Horror...take on vampirism and addiction?

This is a movie I believe I rented in the 90’s…maybe? It was about a man and woman that were either doctors or research scientists. I believe they were actually married. They were holding this young girl captive as a sort of lab subject She had some sort of virus or blood disease. There was something weirdly romantic or just lusty going on between the three of them I believe. The blood of the girl would cause a euphoric sensation when you drank or injected it…and it had the ability to create an addiction. In the end, the man wakes up and both the wife and the girl are dead. The girl is dead because he used too much of her blood. I think he may have killed his wife/partner. Something like that. It seems like it was an interesting take on vampirism and addiction…maybe.
Thanks

I thought I remembered this movie plot from a question years ago. I found it.
“blood”

Hah! Thank you so much! I cant wait to rewatch this and see what I think this go around.

Much appreciated. :slightly_smiling_face: