Police said that Christopher Johnson of 2363 26th St. in Astoria, N.Y., was charged in connection with Sunday's 8:35 a.m. robbery of 1,600 prescription pills at Trotta's Pharmacy at 15 Halstead Ave. Johnson was taken into custody shortly after the robbery by Harrison police officers in the 400 block of Carroll Avenue in Mamarroneck, police said. The black handgun displayed at the scene of the crime was recovered during the arrest.