While I sympathize with you the drive thru pharmacy is for prescription pick up only.
If you ask for an OTC medication how do they know its the strength you want, the amount/ounces, etc, or even the brand?

I was standing at the pick-up window at Walgreens one day when over the speaker came a voice from someone out in their car asking for 1 gal of 2% milk, 1 dozen eggs and some other items because they could not come into the store physically to pick these up.
The clerk on duty did all of this for this elderly gentleman (the dairy coolers were located right near the pharmacy) but the pharmacist on duty reprimanded him (not harshly) telling him that he should not do this as the drive up window was for prescription pick up only.

Not that the clerk did anything wrong as far as I can see, but I can see where this would get out of hand in some cases.

Again, while I can sympathize with you I believe that only prescription ordered medications/items should be purchased thru these drive thru's.