Baclofen Safety in Rhabdomyolysis
Baclofen should be avoided in patients with rhabdomyolysis due to the risk of accumulation and toxicity in the setting of acute kidney injury, which is the most serious complication of rhabdomyolysis.
Primary Concern: Renal Dysfunction and Drug Accumulation
Rhabdomyolysis frequently causes acute renal failure (ARF), occurring in approximately 10% of all ARF cases, making renally-excreted drugs particularly dangerous 1, 2.
Baclofen is primarily eliminated via the kidneys, and toxicity becomes a serious risk when kidney function is impaired 3.
In patients with severely reduced kidney function (eGFR <30 mL/min/1.73m²) or those requiring renal replacement therapy, baclofen should be avoided entirely 3.
Even with moderately reduced kidney function (eGFR 30-60 mL/min/1.73m²), baclofen dosing must be significantly reduced 3.
Clinical Manifestations of Baclofen Toxicity
Baclofen toxicity presents with neurotoxicity (drowsiness, dizziness, sedation, altered mental status) and hemodynamic instability, which can be life-threatening 3, 4.
Central nervous system depression from baclofen can worsen the clinical picture in rhabdomyolysis patients who may already have altered mental status from electrolyte abnormalities, myoglobinemia, or uremia 5, 2.
Baclofen may also worsen obstructive sleep apnea by promoting upper airway collapse, adding respiratory risk 4, 6.
Withdrawal Risk Considerations
Abrupt discontinuation of baclofen can cause potentially life-threatening withdrawal symptoms including hallucinations, delirium, seizures, fever, tremors, tachycardia, and autonomic instability 4, 6.
This creates a clinical dilemma: continuing baclofen risks toxicity in the setting of renal dysfunction, but stopping it abruptly risks severe withdrawal 4.
Management Algorithm for Patients on Baclofen Who Develop Rhabdomyolysis
Immediately assess kidney function (creatinine, eGFR, urine output) and creatine kinase levels to determine severity 1, 7.
If eGFR <30 mL/min/1.73m² or patient requires dialysis: Hold baclofen and consider urgent hemodialysis if toxicity symptoms are present, as hemodialysis effectively removes baclofen 3.
If eGFR 30-60 mL/min/1.73m²: Reduce baclofen dose by at least 50-75% and monitor closely for toxicity symptoms 3.
If patient has been on chronic baclofen: Taper slowly rather than stopping abruptly, even in the setting of renal dysfunction, to avoid withdrawal complications 4, 6.
Initiate aggressive intravenous fluid resuscitation (the only conditionally recommended treatment for rhabdomyolysis) to prevent further renal deterioration 1.
Alternative Muscle Relaxant Considerations
If muscle spasm management is essential during rhabdomyolysis recovery, consider alternatives with less renal dependence 8.
Benzodiazepines may be used for muscle spasm relief, though they carry their own risks of sedation and respiratory depression, particularly when combined with other CNS depressants 8.
Non-pharmacological interventions (positioning, range of motion exercises, stretching) should be prioritized when possible 6.
Key Clinical Pitfalls to Avoid
Do not continue standard baclofen dosing in patients with rhabdomyolysis-induced renal dysfunction—this will lead to drug accumulation and toxicity 3.
Do not abruptly stop baclofen in chronic users without a tapering plan, even if renal function is compromised 4, 6.
Do not assume normal kidney function persists—monitor creatinine and CK levels serially, as renal dysfunction can develop or worsen rapidly in rhabdomyolysis 1, 7, 2.
Do not combine baclofen with other CNS depressants (opiates, benzodiazepines) in this setting, as this increases risk of respiratory depression and altered mental status 4, 5.