I am trying to understand how billing works for m.D.S performing a service or for pharma prescriptions in different settings (hospital, dr's office)?

E&M codes. Mds bill for their services using e/ m (evaluation and management) codes. The code used depends on the level of service and the location that the service is provided (office, hospital, er). Mds can also bill for medications (not a prescription) that are administered, or procedure performed in the office. Medications administered in hospital or er are billed by the hospital, not md.