Manufacturer:

CNS Therapeutics

Pharmacological Class:

Muscle relaxant (central), antispastic agent.

Active Ingredient(s):

Baclofen 50mcg/mL, 500mcg/mL, 2000mcg/mL; for intrathecal inj; preservative-free.

Indication(s):

Severe spasticity of cerebral or spinal origin, when oral baclofen not appropriate.

Pharmacology:

Baclofen is a gamma aminobutyric acid (GABA) ergic agonist whose mechanism of action as a muscle relaxant has not been fully elucidated. It inhibits both monosynaptic and polysynaptic reflexes at the spinal level. It may exert its action by stimulation of the GABA_B receptor subtype.

Clinical Trials:

Randomized, controlled investigations compared the effects of either a single intrathecal dose or a 3-day intrathecal infusion of baclofen compared to placebo in patients with severe spasticity and spasms due to either spinal cord trauma or multiple sclerosis. Intrathecal baclofen was shown to be superior to placebo in the change from baseline in the Ashworth rating of spasticity and the frequency of spasms.

Three controlled clinical trials in patients with spasticity of cerebral origin were conducted. Two studies enrolled patients with cerebral palsy and one with spasticity due to previous brain injury. In the first study, a randomized controlled crossover trial of 51 patients with cerebral palsy, yielded significant results. Intrathecal baclofen was superior to placebo in reducing spasticity (as measured by the Ashworth Scale). A second crossover study that was conducted in 11 patients with spasticity due to brain injury provided favorable results, despite the small sample size. The last study, however, did not provide reliable analyzable results.

Legal Classification:

Rx

Contraindication(s):

Not for IV, IM, SC or epidural administration.

Adults & Children:

<4yrs: not recommended. ≥4yrs: Give test dose 1^st by intrathecal inj via spinal catheter or lumbar puncture (see literature for dose and timing; use 50mcg/mL syringe). Dose titration: see literature. Maintenance: titrate individually; use lowest effective dose; maintain some degree of muscle tone. Spinal cord origin: usually 300–800mcg/day. Cerebral origin: usually 90–700mcg/day. Avoid abrupt cessation (may be severe/fatal); closely monitor pump, alarms, and refill schedule; wean orally-administered antispasticity drugs carefully.

Warnings/Precautions:

Do not discontinue abruptly; may result in high fever, altered mental status, rebound spasticity, muscle rigidity. Apparent risk patients (eg, spinal cord injury at T-6 or higher, communicative impairment, history of withdrawal symptoms): closely monitor infusion system, dosing schedule, refills, pump alarms, clinical signs of withdrawal or overdose. Supervise 1^st dose, during titration and refills; have resuscitative equipment and trained personnel available. Do not use chronically if test dose ineffective. For chronic dosing use approved pump (eg, Medtronic SynchroMed II Programmable). Allow at least one year after traumatic brain injury before starting. Psychosis. Schizoaffective disorders. Confusion. Autonomic dysreflexia. Infections. Hospitalize immediately if pump malfunction suspected. Pregnancy (Cat.C). Nursing mothers: not recommended.

Interaction(s):

Hypotension, dyspnea with morphine. Additive CNS depression with alcohol, other CNS depressants. Do not mix with other drugs in pump or catheter. Physostigmine may be useful in reversing effects (see literature).

Adverse Reaction(s):

Hypotonia, somnolence, dizziness, paresthesia, GI upset, headache, constipation, convulsion, hypotension, coma, drowsiness, psychosis, confusion, agitation, leukocytosis, chills, urinary retention; CNS depression, cardiovascular collapse, respiratory failure; others.

How Supplied:

Screening dose prefilled syringe (50mcg/1mL)—1
Single-use vial (10,000mcg/20mL)—1
Single-use vial (40,000mcg/20mL)—1

Last Updated:

12/16/2010