not seen for 5-10 days

Absorption: Oral: Rapid; absorption from GI tract is thought to be dose dependent

Protein binding: 30%

Metabolism: Minimally in the liver

Half-life: 3.5 hours

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

Elimination: 85% of oral dose excreted in urine and feces as unchanged drug

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

greater than or equal to 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

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.

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.

For screening dosages, dilute with preservative-free sodium chloride to a final concentration of 50 mcg/mL for bolus injection into the subarachnoid space; for maintenance infusions, concentrations of 500-2000 mcg/mL may be used

alkaline phosphatase, AST, glucose, ammonia (B); bilirubin (S)

Drowsiness and insomnia are common; rare reports of depression, euphoria, and hallucinations

Concurrent use with psychotropics may produce additive sedation; concurrent use with MAOIs may potentiate their hypotensive effects

No information available to require special precautions

No effects or complications reported

Take this drug as prescribed. Do not discontinue without consulting prescriber (abrupt discontinuation may cause hallucinations). Do not take any prescription or OTC sleep-inducing drugs, sedatives, antispasmodics without consulting prescriber. Avoid alcohol use. You may experience transient drowsiness, lethargy, or dizziness; use caution when driving or engaging in tasks requiring alertness until response to drug is known. Frequent small meals or lozenges may reduce GI upset. Report unresolved insomnia, painful urination, change in urinary patterns, constipation, or persistent confusion. Pregnancy precautions: Inform prescriber if you are or intend to be pregnant.

Epileptic patients should be closely monitored; supervise ambulation; avoid abrupt withdrawal of the drug

Injection, intrathecal, preservative free: 500 mcg/mL (20 mL); 2000 mcg/mL (5 mL)

Tablet: 10 mg, 20 mg

Make a 5 mg/mL suspension by crushing fifteen 20 mg tablets; wet with glycerin, gradually add 45 mL simple syrup in 3 x 5 mL aliquots to make a total volume of 60 mL; refrigerate; stable 35 days

Abarbanel J, Herishanu Y, Frisher S, "Encephalopathy Associated With Baclofen," Ann Neurol, 1985, 17(6):617-8.

Cooke DE and Glasstone MA, "Baclofen Poisoning in Children," Vet Hum Toxicol, 1994, 36(5):448-50.

Khorasani A and Peruzzi WT, "Dantrolene Treatment for Abrupt Intrathecal Baclofen Withdrawal," Anesth Analg, 1995, 80(5):1054-6.

May CR, "Baclofen Overdose," Ann Emerg Med, 1983, 12:171-3.

Muller-Schwefe G and Penn RD, "Physostigmine in the Treatment of Intrathecal Baclofen Overdose. Report of Three Cases," J Neurosurg, 1989, 71(2):273-5.

Roberge RJ, Martin TG, Hodgman M, et al, "Supraventricular Tachyarrhythmia Associated With Baclofen Overdose," J Toxicol Clin Toxicol, 1994, 32(3):291-7.

Tan AK and Tan CB, "The Syndrome of Painful Legs and Moving Toes...A Case Report," Singapore Med J, 1996, 37(4):446-7.