The present invention relates to an implantable drug delivery device which includes a fluid drug reservoir, a catheter, a controllable fluid transfer device, e.g., a pump or valve, and a drug delivery control means. The control means in accordance with the invention is configured to initially clear a first, or old, drug from the device based on the content of the Current Profile data containing a first, or old, delivery profile. After the old drug is cleared, then the control means automatically modifies the Current Profile data to match a second, or new, delivery profile for controlling delivery of a second, or new, drug.