Baclofen

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Baclofen is a muscle relaxant and antispastic medication available as a tablet for oral administration. It has been available under various brand names, including Lioresal, Kemstro, Liofen, and Gablofen, and now is manufactured in generic form by Vintage Pharmaceuticals. It is also available as Lioresal Intrathecal (baclofen injection), formulated for intrathecal infusion (delivered into the spinal fluid) using an implantable pump. This product is manufactured and marketed by Medtronic Inc. Baclofen is indicated for the alleviation of signs and symptoms of spasticity related to MS, including flexor spasms and concomitant (accompanying) pain, clonus (involuntary, rhythmic, muscular contractions and relaxations), and muscular rigidity.

 

How does baclofen work?

The exact mechanism by which baclofen works to control spasticity is not known. However, it is known that baclofen inhibits nerve reflex signaling in the spine and other nerve sites. In studies with animals, baclofen has been shown to have a CNS depressant effect.

 

How is baclofen taken?

In tablet form, baclofen is taken orally (by mouth). For the best effect, oral baclofen is usually given at a daily, divided dose of between 40 and 80 mg. However, it must be started at a low dosage (5 mg) and gradually increased in increments of 5 mg over the course of several weeks. Patients who require more than a 80 mg oral baclofen daily dose may be candidates for intrathecal baclofen pump. Talk to your doctor for more information.

Lioresal Intrathecal (baclofen injection) is given as a single bolus injection or via implantable pump as shown in the illustration. The word intrathecal means inside the sheath or covering. Thus, baclofen intrathecal injection is an injection that delivers medicine through the covering of the spinal cord into the canal that holds spinal fluid. To qualify for the “baclofen pump” delivery system, you must demonstrate positive clinical response to an intrathecal injection of baclofen during a screening phase. The implantable pump can be programmed to deliver an intrathecal infusion of baclofen on a regular schedule.

 

Are there people who should not take baclofen?

Baclofen should not be taken by persons who demonstrate hypersensitivity or allergy to the drug. It should be used with caution and the dosage reduced in people with impaired kidney function. People who have had a stroke may have difficulty tolerating baclofen and may not get much benefit from the drug. In animal studies, baclofen has been shown to cause fetal abnormalities. Therefore, it should only be used during pregnancy if the benefit clearly outweighs the potential risk to the fetus. It is not known whether baclofen passes into the breast milk of nursing mothers. Therefore, it should only be used by nursing mothers if the benefit of treatment outweighs possible risks to the nursing infant. Oral baclofen has not been shown to be safe in children below the age of 12 years; therefore, it is not recommended for use in this age group.

There is the potential for life-threatening CNS depression, cardiovascular collapse, and/or respiratory failure with Lioresal Intrathecal given as a single bolus injection or via an implantable pump. Therefore, this form of baclofen should only be given in a setting where therapy can be monitored by a health professional adequately trained in chronic intrathecal infusion therapy. The safety and effectiveness of Lioresal Intrathecal has not been shown in children below the age of 4 years. Children above this age must have sufficient body mass to accommodate the implantable pump for chronic infusion therapy.

 

What evidence do we have that baclofen works?

Several studies have shown the effectiveness of baclofen in controlling spasticity in people with MS. In one study conducted in 106 people with MS, baclofen was more effective than placebo in relieving symptoms of spasticity, such as flexor spasms, pain and stiffness, resistance to passive joint movements, and tendon stretch reflexes, and in reducing clonus, while causing only mild and transient side effects. While baclofen benefited patients with more advanced MS, providing symptomatic relief and making immobility more tolerable, it was most useful when given during early stages of MS.

Last updated: January 23, 2013

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