Hours before its third-quarter results are released, AstraZeneca has been stung by the news that the generics firm Cobalt Pharmaceuticals is challenging the Anglo-Swedish drugmaker’s US patents on the blockbuster cholesterol drug Crestor.

The firm has received a notice-letter from Canada’s Cobalt stating that it has submitted an Abbreviated New Drug Application to the US Food and Drug Administration for approval to market copycat versions of Crestor (rosuvastatin) in 5, 10, 20 and 40mg strengths. Cobalt added that its ANDA contains a Paragraph IV certification alleging that the claims of two patents, which expire in January 2016 and August 2020 “are not infringed, invalid or unenforceable” by its move. It is also challenging a third patent, which expires in December 2021.

AstraZeneca responded by saying that it is evaluating Cobalt's “allegations and certifications," adding that it has “full confidence in its intellectual property portfolio protecting Crestor". A company spokesman told PharmaTimes World News that of the top 20 drugs in the world, almost all are facing some sort of patent challenge, whether the cases have any merit or not and analysts are not setting too much store by the Cobalt move as such challenges are now seen as standard.

AstraZeneca now has 45 days to commence a patent infringement lawsuit against Cobalt that would automatically stay, or bar, the FDA from approving the ANDA for 30 months, or until an adverse court decision, whichever may occur earlier.

The importance of Crestor to AstraZeneca cannot be doubted as it contributed $678 million to the firm’s coffers in the second quarter. It is also looking develop the first statin/fibrate combination using Crestor in a link-up with Abbott Laboratories and the sales that the drug is generating will be vital as a number of key drugs come under genuine generic threat, such as the antiulcerant Nexium (omeprazole) and Seroquel (quetiapine) for schizophrenia.

As for third-quarter sales of Crestor, all will be revealed when the firm presents its financials later today. By Kevin Grogan