This creates awkward situations in a number of ways. First, you know about your friend's conditions and treatments which might be embarrassing. Second, because of your friendship, sometimes you're expected to do things you wouldn't normally do.
For example, I've had friends expect me to:
* Give them early refills on narcotics
* Give them a discount on their co-pay
* Authorize a refill request without actual prescriber approval
These are things that a friend shouldn't ask for because they are a friend! When someone asks you to put your job in jeopardy for them, that's asking too much. You could always try to keep a little humor in it and present them with this card:
How do you handle it without straining the friendship? What seems to work for me is to simply tell the friend "I wish I could, but this could be big trouble for me." If you take the time to explain that pharmacy has a set of rules which are strictly watched, your friend should understand.
Unless they're not a real friend.