Baclofen

Administration

• Type: Muscle relaxant/anti-spasmodic
• Dosage Forms: tablet, intrathecal solution, preservative free intrathecal solution
• Dosage Strengths: tablet: 10, 20mg; intrathecal solution: 50, 500mcg/mL; preservative free intrathecal solution: 500, 1000, 2000 mcg/mL
• Routes of Administration: oral, intrathecal
• Common Trade Names: Lioresal, Gablofen

Adult Dosing

• 5-20mg PO 3-4 times/day
• maintenance intrathecal rate after titration: 22 to 1400 mcg/day

Pediatric Dosing

• 2-7yo: 10 to 15 mg/day PO in 2-3 divided doses, titrate to max 40mg/day in 3-4 divided doses
• >7 yo: 10 to 15 mg/day PO in 2-3 divided doses, titrate to max 60mg/day in 3-4 divided doses
• <12 yo: maintenance intrathecal rate after titration- 24 to 1199 mcg/day

Special Populations

• Pregnancy Rating: C
• Lactation risk: Infant risk minimal

Renal Dosing

• CrCl 50-80 mL/min: reduce dose by 1/3
• CrCl 30-50 mL/min: reduce dose by 1/2
• CrCl <30 mL/min: reduce dose by 2/3
• If HD, use intrathecal with caution, likely reduce dose

Hepatic Dosing

• No adjustment

Contraindications

• Allergy to class/drug

Adverse Reactions

Serious

• GI bleed
• Coma
• Seizure
• Aseptic meningitis
• Pneumonia
• Withdrawal

Common

• Hypotension
• Nausea/vomiting, constipation
• Dizziness, somnolence, asthenia, poor muscle tone
• Urinary complications

Pharmacology

• Half-life: 5 hours (oral), 1.5-4 hours (intrathecal)
• Metabolism: Hepatic (15%)
• Excretion: Mostly renal

Mechanism of Action

• GABA-B agonist

See Also

• Baclofen toxicity
• Baclofen withdrawal

References

• Abarbanel J, Herishanu Y, Frisher S, “Encephalopathy Associated With Baclofen,” Ann Neurol, 1985, 17(6):617-8. [PubMed 4026235]
• Addolorato G, Leggio L, Ferrulli A, et al. Effectiveness and safety of baclofen for maintenance of alcohol abstinence in alcohol-dependent patients with liver cirrhosis: randomized, double-blind controlled study. Lancet. 2007;370:1915-1922. [PubMed 18068515]
• Agarwal SK, Kriel RL, Cloyd JC, et al. A pilot study assessing pharmacokinetics and tolerability of oral and intravenous baclofen in healthy adult volunteers. J Child Neurol. 2015;30(1):37-41. [PubMed 25028414]10.1177/0883073814535504
• Aisen ML, Dietz M, McDowell F, Kutt H. Baclofen toxicity in a patient with subclinical renal insufficiency. Arch Phys Med Rehabil. 1994;75(1):109-111. [PubMed 8291951]
• Albright AL, “Baclofen in Treatment of Cerebral Palsy,” J Child Neurol, 1996, 11(2):77-83. [PubMed 8881981]
• Anderson PO, Sauberan JB. Modeling drug passage into human milk. Clin Pharmacol Ther. 2016;100(1):42-52. [PubMed 27060684]
• ASHP. Standardize 4 Safety Initiative Compounded Oral Liquid Version 1.01. July 2017. https://www.ashp.org/-/media/assets/pharmacy-practice/s4s/docs/s4s-ashp-oral-compound-liquids.ashx?la=en&hash=4C2E4F370B665C028981B61F6210335AD5D0D1D6.
• Averbuch-Heller L, Tusa RJ, Fuhry L, et al. A double-blind controlled study of gabapentin and baclofen as treatment for acquired nystagmus. Ann Neurol. 1997;41(6):818-825. [PubMed 9189045]
• Baclofen tablet [prescribing information]. Pulaski, TN: AvKare Inc; April 2014.
• Brunton LL, Chabner BA, Knollmann BC, eds. Goodman & Gilman's The Pharmacological Basis of Therapeutics. 12th ed. New York, NY: McGraw-Hill Medical; 2011.