Baclofen is used for treating spasm of skeletal muscles that cause muscle clonus, rigidity, and pain due to multiple sclerosis. Baclofen relaxes skeletal muscles, the muscles that move the skeleton (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.
The usual starting dose of Baclofen for adults is 5 mg three times daily. Based on the response, the dose can be increased gradually every three days to a maximum of 80 mg/day in several doses.
Baclofen should be stored between 15°C (59°F) and 30°C (86°F). Keep Baclofen out of the reach of children.
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 (e.g., Elavil, Sinequan) together may cause muscle weakness.
Use of Baclofen and monoamine oxidase inhibitors (e.g. Nardil, Parnate) can result in greater depression of brain function as well as low blood pressure.
As Baclofen can increase blood sugar, doses of antidiabetic drugs may need to be adjusted when Baclofen is taken.
The use of Baclofen by pregnant women has not been evaluated.
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.
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).