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Baclofen

Pronunciation

Pronunciation

(BAK loe fen)

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product

Cream, External:

EnovaRX-Baclofen: 1% (60 g, 120 g) [contains cetyl alcohol]

Equipto-Baclofen: 2% (120 g)

Generic: 2% (60 g)

Solution, Intrathecal [preservative free]:

Gablofen: 50 mcg/mL (1 mL); 10,000 mcg/20 mL (20 mL); 20,000 mcg/20 mL (20 mL); 40,000 mcg/20 mL (20 mL) [antioxidant free]

Lioresal: 0.05 mg/mL (1 mL); 10 mg/20 mL (20 mL); 10 mg/5 mL (5 mL); 40 mg/20 mL (20 mL) [antioxidant free]

Tablet, Oral:

Ed Baclofen: 10 mg [DSC]

Generic: 10 mg, 20 mg

Brand Names: U.S.

  • Ed Baclofen [DSC]
  • EnovaRX-Baclofen
  • Equipto-Baclofen
  • Gablofen
  • Lioresal

Pharmacologic Category

  • Skeletal Muscle Relaxant

Pharmacology

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

Absorption

Oral: Rapid; absorption from the GI tract is thought to be dose dependent; in pediatric patients (age range: 2 to 17 years) with cerebral palsy, absorption from GI tract highly variable and delayed (reported time lag: 0.59 ± 0.28 hours) (He 2014)

Metabolism

Hepatic (15% of dose) (He 2014)

Excretion

Urine (>70% as unchanged drug) and feces (Brunton 2011)

Onset of Action

Intrathecal bolus: 30 minutes to 1 hour; Continuous infusion: 6 to 8 hours after infusion initiation

Peak effect: Intrathecal bolus: 4 hours (effects may last 4 to 8 hours); Continuous infusion: 24 to 48 hours

Time to Peak

Serum: Oral: 1 hour (0.5 to 4 hours) (Brunton 2011)

Half-Life Elimination

Pediatric patients with cerebral palsy (age range: 2 to 17 years): Oral: 4.5 hours (He 2014)

Adults: 3.75 ± 0.96 hours (Brunton 2011); Intrathecal: CSF elimination half-life: 1.5 hours over the first 4 hours

Protein Binding

30%

Use: Labeled Indications

Spasticity:

Oral: Management of reversible spasticity associated with multiple sclerosis or spinal cord lesions

Intrathecal: Management of severe spasticity of spinal cord origin (eg, spinal cord injury, multiple sclerosis) or cerebral origin (eg, cerebral palsy, traumatic brain injury) in patients ≥4 years; may be considered as an alternative to destructive neurosurgical procedures.

Limitations of use: Patients should first respond to a screening dose of intrathecal baclofen prior to consideration for long term infusion via an implantable pump. For spasticity of spinal cord origin, chronic infusion via an implantable pump should be reserved for patients unresponsive to oral baclofen therapy, or those who experience intolerable CNS side effects at effective doses. Patients with spasticity due to traumatic brain injury should wait at least one year after the injury before consideration of long term intrathecal baclofen therapy.

Use: Unlabeled

Intractable hiccups, bladder spasticity, trigeminal neuralgia, cerebral palsy, short-term treatment of spasticity in children with cerebral palsy

Contraindications

Hypersensitivity to baclofen or any component of the formulation

Intrathecal: IV, IM, SubQ, or epidural administration

Dosing: Adult

Spasticity:

Oral: Initial: 5 mg 3 times daily; may increase by 5 mg per dose every 3 days (ie, 5 mg 3 times daily for 3 days, then 10 mg 3 times daily for 3 days, etc.) until optimal response is reached. Usual dosage range: 40 to 80 mg daily. Do not exceed 80 mg daily (20 mg 4 times daily).

Intrathecal:

Screening dose:

U.S. labeling: Initial: 50 mcg (1 mL) for 1 dose; following initial administration, observe patient for 4 to 8 hours. A positive response consists of a significant decrease in muscle tone and/or frequency and/or severity of spasms. If response is inadequate, may give 75 mcg as a second screening dose 24 hours after the first screening dose; observe patient for 4 to 8 hours. If response is still inadequate, may repeat a final screening dose of 100 mcg given 24 hours after the second screening dose. Patients not responding to screening dose of 100 mcg should not be considered for chronic infusion/implanted pump.

Canadian labeling: Initial: 25 to 50 mcg for 1 dose; titrate up in 25 mcg increments at least 24 hours apart until an approximately 4 to 8 hour response is observed. Patients not responding to screening dose of 100 mcg should not be given further increases in dose or be considered for chronic infusion/implanted pump; however, some patients, particularly those with spasticity of cerebral origin, have in rare instances received higher test bolus doses. Note: A 10 mcg dose may be administered if adverse reactions occur with a 25 mcg dose.

Dose titration following pump implant: After positive response to screening dose, a maintenance intrathecal infusion can be administered via an implanted intrathecal pump.

Initial total daily dose via pump: Double the screening dose that gave a positive response and administer over 24 hours, unless efficacy of the bolus dose was maintained for >8 hours (US labeling) or >12 hours (Canadian labeling), then infuse a dose equivalent to the screening dose over 24hours. Do not increase dose in first 24 hours (to allow steady state to be achieved); thereafter, dosage adjustments may be made as follows:

US labeling: Increase daily dose slowly by 10% to 30% (spasticity of spinal cord origin) or 5% to 15% (spasticity of cerebral origin) once every 24 hours until satisfactory response

Canadian labeling: Increase daily dose slowly by 10% to 30% once every 24 hours (if using a programmable pump) or once every 48 hours (if using a nonprogrammable pump)

Maintenance:

US labeling: Daily dose may be increased 5% to 20% (maximum increase: 20%) (spasticity of cerebral origin) or by 10% to 40% (maximum increase: 40%) (spasticity of spinal cord origin). Dose may also be decreased 10% to 20% for adverse effects. Most patients have been adequately maintained on 90 mcg to 703 mcg daily (spasticity of cerebral origin) or 300 mcg to 800 mcg daily (spasticity of spinal cord origin). Experience with doses > 1,000 mcg daily is limited.

Canadian labeling: Daily dose may be increased 10% to 30%. Dose may also be decreased 10% to 20% for adverse effects. Most patients have been adequately maintained on 300 mcg to 800 mcg daily.

Note: Dosage adjustments may be required often during the first few months of therapy to adjust for life style changes due to alleviation of spasticity. Maintain lowest dose that produces adequate response. Most patients require gradual increases over time to maintain optimal response. Sudden large requirements for a dose increase may indicate a catheter complication (eg, kink, dislodgement).Titrate dose to allow sufficient muscle tone and occasional spasms to optimize activities of daily living, support circulation, and possibly prevent DVT formation. Use extreme caution when filling the pump; follow manufacturer instructions carefully. 5% to 10% of patients receiving chronic therapy become refractory to dose adjustments; may consider a drug holiday (hospitalized patients only) with a gradual withdrawal over 2 to 4 weeks and use of alternative spasticity management methods. Following the drug holiday intrathecal baclofen may be resumed at the initial continuous infusion dose.

Hiccups (off-label use): Oral: 5 to 10 mg 3 times daily (maximum: 75 mg daily in divided doses) (Guelaud 1995; Zhang 2014)

Dosing: Geriatric

Oral: Refer to adult dosing; use with caution. If benefits are not observed, withdraw the drug slowly.

Dosing: Pediatric

Oral: Note: Use the lowest effective dose; patients who fail to respond within a reasonable amount of time should be slowly withdrawn from therapy (avoid abrupt withdrawal of drug).

Spasticity:

Oral:

Children ≥12 years and Adolescents: Refer to adult dosing.

Infants, Children, and Adolescents (off-label): Note: Dose-related side effects (eg, sedation) may be minimized by slow titration; lower initial doses than described below (2.5 to 10 mg daily) may be used with subsequent titration to 8 hourly doses. There is limited published data in infants and children; the following is a compilation of small prospective studies (Milla 1977; Scheinberg 2006) and one large retrospective analysis of baclofen use in children (Lubsch 2006). Efficacy results variable (AAN [Delgado] 2010)

Infants ≥4 months and Children <2 years: Limited data available: 10 to 20 mg daily divided every 8 hours; begin at low end of range and titrate dose to patient response, titration intervals of every 3 days to weekly have been used in pediatric patients ≥2 years (Millia 1997; Scheinberg 2006). Maximum daily dose: 40 mg/day (Lubsch 2006). Note: To minimize dose-related side effects (eg, sedation), lower initial doses (eg, 2.5 mg once daily) and slower titration may be considered (eg, weekly) and has been reported in pediatric patients >2 years (Scheinberg 2006).

2 to 7 years: Limited data available: 20 to 40 mg daily divided every 8 hours; begin at low end of range (or even lower [2.5 to 10 mg daily] and titrate dose to patient response; titration intervals of every 3 days to weekly have been used in pediatric patients. Maximum daily dose: 60 mg/day (Lubsch 2006; Millia 1997; Scheinberg 2006).

≥8 years and Adolescents: Limited data available in children <12 years: 30 to 40 mg daily divided every 8 hours; begin at low end of range (or even lower [10 mg to 15 mg daily in 3 divided doses]) and titrate dose to patient response, titration intervals of every 3 days to weekly have been used (Millia 1997; Scheinberg 2006); some patients ≥12 years may require every 6 hour dosing; usual maximum daily dose range: 60 to 80 mg/day (Lubsch 2006; Millia 1977). Note: Higher maximum daily doses (up to 200 mg/day) have been described in some patients in a retrospective review, usually the higher doses were needed over time (Lubsch 2006).

Intrathecal: Children ≥4 years and Adolescents (US labeling):

Screening dose: Initial: 50 mcg (1 mL) for 1 dose; following initial administration, observe patient for 4 to 8 hours. A positive response consists of a significant decrease in muscle tone and/or frequency and/or severity of spasms. If response is inadequate, may give 75 mcg as a second screening dose 24 hours after the first screening dose; observe patient for 4 to 8 hours. If response is still inadequate, may repeat a final screening dose of 100 mcg given 24 hours after the second screening dose. Patients not responding to screening dose of 100 mcg should not be considered for chronic infusion/implanted pump. Note: A 25 mcg initial screening dose may be considered in very small pediatric patients.

Dose titration following pump implant: After positive response to screening dose, a maintenance intrathecal infusion can be administered via an implanted intrathecal pump.

Initial total daily dose via pump: Double the screening dose that gave a positive response and administer over 24 hours, unless efficacy of the bolus dose was maintained for >8 hours, then infuse a dose equivalent to the screening dose over 24 hours. Do not increase dose in first 24 hours (to allow steady state to be achieved); thereafter, increase daily dose slowly by 5% to 15% once every 24 hours until satisfactory response.

Maintenance: Daily dose may be increased 5% to 20% (maximum increase: 20%). Dose may also be decreased 10% to 20% for adverse effects. Patients <12 years required lower daily doses in clinical trials (average dose: 274 mcg daily; dosage range: 24 mcg to 1,199 mcg/day); dose requirements of patients >12 years were similar to that of adults.

Note: Dosage adjustments may be required often during the first few months of therapy to adjust for life style changes due to alleviation of spasticity. Maintain lowest dose that produces adequate response. Most patients require gradual increases over time to maintain optimal response. Sudden large requirements for a dose increase may indicate a catheter complication (eg, kink, dislodgement).Titrate dose to allow sufficient muscle tone and occasional spasms to optimize activities of daily living, support circulation, and possibly prevent DVT formation. Use extreme caution when filling the pump; follow manufacturer instructions carefully. 5% to 10% of patients receiving chronic therapy become refractory to dose adjustments; may consider a drug holiday (hospitalized patients only) with a gradual withdrawal over 2 to 4 weeks and use of alternative spasticity management methods. Following the drug holiday intrathecal baclofen may be resumed at the initial continuous infusion dose.

Dosing: Renal Impairment

Oral: There are no dosage adjustments provided in the manufacturer’s labeling. However, baclofen is primarily renally eliminated; use with caution; dosage reduction may be necessary.

Hemodialysis:

US labeling: There are no dosage adjustments provided in the manufacturer’s labeling.

Canadian labeling: 5 mg once daily

Dosing: Hepatic Impairment

Oral:

US labeling: There are no dosage adjustments provided in the manufacturer’s labeling.

Canadian labeling: No dosage adjustment necessary; use with caution in severe impairment.

Reconstitution

Intrathecal: Screening doses are a 50 mcg/mL concentration and only the 1 mL screening ampul or screening syringe (50 mcg/mL) is used; do not further dilute. Maintenance infusions for patients who require concentrations other than 500 mcg/mL, 1,000 mcg/mL, or 2,000 mcg/mL must be diluted with preservative-free sodium chloride. Discard any unused solution.

Extemporaneously Prepared

A 5 mg/mL oral suspension may be made with tablets. Crush thirty 20 mg tablets in a mortar and reduce to a fine powder. Add a small amount of glycerin and mix to a uniform paste. Mix while adding Simple Syrup, NF in incremental proportions to almost 120 mL; transfer to a calibrated bottle, rinse mortar with vehicle, and add a sufficient quantity of vehicle to make 120 mL. Label “shake well” and “refrigerate”. Stable for 35 days (Johnson, 1993).

A 10 mg/mL oral suspension may be made with tablets. Crush one-hundred-twenty 10 mg tablets in a mortar and reduce to a fine powder. Add small portions (60 mL) of a 1:1 mixture of Ora-Sweet® and Ora-Plus® and mix to a uniform paste; mix while adding the vehicle in incremental proportions to almost 120 mL; transfer to a calibrated bottle, rinse mortar with vehicle, and add quantity of vehicle sufficient to make 120 mL. Label “shake well” and “refrigerate”. Stable for 60 days (Allen, 1996).

Allen LV Jr and Erickson MA 3rd, "Stability of Baclofen, Captopril, Diltiazem Hydrochloride, Dipyridamole, and Flecainide Acetate in Extemporaneously Compounded Oral Liquids," Am J Health Syst Pharm, 1996, 53(18):2179-84.8879325Johnson CE and Hart SM, “Stability of an Extemporaneously Compounded Baclofen Oral Liquid,” Am J Hosp Pharm, 1993, 50(11):2353-5.8266961

Administration

Intrathecal: For screening dosages, administer as a bolus injection (50 mcg/mL concentration) by barbotage into the subarachnoid space over at least 1 minute, followed by maintenance continuous infusion.

Oral: The Canadian labeling recommends administering with food or milk in patients with persistent nausea despite dose reductions.

Compatibility

Stable in sterile, preservative-free NS.

Storage

Injection: Do not store above 30°C (86°F). Does not require refrigeration. Do not freeze or heat sterilize.

Tablets: Store at 20°C to 25°C (68°F to 77°F).

Drug Interactions

Alcohol (Ethyl): CNS Depressants may enhance the CNS depressant effect of Alcohol (Ethyl). Monitor therapy

Azelastine (Nasal): CNS Depressants may enhance the CNS depressant effect of Azelastine (Nasal). Avoid combination

Blonanserin: CNS Depressants may enhance the CNS depressant effect of Blonanserin. Consider therapy modification

Brimonidine (Topical): May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Buprenorphine: CNS Depressants may enhance the CNS depressant effect of Buprenorphine. Management: Consider reduced doses of other CNS depressants, and avoiding such drugs in patients at high risk of buprenorphine overuse/self-injection. Initiate buprenorphine patches (Butrans brand) at 5 mcg/hr in adults when used with other CNS depressants. Consider therapy modification

Cannabis: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

CNS Depressants: May enhance the adverse/toxic effect of other CNS Depressants. Exceptions: Levocabastine (Nasal). Monitor therapy

Doxylamine: May enhance the CNS depressant effect of CNS Depressants. Management: The manufacturer of Diclegis (doxylamine/pyridoxine), intended for use in pregnancy, specifically states that use with other CNS depressants is not recommended. Monitor therapy

Dronabinol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Droperidol: May enhance the CNS depressant effect of CNS Depressants. Management: Consider dose reductions of droperidol or of other CNS agents (e.g., opioids, barbiturates) with concomitant use. Consider therapy modification

Hydrocodone: CNS Depressants may enhance the CNS depressant effect of Hydrocodone. Management: Consider starting with a 20% to 30% lower hydrocodone dose when using together with any other CNS depressant. Dose reductions in the other CNS depressant may also be warranted. Consider therapy modification

HydrOXYzine: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Kava Kava: May enhance the adverse/toxic effect of CNS Depressants. Monitor therapy

Lacidipine: Baclofen may enhance the hypotensive effect of Lacidipine. Monitor therapy

Magnesium Sulfate: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Methotrimeprazine: CNS Depressants may enhance the CNS depressant effect of Methotrimeprazine. Methotrimeprazine may enhance the CNS depressant effect of CNS Depressants. Management: Reduce adult dose of CNS depressant agents by 50% with initiation of concomitant methotrimeprazine therapy. Further CNS depressant dosage adjustments should be initiated only after clinically effective methotrimeprazine dose is established. Consider therapy modification

Metyrosine: CNS Depressants may enhance the sedative effect of Metyrosine. Monitor therapy

Minocycline: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Mirtazapine: CNS Depressants may enhance the CNS depressant effect of Mirtazapine. Monitor therapy

Nabilone: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Orphenadrine: CNS Depressants may enhance the CNS depressant effect of Orphenadrine. Avoid combination

OxyCODONE: CNS Depressants may enhance the CNS depressant effect of OxyCODONE. Management: When oxycodone is combined with another CNS depressant, a dose reduction of one or both agents should be considered. The extended release oxycodone starting dose should be reduced 50% to 67% when initiated in patients already receiving CNS depressants. Consider therapy modification

Paraldehyde: CNS Depressants may enhance the CNS depressant effect of Paraldehyde. Avoid combination

Perampanel: May enhance the CNS depressant effect of CNS Depressants. Management: Patients taking perampanel with any other drug that has CNS depressant activities should avoid complex and high-risk activities, particularly those such as driving that require alertness and coordination, until they have experience using the combination. Consider therapy modification

Pramipexole: CNS Depressants may enhance the sedative effect of Pramipexole. Monitor therapy

ROPINIRole: CNS Depressants may enhance the sedative effect of ROPINIRole. Monitor therapy

Rotigotine: CNS Depressants may enhance the sedative effect of Rotigotine. Monitor therapy

Rufinamide: May enhance the adverse/toxic effect of CNS Depressants. Specifically, sleepiness and dizziness may be enhanced. Monitor therapy

Selective Serotonin Reuptake Inhibitors: CNS Depressants may enhance the adverse/toxic effect of Selective Serotonin Reuptake Inhibitors. Specifically, the risk of psychomotor impairment may be enhanced. Monitor therapy

Sodium Oxybate: May enhance the CNS depressant effect of CNS Depressants. Management: Consider alternatives to combined use. When combined use is needed, consider minimizing doses of one or more drugs. Use of sodium oxybate with alcohol or sedative hypnotics is contraindicated. Consider therapy modification

Suvorexant: CNS Depressants may enhance the CNS depressant effect of Suvorexant. Management: Dose reduction of suvorexant and/or any other CNS depressant may be necessary. Use of suvorexant with alcohol is not recommended, and the use of suvorexant with any other drug to treat insomnia is not recommended. Consider therapy modification

Tapentadol: May enhance the CNS depressant effect of CNS Depressants. Management: Start tapentadol at a dose of one-third to one-half of the normal dose if being initiated in a patient who is taking another drug with CNS depressant effects. Monitor closely for evidence of excessive CNS depression. Consider therapy modification

Tetrahydrocannabinol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Thalidomide: CNS Depressants may enhance the CNS depressant effect of Thalidomide. Avoid combination

Trimeprazine: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Zolpidem: CNS Depressants may enhance the CNS depressant effect of Zolpidem. Management: Reduce the Intermezzo brand sublingual zolpidem adult dose to 1.75 mg for men who are also receiving other CNS depressants. No such dose change is recommended for women. Avoid use with other CNS depressants at bedtime; avoid use with alcohol. Consider therapy modification

Adverse Reactions

>10%:

Central nervous system: Hypotonia (2% to 35%), drowsiness (6% to 21%), confusion (1% to 11%), headache (2% to 11%)

Gastrointestinal: Nausea (1% to 12%), vomiting (2% to 11%)

1% to 10%:

Cardiovascular: Hypotension (≤9%), peripheral edema (≤3%)

Central nervous system: Convulsions (≤10%), dizziness (2% to 8%), insomnia (≤7%), paresthesia (≤7%), hypertonia (≤6%), pain (≤4%), speech disturbance (≤4%), depression (2%), coma (≤2%), abnormality in thinking (≤1%), agitation (≤1%), chills (≤1%)

Dermatologic: Pruritus (4%), urticaria (≤1%)

Gastrointestinal: Constipation (≤6%), sialorrhea (3%), xerostomia (≤3%), diarrhea (≤2%)

Genitourinary: Urinary retention (≤8%), urinary frequency (≤6%), difficulty in micturition (2%), impotence (≤2%), urinary incontinence (≤2%)

Neuromuscular & skeletal: Back pain (≤2%), weakness (≤2%), tremor (≤1%)

Ophthalmic: Ambylopia (≤2%)

Respiratory: Hypoventilation (≤4%), pneumonia (≤2%), dyspnea (≤1%)

Miscellaneous: Accidental injury (≤4%)

<1% (Limited to important or life-threatening): Accommodation disturbance, akathisia, albuminuria, alopecia, amnesia, apnea, ataxia, blurred vision, bradycardia, bradypnea, carcinoma, chest pain, decreased appetite, deep vein thrombosis, dehydration, diaphoresis, diplopia, disorientation, dysarthria, dysautonomia, dysgeusia, dysphagia, dysphoria, dystonia, dysuria, epilepsy, facial edema, fecal incontinence, gastrointestinal hemorrhage, hyperglycemia, hyperhidrosis, hypertension, hyperventilation, hypothermia, hysteria, inhibited ejaculation, intestinal obstruction, lethargy, leukocytosis, loss of postural reflex, lower extremity weakness, malaise, miosis, muscle rigidity, myalgia, mydriasis, nephrolithiasis, nocturia, nystagmus, occult blood in stools, oliguria, opisthotonus, pallor, palpitations, petechial rash, pulmonary embolism, respiratory depression, sedation, slurred speech, strabismus, suicidal ideation, syncope, vasodilatation

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

ALERT: U.S. Boxed Warning

Abrupt withdrawal (injection):

Abrupt discontinuation of intrathecal baclofen, regardless of the cause, has resulted in sequelae that include high fever, altered mental status, exaggerated rebound spasticity, and muscle rigidity, which in rare cases has advanced to rhabdomyolysis, multiple organ-system failure, and death.

Prevention of abrupt discontinuation of intrathecal baclofen requires careful attention to programming and monitoring of the infusion system, refill scheduling and procedures, and pump alarms. Advise patients and caregivers of the importance of keeping scheduled refill visits and educate them on the early symptoms of baclofen withdrawal. 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). Consult the technical manual of the implantable infusion system for additional postimplant clinician and patient information.

Warnings/Precautions

Concerns related to adverse effects:

• CNS depression: May cause CNS depression, which may impair physical or mental abilities; patients must be cautioned about performing tasks which require mental alertness (eg, operating machinery or driving).

• Ovarian cysts: Animal studies have shown an increased incidence in ovarian cysts; however, incidence observed in multiple sclerosis patients treated with baclofen for up to one year was similar to the estimated incidence in healthy females. Spontaneous resolution occurred in most of these MS patients while continuing treatment.

• Urinary retention: May cause acute urinary retention (may be related to underlying disease); use with caution in patients with urinary obstruction.

Disease-related concerns:

• Gastrointestinal disorders: Use with caution in patients with peptic ulcer disease, decreased GI motility, and/or gastrointestinal obstructive disorders.

• Infections: Patients receiving intrathecal baclofen should be infection-free prior to the test dose and pump implantation.

• Psychiatric disease: Use with caution; may cause exacerbation of condition.

• Renal impairment: Use with caution in patients with renal impairment; baclofen is eliminated primarily unchanged via the kidneys. Multiple cases describing neurotoxicity due to oral baclofen accumulation in adult patients with varying levels of renal impairment have been reported in the literature. In patients with renal impairment, initiation of oral baclofen at lower doses and/or extended intervals has been suggested (Aisen 1994; Chen 1997; Chou 2006; El-Husseini 2011; Peces 1998; Su 2009; Vlavonu 2014).

• Respiratory disease: Use with caution in patients with respiratory disease.

• Seizure disorder: Use with caution in patients with a history of seizure disorder; monitor regularly for loss of seizure control.

Special populations:

• Elderly: Use with caution in elderly patients; may be more sensitive to adverse CNS effects, especially at higher doses.

Concurrent drug therapy issues:

• Drug-drug interactions: Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information.

Other warnings/precautions:

• Abrupt withdrawal: [US Boxed Warning]: Abrupt withdrawal of intrathecal baclofen has resulted in severe sequelae (hyperpyrexia, obtundation, rebound/exaggerated spasticity, muscle rigidity, and rhabdomyolysis), leading to organ failure and some fatalities. Prevention of abrupt discontinuation requires careful attention to programming and monitoring of infusion system, refill scheduling and procedures, and pump alarms. Risk may be higher in patients with injuries at T-6 or above, history of baclofen withdrawal, or limited ability to communicate. Abrupt withdrawal of oral therapy has been associated with hallucinations and seizures; gradual dose reductions (over ~1 to 2 weeks) are recommended in the absence of severe adverse reactions.

• Appropriate use: Efficacy of oral baclofen has not been established in patients with stroke, Parkinson disease, or cerebral palsy; therefore, use is not recommended. Not indicated for spasticity associated with rheumatic disorders. Use with caution when spasticity is utilized to sustain upright posture and balance in locomotion, or when spasticity is necessary to obtain increased function. Adverse effects are more likely in patients with spastic states of cerebral origin; cautious dosing and careful monitoring are necessary.

• Intrathecal use: Clinicians should be experienced with chronic intrathecal infusion therapy. Pump should only be implanted if patient's response to bolus intrathecal baclofen was adequately evaluated and found to be safe and effective. Resuscitative equipment should be readily available. Monitor closely during the initial phase of pump use and when adjusting the dosing rate and/or the concentration in the reservoir. Educate patients and caregivers on proper home care of the pump and insertion site; early symptoms of baclofen withdrawal (eg, return of baseline spasticity, hypotension, paresthesia, pruritus); signs/symptoms of overdose (eg, dizziness, somnolence, respiratory depression, seizures); and appropriate actions in the event of an overdose. Cases (most from pharmacy compounded preparations) of intrathecal mass formation at the implanted catheter tip have been reported; may lead to loss of clinical response, pain or new/worsening neurological effects. Neurosurgical evaluation and/or an appropriate imaging study should be considered if a mass is suspected. Use caution with history of autonomic dysreflexia; presence of nociceptive stimuli or abrupt baclofen withdrawal may cause an autonomic dysreflexia episode.

Monitoring Parameters

Regular electroencephalogram (EEG) in patients with epilepsy (loss of seizure control has been reported).

Pregnancy Risk Factor

C

Pregnancy Considerations

Adverse events were observed in animal reproduction studies. Withdrawal symptoms in the neonate were noted in a case report following the maternal use of oral baclofen 20 mg 4 times/day throughout pregnancy (Ratnayaka, 2001). Plasma concentrations following administration of intrathecal baclofen are significantly less than those with oral doses; exposure to the fetus is expected to be limited (Morton, 2009).

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Patient may experience insomnia, nausea, headache, or constipation. Have patient report immediately to prescriber signs of withdrawal (high fever, mental changes, increased spasm, or muscle rigidity), loss of strength and energy, severe dizziness, passing out, illogical thinking, fatigue, polyuria, behavioral changes, seizures, vision changes, angina, muscle pain, burning or numbness feeling, signs of breathing problems (shortness of breath, wheezing, coughing, or breathing gets worse), urinary retention, change in amount of urine passed, blood in urine, mood changes, hallucinations, abnormal movements, twitching, change in balance, dysphagia, difficulty speaking, involuntary eye movements, or arrhythmia (HCAHPS).

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for healthcare professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience and judgment in diagnosing, treating and advising patients.

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