Troches or lozenges are designed to deliver the medication to the locally affected area, specifically, the throat. Through this, the highest concentration can be achieved where it is needed (throat) and minimized where it is not needed (absorbed).
As such these products should be placed far back into the throat and allowed to dissolve, releasing its medication. The normal tablet shaped lozenges may present a choking hazard when placed at the back of the throat.
S.P. Troches is designed with a hole in the middle, with an enlarged outer diameter. The bigger diameter reduces the choking risk. Moreover, should any accident happen, breathing is still facilitated through the hole.
Eventually when the troche has been dissolved sufficiently, the troche can be easily crushed with a swallowing action.