Patent ID: 7347854

Claim:
A method of operating an implantable drug delivery that includes a reservoir, a fluid transfer device, and a catheter, said method comprising the steps of: filling said reservoir with a first drug; controllably transferring said first drug from said reservoir to said catheter and a body site in accordance with a first delivery profile specifying a schedule of at least two different flow rates during a delivery period of certain duration; evacuating said first drug from said reservoir; filling said reservoir with a second drug; providing a second delivery profile specifying a schedule of flow rates for transferring said second drug to said catheter; determining the quantity of first drug remaining by monitoring activity of the fluid transfer device, and continuing to transfer the remaining quantity of said first drug in said delivery device to said body site in accordance with said first delivery profile, after evacuating said reservoir; and initiating controllable transfer of said second drug from said reservoir to said catheter in accordance with said second delivery profile after said remaining quantity of said first drug has been cleared from said device in accordance with the first delivery profile.