Baclofen

Baclofen
Clinical data
Trade names	Gablofen, Lioresal, others
Other names	• β-(4-chlorophenyl)-γ-Aminobutyric acid; • β-(4-chlorophenyl)-GABA
AHFS/Drugs.com	Monograph
MedlinePlus	a682530
License data	US DailyMed: Baclofen;
Pregnancy; category	AU: B3; ;
Routes of; administration	By mouth, intrathecal, transdermal
Drug class	• GABAB receptor agonist • GABA-derivative Skeletal muscle relaxant • Gabapentinoid
ATC code	M03BX01 (WHO) ;
Legal status
Legal status	AU: S4 (Prescription only); CA: ℞-only; NZ: Prescription only; UK: POM (Prescription only); US: ℞-only;
Pharmacokinetic data
Bioavailability	Well-absorbed
Protein binding	30%
Metabolism	85% excreted in urine/faeces unchanged. 15% metabolised by deamination
Elimination half-life	2.5–7 hours
Excretion	Kidney (70–80%)
Identifiers
	IUPAC name (RS)-4-Amino-3-(4-chlorophenyl)butanoic acid;
CAS Number	1134-47-0;
PubChem CID	2284;
IUPHAR/BPS	1084;
DrugBank	DB00181;
ChemSpider	2197;
UNII	H789N3FKE8;
KEGG	D00241;
ChEBI	CHEBI:2972;
ChEMBL	ChEMBL701;
CompTox Dashboard (EPA)	DTXSID5022641 ;
ECHA InfoCard	100.013.170
Chemical and physical data
Formula	C10H12ClNO2
Molar mass	213.66 g·mol−1
3D model (JSmol)	Interactive image;
Chirality	Racemic mixture
	SMILES NCC(CC(=O)O)c1ccc(Cl)cc1;
	InChI InChI=1S/C10H12ClNO2/c11-9-3-1-7(2-4-9)8(6-12)5-10(13)14/h1-4,8H,5-6,12H2,(H,13,14); Key:KPYSYYIEGFHWSV-UHFFFAOYSA-N;

Baclofen, sold under the brand names Gablofen and Lioresal among others, is a medication used to treat muscle spasticity, such as from a spinal cord injury or multiple sclerosis. Baclofen is a powerful GABA-derivative skeletal muscle relaxant and a potent GABA_B receptor agonist. It may also be used for hiccups and muscle spasms near the end of life, and off-label to treat alcohol use disorder or opioid withdrawal symptoms. It is taken orally or by intrathecal pump (delivered into the spinal canal via an implantable pump device). It is believed to work by decreasing levels of certain neurotransmitters.

Baclofen should be avoided in the setting of chronic kidney disease and end stage renal disease as even small doses can cause excessive toxicity. Common side effects include sleepiness, weakness, and dizziness. Serious side effects, such as seizures and rhabdomyolysis, may occur if use of baclofen is stopped abruptly. Use during pregnancy is of unclear safety, whilst use during breastfeeding is likely safe, and even more so if oral administration is avoided.

The adverse effects and safety profile associated with baclofen when it is combined with sedative drugs (for example alcohol or benzodiazepines) range depending on the dose and the individual. The interaction may increase the sedative effects of all ingested sedatives and as such is not generally recommended. In high doses the interaction can cause de novo seizures.

Baclofen was approved for medical use in the United States in 1977. It is available as a generic medication. It is on the World Health Organization's List of Essential Medicines. In 2023, it was the 87th most commonly prescribed medication in the United States, with more than 7 million prescriptions.