Secondary patents associated with blockbuster drugs are granted for follow-on innovations relating to the active pharmaceutical ingredient (‘API’) of the drug. Our analysis of all sec-ondary patents for 13 top-selling drugs in Australia shows that, while the majority of fol-low-on innovations are made by entities other than the originator of the drug, the innova-tions with the highest private value are undertaken by the drug’s originator and concern a delivery mechanism or an alternative formulation for the API. Since that is the type of follow-on innovation most commonly undertaken by drug originators, and considered most likely to result in a de facto extension of marketplace monopoly over the drug, we see in these findings evidence that the originators of blockbuster drugs engage in secondary patenting that has an ‘evergreening’ effect
