Scientist perfects a chemical unleashing the beast within, but before he can create an antidote, his neglected wife accidentally is dosed when he has to rush a batch home to keep it refrigerated. Her mild resentment of his endless hours at the lab accelerates into a torrent, after she gobbles pie on which the potion dripped.
https://www.imdb.com/title/tt0717061/plotsummary?ref_=tt_ov_pl
Thios video is in the Public Domain.