Baclofen in the Treatment of Spinal Cord Injuries
Original Editor - Mohamed Ahmed Awad as part of the Winston-Salem State University Pharmacology Project
Baclofen, commonly known as Kemstro or Lioresal, is a medication used in the treatment of spasticity in spinal cord injuries. This drug acts as an allosteric modulator to GABA b receptors which leads to the inhibition of alpha motor neurons within the spinal cord. Pre- and postsynaptic inhibition leads to reduction in skeletal muscle tone. The weak permeability to the blood-brain barrier makes baclofen more effective in treating spasticity at the level of the spinal cord. Additionally, baclofen does not cause the type of generalized muscle weakness seen with other medications like dantrolene.
Intrathecal administration utilizes a surgically implanted catheter connected to a pump that delivers the drug into the subarachnoid space, around the level of the lesion, which allows for higher efficacy with smaller doses. The initial adult dose is 5 mg, increased by 5 mg at 72-hour intervals, up to 80 mg/day . There is no specific pediatric dose, the child's size and weight is used to calculate the appropriate dose. The half-life ranges between 2.5-4 hours, and the rate of clearances is 4-8 hours according to the patient's metabolic rate. The main adverse effects to look for are nausea, dizziness, drowsiness, fatigue, and weakness.
Adverse Effects & PT Implications
The main adverse effects are nausea, dizziness, drowsiness, fatigue, and weakness. Monitoring for specific CNS symptoms, such as seizures and nausea, are important for maintaining patient safety. Similar to other drug classes like benzodiazepines, withdrawal symptoms can occur without proper discontinuation of the drug. Scheduling therapy sessions according to the drug therapeutic index is necessary as baclofen acts as an alternative to other sedative-hypnotics. For patients with an intrathecal delivery system, pump placement and overall knowledge of the pump is important to ensure safety during treatment and interventions.
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