Who knows the name of this book?

I read it a long time ago. I only remember the outline of a story. It's about a very kind doctor who developed a medicine that could turn a good person into a bad person. He experimented on it himself and succeeded. Sometimes the bad person was called Hyde? He often bullied others. Sometimes, it was the kind doctor who made mistakes when he went to deal with the bad guys. Later on, he would become a bad person even without using drugs. Later on, he had to develop an antidote. But he failed. Later, the doctor died. (Suicide?)
That's probably what it means
Help me find it! Thank you!

Answer 1

I don't know which book you're referring to. If you can provide more context or information, I will try my best to answer your questions.