Background on animal testing in the drug delivery systems program.

In the screening and selection of candidate long-acting narcotic antagonist preparations, careful consideration must be given to the choice of animal evaluation models. A simple, rapid method, using analgesia suppression in the mouse tail-flick test, was chosen for preliminary screening. Suitable candidates were then evaluated by following urinary excretion rates and blood levels in the monkey. Afterwards, the most promising preparations were rigorously tested in their ability to interfere with morphine self-administration in monkeys. Final evaluation involved toxicological studies in injection sites and on the whole animal.