Baclofen-related deaths in Australia 2000-2022

In Australia, the therapeutic indication of baclofen (oral tablets) is for the treatment of muscle spasm. Deaths related to baclofen have been reported, as well as misuse, dependence and self-poisoning. This national retrospective study aimed to investigate the number, characteristics, circumstances, and toxicology of baclofen-related deaths in Australia, 2000-2022. We identified 102 baclofen-related deaths, with a mean age of 45.6 years and 51 % being male. Circumstances of death were: intentional toxicity (54.9 %), unintentional toxicity (30.4 %), unintentional toxicity/disease (9.8 %), and accidental injury (4.9 %). Multiple sclerosis or spinal injury was documented in 15.7 % of cases, substance use problems in 43.1 % and specifically alcohol use problems in 38.2 %. Mental health problems were documented in 73.5 %, a previous self-harm or suicide attempt in 30.4 %, and chronic pain in 37.3 %. The median baclofen blood concentration for all cases was 3.10 mg/L (25th 0.70, 75th 8.10, range 0.04-110.00), unintentional toxicity 1.95 mg/L (25th 0.70, 75th 4.35, range 0.04-24.0), intentional toxicity 6.00 mg/L (25th 1.10, 75th 13.0, range 0.05-110.0). Concomitant substance use was seen in 93.8 %, with antidepressants (69.8 %) and benzodiazepines (64.6 %) most frequently detected. In conclusion, the 'typical' case was middle-aged, most dying due to intentional toxicity, and likely to have a history of mental health and substance use problems. We suggest caution is needed in prescribing baclofen given its potential to be used in intentional and non-intentional overdose.