baclofen, Lioresal, Kemstro (discontinued)

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Pharmacy Author:

Omudhome Ogbru, PharmD

Omudhome Ogbru, PharmD

Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.

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Medical and Pharmacy Editor:

Jay W. Marks, MD

Jay W. Marks, MD

Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

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GENERIC NAME: baclofen

BRAND NAME: Lioresal, Kemstro (discontinued)

DRUG CLASS AND MECHANISM: Baclofen is an oral and injectable medication that relaxes skeletal muscles, the muscles that move the skeleton (and also called striated muscle). Chemically, baclofen is related to gamma-aminobutyric acid (GABA), a naturally-occurring neurotransmitter in the brain. Neurotransmitters are chemicals that nerves use to communicate with one another. GABA released by some nerves causes the activity of other nerves to decrease. It is believed that baclofen, acting like GABA, blocks the activity of nerves within the part of the brain that controls the contraction and relaxation of skeletal muscle. Baclofen was approved by the FDA in November 1977.

PRESCRIPTION: Yes

GENERIC AVAILABLE: Yes

PREPARATIONS: Tablets: 10 and 20 mg. Intrathecal: 0.05 mg/ml, 0.5 mg/ml, 2 mg/ml

STORAGE: Baclofen should be stored between 15 C (59 F) and 30 C (86 F).

PRESCRIBED FOR: Baclofen is used for treating spasm of skeletal muscles, muscle clonus, rigidity, and pain caused by disorders such as multiple sclerosis. It is also injected into the spinal cord (intrathecal) for management of severe spasticity.

DOSING: The usual starting dose of oral baclofen for adults is 5 mg given three times daily. Based on the response, the dose can be increased by 15 mg every three days to a maximum of 80 mg/day in divided doses.

DRUG INTERACTIONS: Use of baclofen with other drugs that also depress the function of nerves may lead to additional reduction in brain function.

In addition to the risk of depressing brain function, the use of baclofen and tricyclic antidepressants (for example, amitriptyline [Elavil, Endep], doxepin [Sinequan, Adapin]) together may cause muscle weakness.

Use of baclofen and monoamine oxidase inhibitors (for example, phenelzine [Nardil], tranylcypromine or [Parnate]) can result in greater depression of brain function as well as low blood pressure.

Because baclofen can increase blood sugar, doses of antidiabetic drugs may need to be adjusted when baclofen is begun.

PREGNANCY: The use of baclofen by pregnant women has not been evaluated.

NURSING MOTHERS: Baclofen can be detected in the breast milk of mothers taking oral baclofen. No information is available on the presence of baclofen in the breast milk of mothers receiving baclofen intrathecally.

SIDE EFFECTS: Baclofen may cause drowsiness, weakness, dizziness, headache, seizures, nausea, vomiting, low blood pressure, constipation, confusion, respiratory depression, inability to sleep, and increased urinary frequency or urinary retention.

Abrupt discontinuation of oral baclofen may cause seizures and hallucinations. Abrupt discontinuation of intrathecal baclofen may result in high fever, rebound spasticity, muscle rigidity, and rhabdomyolysis (muscle breakdown) that can progress to failure of several organs, including the kidney, and even death.

Reference:

FDA Prescribing Information

AHFS Drug Information for baclofen

Report Problems to the Food and Drug Administration You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088. Need help identifying pills and medications? Use the pill identifier tool on RxList.