Time of Action of Baclofen
Oral baclofen should be initiated at 5-10 mg/day and titrated slowly, with assessment occurring within 24 hours of each dose change, as the therapeutic effect develops gradually over days to weeks of titration. 1
Oral Baclofen Onset and Titration
Start with 5 mg up to three times daily to minimize side effects and optimize tolerability, particularly in older adults 2
Assessment should occur within 24 hours of any dose change to evaluate therapeutic response 3
The typical therapeutic dosing range is 30-80 mg/day divided into 3-4 doses, though older persons rarely tolerate doses greater than 30-40 mg per day 1, 2
Daily dose increases may be 5-15% once every 24 hours for cerebral-origin spasticity and 10-30% once every 24 hours for spinal-origin spasticity in adults 3
Gradual titration is essential because adverse effects are dose-related and typically appear at doses >60 mg/day 4
Intrathecal Baclofen Onset
Intrathecal baclofen produces effects within hours, with significant reduction of spasticity lasting 24-48 hours after each injection in multiple sclerosis patients 5
When initiating intrathecal therapy, monitoring should occur for at least 8 hours after pump fill and drug delivery begins 3
The starting daily intrathecal dose should be twice the effective bolus screening dose, or equal to the screening dose if the patient had a prolonged response (greater than 8 hours) 3
Only 10% of the systemic oral dose is required for equianalgesia via the intrathecal route, allowing for much lower doses with fewer central side effects 1
Important Clinical Considerations
Oral antispasmodics can be weaned one drug at a time, beginning with oral baclofen, after intrathecal therapy begins 3
Abrupt discontinuation must be avoided as it can cause central nervous system irritability and potentially severe withdrawal symptoms including hallucinations, anxiety, delirium, fever, tremors, tachycardia, and seizures 6, 2
Intrathecal baclofen withdrawal syndrome evolves over 1-3 days and may become fulminant if not recognized promptly, with the best management being resumption of intrathecal infusion as soon as possible 1