Can you tell me how fentanol citrate effect propofol?

They are both: respiratory depressants, fentanyl adds analgesia to Propofol

No interaction: Propofol induces sleep. Fentanyl is a pain reliever, a narcotic, in the same drug class as morphine and Demerol (meperidine hydrochloride). There is no direct interaction between the two. But when used in combination they can cause breathing to slow or stop, so must be used with caution by anesthesia professionals. Both can also cause blood pressure to drop.