Coincidentally there was a very informative programme on Radio 4 the other day, all about Bald's Leechbook, an ancient Celtic text of medicinal remedies. Oddly enough there is not one single remedy that uses a leech!
Maybe not exactly what you had in mind but I thought to mention it anyway -
as an interesting point was made about the use of poetry, songs and incantations, when used with the application of medicines. Because the ancients didn't have the luxury of watches and timers, poems and such where used instead.
Did you know that Art Garfunkel's, Bridge Over Troubled Water, can be used to time a perfect hard boiled egg.
Just saying ...
British Library Webbie