GABLOFEN

Clinical safety rating: caution

Comprehensive clinical and safety monograph for GABLOFEN (GABLOFEN).

How it works

GABLOFEN (baclofen) is a GABA-B receptor agonist that reduces spinal reflex transmission and inhibits excitatory neurotransmitter release.

What the body does with it

Metabolism	Hepatic metabolism via deamination; minor CYP450 involvement. Approximately 15% is metabolized; 85% excreted unchanged in urine.
Excretion	Renal: 70-80% unchanged; biliary/fecal: <5% as metabolites. Total clearance 2.5-3.0 L/h.
Half-life	Terminal half-life 5-7 hours; clinically relevant for dosing interval of every 6-8 hours.
Protein binding	30-35% bound to albumin.
Volume of Distribution	0.5-0.8 L/kg; indicates distribution into extracellular fluid and tissues.
Bioavailability	Oral: 70-90%; intrathecal: near 100% (direct CSF delivery).
Onset of Action	Oral: 1-2 hours; intrathecal bolus: 0.5-1 hour; continuous intrathecal infusion: 4-8 hours to steady state.
Duration of Action	Oral: 4-8 hours; intrathecal bolus: 4-12 hours; continuous infusion: sustained while infused.

Classification & Brands

Dosing & administration

10 mg orally three times daily, may increase by 10 mg/day every 3 days to a maximum of 80 mg/day (20 mg four times daily).

Dosage form	INJECTABLE
Renal impairment	GFR > 60 mL/min: no adjustment; GFR 30-60 mL/min: reduce dose by 50%; GFR < 30 mL/min: avoid use.
Liver impairment	Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: avoid use.
Pediatric use	Age 2-16 years: initial 5 mg orally twice daily, increase by 5 mg/day every 3 days to maximum 40 mg/day (10 mg four times daily) for weight < 50 kg; for weight ≥ 50 kg, use adult dosing.
Geriatric use	Initial 5 mg orally twice daily, increase slowly; maximum 40 mg/day; monitor for sedation and dizziness.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for GABLOFEN (GABLOFEN).

Breastfeeding	Baclofen (active ingredient) is excreted into breast milk; M/P ratio approximately 0.5. Low relative infant dose (estimated 0.3-0.5% of maternal weight-adjusted dose). Monitor infant for sedation, hypotonia, and poor feeding. Caution with moderate to high maternal doses.
Teratogenic Risk	First trimester: Limited data; animal studies show increased risk of neural tube defects and skeletal abnormalities at supratherapeutic doses. Second and third trimesters: Risk of fetal growth restriction, oligohydramnios, and neonatal withdrawal syndrome (hypertonia, tremors, seizures) if used chronically. Avoid in all trimesters unless benefit outweighs risk.

Warnings & precautions

■ FDA Black Box Warning

Abrupt discontinuation of intrathecal baclofen may precipitate severe withdrawal reactions including hyperpyrexia, altered mental status, rebound spasticity, and rhabdomyolysis, which can be life-threatening. Pump failure or dosage error may cause overdose or withdrawal.

Side Effect Profile

Serious Effects

Absolute Contraindications

Hypersensitivity to baclofen; concomitant use of opioids or other CNS depressants causing respiratory depression; intrathecal administration in patients with severe respiratory insufficiency or active infection at injection site.

Clinical Precautions

Precautions

Withdrawal reactions after abrupt cessation; renal impairment requiring dose adjustment; sedation and dizziness impairing ability to drive/operate machinery; increased risk of seizures in epileptic patients; exacerbation of psychotic disorders; respiratory depression when combined with CNS depressants.

Clinical Tips & Counseling

Drug interactions

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GABLOFEN

Clinical safety rating: caution

Comprehensive clinical and safety monograph for GABLOFEN (GABLOFEN).

How it works

GABLOFEN (baclofen) is a GABA-B receptor agonist that reduces spinal reflex transmission and inhibits excitatory neurotransmitter release.

What the body does with it

Metabolism	Hepatic metabolism via deamination; minor CYP450 involvement. Approximately 15% is metabolized; 85% excreted unchanged in urine.
Excretion	Renal: 70-80% unchanged; biliary/fecal: <5% as metabolites. Total clearance 2.5-3.0 L/h.
Half-life	Terminal half-life 5-7 hours; clinically relevant for dosing interval of every 6-8 hours.
Protein binding	30-35% bound to albumin.
Volume of Distribution	0.5-0.8 L/kg; indicates distribution into extracellular fluid and tissues.
Bioavailability	Oral: 70-90%; intrathecal: near 100% (direct CSF delivery).
Onset of Action	Oral: 1-2 hours; intrathecal bolus: 0.5-1 hour; continuous intrathecal infusion: 4-8 hours to steady state.
Duration of Action	Oral: 4-8 hours; intrathecal bolus: 4-12 hours; continuous infusion: sustained while infused.

Classification & Brands

Dosing & administration

10 mg orally three times daily, may increase by 10 mg/day every 3 days to a maximum of 80 mg/day (20 mg four times daily).

Dosage form	INJECTABLE
Renal impairment	GFR > 60 mL/min: no adjustment; GFR 30-60 mL/min: reduce dose by 50%; GFR < 30 mL/min: avoid use.
Liver impairment	Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: avoid use.
Pediatric use	Age 2-16 years: initial 5 mg orally twice daily, increase by 5 mg/day every 3 days to maximum 40 mg/day (10 mg four times daily) for weight < 50 kg; for weight ≥ 50 kg, use adult dosing.
Geriatric use	Initial 5 mg orally twice daily, increase slowly; maximum 40 mg/day; monitor for sedation and dizziness.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for GABLOFEN (GABLOFEN).

Breastfeeding	Baclofen (active ingredient) is excreted into breast milk; M/P ratio approximately 0.5. Low relative infant dose (estimated 0.3-0.5% of maternal weight-adjusted dose). Monitor infant for sedation, hypotonia, and poor feeding. Caution with moderate to high maternal doses.
Teratogenic Risk	First trimester: Limited data; animal studies show increased risk of neural tube defects and skeletal abnormalities at supratherapeutic doses. Second and third trimesters: Risk of fetal growth restriction, oligohydramnios, and neonatal withdrawal syndrome (hypertonia, tremors, seizures) if used chronically. Avoid in all trimesters unless benefit outweighs risk.