The relative lethal toxicity of pharmaceutical and illicit substances: A 16-year study of the Greater Newcastle Hunter Area, Australia

Comparison of poisoning deaths with wastewater-based consumption estimates and assessment of fatal toxicity for amphetamine-type stimulant drugs

Among several established indicators that are used to monitor the illicit drug scene, drug-related deaths and wastewater-based epidemiology (WBE) stand out for population-level coverage. In this study, we aimed to compare temporal trends with respect to amphetamine, methamphetamine and methylenedioxymethamphetamine (MDMA) revealed by these indicators and explore the differences in fatal toxicity between the stimulants. All deaths in which poisoning caused by amphetamine, methamphetamine or MDMA was either the underlying or contributing cause of death in Finland in 2012, 2014, 2016, 2018 and 2020 were included in the study. Consumption of the studied drugs was measured by WBE in the same years. There was a significant correlation between poisoning and drug consumption for all three stimulants, and for amphetamine and MDMA, these figures increased over the study period. The highest fatal toxicity, as expressed by the number of deaths per million doses, was obtained for methamphetamine at an estimated dose of 50 mg, followed by MDMA (100 mg dose) and with amphetamine (50 mg dose). The fatal toxicity found here for the stimulants was close to that previously reported for many prescription opioids and tricyclic antidepressants. Our study is the first to quantitatively investigate the fatal toxicity of amphetamine-type stimulants by comparing deaths with consumption estimates derived from WBE. It shows that amphetamine, methamphetamine and MDMA possess a quite similar capacity to cause death. This new approach adds to the earlier methods of estimating drug-related harm.

Three safety indices for the fourteen most prescribed antidepressants in the US, 2013-2020

OBJECTIVE

This study provides three prevalence-based metrics of potential harm, the fatal toxicity index (FTI), serious morbidity index (SMI) and healthcare utilization index (HUI) for fourteen of the most prescribed antidepressants in the US.

METHOD

For the years 2013-2020, adverse events for single drug exposures were obtained from the National Poison Data System. Prescription estimates were taken from the Agency for Healthcare Research and Quality's Medical Expenditure Survey. 95% confidence intervals were calculated using a Poisson distribution. Chi-square testing was used where significance was not clear.

RESULTS

SSRIs and SNRIs had the lowest overall indices (FTI 0.02-0.26). Bupropion's FTI (0.27-0.43) was not statistically significantly different from that of imipramine (FTI 0-1.3, p = .62) or nortriptyline (FTI 0.25-0.78, p = .22), though its SMI and HUI were significantly greater. There was a statistically significant difference in all indices between TCAs (p < .0047). The difference between the FTI of all SSRIs did not remain significant after correction (p = .045).

CONCLUSION

SSRIs and SNRIs are safer than alternative agents on all measures. Bupropion exposure was as likely to cause mortality, and more likely to cause morbidity or require treatment in a healthcare facility, than TCAs nortriptyline and imipramine.

Patterns of filled prescriptions and the association with risk of drug-induced death. A population-based nested case-control register study

PURPOSE

Opioid analgesics (OA) and other pharmaceuticals have been associated with drug-induced deaths. However, there is a lack of knowledge regarding patterns of use of these pharmaceuticals in the population and regarding such associations. We identify and describe subgroups of people with different patterns of filled prescriptions of OA and other relevant pharmaceuticals and examine associations with drug-induced deaths. In addition, we estimate the proportion of drug-induced deaths with a filled OA prescription and OA as cause of death.

METHODS

A Norwegian population-based nested case-control register study with cases (drug-induced deaths 2010-2018, N = 2388) and population controls matched for age, gender and year of inclusion (N = 21 465). Patterns of filled prescriptions for opioid analgesics (OA), benzodiazepines and benzodiazepine-related drugs, gabapentinoids, ADHD medication and antidepressants/antipsychotics were explored by k-means cluster analysis. Associations with drug-induced deaths were estimated by conditional logistic regression adjusted for sociodemographic characteristics. Overlap of filled OA prescriptions and OA as cause of death was estimated.

RESULTS

Five clusters were identified: 'few prescriptions', 'weak OA', 'ADHD medication', 'sedative/psychiatric morbidity' and 'strong OA'. The 'strong OA' cluster had higher socioeconomic status compared to the other groupings. The risk of drug-induced death was also highest in this cluster (OR = 35.5; CI 25.6-49.3) and, for 68% (CI 64-73) of cases, filled prescriptions for OA was indicated as the underlying cause of death.

CONCLUSIONS

The cluster analysis identified a subgroup with filled prescriptions of OA and other pharmaceuticals and a higher socioeconomic status than other subgroups. This subgroup had a high risk of drug-induced death that needs to be addressed.

Patterns of suboptimal antipsychotic use and misuse in Australia: What can routinely collected data tell us?

AIMS

There are increasing concerns about harms related to suboptimal antipsychotic use. Here we describe recent population-based trends in antipsychotic use and harms in Australia and identify population groups exhibiting patterns of use likely to contribute to these harms.

METHODS

Using population-based data from the Australian Pharmaceutical Benefits Scheme (2015-2020), poisoning calls to the New South Wales (NSW) Poisons Information Centre (2015-2020) and poisoning deaths in all coronial records (2005-2018) in Australia, we measured trends in the prevalence of antipsychotic use and related deaths and poisonings. We applied latent class analyses to identify patterns of antipsychotic use that may contribute to harms.

RESULTS

Quetiapine and olanzapine had the highest prevalence of use between 2015 and 2020. Noteworthy trends included increases of 9.1% and 30.8% in quetiapine use and poisonings, while olanzapine use decreased by 4.5% but poisonings increased by 32.7%. Quetiapine and olanzapine poisonings and related deaths had the highest rates of co-ingestion of opioids, benzodiazepines and pregabalin compared to other antipsychotics. We identified six distinct population groups using antipsychotics: (i) ongoing high-dose use with sedatives (8%), (ii) ongoing use (42%), (iii) ongoing use with analgesics and sedatives (11%), (iv) long-term low-dose use (9%), (v) sporadic use (20%) and (vi) sporadic use with analgesics (10%).

CONCLUSION

Ongoing potentially suboptimal antipsychotic use and associated harms highlight the need to monitor such patterns of use, for example through prescription monitoring systems.

A retrospective matched case-control comparison of non-fatal hanging to non-fatal self-poisoning in a sample of Australian men and women

OBJECTIVE

Our study examined the characteristics of individuals who survived attempted hanging and compared this group to a randomly selected comparison group of patients with non-fatal self-poisoning.

METHOD

Non-fatal hanging cases were identified from case files from an Australian public hospital. They were matched by age, sex, and month of presentation with double the number of non-fatal self-poisoning cases. Patients were compared on demographic and clinical characteristics, as well as length of stay in hospital and discharge plan.

RESULTS

Most non-fatal hanging patients were males with medium suicidal intent, and a significant proportion misused alcohol. In this group, women were more likely than men to have past psychiatric care, and men were more likely to misuse alcohol and stimulants. In comparison to the self-poisoning group, the non-fatal hanging group had higher suicidal intent but proportionally lower history of self-harm and psychiatric care, or benzodiazepine misuse.

CONCLUSION

People who self-harm by hanging have higher suicidal intent, misuse alcohol more often, and are less likely to be in psychiatric care. They may benefit from a general community intervention, rather than one based upon interventions with people already in psychiatric care.

The Toxicity Potential of Antidepressants and Antipsychotics in Relation to Other Medication and Alcohol: A Naturalistic and Retrospective Study

QT interval prolongation and ventricular tachyarrhythmia are potential adverse effects of antidepressant (AD) and antipsychotic- (AP) agents, especially when overdosed. Since AD and AP agents are often prescribed to patients suffering from suicidal intentions, it is essential to estimate these risks in the context of intoxications. This retrospective and naturalistic one-year registry study included 105 patients treated for oral intoxication at the University Department of Emergency Medicine in Vienna, Austria. AD/AP intoxications were present in 26 patients, while in the control group (n = 79) non-AD/AP drugs (n = 54) and exclusively alcohol (n = 25) were the toxic agents. QT intervals, the necessity of intubation, the extent of conscious state, and the subsequent discharge management were compared. The mean age was 34.94 ± 14.6 years, 62 patients (59%) were female. There were no significant between-group differences regarding QT prolongation >470 ms using Bazett's correction (p = 0.178), or >440 ms using Fridericia's correction (p = 0.760). No significant group differences concerning the need for intubation were observed (p = 0.747). The AD/AP and the control group did not significantly differ regarding Glasgow Coma Scale scores (p = 0.439). Patients with AD/AP intoxication were significantly more often transferred to the psychiatric department, while discharge to home was more likely in the control group (p = 0.002). These results suggest that the risk of a potentially life-threatening outcome in cases of intoxication with AD/AP is not substantially higher than in other easily available toxic agents, in line with the advantageous risk/benefit ratio of newer ADs and APs.

Fatal poisonings involving clozapine: A 16-year review of Australian coronial investigations

OBJECTIVE

Concerns about intentional and unintentional poisoning present a barrier to wider use of clozapine in treatment-resistant schizophrenia. The objective of this study was to investigate decedent demographics and trends in fatal poisonings in Australia involving clozapine.

METHODS

This was a retrospective case series of all fatal drug toxicity reported to an Australian coroner between 1 May 2000 and 31 December 2016 where toxicological analysis detected clozapine. Cases were identified using the National Coronial Information System. Demographics extracted included age and gender of the decedent, year and location of death, cause and manner of death and drugs detected in post-mortem samples.

RESULTS

There were 278 poisoning deaths where clozapine was detected in toxicological analyses. Three-quarters of all cases (n = 207) involved men and the median age at death was 38.5 years (interquartile range: 16 years). Three-quarters of the deaths occurred in the home. Overall, 15.8% of deaths were deemed intentional, 57.5% unintentional and 24.5% of unknown intent. While the annual number of intentional self-poisonings remained constant with <5 per year, the overall number of fatalities increased due to an increase in unintentional poisonings. Multiple drug toxicity was reported in 55.0% of cases and clozapine alone in 45.0% of cases. The most common co-reported medications were antidepressants, benzodiazepines and opioids detected in 47.1%, 44.4% and 41.2% of multiple drug toxicities, respectively.

CONCLUSION

This was the first Australia-wide review of all fatal drug poisonings reported to a coroner involving clozapine. Fatalities were most common in men and occurred at home. Multiple drug toxicity generally involved psychotropic, sedative or opioid analgesic medications. Despite increasing clozapine use, rates of intentional poisoning have remained constant and low. Developing a better knowledge of unintentional fatalities presents an opportunity to minimise harm.

Add-On Selective Estrogen Receptor Modulators for Methadone Maintenance Treatment

Methadone maintenance treatment (MMT) remains the cornerstone for the management of opiate abuse. However, MMT can be associated with complex factors, including complications during the tolerance phase, the inability of some patients to maintain treatment effects during the tapering or abstinence phases, and the development of methadone dependence. Previous studies have revealed a sex disparity in MMT efficacy, showing that women undergoing MMT experiencing an increase in psychological symptoms compared with men and suggesting a link between disparate responses and the effects of estrogen signaling on methadone metabolism. More specifically, estradiol levels are positively associated with MMT dosing, and the expression of a single-nucleotide polymorphism (SNP) associated with estrogen receptor (ER) regulation is also associated with MMT dosing. In addition to performing mechanistic dissections of estrogen signaling in the presence of methadone, past studies have also proposed the targeting of estrogen signaling during MMT. The present report provides an overview of the relevant literature regarding sex effects, including differences in sex hormones and their potential impacts on MMT regimens. Moreover, this article provides a pharmacological perspective on the targeting of estrogen signals through the use of selective ER modulators (SERMs) during MMT. Preliminary preclinical experiments were also performed to evaluate the potential effects of targeting estrogen signaling with tamoxifen on methadone metabolism.

Optimising alkalinisation and its effect on QRS narrowing in tricyclic antidepressant poisoning

AIMS

The objectives were to determine the effect of NaHCO₃ and/or mechanical ventilation on the biochemical profile and serum alkalinisation in tricyclic antidepressant (TCA) poisoning and investigate the impact of effective alkalinisation therapy on the QRS interval in TCA poisoning.

METHODS

This was a retrospective review of TCA poisonings from three Australian toxicology units and a poisons information centre (Jan 2013 to Jan 2019). We included patients with TCA toxicity who ingested>10 mg/kg or had clinically significant toxicities consistent with TCA poisoning, and analysed patients' clinical, electrocardiogram and biochemical data.

RESULTS

Of 210 patients, 84 received NaHCO₃ and ventilation (dual therapy), 12 NaHCO₃ , 46 ventilation and 68 supportive care treatment. When compared with single/supportive groups, patients who received dual therapy had taken a significantly higher median dose of TCA (1.5 g vs1.3 g, P < .001), a longer median maximum QRS interval (124 ms, interquartile ranges [IQR] 108-138 vs106 ms, IQR 98-115, P < .001) and were more likely to have seizures (14% vs3%, P = .006) and arrhythmias (17% vs1%, P < .001). The dual therapy group demonstrated greater increases in serum pH (median 0.11, IQR 0.04-0.17) compared to the single/supportive therapy group (median 0.03, IQR -0.01-0.09, p < .001). A greater proportion of patients reached the target pH 7.45-7.55 in the dual therapy group (59%) compared to the single/supportive therapy group (10%) (P < .001). For each 100 mmol bolus of NaHCO₃ given, the median increase in serum sodium was 2.5 mmol/L (IQR 1.5-4.0). QRS narrowing occurred twice as quickly in the dual therapy vs single/supportive therapy group.

CONCLUSIONS

A combination of NaHCO₃ and mechanical ventilation was most effective in achieving serum alkalinisation and was associated with a more rapid narrowing of the QRS interval. We advise that the maximal dose of NaHCO₃ should be <400 mmol (6 mmol/kg).

The impact of guidance on the supply of codeine-containing products on their use in intentional drug overdose

Background

Concerns about the misuse of codeine led to the introduction of guidance restricting the supply of over-the-counter (OTC) codeine-containing products in Ireland in 2010. The aim of this study was to examine the impact of this guidance on the national rate of hospital-presenting self-harm involving codeine-related intentional drug overdose (IDO).

Methods

Presentations involving IDO to Irish general hospitals between 1 January 2007 and 31 December 2013, as recorded by the National Self-Harm Registry Ireland, were analyzed. Event-based rates per 100 000 were calculated using national population data. Poisson regression models were used to assess rate changes between pre- and post-guidance periods and to calculate excess presentations.

Results

Between January 2007 and December 2013, a total of 57 759 IDOs were recorded, with 4789 (8.3%) involving a codeine-containing product. The rate of codeine-related IDOs was 20% lower in the period following implementation of the guidance (incidence rate ratio: 0.80; 95% CI: 0.75 to 0.85), representing a total of 509 (95% CI: −624, −387) fewer codeine-related IDOs in that period. Reductions were observed across all ages and were more pronounced for females (0.76, 0.71 to 0.82) than males (0.87, 0.79 to 0.97). The rate of IDOs involving other drugs decreased by 3% in the same period (0.97, 0.95 to 0.98).

Conclusion

Our findings indicate that the rate of codeine-related IDOs was significantly lower in the period following the implementation of the guidance. There is a large body of evidence supporting the restriction of potentially harmful medication as an effective strategy in suicide prevention.

Methadone-related deaths among youth and young adults in Sweden 2006-15

AIMS

To identify methadone-related deaths and determine the prevalence among youth and young adults in Sweden 2006-15.

DESIGN, SETTING AND PARTICIPANTS

National retrospective registry study comparing data from all forensic autopsy examinations and toxicology cases involving methadone during 2006-15 in individuals aged 15-29 years with police records, previous pharmaceutical prescriptions and health-care episodes.

MEASUREMENTS

Multinomial logistic regression. To assess the factors contributing to the deaths, we compared individuals with and without previous substance use treatment and opioid use-related diagnoses with regard to previous opioid agonist treatment (OAT), psychiatric care and previous pain medication. To assess the circumstances of deaths, we analyzed the presence of other drugs and other factors at time of death.

FINDINGS

We identified 269 methadone-related deaths, and the rate increased during the study period. Seventy-two (27%) cases had not previously received substance use treatment, 112 (42%) had received treatment but had no opioid use-related diagnosis and 85 (32%) had received treatment and had an opioid use-related diagnosis. In total, only 10 individuals had been prescribed methadone during the year before death. Prescriptions of benzodiazepines (60%), antidepressants (62%) and opioids for pain (22%) the year before death were common. Most deaths occurred during sleep with a time lag from ingestion of methadone.

CONCLUSION

Prescription opioid- and methadone-related deaths increased in the group aged 15-29 years in Sweden between 2006 and 2015. Exposure to non-prescribed methadone and prescribed benzodiazepines, antidepressants and opioids for pain appears to be common in drug-related deaths in youth and young adults in Sweden.

Intravenous lipid emulsion as an adjuvant therapy of acute clozapine poisoning

Introduction:

Clozapine is a frequently prescribed atypical antipsychotic drug. Various case reports documented the successful recovery of acute antipsychotics toxicity in association with the administration of intralipid emulsion (ILE).

Aim:

This study aimed to assess the adjuvant therapeutic role of SMOF Lipid administration on the outcomes of acute clozapine poisoning.

Methods:

Forty patients with acute clozapine poisoning were randomly allocated into two equal groups. The control group received the standard supportive treatment only, whereas the intervention group received the standard supportive treatment plus SMOF Lipid 20% infusion. All patients were subjected to history taking, full clinical examination, and laboratory investigations. The study outcomes were evaluated.

Results:

The mean Glasgow Coma Scale (GCS) at 6 hours (13.1 ± 2.3 vs 9.2 ± 2, p < 0.001) and 12 hours (14.3 ± 1.5 vs 9.6 ± 2, p < 0.001) after admission was significantly higher in the intervention group compared to the control group. The intervention group showed a significantly lower frequency of prolonged QTc interval 12 hours after admission (p = 0.003), as well as a significantly shorter hospital stay (p < 0.001).

Conclusions:

SMOF Lipid infusion seemed to have improved GCS, the prolonged QTc interval, and shortened the length of hospital stay. Furthermore, there were no adverse effects related to its administration.

Attitudes and Knowledge of Australian Gastroenterologists Around the Use of Medicinal Cannabis for Inflammatory Bowel Disease

Background

Medicinal cannabis (MC) is being used for symptomatic relief by many patients with inflammatory bowel disease (IBD), often independently of clinical guidance. Such use presents challenges for supporting clinicians. The aim of this study was to determine the current attitudes, knowledge, and experience of gastroenterologists toward patient use of MC for symptom management in IBD.

Methods

Australian gastroenterologists (n = 70) and trainees (n = 23) completed an anonymous, 30-item questionnaire, probing their knowledge, attitudes, and experience with MC in managing IBD. Survey data were collected between April and August 2019.

Results

Thirty-nine percent of survey respondents reported having patients using MC; however, only a minority supported use of MC in IBD (21%) or expressed a desire to prescribe (28%). Only 6% claimed good understanding of current patient access pathways and only 31% felt comfortable discussing MC with their patients. Some respondents (20%) cited adverse side effects as a reason for not wanting to prescribe, with driving impairment (64%) and impacts on the developing brain (56%) cited as significant concerns. Nonetheless, MC was ranked as less hazardous than corticosteroids, immunomodulators, and biologics by most respondents, and many (53%) were encouraging of patient participation in future clinical trials.

Conclusions

Specialist support for the use of MC in IBD patients is relatively low, potentially reflecting the lack of experience and knowledge with MC, uncertain evidence for efficacy, and the often-unorthodox nature of current MC use in patients. This situation may change rapidly with increased familiarity, evidence development, and education around MC prescribing.

Poisoning and associated factors to death from pesticides: case-control study, Brazil, 2017

BACKGROUND

Pesticide poisoning causes high morbidity and mortality. Surveillance is required for post-marketing monitoring of these products.

AIM

To assess poisonings and associated factors with lethality by pesticides.

METHOD

This is a case-control study based on the cases of pesticide poisoning assisted in 2017 by Brazilian Poison Control Centers. Patients who died were the cases and the survivors, the control. The odds ratio (OR) of death and 95% confidence interval (CI) were calculated. From the regression model, a predictive model of death was developed, stratified by age, gender and occupational context to investigate the risk of agricultural workers poisoned by extremely hazardous agents.

RESULTS

3,826 patients poisoned by pesticides were identified, of which 146 died. Older people (OR = 4.94; 95%CI 2.49 - 9.80), males (OR = 1.68; 95%CI 1.15 - 2.46), agricultural workers (OR = 2.20; 95%CI 1.15 - 4.24), suicide attempts (OR = 13.27; 95%CI 6.48 - 27.19) and exposure to extremely hazardous products (OR = 2.77; 95%CI 1.84 - 4.16) odds of death from pesticide poisoning.

CONCLUSION

Out of 100 pesticides poisoning, four died. Elderly, males, working in the agricultural sector, suicide attempts and extremely hazardous products had a higher risk of death.

Potentially inappropriate benzodiazepine use in Australian adults: A population-based study (2014-2017)

INTRODUCTION AND AIMS

Inappropriate benzodiazepine use continues to cause substantial morbidity and mortality globally. We aimed to characterise the initiation of new benzodiazepine treatment episodes in Australia and identify correlates of potentially inappropriate benzodiazepine use.

DESIGN AND METHODS

We conducted a population-based cohort study using dispensing claims from a 10% sample of Pharmaceutical Benefit Scheme eligible Australians (2014-2017). Our cohort comprised adults initiating a new benzodiazepine treatment; we defined potentially inappropriate use as ≥3 benzodiazepine dispensing over any continuous 90-day period in the year following initiation. We examined characteristics associated with potentially inappropriate benzodiazepine use using multivariable logistic regression.

RESULTS

People initiating a new benzodiazepine treatment episode (n = 276 765) were more frequently female (59.1%) and <65 years of age (73.6%). In the 90 days prior to initiating benzodiazepine, people were commonly dispensed antidepressants (26.5%), opioid analgesics (17.6%) and antipsychotics (4.7%). In the first year after initiation, 20 938 (9.5%) people experienced 'potentially inappropriate use'. Having a greater initial quantity of benzodiazepine dispensed [odds ratio (OR), 1.10; 95% confidence interval (CI) 1.08-1.12 per 10 defined daily doses increase], dispensing of antipsychotics (OR 3.00, 95% CI 2.86-3.15) and >5 unique medicines (OR 2.54, 95% CI 2.44-2.64; vs. ≤5 unique medicines) in the 90 days prior to initiation were associated with potentially inappropriate benzodiazepine use.

DISCUSSION AND CONCLUSIONS

Approximately, 1 in 10 people who initiated benzodiazepines were using it beyond the guideline recommended period. We identified factors at the time of initiation associated with potentially inappropriate use; clinicians should consider these before prescribing benzodiazepines and initiate conversations about alternative therapy when necessary.

A national case fatality study of drugs taken in intentional overdose

BACKGROUND

Intentional drug overdose (IDO) has been linked with marked increases in premature mortality risk due to suicide, accidents and other causes, yet little is known about how case fatality risk varies according to the type of drug/s taken. This study aimed to examine the incidence of IDO, to identify the predictors of fatal IDO and to establish which drugs are linked with greater risk of a fatal outcome.

METHODS

Data from the National Self-Harm Registry, and the National Drug-Related Deaths Index, 2007-2014, were used to calculate incidence, examine overdose characteristics and estimate case fatality risk ratios.

RESULTS

We examined 63,831 non-fatal and 364 fatal IDOs (incidence: 148.8 and 1.01 per 100,000 respectively). Compared to non-fatal IDOs, fatal cases were more often male (55.2% vs. 42.0%), older in age (median 44 vs. 35 years), and more frequently involved multiple drugs (78.3% vs. 48.5%). Tricyclic antidepressants were associated with a 15-fold increased risk of death and opioids a 12-fold increased risk, relative to the reference category (non-opioid analgesics). While the risk of fatal outcome was higher for males than females, the elevation in risk was greater in females when tricyclic antidepressants or opioids were taken.

CONCLUSION

Male gender, increasing age and multiple drug use were associated with fatal IDO outcome. Tricyclic antidepressants and opioids were associated with a significantly increased risk of death following intentional overdose. Clinicians need to consider the case fatality risk of drugs when determining treatment for patients at risk of or those who have previously harmed themselves.

The relative lethal toxicity of pharmaceutical and illicit substances: A 16-year study of the Greater Newcastle Hunter Area, Australia

AIMS

We aim to calculate 2 metrics of relative lethal toxicity; the fatal toxicity index (FTI; number of deaths per year of a daily dose) and the case fatality (CF; number of deaths per overdose) with a focus on opioids, antidepressants, antipsychotics, benzodiazepines and illicit drugs.

METHODS

This descriptive cohort study used the Australian National Coronial Information System (NCIS) to identify a population of individuals with drug-associated deaths in the Greater Newcastle Hunter Area between January 2002 and December 2016. This was combined with Australian medicine dispensing data and corresponding data from the Hunter Area Toxicology Service to calculate FTI and CF.

RESULTS

There were 444 drug-related deaths and 21,296 overdoses during the study period. FTI and CF were well correlated (Spearman's rho 0.64, P < .001). Of the classes of interest, opioids had the highest FTI (40.3 95% confidence interval [CI] 35.2-45.4 deaths per 100 years of use at the defined daily dose or deaths/DDD/100 years) and CF (12.4% 95%CI 11.0-13.9). Fentanyl, methadone and morphine had the highest relative fatal toxicity within this class. Tricyclic antidepressants had the highest relative fatal toxicity of all antidepressants (FTI 14.5 95%CI 9.7-19.3 deaths/DDD/100 years and CF 7.1% [95%CI 4.8-9.3]) and benzodiazepines appeared to be more associated with multiple agent deaths than single. Of the illicit drugs, heroin had the highest CF (26.4%, 95%CI 19.1-33.7).

CONCLUSION

Knowledge of relative lethal toxicity is useful to prescribers and medicines and public health policy makers in restricting access to more toxic drugs and may also assist coroners in determining cause of death.