I Am Trying To Find Out What A Round White

I am trying to find out what a round white pill is that was in my son's prescription bottle? It only has the number 8 and 9 on one side and nothing on the other side of the pill? He takes Benztropine and that was in the bottle as well. The other pills in the bottle checked out as Benztropine but I can't find the 8 9 one to determine what it is for sure.