If the friend ask you to, then you can give the doctor your friend's new address. If not, your friend will have to give the doctor her new address.

Can I give the doctor I work for a friend's forwarding address if she did not do so


You work for a doctor. You know the address of your friend. The doctor wants to mail something to your friend. Does the law allow you to give the address to the doctor?

Yes.

There is no law providing otherwise.