Heavily Influenced by Altered States

I've read comments on here that the movie is a rip off of Limitless and 2001. But to me it seems more like it was heavily influenced by, or rather even an homage to, Paddy Chayefsky's/Ken Russell's Altered States. A unique drug ingested by the protagonist causes them to regress all the way back to the beginning of time itself (and the special effect images used by both movies to show it are amazing). The part where Lucy interacts with the ape as she's regressing back further and further even made me comment out loud, hey there's Eddie, Dr. Jessup!!