Similar Devices

Watching the marathon, I notice that a similar device is used in a number of episodes. In Elegy, Wickwire puts something in their drinks to kill them. In Back There, Booth drugs the Professor's drink, in Queen of the Nile she puts something in his coffee so she can suck the life force from him. In the Chaser, Roger puts the love potion in her drink and later is supposed to put the "glove cleaner" in Leila's drink but he can't do it after she says she is pregnant. Mr. Denton on Doomsday, Fate gives him a magic elixir to drink. I think she uses a potion in Jess-Belle (IDR).