Heroin, like other opiates, depresses activity in the brain centre that controls breathing. Sometimes, this effect is so profound that the drug user dies, and becomes yet another overdose casualty.
Some of these victims die because they took too much of the drug.
Others die following self-administration of a dose that appears much too small to be lethal, but why? This is the heroin overdose mystery, and it has been known for more than half a century.
There was a heroin crisis in New York City in the 1960s, with overdose deaths increasing each year of the decade. There were almost 1,000 overdose victims in New York City in 1969, about as many as in 2015.
This shows what others have pointed out: that this opioid crisis is not a new thing, that addictions followed by overdoses have been a problem for decades (and perhaps for all of human history).
The then chief medical examiner of New York, Milton Helpern, together with his deputy chief, Michael Baden, investigated these deaths. They discovered that many died, not from a true pharmacological overdose, but even when, on the day prior, the victim had administered a comparable dose with no ill effects.
They examined heroin packages and used syringes found near dead addicts, and tissue surrounding the sites of fatal injections, and found that victims typically self-administered a normal, usually non-fatal dose of heroin.
In 1972, Helpern concluded that ‘there does not appear to be a quantitative correlation between the acute fulminating lethal effect and the amount of heroin taken’.
independent evaluations of heroin overdoses in New York City, Washington, DC, Detroit, and various cities in Germany and Hungary all confirmed the phenomenon – addicts often die after self-administering an amount of heroin that should not kill them.
Some have suggested that the addict might overdose following a period of abstinence, either self-initiated or caused by imprisonment. If the addict goes back to his or her usual, pre-abstinence routine, the formerly well-tolerated dose could now be lethal.
But there are many demonstrations that opiate tolerance typically does not substantially dissipate merely with the passage of time.
I couldn’t resist looking up this reference from PubMed – and posting it below this article.
One piece of evidence comes from the addict’s hair, which carries a record of drug use.
In a study that analysed the hair of 28 recently deceased heroin-overdose victims in Stockholm, there was no evidence that they had been abstinent prior to death.
A surprising solution to the overdose mystery has been provided by the testimony of addicts who overdosed, then survived to tell the tale.
most overdose survivors said that they’d administered heroin in a novel or unusual environment – a place where they had not previously administered heroin.
I’ve seen this called “situational tolerance“, because apparently our tolerance (to just about any substance) is location/situation specific, and does not reliably carry over to new locations/situations.
Case studies suggest an increased risk in an unusual environment, but proof requires an experiment. This experiment cannot ethically be done with people but it has been done with rats and mice.
The consistent finding was that mortality was significantly higher in animals receiving the final dose in an alternative place. In an experiment with heroin, for example, mortality was twice as high in rats receiving their last dose under unusual circumstances.
The findings are bolstered by 40 years of published experiments with many drugs, including caffeine, nicotine and alcohol, showing that effects are augmented when the drugs are taken in a different environment.
Some might simply take too much of the drug, especially when the heroin is enriched with even more potent opioids.
Othersmight die because the effect of a usually sub-lethal dose of opiate is enhanced by other, concomitantly administered, depressive drugs, such as alcohol.
These traditional risk factors have been extensively publicised.
We can add to that the problem of fentanyl being mixed in with their usual heroin dose.
Less widely acknowledged is the risk that addicts face if they administer the drug in [new] contexts that have not, in the past, reliably signalled the drug.
Shepard Siegelis a distinguished university professor of psychology, neuroscience and behaviour at McMaster University in Ontario, Canada
Here’s the study mentioned above:
Evaluation of the role of abstinence in heroin overdose deaths using segmental hair analysis. – Forensic Sci Int. – May 2007
In the body heroin is rapidly metabolized to 6-acetylmorphine and morphine.
Victims of lethal heroin overdose often present with fairly low blood concentrations of morphine.
Reduced tolerance due to abstinence has been proposed to account for this finding.
The aim of the present study was to examine the role of abstinence in drug-related deaths by comparing recent and past exposure to opioids using segmental hair analysis with the postmortem blood morphine concentrations in deceased heroin users.
The study included 60 deceased drug addicts in the Stockholm area, Sweden.
In 32 cases, death was not related to heroin intake.
In 18 of the 28 heroin fatalities, opioids were absent in the most recent hair segment, suggesting a reduced tolerance to opioids.
However, the blood morphine levels were similar to those found in the 10 subjects that showed continuous opioid use.
Hair and blood analysis disclosed an extensive use of additional drugs that directly or indirectly may influence the opioid system.
The results suggest that abstinence is not a critical factor for heroin overdose death.
Obviously tolerant subjects die after intake of similar doses.
Other factors, particularly polydrug use, seem to be more causally important for these deaths.