I have had the PFT and you need to call and ask the respiratory therapist or who ever is doing the test how you need to prepare for the test. I wasn't able to take my steroid inhalers before only my albuterol. You didn't say why your taking the meds? The test will give a true report of what is going on with your breathing and how bad it is. Sometimes they give meds to make you have an asthma attack. Not always though, they test you first to see how your breathing is and then if your not having much trouble they will give a med to make you have one.
But I urge you to call and ask the respiratory dept. about the meds. It's extremely important for a true test.