A nationwide register-based survey of baclofen toxicity

Medication-Induced Central Sleep Apnea: A Unifying Concept

Medication-induced central sleep apnea (CSA) is one of the 8 categories of causes of CSA but in the absence of awareness and careful history may be misclassified as primary CSA. While opioids are a well-known cause of respiratory depression and CSA, non-opioids medications including sodium oxybate, baclofen, valproic acid, gabapentin and ticagrelor are less well-recognized. Opioids-induced respiratory depression and CSA are mediated primarily by µ-opioid receptors, which are abundant in the pontomedullary centers involved in breathing. The non-opioid medications, sodium oxybate, baclofen, valproic acid and gabapentin, act upon brainstem gamma-aminobutyric acid (GABA) receptors, which co-colonize with µ-opioid receptors and mediate CSA. The pattern of ataxic breathing associated with these medications is like that induced by opioids on polysomnogram. Finally, ticagrelor also causes periodic breathing and CSA by increasing central chemosensitivity and ventilatory response to carbon dioxide. Given the potential consequences of CSA and the association between some of these medications with mortality, it is critical to recognize these adverse drug reactions, particularly because discontinuation of the offending agents has been shown to eliminate CSA.

Baclofen in the treatment of alcohol use disorder: tailored doses matter

AIMS

To address the question of tailored baclofen prescribing in alcohol use disorder (AUD) in relation to dose-dependent efficacy and the potential danger of high doses and to provide suggestions for the use of high doses of baclofen in the treatment of AUD. The context is the approvement in France of baclofen in the treatment of AUD without dose limitation, making French physicians, who usually prescribe baclofen in a tailored manner, often use high or very high doses.

METHODS

A narrative review of the results of randomized controlled trials (RCTs) and observational studies that used tailored baclofen prescribing and of the severe adverse effects of baclofen that have been reported in the literature.

RESULTS

The results show that RCTs using tailored doses of baclofen in AUD are not completely demonstrative, though they are encouraging according to certain meta-analyses, while observational studies that used tailored doses constantly show a good effectiveness of baclofen treatment. The results suggest that many severe adverse effects of baclofen could be related to a nonrespect by physicians of prescription rules and appropriate treatment monitoring.

CONCLUSIONS

The use of tailored doses shows that the dose required to suppress cravings is highly variable, low or high, depending on each case. Analysis of the circumstances in which severe adverse effects occur suggest that a careful monitoring of baclofen prescribing might prevent a large majority of severe adverse effects. We propose that the education of the patients and the prescription skills, seriousness, and availability of the prescribing physicians are of major importance in the managing of tailored baclofen treatment of AUD.

Baclofen and the Risk of Encephalopathy: A Real-World, Active-Comparator Cohort Study

OBJECTIVE

To quantify the risk of encephalopathy associated with oral baclofen compared with other muscle relaxants-tizanidine or cyclobenzaprine.

PATIENTS AND METHODS

We conducted a new-user, active-comparator study of 2 pairwise cohorts using tertiary health system data from Geisinger Health in Pennsylvania (January 1, 2005, through December 31, 2018). Adults (aged ≥18 years) newly treated with baclofen or tizanidine were included in cohort 1. Adults newly treated with baclofen or cyclobenzaprine were included in cohort 2. Propensity score-based inverse probability of treatment weighting (IPTW) was used to balance the respective cohorts on 45 patient characteristics. Fine-Gray competing risk regression was used to estimate the risk of encephalopathy.

RESULTS

Cohort 1 included 16,192 new baclofen users and 9782 new tizanidine users. The 30-day risk of encephalopathy was higher in patients treated with baclofen vs tizanidine (IPTW incidence rate, 64.7 vs 28.3 per 1000 person-years) with an IPTW subdistribution hazard ratio (SHR) of 2.29 (95% CI, 1.43 to 3.67). This risk persisted through 1 year (SHR, 1.32 [95% CI, 1.07 to 1.64]). Similarly in cohort 2, baclofen vs cyclobenzaprine was associated with a greater risk of encephalopathy at 30 days (SHR, 2.35 [95% CI, 1.59 to 3.48]) that persisted through the first year of treatment (SHR, 1.94 [95% CI, 1.56 to 2.40]).

CONCLUSION

The risk of encephalopathy was greater with baclofen vs tizanidine or cyclobenzaprine use. The elevated risk was apparent as early as 30 days and persisted through the first year of treatment. Our findings from routine care settings may inform shared treatment decisions between patients and prescribers.

Baclofen (fun drug) and ethanol combined poisoning in humans: A histopathology and morphometry model

BACKGROUND

- This study intends to address the scarcity of data regarding the pathogenesis of Baclofen poisoning in humans, which has seen a recent increase, worldwide, especially amongst the young people. Another reason for the conduction of this study was lack of the substantial data about the histo-pathological findings of lungs, in synergistic toxicity of Baclofen with Ethanol, in-spite of it being very common in humans, and both being respiratory depressant with similar mechanism of action.

PURPOSE

- The authors aimed to understand the pathogenesis of fatal poisonings in humans due to Baclofen in combination with Ethanol via an animal research model. The enhancement of the overall scientific literature by extending research along the lines of the handful studies available in this regard was another adjunct goal of the study.

MATERIAL AND METHODS

Fifteen Wistar rats were divided into control and test group of five and ten subjects respectively. The test group was further divided into two sub-groups of five each, with Baclofen administered to one, and it in conjunction with Ethanol to the other, in lowest dosages adjusted for the humans. Rats in both the groups were euthanized by dislocation of the cervical vertebrae for the histopathology examination.

RESULTS

Capillary and venous plethora, hemorrhages in the inter-alveolar septi, hemorrhages into the alveoli and sludging was seen in the 1st sub-group. The plethora of venules, capillaries and arterioles, with sludging by the WBC (white blood corpuscle) infiltrates was seen in the 2nd sub-group. Desquamation of the ciliated epithelium and edematous thickening of the intra-alveolar septi, along with features suggestive of the peri-vascular edema was seen in the 2nd sub-group. The morphometric analysis of the micro vessels showed a significantly higher value of the arteriolar diameter in the 2nd sub-group, in comparison to 1st, but the venular diameter in the two sub-groups did not differ to any extent.

Transient alteration of consciousness in spinal cord injury secondary to Baclofen use: a case report

INTRODUCTION

Oral baclofen is commonly used for spasticity management, especially with neurogenic bladder in spinal cord injury (SCI). A less common side effect of baclofen is transient alterations of consciousness, which can easily be confused for altered mental status secondary to orthostatic hypotension in SCI.

CASE PRESENTATION

A 43-year-old man with an acute SCI secondary to an aortic dissection was found to have episodes of confusion after titrating oral baclofen from 5 mg three times per day to 10 mg three times per day at an acute rehabilitation facility. Orthostatic hypotension was initially suspected as the cause of transient alterations of consciousness; however, he was never found to be hypotensive during these episodes. His confusion resolved several days after discontinuation of baclofen.

DISCUSSION

Although, confusion and lightheadedness in SCI are commonly caused by orthostatic hypotension, it is important for physicians to be cognizant of baclofen's side effects, which increase in the setting of acute kidney injury (AKI). If an adverse effect is suspected, baclofen should be tapered while remaining observant for signs of baclofen withdrawal, which can be life-threatening. This case report is a reminder for clinicians to be aware of the uncommon adverse effects of baclofen when initiating therapy in SCI, especially in patients with AKI and neurogenic bladders.

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.

Baclofen therapeutics, toxicity, and withdrawal: A narrative review

Baclofen is an effective therapeutic for the treatment of spasticity related to multiple sclerosis, spinal cord injuries, and other spinal cord pathologies. It has been increasingly used off-label for the management of several disorders, including musculoskeletal pain, gastroesophageal reflux disease, and alcohol use disorder. Baclofen therapy is associated with potential complications, including life-threatening toxicity and withdrawal syndrome. These disorders require prompt recognition and a high index of suspicion. While these complications can develop following administration of either oral or intrathecal baclofen, the risk is greater with the intrathecal route. The management of baclofen toxicity is largely supportive while baclofen withdrawal syndrome is most effectively treated with re-initiation or supplementation of baclofen dosing. Administration of other pharmacologic adjuncts may be required to effectively treat associated withdrawal symptoms. This narrative review provides an overview of the historical and emerging uses of baclofen, offers practical dosing recommendations for both oral and intrathecal routes of administration, and reviews the diagnosis and management of both baclofen toxicity and withdrawal.

Baclofen Toxicity in Children With Acute Kidney Injury: Case Reports and Review of the Literature

Baclofen is a medication used for tone management in cerebral palsy. Although it acts mainly at the spinal cord level, it can cause central nervous system adverse reactions at higher doses. Baclofen is mainly eliminated by renal excretion and there have been reports on adverse events when used in adults with renal impairment; however, there are no consensus guidelines as to the dose adjustments required due to renal impairment. The authors describe 2 children with acute kidney injury (AKI) and systemic side effects with initiation of oral baclofen, which was started for treatment of dystonia/spasticity in the recovery phase of their kidney injury. Following the initiation of the drug, they both had decreased level of consciousness and respiratory difficulties, which warranted discontinuation of the drug. These cases highlight the need for reduced initial dose, slow titration, and close monitoring when initiating baclofen treatment in children with AKI.

Polysomnographic Analysis of a Pediatric Case of Baclofen-Induced Central Sleep Apnea

ABSTRACT

Respiratory disorders may follow brain injury and may also occur because of comorbidities and drug use, especially central depressants or muscle relaxants. Sleep can precipitate respiratory disorders, thus polysomnography can be a powerful diagnostic tool. By revealing breathing patterns that identify specific sleep disorders, polysomnography may unmask adverse pharmacological effects, for instance connecting central depressant drugs with central sleep apneas. We describe the case of a pediatric patient in rehabilitation from brain injury who developed a central sleep apnea following a baclofen dose increase within the therapeutic range, while assuming an under-dosed benzodiazepine. Polysomnography identified a typical respiration pattern, previously observed in adults treated with baclofen and other central depressants. Baclofen tapering resolved the central sleep apnea. Polysomnography, and this specific pattern, may be proposed as diagnostic tools in patients with high dose baclofen that can be used to prevent potential respiratory disorders in children.

Progress in Developing Pharmacologic Agents to Treat Bulimia Nervosa

This paper reviews past and current progress in developing pharmacologic agents for the treatment of individuals with bulimia nervosa (BN). We searched the literature and clinical trial registries for compounds studied in BN, the related condition, binge eating disorder (BED), and preclinical models of binge-eating behavior. Drug classes evaluated included antidepressants, antiepileptic drugs, stimulants and other medications for attention-deficit/hyperactivity disorder, opioid antagonists, and weight loss agents, among others. The only available drugs with established efficacy in BN at this time include antidepressants (especially selective serotonin reuptake inhibitors [SSRIs]) and the antiepileptic topiramate, though the efficacy of these compounds is modest at best. The only medications we found currently receiving empirical study in people with BN were fluoxetine, other serotonergic antidepressants, intranasal naloxone, lisdexamfetamine dimesylate, phentermine-topiramate combination, the antiandrogenic oral contraceptive ethinyl estradiol plus drospirenone, and prazosin. Preclinical models suggest that nociceptin receptor antagonists, the selective serotonin 5-HT2C receptor agonist lorcaserin, monoamine stabilizers, and selective orexin-1 receptor antagonists might be helpful. We found no evidence of a drug developed specifically for the treatment of individuals with BN. Future areas for research in the pharmacotherapy of BN are suggested. Importantly, until drugs are developed specifically for eating disorders, drugs developed for other conditions that are centrally acting and associated with beneficial psychotropic effects and/or reduced appetite or weight loss might be considered for repurposing in BN.

Efficacy and Safety of Botulinum Toxin Type A in Spasticity Caused by Spinal Cord Injury: A Randomized, Controlled Trial

Background

Baclofen is approved by the US FDA to treat spasticity, but its sustained use may cause drug addiction. The objective of this study was to compare the efficacy and safety of botulinum toxin type A versus baclofen in spasticity.

Material/Methods

A total of 336 patients who had spasticity caused by spinal cord injury were enrolled in a randomized (in 1: 1: 1: ratio) for placebo, controlled trial. Patients had received baclofen (BA group, n=112), local intramuscular injection of 500 U Botulinum toxin type A (BTI group, n=112), or physical therapies alone (placebo group, n=112). Modified Ashworth scale (mAS) score, disability assessment scale (DAS) score, modified medical research council (mMRC) score, the Barthel Index (BI) score, and treatment-emergent adverse effects were evaluated during the follow-up period. Wilcoxon test or one-way ANOVA/Tukey post hoc tests were performed at 95% of confidence level.

Results

Baclofen (1.504±0.045 vs. 1.53±0.06, p=0.003, q=4.068) and botulinum toxin type A (1.49±0.09 vs. 1.528±0.15, p=0.0224, q=3.5541) had improved mAS scores after 2 weeks. Baclofen had a more strongly improved DAS score than botulinum toxin type A at 4 (p=0.0496, q=3.48) and 6 (p<0.0001, q=6.48) weeks. Baclofen and botulinum toxin type A had consistently improved BI scores. Baclofen caused asthenia and sleepiness, while botulinum toxin type A caused bronchitis and elevated blood pressure.

Conclusions

Botulinum toxin type A may be an effective therapeutic option for spasticity caused by spinal cord injury.

Efficacy and side effects of baclofen and the novel GABAB receptor positive allosteric modulator CMPPE in animal models for alcohol and cocaine addiction

RATIONALE

Preclinical studies suggest that the GABA_B receptor is a potential target for treatment of substance use disorders. However, recent clinical trials report adverse effects in patients treated with the GABA_B receptor agonist baclofen and even question efficacy. How can the discrepancy between preclinical and clinical findings be explained?

OBJECTIVE

To test efficacy and adverse effects of baclofen and the novel GABA_B positive allosteric modulator (PAM) CMPPE in rat addiction models, which were developed in accordance with DSM.

METHODS

We used a well-characterized rat model of long-term alcohol consumption with repeated deprivation phases that result in compulsive alcohol drinking in a relapse situation, and a rat model of long-term intravenous cocaine self-administration resulting in key symptoms of addictive behavior. We tested repeated baclofen (0, 1, and 3 mg/kg; i.p.) and CMPPE doses (0, 10, and 30 mg/kg; i.p.) in relapse-like situations, in either alcohol or cocaine addicted-like rats.

RESULTS

Baclofen produced a weak anti-relapse effect at the highest dose in alcohol addicted-like rats, and this effect was mainly due to the treatment-induced sedation. CMPPE had a better profile, with a dose-dependent reduction of relapse-like alcohol drinking and without any signs of sedation. The cue-induced cocaine-seeking response was completely abolished by both compounds.

CONCLUSION

Positive allosteric modulation of the GABA_B receptor provides efficacy, and no observable side effects in relapse behavior whereas baclofen may cause, not only sedation, but also considerable impairment of food intake or metabolism. However, targeting GABA_B receptors may be effective in reducing certain aspects of addictive-like behavior, such as cue-reactivity.

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).

Safety Challenges of Using High Dose Baclofen for Alcohol Use Disorder: A Focused Review

Since the early 2000s, the gamma-aminobutyric acid type B (GABA-B) receptor agonist baclofen has been extensively used for treating alcohol use disorder (AUD). In some countries, like France, Australia, or Germany, baclofen has been used at patient-tailored dose regimens, which can reach 300 mgpd or even more in some patients. The GABA-B-related pharmacology of baclofen expose patients to a specific profile of neuropsychiatric adverse drug reactions (ADRs), primarily some frequent sedative symptoms whose risk of occurrence and severity are both related to the absolute baclofen dosing and the kinetics of dose variations. Other frequent neuropsychiatric ADRs can occur, i.e., tinnitus, insomnia, or dizziness. More rarely, other serious ADRs have been reported, like seizures, manic symptoms, or sleep apnea. However, real-life AUD patients are also exposed to other sedative drugs, like alcohol of course, but also benzodiazepines, other drugs of abuse, or other sedative medications. Consequently, the occurrence of neuropsychiatric safety issues in these patients is essentially the result of a complex multifactorial exposure, in which baclofen causality is rarely obvious by itself. As a result, the decision of initiating baclofen, as well as the daily dose management should be patient-tailored, according the medical history but also the immediate clinical situation of the patient. The overall safety profile of baclofen, as well as the clinical context in which baclofen is used, have many similarities with the use of opiate substitution medications for opiate use disorder. This empirical statement has many implications on how baclofen should be managed and dosing should be adjusted. Moreover, this constant patient-tailored adjustment can be difficult to adapt in the design of clinical trials, which may explain inconsistent findings in baclofen-related literature on AUD.

Baclofen for alcohol dependence: Relationships between baclofen and alcohol dosing and the occurrence of major sedation

High-dose baclofen, i.e., 300 mg/d or more, has recently emerged as a strategy for treating alcohol dependence. The impact that the co-exposure of large amounts of alcohol and baclofen has on sedation is unclear. In a prospective cohort of 253 subjects with alcohol dependence, we collected daily alcohol and baclofen doses across the first year of baclofen treatment and the monthly maximum subjective sedation experienced by each patient (0-10 visual analog scale). For each patient-month, we determined the average weekly alcohol consumption (AWAC; standard-drinks/week) and the maximum daily dose of baclofen (DDB; mg/d). The occurrence of an episode of major sedation (EMS) during a patient-month was defined as a sedation score ≥7. The relationship between the EMS occurrence and the concurrent AWAC and DDB was investigated using a generalized estimating equation model. In total, 1528 patient-months were compiled (70 with an EMS). Univariate analyses demonstrated that the rate of patient-month to EMS increased gradually with AWAC (p<0.001), from 0.9% for AWAC=0 to 9.4% for AWAC >35. There was also a significant gradual risk for EMS associated with DDB (<0.001). Multivariate analysis demonstrated a significant interaction between DDB and AWAC on EMS risk (p=0.047). Each 20mg/d increase in DDB was associated with an OR of EMS in AWAC >35 of 1.22 (95%CI, 1.08-1.38) versus 1.11 (95%CI, 0.96-1.29) in AWAC=1-35, and 0.95 (95%CI, 0.76-1.19) in AWAC=0. The level of sedation observed in patients using baclofen for alcohol dependence appears to directly depend on the immediate doses of both the baclofen and the alcohol.

Encephalopathy and hypotonia due to baclofen toxicity in a patient with end-stage renal disease

BACKGROUND

Baclofen is a centrally acting gamma-aminobutyric acid agonist used for the symptomatic relief of skeletal muscle spasm and spasticity in traumatic spinal cord lesions, multiple sclerosis, cerebral palsy, and stroke. It is also used in the treatment of chronic hiccups and cocaine abuse. Baclofen-induced central nervous system depression is rare at the usual therapeutic doses. However, patients with impaired renal function are at a higher risk of developing baclofen toxicity, even at a lower dose.

CASE REPORT

A 57-year-old woman with end-stage renal disease on hemodialysis was admitted to our emergency department with progressive confusion and a generalized decrease in muscular tone. There was no obvious metabolic or infectious etiology that could have explained her condition. A comprehensive laboratory and imaging workup was negative. A review of her medication showed that she had recently been prescribed baclofen for muscular spasm. She was diagnosed with baclofen toxicity and was treated with emergent hemodialysis, which improved her mental status and her decreased muscle tone. Repeated sessions of hemodialysis administered on her second and third days of admission ultimately produced sustained clinical improvement and a complete return to her baseline mental status. She was subsequently discharged home with instructions to stay off baclofen.

CONCLUSIONS

Baclofen toxicity is an under-diagnosed condition, especially in patients with renal dysfunction. Physicians should consider baclofen toxicity in patients with suboptimal kidney function on baclofen who present with altered mental status. Emergent hemodialysis and intensive care unit monitoring is recommended.

Treatment of motor and behavioural symptoms in three Lesch-Nyhan patients with intrathecal baclofen

Current therapies for the Lesch-Nyhan Syndrome (OMIM: 300322) are off-label and experimental, often leading to inconsistent outcomes. We here report the effects of an intrathecal baclofen therapy, carried out at the Scientific Institute Eugenio Medea (Lecco, Italy), on three patients who no longer received benefit from previous therapies. This treatment, as expected, ameliorated the motor symptoms and, unexpectedly, it also improved behavioural components. This result may involve a functional interaction between baclofen and dopamine, complemented by an anxiolytic effect. Our observations provide the rationale for the use of intrathecal baclofen administration in the therapy of the Lesch-Nyhan Syndrome.