Pharmacopée Royale Galénique et Chymique, first published in 1676, was the best-known of Charas"s works and was the first medical book from Europe translated into Chinese. A medication included in his formulary was theriac which was first made popular by the Greeks as an antidote to animal bites and disseminated over the Silk Route. The formula for theriac included as many as 600 separate ingredients and was kept secret for over seventeen centuries.
Another medication included was orvietan.
Charas is considered an important figure for the dissemination of medical knowledge. He was an expert in areas such poisons, antidotes, opium, and vipers.
There is evidence that his nomination and acceptance into the Academie Des Sciences was based on the importance of his publications on pharmacology rather than on his credentials as a scientific researcher, contrary to the usual practice of the day.