Monocane

Described by Dr. Cranley as "terrible," monocane was an obscure West Indian drug with powerful bleaching properties. German scientists experimenting with it tried it on a dog, turning the animal dead white and driving it mad. Monocane was used by Dr. Jack Griffin was a key ingredient in his invisibility formula (something he did without knowing about monocane's ghastly side-effects), and later his brother Frank's as well.

Comments

In The Invisible Man Returns, the drug is referred to as duocane, although it is clearly the same as monocane.)