Baclofen
Baclofen is a GABA-B receptor agonist prescribed as a skeletal muscle relaxant for spasticity from spinal cord injury and multiple sclerosis. It is also used off-label for alcohol dependence and produces anxiolysis and sedation. It is not a gabapentinoid but is a core non-benzodiazepine GABAergic calming agent, with a significant and sometimes dangerous withdrawal syndrome.
01 Overview
Baclofen has decades of clinical use for spasticity, delivered orally or, in severe cases, intrathecally via an implanted pump. Off-label high-dose regimens for alcohol use disorder have been studied with mixed results.
Abrupt discontinuation, particularly of intrathecal or high oral doses, can cause a severe withdrawal syndrome with rebound spasticity, hyperthermia, seizures, hallucinations and, rarely, death. Overdose causes profound CNS and respiratory depression. It must be tapered.
02 Mechanism
Selective agonist at GABA-B receptors, hyperpolarising neurons via potassium channel opening and inhibition of calcium influx, which reduces mono- and polysynaptic reflex transmission in the spinal cord.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Spasticity | 15–80 mg/day | Oral | Titrate from 5 mg three times daily; usual max 80 mg/day in divided doses. |
| Alcohol use disorder (off-label) | 30–300 mg/day | Oral | High-dose off-label regimens used in trials; specialist supervision required. |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Reduced spasticityDecreases muscle tone, spasm frequency and clonus in spinal spasticity. | Marked | Clinical | |
| Anxiolysis and calmingReduces anxiety and craving in some studies of alcohol dependence. | Moderate | Clinical |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Sedation and weaknessDrowsiness, fatigue and muscle weakness, dose-dependent. | Mild | Very common | Clinical | |
| Withdrawal syndromeAbrupt cessation can cause rebound spasticity, fever, seizures, hallucinations and rhabdomyolysis, most dangerously with intrathecal therapy. | Life-threatening | Uncommon but severe | Clinical | |
| Overdose CNS/respiratory depressionLarge ingestions cause coma, hypotonia and respiratory failure. | Life-threatening | Rare | Clinical |