Decision information systems, methods, and computer programs for better informing decisions to use multiple drugs in 
drug delivery devices, including implantable devices, for 
drug administration. 
Executable computer programs and logic embodying methods of the invention can calculate consistent multiple 
drug mixture amounts and 
drug delivery flow rates. One program accepts 
user input indicating a desired first drug 
dose rate, an initial first 
drug concentration, a desired second drug 
dose rate, an initial second 
drug concentration, and the reservoir size of the 
drug delivery device. The program method calculates a first drug amount and a second drug amount to combine in a mixture as well as a first drug true concentration in the mixture. The drugs can be mixed consistent with the physician's instructions using the program output. The first drug true concentration can be entered into a 
programmer device as the only 
drug concentration entered. Another program calculates a consistent first drug, second drug, and 
diluent amount to be added to a mixture for injection into a fixed flow rate, implantable 
drug delivery device. Methods preferably output true concentrations and 
dose rates for all drugs to be added and most preferably show all calculations used to arrive at the flow rate and mixture amount calculations. Yet another program receives a new desired drug 
dose rate for a previously filled device. The program accepts the existing mixture volume and true drug concentrations for a partially depleted device and calculates a new mixture flow rate to achieve the desired 
dose rate using the existing mixture. The methods can be implemented as 
executable computer programs in 
programmer devices, 
general purpose computers, servers, handheld computers, and personal digital assistants.