Prove who you are....

[glasgowcyclist]

For instance is say Mrs Smith came in to pick up her prescription we used to say there is one here for Mr Smith here too. Now we can't do that. We can hand it over if she comes in and asks for it but we can’t let her know he has one otherwise.

I suppose you could always ask Mrs Smith if she's expecting a prescription for anyone else at her address.
That way you're not actually disclosing its existence.