Police say surveillance video shows a man walking into one of the offices with his face covered.
The suspect is a thin black man, who was last seen wearing blue jeans, a blue jacket and a blue baseball cap with an unidentifiable white emblem.
Investigators say the bandit breaks locks on rear doors and disables the security alarm.
In addition to narcotics, the bandit is also grabbing petty cash.
Officials say there have been 16 incidents of medical offices being burglarized in Cary since September.
Anyone near the area during the time of the burglaries is encouraged to contact the Town of Cary Police Department at (919) 469-4012 or Cary Crime Stoppers at 226-CRIM(E). Crime Stoppers pays up to $2,500 for the arrest or indictment of those responsible for committing certain types of crimes.