Dr. Jekyll & Sister Hyde (1971)

In Victorian London, Dr. Henry Jekyll is a research scientist who searches the cure of many common diseases. However, he is a very reserved and shy man and spends most of his time working on his home laboratory. One day, his friend Professor Robertson visits him and advises that he would probably die before the conclusion of his studies. Dr. Jekyll decides to create an elixir of life, based on feminine hormones, to extend his life since women live longer than men. He uses feminine hormones stolen from fresh corpses. The effect of the elixir of life releases his feminine repressed side, and he becomes an aggressive, gorgeous and evil woman, Mrs. Hyde. When the bodies finish in the city morgue, Dr. Jekyll begins killing a number of young women to proceed with his research.

IMDb: https://www.imdb.com/title/tt0068502