It is my understanding that the coating on the Sinemet CR pill retards absorption of the medicine giving it its constant release properties. If you break the pill, the pill is not entirely covered by this coating causing faster intake of the medicine into the blood stream. When I received Sinemet CR, the bottle had one of the pharmacy warning labels saying not to break the pill. I also do not remember it being ribbed for breaking. However the Sinemet (not Sinemet CR) was ribbed and had no such warning. Steve McGinnis [log in to unmask]