Dr. Jekyll & Sister Hyde (1971)

In Victorian London, Dr. Henry Jekyll attempts to create an elixir of life using female hormones stolen from fresh corpses. He reasons that these hormones will wipe out all common diseases and extend his life since women live much longer than men. However, once Dr. Jekyll drinks the serum himself, he transforms into a gorgeous but evil woman. He soon needs female hormones for his serum to maintain, so a number of London women meet bloody deaths.