So far, it's been more of a read focused on entertainment than teaching me about deep science. The medications discussed so far:

Opium (as well as Morphine + Heroin)

I had not realized exactly what the basis for the Opium Wars was until this book, but the gist is that the Chinese were attempting to ban Opium from entering the country, which British smugglers kept sneaking into the country. I also had not realized how many drugs Bayer was famous for creating (Aspirin, Heroin),

Smallpox Vaccine

If you aren't familiar with the history of the vaccine, it originally came from a relative of smallpox called cowpox. Cowpox was a disease that infected cow udders, and could spread to humans with just a mild effect. Injecting Cowpox into (the name comes from Vacca latin for cow).

Sulfonamide

The precursor to Penicillin. Apparently Sulfonamides or Sulfa was originally shown to have strong antibiotic properties by Bayer... though they had mistaken the red dye originally thought to cause antibiotic effects for the common sulfonamide functional group. Bayer couldn't find a good way to patent and monetize the drug for another two years, so they didn't bring it to market until they modified the compounds in a more proprietary way.

My meta-observation is: boy, it would've been terrifying to get sick any time more than 100 years ago. The book is filled with dozens of accounts of people dying from simple colds, fevers, and infections that are easily treatable with modern medicine.