Deuterated drug

A deuterated drug is a small molecule medicine in which one or more hydrogen atoms have been swapped for deuterium, the heavier stable isotope of hydrogen. The change is small in size and shape, but because of the kinetic isotope effect the carbon to deuterium bond can resist metabolism better than the ordinary carbon to hydrogen bond, so a deuterated version may break down more slowly and stay in the body longer than its non-deuterated twin. The idea is an example of bioisosterism, in which an analog is designed to keep the biological effect of a known drug while improving its properties. Patents on deuterated molecules date back to the 1970s and have become more common since.