IIT BHU has four different for M. Pharmacy which are Pharmaceutics, Pharmaceutical chemistry, Pharmacology and Pharmacognosy so they declared cutoff ranks according to your marks for each category  every year cutoff changes due to various factors.They called 7 times more number students for counseling than the total seat available there.some application also get rejected because of not having gpat score and lack of eligibility so they create chance for other candidates.

So,If You want to be on Safe side you should achieve atleast below 500 rank in GPAT.