Santovin was a veterinary medicine for sheep manufactured by Stephen Pettifer & Sons in Malmesbury, Wiltshire. A sign for this manufacturer was recreated for Sherlock Holmes Program 3A.
In 2365, when Data (as Sherlock Holmes), Geordi La Forge (as John H. Watson), and Katherine Pulaski were walking along a London street, they passed this sign, which mentioned this medicine. (TNG: "Elementary, Dear Data")