BINGHAM, Me.  The orange signs posted throughout Chet Hibbard’s pharmacy here relay a blunt warning: We Do Not Stock OxyContin.

Mr. Hibbard stopped dispensing the highly addictive painkiller last July, after two robbers in ski goggles demanded it at knifepoint one afternoon as shocked customers looked on. It was one in a rash of armed robberies at Maine drugstores last year, a sharp increase that has rattled pharmacists and put the police on high alert.

“I want people to know before they even get in the door that we don’t have it,” Mr. Hibbard said of OxyContin, which the authorities say is the most common target of pharmacy robberies here. “Outside hiring an armed guard to be in here 24/7, I don’t know what else to do.”

Maine’s problem is especially stark, but it is hardly the only state dealing with pharmacy robberies, one of the more jarring effects of the prescription drug abuse epidemic that has left drugstores borrowing heist-prevention tactics from the more traditional targets, banks. In at least one case, a tiny tracking device affixed to a bottle let the police easily track a thief after a robbery.