Severity of Deliberate Acute Baclofen Poisoning: A Nonconcurrent Cohort Study

Recommendations from the EXTRIP workgroup on extracorporeal treatment for baclofen poisoning

Baclofen toxicity results from intentional self-poisoning ("acute baclofen poisoning") or accumulation of therapeutic dose in the setting of impaired kidney function. Standard care includes baclofen discontinuation, respiratory support and seizure treatment. Use of extracorporeal treatments (ECTRs) is controversial. To clarify this, a comprehensive review of the literature on the effect of ECTRs in baclofen toxicity was performed and recommendations following EXTRIP methods were formulated based on 43 studies. (1 comparative cohort, 1 aggregate results cohort, 1 pharmacokinetic modeling, and 40 patient reports or series). Toxicokinetic data were available for 20 patients. Baclofen's dialyzability is limited by a high endogenous clearance and a short half-life in patients with normal kidney function. The workgroup assessed baclofen as "Moderately dialyzable" by intermittent hemodialysis for patients with normal kidney function (quality of evidence C) and "Dialyzable" for patients with impaired kidney function (quality of evidence C). Clinical data were available for 25 patients with acute baclofen poisoning and 46 patients with toxicity from therapeutic baclofen in kidney impairment. No deaths or sequelae were reported. Mortality in historical controls was rare. No benefit of ECTR was identified in patients with acute baclofen poisoning. Indirect evidence suggests a benefit of ECTR in reducing the duration of toxic encephalopathy from therapeutic baclofen in kidney impairment. These potential benefits were balanced against added costs and harms related to the insertion of a catheter, the procedure itself, and the potential of baclofen withdrawal. Thus, 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.

Classics in Chemical Neuroscience: Baclofen

Baclofen, β-(4-chlorophenyl)-γ-aminobutyric acid, holds a unique position in neuroscience, remaining the only U.S. Food and Drug Administration (FDA) approved GABA_B agonist. While intended to be a more brain penetrant, i.e, ability to cross the blood-brain barrier (BBB), version of GABA (γ-aminobutyric acid) for the potential treatment of epilepsy, baclofen's highly efficacious muscle relaxant properties led to its approval, as a racemate, for the treatment of spasticity. Interestingly, baclofen received FDA approval before its receptor, GABA_B, was discovered and its exact mechanism of action was known. In recent times, baclofen has a myriad of off-label uses, with the treatment for alcohol abuse and drug addiction garnering a great deal of attention. This Review aims to capture the >60 year legacy of baclofen by walking through the history, pharmacology, synthesis, drug metabolism, routes of administration, and societal impact of this Classic in chemical neuroscience.

Toxicological considerations in the prescription of baclofen for the treatment of substance use disorders

Introduction: For many years, applications for baclofen have widened in the treatment of substance abuse disorder (SUD), mainly alcohol use disorder, with a growing rate of off-label prescriptions in Europe. Clinical effects seem to be both a decrease of craving and anxiety, leading to a decrease of drug or alcohol consumption. We described baclofen poisoning circumstances, therapeutic options and outcomes when used in substance use disorders.Areas covered: This review summarizes the toxicological considerations where baclofen was prescribed in humans for substance use or abuse disorder in randomized clinical trials, case series, case reports and observational studies between 1990 and 2020 according to the Preferred Reporting Items for Systemic reviews and Meta-Analysis.Expert opinion: The most frequent cause of severe intoxication is self-poisoning. A dose above 180 mg are expected to cause severe toxicity and death. The treatment is only symptomatic as no antidote is available. Off-label prescription remains unsafe because the optimal dose is not known and varies greatly between patients. As SUD are frequently associated with psychiatric disorders and such patients may have suicidal thoughts, the risk of self-poisoning is high. Potential co-ingestants should also be considered, especially CNS depressants, and they need to be closely monitored.

Baclofen for alcohol withdrawal

BACKGROUND

Alcohol withdrawal syndrome (AWS) is a distressing and life-threatening condition that usually affects people who are alcohol dependent when they discontinue or decrease their alcohol consumption. Baclofen shows potential for rapidly reducing symptoms of severe AWS in people with alcoholism. Treatment with baclofen is easy to manage and rarely produces euphoria or other pleasant effects, or craving for the drug. This is an updated version of the original Cochrane Review first published in 2011 and last updated in 2017.

OBJECTIVES

To assess the efficacy and safety of baclofen for people with AWS.

SEARCH METHODS

We updated our searches of the following databases to June 2019: the Cochrane Drugs and Alcohol Group Specialised Register, CENTRAL, PubMed, Embase, and CINAHL. We also searched registers of ongoing trials. We handsearched the references quoted in the identified trials, and sought information from researchers, pharmaceutical companies, and relevant trial authors about unpublished or uncompleted trials. We placed no restrictions on language.

SELECTION CRITERIA

We included all randomised controlled clinical trials (RCTs) evaluating baclofen versus placebo or any other treatment for people with AWS. We excluded uncontrolled, non-randomised, or quasi-randomised trials. We included both parallel group and cross-over studies.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included four RCTs with 189 randomised participants (one RCT new for this update). None of the included studies reported the primary outcomes of alcohol withdrawal seizures, alcohol withdrawal delirium, or craving. For the comparison of baclofen and placebo (1 study, 31 participants), there was no evidence of a difference in Clinical Institute Withdrawal Assessment of Alcohol Scale, Revised (CIWA-Ar) scores in eight-hour periods from days one to five (very low-quality evidence). For the comparison of baclofen and diazepam (2 studies, 85 participants), there was no evidence of a difference in change from baseline to days 10 to 15 on CIWA-Ar scores (very low-quality evidence, meta-analysis was not performed due to insufficient data). In one study (37 participants), there was no evidence of a difference in participants with at least one adverse event (risk difference (RD) 0.00, 95% confidence interval (CI) -0.10 to 0.10; very low-quality evidence), dropouts (RD 0.00, 95% CI -0.10 to 0.10; very low-quality evidence), and dropouts due to adverse events (RD 0.00, 95% CI -0.10 to 0.10; very low-quality evidence). For the comparison of baclofen and chlordiazepoxide (1 study, 60 participants), there was no evidence of a difference in difference from baseline to nine-day decremental fixed-dose intervention: CIWA-Ar scores (mean difference (MD) 1.00, 95% CI 0.70 to 1.30; very low-quality evidence), global improvement (MD 0.10, 95% CI -0.03 to 0.23; very low-quality evidence), 14/60 participants with adverse events (RD 2.50, 95% CI 0.88 to 7.10; very low-quality of evidence), dropouts (RD 0.00, 95% CI -0.06 to 0.06; very low-quality evidence), and dropouts due to adverse events (RD 0.00, 95% CI -0.06 to 0.06; very low-quality evidence). None of the RCTs provided information on random sequence generation or allocation concealment, therefore, we assessed them at unclear risk of bias. Two RCTs were not of double-blind design and had a high risk of bias in blinding (Addolorato 2006; Girish 2016). One RCT had more than 5% dropouts with high risk of attrition bias (Lyon 2011). We could not assess reporting bias as none of the prepublished protocols were available.

AUTHORS' CONCLUSIONS

No conclusions can be drawn about the efficacy and safety of baclofen for the management of alcohol withdrawal because we found insufficient and very low-quality evidence.

Pharmacologically controlled drinking in the treatment of alcohol dependence or alcohol use disorders: a systematic review with direct and network meta-analyses on nalmefene, naltrexone, acamprosate, baclofen and topiramate

BACKGROUND AND AIMS

Pharmacologically controlled drinking in the treatment of alcohol dependence or alcohol use disorders (AUDs) is an emerging concept. Our objective was to explore the comparative effectiveness of drugs used in this indication.

DESIGN

Systematic review with direct and network meta-analysis of double-blind randomized controlled trials (RCTs) assessing the efficacy of nalmefene, naltrexone, acamprosate, baclofen or topiramate in non-abstinent adults diagnosed with alcohol dependence or AUDs. Two independent reviewers selected published and unpublished studies on Medline, the Cochrane Library, Embase, ClinicalTrials.gov, contacted pharmaceutical companies, the European Medicines Agency and the Food and Drug Administration, and extracted data.

SETTING

Thirty-two RCTs.

PARTICIPANTS

A total of 6036 patients.

MEASUREMENTS

The primary outcome was total alcohol consumption (TAC). Other consumption outcomes and health outcomes were considered as secondary outcomes.

FINDINGS

No study provided direct comparisons between drugs. A risk of incomplete outcome data was identified in 26 studies (81%) and risk of selective outcome reporting in 17 (53%). Nalmefene [standardized mean difference (SMD) = -0.19, 95% confidence interval (CI) = -0.29, -0.10; I²  = 0%], baclofen (SMD = -1.00, 95% CI = -1.80, -0.19; one study) and topiramate (SMD = -0.77, 95% CI = -1.12, -0.42; I²  = 0%) showed superiority over placebo on TAC. No efficacy was observed for naltrexone or acamprosate. Similar results were observed for other consumption outcomes, except for baclofen (the favourable outcome on TAC was not reproduced). The number of withdrawals for safety reasons increased under nalmefene and naltrexone. No treatment demonstrated any harm reduction (no study was powered to explore health outcomes). Indirect comparisons suggested that topiramate was superior to nalmefene, naltrexone and acamprosate on consumption outcomes, but its safety profile is known to be poor.

CONCLUSIONS

There is currently no high-grade evidence for pharmacological treatment to control drinking using nalmefene, naltrexone, acamprosate, baclofen or topiramate in patients with alcohol dependence or alcohol use disorder. Some treatments show low to medium efficacy in reducing drinking across a range of studies with a high risk of bias. None demonstrates any benefit on health outcomes.

How to Manage Self-Poisoning With Baclofen in Alcohol Use Disorder? Current Updates

Specialists in addiction medicine continue to debate whether baclofen is still indicated to treat alcohol use disorders in view of conflicting results as to its efficacy. This review summarizes current knowledge on self-poisoning with baclofen focusing of alcohol-use disorder in order to provide an overview of the reliable scientific knowledge on management of such an intoxication. Moreover, as alcohol-dependent patients experience many psychiatric co-morbidities, the risk in suicide attempt using baclofen seems real. Numerous studies have suggested that patients given daily-doses of baclofen higher than 80 mg/day are more likely to attempt suicides than others. Following an ingestion of a large amount of baclofen, central nervous system depression is usually observed. Seizures require the patient to be admitted in intensive care unit and should be treated like other toxicological seizures. Cardiac complications include prolonged QTc interval, degree heart block, premature atrial contractions, and supraventricular tachycardia, hypotension and bradycardia. In cases of intoxication, the elimination half-life of baclofen may last between 12 and 36 h post-overdose and renal failure is known to delay its clearance. Rarely measured in clinical practice, the toxic level of baclofen blood level ranges from 1.1 to 3.5 mg/l, and coma or fatal intoxication are observed from 6 to 9.6 mg/l. Baclofen withdrawal has been observed but making the diagnosis of withdrawal in case of suspected self-poisoning is difficult as baclofen intoxication and baclofen withdrawal share many clinical signs. Admission to hospital to manage of suicide attempt with baclofen is mandatory and should not be limited to baclofen alone. It needs to include other aspects of the overall care of patients with alcohol disorders (psychological and psychosocial interventions, management of comorbid mental conditions and physical complications).

Baclofen for alcohol withdrawal

BACKGROUND

Baclofen shows potential for rapidly reducing symptoms of severe alcohol withdrawal syndrome (AWS) in people with alcoholism. Treatment with baclofen is easy to manage and rarely produces euphoria or other pleasant effects, or craving for the drug. This is an updated version of the original Cochrane Review published in 2015, Issue 4.

OBJECTIVES

To assess the efficacy and safety of baclofen for people with AWS.

SEARCH METHODS

We updated our searches of the following databases to March 2017: the Cochrane Drugs and Alcohol Group Specialised Register, CENTRAL, PubMed, Embase, and CINAHL. We also searched registers of ongoing trials. We handsearched the references quoted in the identified trials, and sought information from researchers, pharmaceutical companies, and relevant trial authors about unpublished or uncompleted trials. We placed no restrictions on language.

SELECTION CRITERIA

We included all randomised controlled clinical trials (RCTs) evaluating baclofen versus placebo or any other treatment for people with AWS. We excluded uncontrolled, non-randomised, or quasi-randomised trials. We included both parallel group and cross-over studies.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included three RCTs with 141 randomised participants. We did not perform meta-analyses due to the different control interventions. For the comparison of baclofen and placebo (1 study, 31 participants), there was no significant difference in Clinical Institute Withdrawal Assessment of Alcohol Scale, Revised (CIWA-Ar) scores (very low quality evidence). For the comparison of baclofen and diazepam (1 study, 37 participants), there was no significant difference in CIWA-Ar scores (very low quality evidence), adverse events (risk difference (RD) 0.00, 95% confidence interval (CI) -0.10 to 0.10; very low quality evidence), dropouts (RD 0.00, 95% CI -0.10 to 0.10; very low quality evidence), and dropouts due to adverse events (RD 0.00, 95% CI -0.10 to 0.10; very low quality evidence). For the comparison of baclofen and chlordiazepoxide (1 study, 60 participants), there was no significant difference in CIWA-Ar scores (mean difference (MD) 1.00, 95% CI 0.70 to 1.30; very low quality evidence), global improvement (MD 0.10, 95% CI -0.03 to 0.23; very low quality evidence), adverse events (RD 2.50, 95% CI 0.88 to 7.10; very low quality of evidence), dropouts (RD 0.00, 95% CI -0.06 to 0.06; very low quality evidence), and dropouts due to adverse events (RD 0.00, 95% CI -0.06 to 0.06; very low quality evidence).

AUTHORS' CONCLUSIONS

No conclusions can be drawn about the efficacy and safety of baclofen for the management of alcohol withdrawal because we found insufficient and very low quality evidence.

Baclofen Abuse due to Its Hypomanic Effect in Patients with Alcohol Dependence and Comorbid Major Depressive Disorder

Baclofen is a gamma-aminobutyric acid type B receptor agonist used as an anti-craving agent for treatment of alcohol dependence. It has gained popularity in the recent times because it is well tolerated even in patients with hepatic impairments. Herein we are summarizing the latest literature about baclofen induced hypomania and are reporting a case of baclofen abuse because of its mood elevating property in a patient of alcohol dependence with comorbid major depressive disorder. Literature review and case study of a 36-year-old male with alcohol dependence with comorbid major depressive disorder was prescribed with tablet baclofen as an anti-craving agent along with antidepressant medicines. The patients who did not improve with conventional antidepressant therapy started feeling better in terms of his mood symptoms on taking tablet baclofen. Owing to the mood elevating property he started abusing baclofen. Despite its safety profile in hepatic impairment, one must be very cautious in prescribing baclofen because of its mood altering property which may account for its abuse potentiality.

Quantitative pharmacokinetic-pharmacodynamic modelling of baclofen-mediated cardiovascular effects using BP and heart rate in rats

BACKGROUND AND PURPOSE

While the molecular pathways of baclofen toxicity are understood, the relationships between baclofen-mediated perturbation of individual target organs and systems involved in cardiovascular regulation are not clear. Our aim was to use an integrative approach to measure multiple cardiovascular-relevant parameters [CV: mean arterial pressure (MAP), systolic BP, diastolic BP, pulse pressure, heart rate (HR); CNS: EEG; renal: chemistries and biomarkers of injury] in tandem with the pharmacokinetic properties of baclofen to better elucidate the site(s) of baclofen activity.

EXPERIMENTAL APPROACH

Han-Wistar rats were administered vehicle or ascending doses of baclofen (3, 10 and 30 mg·kg(-1) , p.o.) at 4 h intervals and baclofen-mediated changes in parameters recorded. A pharmacokinetic-pharmacodynamic model was then built by implementing an existing mathematical model of BP in rats.

KEY RESULTS

Final model fits resulted in reasonable parameter estimates and showed that the drug acts on multiple homeostatic processes. In addition, the models testing a single effect on HR, total peripheral resistance or stroke volume alone did not describe the data. A final population model was constructed describing the magnitude and direction of the changes in MAP and HR.

CONCLUSIONS AND IMPLICATIONS

The systems pharmacology model developed fits baclofen-mediated changes in MAP and HR well. The findings correlate with known mechanisms of baclofen pharmacology and suggest that similar models using limited parameter sets may be useful to predict the cardiovascular effects of other pharmacologically active substances.

Application of high-resolution mass spectrometry to determination of baclofen in a case of fatal intoxication

The study focused on the application of high-resolution mass spectrometry (HRMS) to postmortem toxicological analysis. Fast and simple sample preparation involved precipitation with acetonitrile, removal of phospholipids using special columns and filtration. Qualitative and quantitative analyses were performed using ultra-performance liquid chromatography coupled with quadrupole time-of–flight mass spectrometry. The method was validated by determining the limit of quantification, precision, recovery and matrix effect. The use of a high-resolution spectrometer allowed us to determine the precise masses of the fragments of interest and to suggest the fragmentation pathway of baclofen. The usefulness, effectiveness and assets of the procedure were confirmed by an authentic case of a 25-year-old woman fatally intoxicated with baclofen who was found dead in her apartment. Toxicological analysis of postmortem blood samples demonstrated that the baclofen concentration was 30.7 μg/mL. In only one published case describing fatal baclofen intoxication were no other xenobiotics (that could interact with baclofen) found. To our knowledge, this is the first report dealing with analysis of baclofen by HRMS.

High doses of Baclofen as suicide attempt in patients with alcohol use disorders - A serious concern

Baclofen is increasingly being used as an off label anti-craving agent in alcohol use disorders in various parts of the world. The lack of proper recommendations regarding the dosage has important implications for safety in clinical management. In this context, we report two patients who were started with Baclofen as an anti-craving agent, and later developed serious complications following acute self inflicted overdose. We also highlight the important mechanisms of such complications and precautions that needs to be exerted while prescribing.

Baclofen for alcohol withdrawal

BACKGROUND

The treatment baclofen shows potential for rapidly reducing symptoms of severe alcohol withdrawal syndrome (AWS) in people with alcoholism. Treatment with baclofen is easy to manage and rarely produces euphoria or other pleasant effects, or craving for the drug. This is an updated version of the original Cochrane review published in Issue 2, 2013.

OBJECTIVES

To assess the efficacy and safety of baclofen for people with AWS.

SEARCH METHODS

We searched the Cochrane Drugs and Alcohol Group Specialised Register (searched 13 January 2015), the Cochrane Central Register of Controlled Trials (CENTRAL; 2015, Issue 1), MEDLINE (1966 to January 2015), EMBASE (1980 to January 2015), and CINAHL (1982 to January 2015). We also searched registers of ongoing trials, including ClinicalTrials.gov, the ISRCTN registry, and the European Clinical Trials Database. At the same time, we handsearched the references quoted in the identified trials, and sought information from researchers, pharmaceutical companies, and relevant trial authors about unpublished or uncompleted trials. We placed no restrictions on language.

SELECTION CRITERIA

We included all randomised controlled clinical trials (RCTs) evaluating baclofen versus placebo or any other treatment for people with AWS. We excluded uncontrolled, non-randomised, or quasi-randomised trials. We included both parallel group and cross-over studies.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed references retrieved for possible inclusion. Any disagreements were resolved by an independent party. We contacted study authors for additional information where needed. We collected adverse effects information from the trials.

MAIN RESULTS

Two RCTs with a total of 81 participants were eligible according to the inclusion criteria. One study suggested that both baclofen and diazepam significantly decreased the Clinical Institute Withdrawal Assessment of Alcohol Scale, Revised (CIWA-Ar) score, without any significant difference between the two interventions. The other study showed no significant difference in CIWA-Ar score between baclofen and placebo, but a significantly decreased dependence on high-dose benzodiazepines with baclofen compared to placebo. Only one study reported on the safety of baclofen, without any side effects.

AUTHORS' CONCLUSIONS

The evidence for recommending baclofen for AWS is insufficient. We therefore need more well-designed RCTs to prove its efficacy and safety.