He noticed there were several sheets with letterheads hinting at its past, like a page from a prescription pad from a Waco store titled "W.B. Morrison & Co. Old Corner Drug Store." An Internet search revealed Dr Pepper, first served in 1885, was invented at the Old Corner Drug Store in Waco by a pharmacist named Charles Alderton. Wade Morrison was a store owner.
Faded letters on the book's fraying brown cover say "Castles Formulas." John Castles was a partner of Morrison's for a time and was a druggist at that location as early as 1880, said Mary Beth Webster, collections manager at the Dr Pepper Museum and Free Enterprise Institute in Waco.
Speaking for Dr. Pepper Greg Artkop said the recipe certainly bears no resemblance to any Dr Pepper recipes the company knows of. The drink's 23-flavor blend is a closely guarded secret, only known by three Dr Pepper employees. So, Dr. Pepper maintains that the formula is still a trade secret.
From Michael Riley: At first, Alderton's drink inspired by the smells in the drugstore was called "a Waco." "People would come in and say, 'Shoot me a Waco,'" So, one has a trademark re-branding from "a Waco" to a Dr. Pepper.