I work in a pharmacy and from what I've seen even though you would be getting the same dosage, often times when you receive a dose is important. So I would say that you should consult with your doc and if he/she is ok with it then he/she can write a new rx so that the pharmacy is also up to date. You can probably just leave a message with the medical assistant and shouldn't have to make an appointment or anything, and then they can call or fax your pharmacy with the new script =)