Near Death by Viagra?

by Natalie

I'm trying to find the name of a movie where the killer is a science teacher who collects flowers.

In one scene, a couple has sex in a random building and the boyfriend takes a large amount of a Viagra-like pill and almost dies, but then is finished off by the killer, along with his girlfriend.

In another scene, the killer offs some lesbians in the woods.

If someone could help me out with the title, I'd really appreciate it!