Circuits within the central nervous system function via two chief chemical messengers, namely the excitatory signal glutamate and the inhibitory signal gamma-aminobutyric acid (GABA). Baclofen works as a GABA receptor agonist, increasing the activity of the GABAergic system in the brain and spinal cord. Because the drug targets a particular subset of GABA receptors that mainly populate the spinal cord, neurologists usually prescribe baclofen to address muscle spasticity associated with multiple sclerosis (MS), cerebral palsy or amyotrophic lateral sclerosis. In medical parlance, baclofen is a "myorelaxant." Movement disorders like MS sometimes entail conditions where the muscles lock into long bouts of tight contraction. This state interferes with simple daily routines and subjects patients to uncomfortable stiffness or pain. Baclofen mitigates the discomfort brought on by muscle spasticity. Despite its efficacy, baclofen exhibits a number of side effects. Many of these effects are similar to those that occur during alcohol intoxication.
Drowsiness and Muscle Weakness
Baclofen works as a muscle relaxant, but its actions can often overshoot, especially in patients already compromised by mobility problems. For instance, people taking baclofen can experience severe muscle weakness and general drowsiness to the point of compromising vestibular balance and fine motor coordination. The level of dysfunction can rival the original disease symptoms in individuals with MS and preclude independent activities such as riding a bike or driving a car. According to Medline Plus, one should limit alcohol consumption while taking baclofen because alcohol can worsen the level of drowsiness caused by the drug.
Confusion
Like alcohol, another GABA agonist, baclofen can interfere with learning and memory. The confusion that ensues might represent an inability to properly convert short-term memories constructed from moment-to-moment experiences into long-term ones. In contrast to its myorelaxant properties, which are derived from its actions within the spinal cord, baclofen's effects on attention and cognition are probably derived from "supraspinal" actions in the brain.
Upset Stomach
Baclofen can cause stomach unrest in some individuals, including nausea and vomiting. These effects are more pronounced with more drug intake, especially when one attempts to double up on a previously missed dose. As such, the drug should be taken at carefully spaced intervals each day.
Withdrawal
As seen with other GABAergic drugs, sudden discontinuation of baclofen or significant changes in prescription can trigger a withdrawal syndrome characterized by general unease, anxiety, sleeplessness and--in more extreme cases--the development of seizures. People taking baclofen should not stop taking the drug without first consulting a doctor. In the event of extreme side effects, a patient should be gradually weaned from drug administration on a doctor-prescribed dose schedule.
References
- MedlinePlus: Baclofen Oral
- Current Neuropharmacology; "Allosteric modulators of GABA(B) receptors: mechanism of action and therapeutic perspective"; J. P. Pin and L. Prézeau; September 2007.
- National Institute of Neurological Disorders and Stroke: Spasticity Information Page
- National Institute of Neurological Disorders and Stroke: Multiple Sclerosis Information Page
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