Overview
Baclofen is a centrally-acting skeletal muscle relaxant used primarily to treat spasticity associated with multiple sclerosis, spinal cord injuries, and other neurological conditions. It acts as a GABA-B receptor agonist in the spinal cord to inhibit monosynaptic and polysynaptic reflexes.
Mechanism of Action
Baclofen is a gamma-aminobutyric acid (GABA) analog that acts as a selective agonist at GABA-B receptors in the spinal cord and brain. It inhibits the release of excitatory neurotransmitters (glutamate, aspartate) and substance P, reducing monosynaptic and polysynaptic reflex activity, thereby decreasing muscle spasticity.
Indications
- Treatment of spasticity resulting from multiple sclerosis
- Management of spinal cord injuries and other spinal cord diseases
- Treatment of muscle spasticity in cerebral palsy
- Off-label: Treatment of alcohol use disorder
- Off-label: Management of trigeminal neuralgia
Dosage
Initial dose: 5 mg orally three times daily. May increase by 5 mg every 3 days to optimal response. Maximum recommended dose: 80 mg daily (20 mg four times daily). For intrathecal administration: Initial test dose 50 mcg, with gradual titration based on response.
Contraindications
- Hypersensitivity to baclofen
- Intrathecal administration in patients with infection at injection site
- Intrathecal administration in patients with spinal canal obstruction
Side Effects
- Drowsiness
- Dizziness
- Weakness
- Fatigue
- Nausea
- Headache
- Insomnia
- Hypotension
- Constipation
- Urinary retention
- Confusion
- Hallucinations (rare)
- Seizures (with abrupt withdrawal)
Interactions
- CNS depressants (alcohol, benzodiazepines, opioids): Increased sedation and respiratory depression
- Antihypertensives: Enhanced hypotensive effects
- MAO inhibitors: Increased CNS depression
- Tricyclic antidepressants: Increased muscle relaxation effects