Edited by Hannah Stephens, Independent Prescriber - Substance Misuse Services
Baclofen-related deaths in Australia 2000–2022
Zahra E, Darke S, Lappin J, Duflou J, Farrell M (2024) Baclofen-related deaths in Australia 2000–2022. Forensic Science International. 365(0379-0738): Article 112281
This Australian retrospective study aimed to identify relevant factors within baclofen-related deaths and wider considerations for clinical practice related to baclofen prescribing.
Baclofen is a GABA-B receptor agonist indicated for treatment of muscle spasm related to multiple sclerosis and spinal legions, though is also used ‘off label’ for alcohol use disorder (AUD). It exerts effects on the central nervous system, which can result in respiratory depression, reduced consciousness and fatality. There’s reported variability in toxic doses and contraindications include AUD, tricyclic antidepressant use, and psychiatric disorders, and deaths related to baclofen misuse, self-poisoning and dependence have been reported. Case reports describe increased suicidal ideation and self-harm in individuals prescribed baclofen for alcohol cravings.
Australia has seen an increase in baclofen prescriptions and the largest Poison Information Centre in the country has seen a 230% increase in baclofen toxicity over a 13-year period; half involved concomitant use of psychoactive substances or alcohol. Similarly concerning in France, nearly 75% of baclofen-related referrals to national poison control centres were suicide attempts by self-poisoning. However, in Australia, routine toxicology screening during forensic investigations does not include baclofen.
This study identified 102 baclofen-related deaths between 2000-2022, 54.9% were attributed to intentional toxicity, 30.4% unintentional toxicity, with the remaining 14.7% related to wider factors such as disease and accidental injury. Substance use, particularly alcohol use showed significant prevalence compared to multiple sclerosis and spinal injury. Mental health problems, self-harm and chronic pain were also prominent features across the study sample. Concomitant substance use was identified in 93.8% cases, with antidepressants and benzodiazepines most frequently identified; additionally opioids, commonly codeine, oxycodone, tramadol and quetiapine were found most amongst antipsychotic drug groups and pregabalin amongst gabapentinoids. Post-mortem data was available for 91 cases, documenting findings of pulmonary oedema (52.9%), acute pneumonia (24.2%), aspiration of vomitus (11%), coronary arteriosclerosis (18.7%), cardiomegaly (19.8%) and hepatic steatosis (23.1%). Median blood concentrations resulting in fatality varied from 1.95mg-6.00mg, making the fatal toxicity range unclear, and dependent on variables such as intentionality and polypharmacy.
Commentary:
Whilst authors recognise limitations in the study’s ability to attribute overdose deaths to baclofen specifically, it’s certainly a relevant clinical feature, clearly associated with known risk drugs and co-morbidities, providing reason enough to exercise caution in its prescribing supported by sufficient risk and harm reduction advice. UK prescribing guidelines for baclofen mirror that of Australia for both licensed and off licence use, so the greater question is perhaps what’s driving a potential increase in prescribing for what originally was a drug with a limited and clearly defined remit for clinical presentations not synonymous with addiction?
Recent years have seen a significant culture shift in the prescribing practice of opioids, benzodiazapines and gabapentinoids due to increased awareness of dependence and overdose risks. Whilst the prescribing of these drugs is now subject to greater scrutiny and restriction, the interplay between addiction and chronic pain continues. Trauma is both a contributory factor in addiction and pain experience and overrepresented in addiction populations. It is therefore unsurprising that the demand for medical management remains high, indicating ongoing need for awareness in prescribing trends, particularly with drugs that exert central nerve system effects, based on their inherent risk of misuse and overdose potential, particularly in clinically complex presentations, with multiple comorbidities requiring polypharmacy. This study identifies an unsurprising profile of individuals who may seek and be most at risk from baclofen initiation, and post-mortem findings further identify the physical harms of substance use increasing mortality risk.
UK based research involving primary care, addiction and pain specialists could support identification of local trends, potential shifts in prescribing cultures, driving factors and mitigating factors in a potentially lethal novel drug trend.
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