According to the 2003-2004 edition of the MSAR, for the 2001 First Year Class, NW interviewed 660 out of total of 7,852 applicants. The class size was 170. Since not all acceptees actually attend, the number admitted must have been larger, how much larger is not known.
However, know that NW undergraduate school has an honors premedical program from which as many as 60 may be offered places.