The present invention discloses compounds of formula, their optical isomers or pharmaceutically acceptable salts thereof, their preparation and uses thereof, wherein the definitions of R1, R2, R3 and R4 are shown in the description. The method includes disposing a polymeric sheet material over the non-metallic surface and disposing a metal layer between the non-metallic surface and the polymeric sheet material. An inner element may have a bore longitudinally therethrough and may have a threaded end for threadable engagement with the outer body threaded interior wall.