In the realm of pharma patents, a number of techniques have been employed [to hang on to market exclusivity granted by patents]. One is "pay for delay." Another is the granting of "data exclusivity." And a third is the use of "evergreening." For example, AstraZeneca is trying to use a variant of evergreening for its anti-cholesterol pill Crestor. As a New York Times article explains:
Crestor is the company’s best-selling drug, accounting for $5 billion of its $23.6 billion in product sales last year. About $2.8 billion in sales were in the United States, where the retail price is about $260 a month, according to GoodRx.com.
Here's how AstraZeneca hopes to hold on to that lucrative market, even though its patent on the drug is now coming to an end, and it should be entering the public domain:
The company is making a bold attempt to fend off impending generic competition to its best-selling drug, the anti-cholesterol pill Crestor, by getting it approved to treat [a] rare disease. In an unusual legal argument, the company says Crestor is entitled to seven years of additional market exclusivity under the Orphan Drug Act, a three-decade-old law that encourages pharmaceutical companies to develop treatments for rare diseases.
In May, AstraZeneca won approval of Crestor to treat children with the rare genetic disease of homozygous familial hypercholesterolemia (HoFH ). That gives it an additional seven-year patent on the drug, but only for that particular -- very small -- market. However, the designation means that detailed prescription information about using Crestor to treat children in this way must not be included on the label.
AstraZeneca's clever lawyers are trying to turn that into an extended patent for all uses of the drug:
AstraZeneca immediately petitioned the F.D.A., arguing that if the correct dose for children with HoFH could not be on the generic label, then it would be illegal and dangerous to approve any generic versions for any use at all. That is because doctors might still prescribe the generic for children with HoFH and choose the wrong dose, posing "substantial safety and efficacy risks."
The New York Times article goes into more detail about the fascinating legal background to AstraZeneca's argument here, and notes that other drug companies have tried the same approach in the past, without success.