A retired city cop has been busted for allegedly pulling a series of armed robberies at Brooklyn drug stores, in which he made off with powerful painkillers, officials said today.

Salvatore DellaCave has been accused of using a gun to take OxyContin and other similar drugs as he knocked over seven pharmacies in Marine Park between March 3 and May 13, cops said.

In two of the heists, DellaCave allegedly also stole some cash.

DellaCave was injured in the line of duty in September 2007, when he separated his shoulder while struggling with a group of robbery suspects who had fled to a rooftop.

He retired the next year on a disability pension.

Detectives are now trying to determine if the former officer became hooked on painkillers after his injury, sources said.

Charges were still pending as DellaCave awaited arraignment.