Indication
- Spasticity
- Intrathecal baclofen (ITB) can more effectively treat spasticity directly at the level of the spinal cord with less associated systemic side effects
- McCormick 2016: In a cross-sectional matched cohort survey study comparing the two routes of administration, patients who received ITB experienced significantly fewer and less severe spasms compared with those who received oral baclofen. In this study, there were no significant differences between the two groups in regards to pain, sleep, fatigue, or quality of life.
Mechanism of action
- An agonist for GABA-B receptors on pre- and postsynaptic neurons in the central nervous system (CNS) and peripheral nervous system.
- Baclofen is the only FDA-approved GABA-B agonist
- Results in inhibition of the transmission of both mono- and polysynaptic reflexes at the spinal cord, relaxing spasticity.
- GABA-B receptor activation causes
- An influx of potassium (K+) leading to hyperpolarization of the neuronal membrane,
- Decreased calcium (Ca2+) influx at presynaptic nerve terminals.
- GABA-B receptors
- Aare also found on other neurons throughout the body, including in the CNS and sympathetic nervous system, which can account for the side effects of drowsiness and dizziness.
Pharmacodynamic and pharmacokinetics
Route of administration | Onset of action | Peak effect | Half‑life |
Oral | Rapid | 45 minutes – 2.5 hours | 2 – 6 hours |
Intrathecal, bolus | 30 minutes – 1 hour | 4 hours | 1 – 5 hours |
Intrathecal, continuous infusion | 6 – 8 hours after starting infusion | 24 – 48 hours after starting infusion | 5 hours |
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