text: The concept of replacing hydrogen with deuterium is an example of bioisosterism, whereby similar biological effects to a known drug are produced in an analog designed to confer superior properties. The first patent in the US granted for deuterated molecules was in the 1970s. Since then patents on deuterated drugs have become more common.
  The applications of the deuterium isotope effect has increased over time, and it is now applied extensively in mechanistic studies of the metabolism of drugs as well as other studies focused on pharmacokinetics (PK), efficacy, tolerability, bioavailability, and safety. The introduction of deuterated drug candidates that began in the 1970s evolved from earlier work with deuterated metabolites. However, it took more than 40 years for the first deuterated drug, Austedo® (deutetrabenazine), to be approved by the FDA. Numerous publications have discussed the advantages and disadvantages of deuterated drugs.
  A number of publications have discussed aspects of intellectual property of deuterated versions of drugs.