This commonly referenced poison came up in our most recent episode about Thomas Neil Cream, the Lambeth Poisoner.
Strychnine is a naturally occurring product in the seeds of the Strychnos nux-vomica plant. Charming name! Initially used as a rodent and bird poison, it’s not surprising that strychnine is very toxic to humans as well. As a poison, strychnine has a peculiar mechanism of action that is similar to how the toxin from the tetanus bacteria works.
In the connection between our nerve endings and our muscles (the synaptic gap), when we want to contract a muscle, the chemical acetylcholine is sprinkled from the nerve to the muscle, causing contraction. Other inhibiting substances, such as glycine, are released to help stop muscle contractions. Strychnine stops the inhibiting substances from working, causing uncontrolled muscle contraction in high enough doses. If this happens, one cannot breathe which is the predominant cause of death with this poison. It can also cause metabolic disturbances and muscle breakdown (rhabdomyolysis) as well as seizure-like activity. All that is bad, medically speaking.
Though he used other substances, such as chloroform, strychnine was a favorite go-to choice for the late 19th century serial killer/physician, Dr. Thomas Neill Cream. He would either prescribe it under false pretenses or convince people to take it, causing numerous deaths in multiple countries.
Doctor with a mustache.