Blood free morphine levels vary with concomitant alcohol and benzodiazepine use

A descriptive coronial study of heroin toxicity deaths in Australia, 2020-2022: Characteristics, toxicology and survival times

BACKGROUND AND AIMS

Mortality rates among people who use heroin are estimated to be 15 times that of the general population. The study aimed to determine (1) the case characteristics and circumstances of death of heroin-related toxicity deaths in Australia, 2020-2022; (2) their toxicological profile and major autopsy findings; (3) the proportion of cases in which blood 6-acetyl morphine (6AM) was detected, as a proxy measure of survival times; and (4) compare 6AM positive and negative cases on toxicology, circumstances of death and acute clinical presentation.

DESIGN

Retrospective study of heroin toxicity deaths in Australia, 2020-2022, retrieved from the National Coronial Information System.

SETTING

This study was conducted Australia-wide.

CASES

There were 610 cases of fatal heroin-related drug toxicity.

MEASUREMENTS

Information was collected on characteristics, manner of death, toxicology and autopsy results.

FINDINGS

The mean age was 42.6 years (range 18-73 years), 80.5% were male and 7.5% were enrolled in a drug treatment programme. The circumstances of death were as follows: unintentional drug toxicity (86.2%), combined unintentional drug toxicity/disease (11.3%) and intentional drug toxicity (2.5%). The median free morphine concentration was 0.17 mg/L (range 0.00-4.20 mg/L). Psychoactive drugs other than heroin were present in 95.2% (Confidence Interval 93.1%-96.8%), most commonly hypnosedatives (62.3%, 58.2%-66.4%) and psychostimulants (44.8%, 40.7%-49.1%). Major autopsy findings of clinical significance included acute bronchopneumonia (14.8%, 11.3%-18.8%), emphysema (16.9%, 13.2%-21.1%), cardiomegaly (30.1%, 12.7%-28.2%), coronary artery disease (27.4%, 23.0%-32.3%), coronary replacement fibrosis (13.4%, 10.1%-17.3%), hepatic cirrhosis (8.8%, 6.6%-12.2%) and renal fibrosis (10.3%, 7.3%-14.0%). In 47.0% (42.3%-51.2%), 6AM was present in blood.

CONCLUSIONS

The 'typical' heroin overdose case in Australia from 2020 to 2022 was a male who injected heroin, aged in the 40s, not enrolled in a treatment programme and had used multiple drugs. In over half of cases, there had been a sufficient survival time for 6-acetyl morphine to have been metabolised, which may indicate times in excess of 20-30 min.

Pharmacological data science perspective on fatal incidents of morphine treatment

Morphine prescribed for analgesia has caused drug-related deaths at an estimated incidence of 0.3% to 4%. Morphine has pharmacological properties that make it particularly difficult to assess the causality of morphine administration with a patient's death, such as its slow transfer between plasma and central nervous sites of action and the existence of the active metabolite morphine-6-glucuronide with opioid agonistic effects, Furthermore, there is no well-defined toxic dose or plasma/blood concentration for morphine. Dosing is often adjusted for adequate pain relief. Here, we summarize reported deaths associated with morphine therapy, including associated morphine exposure and modulating patient factors such as pharmacogenetics, concomitant medications, or comorbidities. In addition, we systematically analyzed published numerical information on the stability of concentrations of morphine and its relevant metabolites in biological samples collected postmortem. A medicolegal case is presented in which the causality of morphine administration with death was in dispute and pharmacokinetic modeling was applied to infer the administered dose. The results of this analytical review suggest that (i) inference from postmortem blood concentrations to the morphine dose administered has low validity and (ii) causality between a patient's death and the morphine dose administered remains a highly context-dependent and collaborative assessment among experts from different medical specialties.

Frequency and severity of non-fatal opioid overdoses among clients attending the Sydney Medically Supervised Injecting Centre

BACKGROUND

Pharmaceutical opioid overdose rates have increased in recent years. The current study aimed to compare rates per 1000 injections of non-fatal overdose after heroin or oxycodone injection, and their comparative clinical severity.

METHODS

Analysis of prospectively collected data from the Sydney Medically Supervised Injecting Centre (MSIC). Severity of overdose was measured using the Glasgow Coma Scale, oxygen saturation levels, and the administration of naloxone.

RESULTS

Heroin overdoses occurred at three times the rate of oxycodone overdoses (12.7 v 4.1 per 1000 injections). Heroin overdoses appeared to be more severe than oxycodone overdoses, with higher levels of compromised consciousness (31 v 18%) and severe respiratory depression (67 v 48%), but there were no differences in naloxone doses (20 v 17%). Concurrent use of other depressants at the time of overdose was also associated with compromised consciousness, and the need for naloxone.

CONCLUSIONS

Heroin overdoses occurred at a greater rate than oxycodone overdoses, and had more severe clinical indicators.

Heroin overdose

BACKGROUND AND AIMS

This narrative review aims to provide a brief history of the development of the heroin overdose field by discussing a selection of major 'classics' from the latter part of the 20th century.

METHODS

Papers considered landmarks were selected from 1972, 1977, 1983, 1984 and 1999.

RESULTS

Findings of earlier works suggest much of what later research was to demonstrate. These include arguing that overdoses occurred primarily among tolerant older users, that most 'overdose' deaths involved low morphine concentrations, that most overdoses involve polypharmacy, that drug purity has only a moderate influence on overdose rates and that instant death following heroin administration is rare.

CONCLUSIONS

Landmark studies of heroin overdose from the 1970s, 1980s and 1990s laid the foundations for subsequent overdose research, mainly by identifying the major demographic characteristics of overdose cases, risk factors, survival times and behaviours at overdose events.

The toxicology of heroin-related death: estimating survival times

BACKGROUND AND AIMS

The feasibility of intervention in heroin overdose is of clinical importance. The presence of 6-monoacetyl morphine (6MAM) in the blood is suggestive of survival times of less than 20-30 minutes following heroin administration. The study aimed to determine the proportions of cases in which 6MAM was present, and compare concentrations of secondary metabolites and circumstances of death by 6MAM status.

DESIGN

Analysis of cases of heroin-related death presenting to the Department of Forensic Medicine Sydney, 1 January 2013-12 December 2014.

SETTING

Sydney, Australia.

CASES

A total of 145 cases. The mean age was 40.5 years and 81% were male.

MEASUREMENTS

Concentrations of 6MAM, free morphine, morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G). Circumstances of death included bronchopneumonia, apparent sudden collapse, location and other central nervous system (CNS) depressants.

FINDINGS

6MAM was detected in 43% [confidence interval (CI) = 35-51%] of cases. The median free morphine concentration of 6MAM-positive cases was more than twice that of cases without 6MAM (0.26 versus 0.12 mg/l). 6MAM-positive cases also had lower concentrations of the other major heroin metabolites: M3G (0.05 versus 0.29 mg/l), M6G (0.02 versus 0.05 mg/l) with correspondingly lower M3G/morphine (0.54 versus 2.71) and M6G/morphine (0.05 versus 0.50) ratios. Significant independent correlates of 6MAM were a higher free morphine concentration [odds ratio (OR) = 1.7], a lower M6G/free morphine ratio (OR = 0.5) and signs of apparent collapse (OR = 6.7).

CONCLUSIONS

In heroin-related deaths in Sydney, Australia during 2013 and 2014, 6- monoacetyl morphine was present in the blood in less than half of cases, suggesting that a minority of cases had survival times after overdose of less than 20-30 minutes. The toxicology of heroin metabolites and the circumstances of death were consistent with 6- monoacetyl morphine as a proxy for a more rapid death.