From the Guidelines
Baclofen toxicity should be managed with immediate discontinuation of the medication, supportive care, and close monitoring for respiratory depression, as it can worsen obstructive sleep apnea and affect central apnoeas or hypoventilation during sleep 1. When managing baclofen toxicity, it is essential to consider the potential for respiratory depression, which can be exacerbated by the medication's effects on upper airway collapse during sleep, particularly in patients with obstructive sleep apnea (OSA) 1. Key considerations in the management of baclofen toxicity include:
- Discontinuation of baclofen to prevent further toxicity
- Supportive care, including airway protection and ventilatory support as needed
- Monitoring for symptoms such as altered mental status, respiratory depression, hypotension, hypothermia, and seizures
- Consideration of the patient's renal function, as baclofen is primarily excreted by the kidneys and impaired clearance can prolong the duration of toxicity symptoms 1
- Avoidance of baclofen in patients with OSA, due to its potential to worsen the condition 1 It is crucial to prioritize the patient's safety and take a cautious approach when managing baclofen toxicity, given the potential for severe respiratory depression and other complications 1.
From the FDA Drug Label
ADVERSE REACTIONS The most common is transient drowsiness (10% to 63%). In one controlled study of 175 patients, transient drowsiness was observed in 63% of those receiving baclofen compared to 36% of those in the placebo group. Other common adverse reactions are dizziness (5% to 15%), weakness (5% to 15%) and fatigue (2% to 4%) Others reported: Neuropsychiatric:Confusion (1% to 11%), headache (4% to 8%), insomnia (2% to 7%); and, rarely, 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 Clinical Pharmacology ...In studies with animals, baclofen has been shown to have general CNS depressant properties as indicated by the production of sedation with tolerance, somnolence, ataxia, and respiratory and cardiovascular depression.
Baclofen toxicity can manifest as CNS depression, including symptoms such as:
- Drowsiness
- Dizziness
- Weakness
- Fatigue
- Confusion
- Ataxia
- Somnolence
- Respiratory depression
- Cardiovascular depression Other possible symptoms of baclofen toxicity include:
- Neuropsychiatric effects: hallucinations, euphoria, excitement, depression
- Gastrointestinal effects: nausea, constipation
- Genitourinary effects: urinary frequency, urinary retention 2 2
From the Research
Baclofen Toxicity Overview
- Baclofen toxicity can result from intentional self-poisoning or accumulation of therapeutic doses in patients with impaired kidney function 3.
- Symptoms of baclofen poisoning can progress rapidly, and toxicity has been observed even with doses as low as 150 mg 4.
- Clinical manifestations of baclofen toxicity include deep coma, respiratory depression, seizures, and cardiovascular events such as hypo- or hypertension and bradycardia 4.
Diagnosis and Treatment
- Diagnosis of baclofen overdose can be challenging due to the lack of immediate laboratory testing, and a high index of suspicion is needed for definitive diagnosis 5.
- Treatment of baclofen toxicity includes standard care such as baclofen discontinuation, respiratory support, and seizure treatment 3.
- The use of extracorporeal treatments (ECTRs) is controversial, but the EXTRIP workgroup suggests against performing ECTR in addition to standard care for acute baclofen poisoning and suggests performing ECTR in toxicity from therapeutic baclofen in kidney impairment, especially in the presence of coma requiring mechanical ventilation 3.
- Activated charcoal may be beneficial in reducing the absorption of baclofen, especially if administered soon after ingestion 6.
Prognosis and Outcomes
- Baclofen toxicity can mimic brain death clinically, but appropriate management can lead to full recovery 7.
- Severe baclofen intoxication can result in temporary pathological electroencephalographic findings, but complete recovery is possible with proper treatment 7.
- Mortality from baclofen poisoning is rare, and no deaths or sequelae were reported in a study of 25 patients with acute baclofen poisoning and 46 patients with toxicity from therapeutic baclofen in kidney impairment 3.