Baclofen
Mechanism :
Baclofen is a muscle relaxant and antispastic. It is derived from gamma-aminobutyric acid (GABA). The mechanism of action of baclofen is not known precisely. Baclofen is capable of inhibiting both monosynaptic and polysynaptic reflexes at the spinal level, possibly by hyperpolarization of afferent terminals, although actions at supraspinal sites may also occur and contribute to its clinical effect.
Indication :
- Spasticity resulting from multiple sclerosis, cerebral palsy, neurodegenerative diseases
Contraindications :
Hypersensitivity to baclofen.
Dosing :
Spasticity: Oral
≥4 months-7 years: 10 to 15 mg daily divided doses every 8 hourly; begin at low dose of 2.5 mg daily and titrate dose every 3rd day according to patient response.
8-11 years: 10 to 40 mg daily divided doses every 8 hourly, begin at low end of range and titrate dose.
>12 years: 20-60 mg daily divided every 8 hours; begin at low end of range and titrate dose.
Spasticity: Intrathecal (<4 years: Safety and efficacy not established)
Test bolus: 50 mcg intrathecal over 1 minute; if inadequate response within 8 hours, 75 mcg 24 hours later; if still inadequate, 100 mcg 24 hours later. (Patients who do not respond to a 100 mcg intrathecal bolus should not be considered candidates for an implanted pump for chronic infusion. Initial implant dose: 2 times screening dose that gave positive effect, administer over 24 hours period. After the first 24 hours, the daily dose should be increased slowly by 5-15% only once every 24 hours, until desired clinical effect is achieved).
Adverse Effect :
Confusion, headache, insomnia, euphoria, excitement, depression, hallucinations, paresthesia, muscle pain, tinnitus, slurred speech, coordination disorder, tremor, rigidity, dystonia, ataxia, blurred vision, nystagmus, strabismus, miosis, mydriasis, diplopia, dysarthria, epileptic seizure, hypotension, dyspnea, palpitation, chest pain, syncope, nausea, constipation, dry mouth, anorexia, taste disorder, abdominal pain, vomiting, diarrhea, and positive test for occult blood in stool, urinary frequency, urinary retention, dysuria, impotence, inability to ejaculate, nocturia, hematuria, rash, pruritus, excessive perspiration.
Interaction :
Anti-hypertensives: Enhanced hypotensive effect.
Renal Dose :
Dose in Renal Impairment GFR (mL/min)
| 20-50 | 5 mg, 3 times a day and titrate according to response |
| 10-20 | 5 mg, twice a day and titrate according to response |
| <10 | 5 mg, once a day and titrate according to response |
Dose in Patients undergoing Renal Replacement Therapies
| CAPD | Unknown dialysability. Dose as in GFR<10 mL/min |
| HD | Dialysed. Dose as in GFR<10 mL/ min |
| HDF/High flux | Dialysed. Dose as in GFR<10 mL/ min |
| CAV/VVHD | Unknown dialysability. Dose as in GFR=10–20 mL/min |
Hepatic Dose :
No dosage adjustments are recommended.