how to remove last character if its a letter?

[MsAxes]

Hello all, I currently have this expression

IIF([Field1] Like "*Dr*",LEFT([Field2] & [Field3],LEN([Field2] & [Field3]-1),"")

that removes the last character if field1 contains 'Dr'. It works except some of the data that is in field 3 ends in a letter that wasn't there before when i was conducting my analysis. The length varies so I can't use the mid function. Is it possible to just remove the last character of a field if its a letter and ignore it if its a number?

[June7]

Don't see how that expression can work because need paren in front of -1.

IIf(IsNumeric(Right([Field3],1)), do this, else this)

IIf([Field1] LIKE "*Dr*", [Field2] & Left([Field3], Len([Field3]) - IIf(IsNumeric(Right([Field3],1)), 1, 0)), "")

[MsAxes]

you are amazingly sharp or I'm amazingly dumb - thank you. Your last expression did the trick.