Satanik (1968) on Netflix

Plot summary

Dr. Marnie Bannister is a disfigured woman. A colleague of hers has developed a serum that can rejuvenate living beings, and he calls her to see what it does. The serum brings an animal that is near death back to health in seconds. The colleague refuses to test it on humans until he has run more experiments. Bannister kills him while his attention is elsewhere, then drinks the serum. She is shaken by convulsions and falls to the floor, and when she wakes she is young and beautiful.