Baclofen for Muscle Spasms
Baclofen is the medication starting with "B" used to decrease muscle spasms, recommended as a first-line treatment at doses of 10-30 mg/day with gradual titration. 1, 2
Mechanism and Efficacy
Baclofen is a GABA-B receptor agonist that has documented efficacy for treating muscle spasms, particularly those of spinal origin. 3 It works centrally at the brain stem level to reduce tonic somatic motor activity, influencing both gamma and alpha motor systems. 4
- Studies demonstrate that 72-80% of patients with spasticity of spinal origin experience effective reduction in muscle spasms with oral baclofen. 5, 6
- Baclofen reduces both the number and severity of spasms in 76-87% of patients. 6
- It is particularly effective for severe spasticity resulting from central nervous system injury, demyelinating conditions, and other neuromuscular disorders. 3
Dosing Strategy
Start with 10 mg/day and increase gradually in weekly increments of 10 mg/day up to 30 mg/day to minimize side effects. 2
- For geriatric patients, start at 5 mg up to three times daily (maximum 15 mg/day initially) with careful monitoring. 2
- Allow at least 72 hours between dose increases to assess the full effect due to baclofen's long half-life (18 hours, range 8-37 hours). 7, 4
- Some patients may require doses exceeding 80 mg/day for adequate symptomatic relief, though this exceeds conventional recommendations. 8
Critical Safety Considerations
Never abruptly discontinue baclofen after prolonged use—implement a slow tapering period to prevent potentially life-threatening withdrawal symptoms including seizures, psychic symptoms, and hyperthermia. 3, 1, 2
- Common side effects include dizziness, somnolence, and gastrointestinal symptoms, which can be minimized by starting low and titrating slowly. 3, 2
- Monitor for muscle weakness, urinary dysfunction, cognitive effects, and sedation, especially in elderly patients. 2
- Elderly patients have approximately 1.7-fold higher plasma concentrations, with elderly males showing 2.4-fold increases. 4
- Baclofen is primarily renally excreted; use with extreme caution in patients with renal impairment as limited data suggest unnecessarily high risk. 5
When to Consider Alternatives
Benzodiazepines may be justified for muscle spasm relief when anxiety and muscle spasm coexist, though they carry a high risk profile in older adults and should generally be avoided. 3
- Tizanidine is an alternative first-line agent, particularly for spasticity of cerebral origin. 1, 7
- For refractory cases unresponsive to maximum oral doses, intrathecal baclofen via surgically implanted pump provides >80% improvement in tone and >65% improvement in spasms. 9, 5, 10
Common Pitfalls to Avoid
- Do not confuse baclofen with other muscle relaxants like cyclobenzaprine, which despite being marketed as "muscle relaxants," have nonspecific effects not actually related to muscle relaxation. 3
- Cyclobenzaprine is structurally identical to amitriptyline and should not be prescribed with the mistaken belief that it directly relieves muscle spasm. 3, 7
- Monitor for worsening mental status in patients at risk for hepatic encephalopathy. 2
- Be aware that many muscle relaxants are associated with greater risk for falls in older persons. 3