Xanzolam is a fictional highly addictive central nervous system depressant that was prescribed for anxiety. It is a driving force in the Netflix miniseries, The Queen's Gambit, as the protagonist, Beth Harmon, struggles with her childhood addiction, where she used Xanzolam to enhance her chess studies.
In the miniseries, it was banned from being prescribed to children in 1958. Before then, Methuen Home had regularly prescribed their residents with Xanzolam under the guise that they would "even [their] disposition".
Throughout the show, Xanzolam is also referred to as vitamins, tranquilizers, and, by Harmon, "the pills".
Speculation[]
It's unknown what Medicine Xanzolam is based off of. However, it can be assumed it is either a Barbituate, which were more commonly prescribed at the time, or a benzodiazepine.
The name Xanzolam is an obvious portmanteau of Xanax and alprazolam, which is the generic name for Xanax. Based on its name that would make it a benzodiazepine. However, Xanax did not yet exist during the time that the series is set.
The medicine shares similarities with Librium, another benzodiazepine that existed during that time; however it also has unique traits, such as the side effects Beth abused.