What it's for (Indications)
- Treatment of muscular spasms, particularly spasticity of spinal cord origin and cerebral origin (e.
- g.
- , due to cerebrovascular accidents).
- It may be suitable for children above 33kg, but medical consultation is essential.
Dosage Information
| Type | Guideline |
|---|---|
| Standard | Baclofen is administered in various formulations, including oral tablets and intrathecal injection. For oral administration, tablets should be swallowed whole and not crushed or chewed. Administer exactly as instructed by your doctor. If a dose is missed, take it as soon as remembered unless it is almost time for the next dose; in that case, skip the missed dose and do not double the dose. For intrathecal administration, Baclofen injection is intended for intrathecal use via spinal catheter or lumbar puncture for single bolus test doses, and for chronic administration via an implanted programmable pump (e.g., Medtronic SynchroMed® II). Patients who do not respond to a 100 mcg intrathecal bolus should not be considered for an implanted pump for chronic infusion. Dosage must be titrated individually to achieve the lowest effective dose. Typical maintenance doses for intrathecal use generally range from 300-800 mcg/day for spasticity of spinal cord origin and 90-700 mcg/day for spasticity of cerebral origin. Always refer to the specific pump manufacturer's manual for detailed instructions and precautions regarding programming and refilling. |
Safety & Warnings
Common Side Effects
- Common side effects include somnolence (drowsiness, sedation), dizziness, nausea, headache, hypotension (low blood pressure), constipation, agitation, chills, urinary retention, and hypotonia (decreased muscle tone).
- Convulsions may also occur.
- Leukocytosis has been reported.
- There are reports of severe mood changes and self-harm, especially in patients with pre-existing depression and alcoholism.
- If oral baclofen is stopped suddenly, patients may experience unpleasant side effects such as muscle spasms, fast heart rate, fever, hallucinations, mood changes, confusion, and convulsions.
Serious Warnings
- Black Box Warning: WARNING: DO NOT DISCONTINUE ABRUPTLY. Abrupt discontinuation of intrathecal baclofen, regardless of the cause, has resulted in severe sequelae including high fever, altered mental status, exaggerated rebound spasticity, and muscle rigidity. In rare cases, this has progressed to rhabdomyolysis, multiple organ-system failure, and death. Preventing abrupt discontinuation of intrathecal baclofen requires careful attention to programming and monitoring of the infusion system, as well as adherence to refill schedules.
- Caution is advised in patients with liver or kidney impairment, mental disorders, mood disorders, lung diseases, stroke, epilepsy, Parkinson's disease, high blood pressure, and alcoholism.
- Use with extreme caution in patients with epileptic or psychotic disorders.
- Patients should avoid alcohol consumption while on this medication.
- The safety of this medicine during pregnancy must be determined by a doctor; risk cannot be ruled out.
- Consultation with a doctor is essential.
- This medicine is probably safe for nursing females, but consultation with a doctor is recommended.
- Due to potential drowsiness and dizziness, patients should avoid driving or operating heavy machinery.
- Medicines that may interfere with Baclofen include Tizanidine, Lithium, Amitriptyline, Ibuprofen, Diltiazem, and Morphine.
- Patients should be monitored for sudden mood changes, severe mood changes, or self-harm, especially those with pre-existing depression or alcoholism; report any such changes to a doctor immediately.
- Oral tablets should be swallowed whole and not crushed or chewed.
- Use exactly as instructed by a doctor.
- Do not alter, skip, or double a dose.
- Inform your doctor about your complete medical history, if the medicine doesn't seem to work, or if severe side effects occur.
How it Works (Mechanism of Action)
The precise mechanism of action of baclofen as a muscle relaxant and antispasticity agent is not fully understood. Baclofen inhibits both monosynaptic and polysynaptic reflexes at the spinal level, possibly by decreasing excitatory neurotransmitter release from primary afferent terminals, although actions at supraspinal sites may also occur. It is a structural analog of gamma-aminobutyric acid (GABA) and may exert its effects by stimulation of the GABAB receptor subtype. When administered intrathecally, it achieves effective CSF concentrations with significantly lower plasma concentrations compared to oral administration. Baclofen also exhibits general CNS depressant properties, leading to effects such as sedation, somnolence, ataxia, and potential respiratory and cardiovascular impacts.