In an embodiment, a method is provided for communicating a medical prescription with a mobile processing system. In this method, a first request to fulfill the medical prescription is received from the mobile processing system. This first request is formatted in an instant messaging protocol and includes a mobile processing system identifier and a transaction identifier. A patient identifier that is associated with the mobile processing system identifier is identified, and transactions associated with the patient identifier are accessed to identify a transaction that is associated with the transaction identifier. The transaction then is transmitted in a second request to a pharmacy system that is configured to fulfill the medical prescription.