The murders that occur in my novels and short stories often involve a lethal medicine or a poison. To create a believable plot, I make sure to do my homework to get the toxic effects of those substances correct. That’s where toxidromes play a key role in that research.
Toxidromes are a groups of signs and symptoms that constitute the basis for a diagnosis of a specific poison. They are the telltale signs as to what type of substance the murder weapon is. These key details help determine which specific substance was responsible for the lethal outcome.
Many times in the real world of clinical detective work to identify a poison, a tox screen is not as helpful as one would think. This is because it only detects the most common drugs or toxins, and there is also a chance for false positive or negative results with general toxicology screening.
An astute medical professional first looks for obvious telltale signs of a poison and attempts to understand how the patient was acting in the moments before death to narrow down the type of poison before testing for drugs/poisons that could be the likely toxic substance.
There are six general categories of toxidromes in modern toxicology: Opiod, Stimulant, Anticholinergic, Cholinergic, Sedative/Hypnotic and Serotonin Syndrome Substances.
Murder scenes in fiction often focus on substances that create interesting drama as the offending drug or poison generates its lethal effects. Two toxidrome categories are the most popular in modern fiction writing: opiate and stimulant overdoses. Each produces interesting, dramatic and specific lethal effects.
Opiod/Opiate Drug Toxidromes: Opiates (natural opium plant derivatives such as morphine) and opiods (synthetic variations of natural opiates such as fentanyl, acetyl fentanyl and desmorphine) each create lethargy, confusion, slurred speech and then lead to a coma prior to death. Respiratory depression is often the cause of death. The victim simply ceases to breathe. Heroin is a common lethal drug in this category.
Opiod/opiate tox screens often don’t give reliable positive results and further testing is required to identify the specific lethal substance. If the victim is found alive, chances for a full recovery are good with the opiod reversal drug naloxone. This drug binds to the opiate drug receptors to block the lethal depressant effects of opiates and opiods and is the usual treatment of first responders and law enforcement when an overdose is suspected. Naloxone auto-injectors with a premeasured opiod-antidote dose are available for rapid use by first responders on a suspected overdose victim.
Stimulant Drug Toxidromes: Drugs/poisons that create these toxidromes produce extreme agitation, hallucinations and paranoia. Often the victim has a dramatic rise in blood pressure and the heart races. Hyperthermia that includes hot skin, a fever and extreme sweating are telltale signs of a stimulant drug overdose. Tremors and seizures often precede death. “Hot and mad” are the usual telltale signs of stimulant overdoses.
The offending drugs in the stimulant category include amphetamines (speed), MDMA (ecstasy), “bath salts”, herbal stimulants, pseudoephedrine and caffeine. Cocaine is a common lethal stimulant drug. If the victim is found alive, benzodiazepine sedatives (such as Ativan, Valium and Xanax) are often administered to prevent or stop seizures and the other lethal side effects.
It’s often said that the eyes tell the story in many overdose situations, at least until death occurs. Depressant drugs such as opiods constrict the pupils; whereas, stimulant drugs dilate the pupils.
Both of these drug categories on either end of the depressant/stimulant spectrum produce dramatic lethal effects and toxidrome-specific manifestations as the victim progresses toward death. Identification of the actual deadly substance can become its own nightmare for the medical examiner in your story, however. Solving the murder usually includes an intricate mix of clinical testing, old-fashion detective snooping and the recreating of the last moments of a victim’s life.
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