Mr Justice Arnold’s decision in Teva and others v Astrazeneca AB [2012] EWHC 655 (Pat) invalidated Astrazeneca’s patent for a sustained release formulation of the anti-psychotic drug quetiapine in the United Kingdom, on the grounds of obviousness, just days after the same patent was found to be valid in the Netherlands.  


Teva and others (the Claimants) sought revocation of Astrazeneca’s European patent for a sustained release formulation of quetiapine, marketed by Astrazeneca under the trade mark Seroquel XR. The Claimants timed their action to coincide with the expiry of the supplementary protection certificates for a different European patent that relates to the immediate release form of quetiapine, in order to clear the way for generic drug production.


Arnold J held that it was common knowledge that it was desirable to keep psychotic symptoms under control with as few doses as possible so patients and their carers could benefit from the convenience of less frequent administration. Prior art showed that quetiapine is capable of being efficacious if administered in once or twice daily doses. Arnold J held that it would be obvious for a person skilled in the art to achieve this by creating a sustained release formulation and that it was within the competence of an ordinarily-skilled formulator at the time.  

Astrazeneca claimed that a person skilled in the art would have thought that quietiapine’s high first-pass metabolism would prevent the successful development of a sustained release form of the drug. However, Arnold J determined that a person skilled in the art would only have thought that high first-pass metabolism would be a problem for developing a sustained release form if liver enzymes were shown to be saturated by a clinical dose.

Routine testing and prior art would have revealed linear pharmacokinetic data for quetiapine, so the skilled team would not have been concerned about saturation of first-pass metabolism. As such, Arnold J held that there was nothing to discourage the use of a sustained release formulation and, as a suitable formulation could have been achieved without excessive experimentation, the invention was obvious.  

Arnold J concluded his judgment by expressing regret that different European courts considering the validity of the same patent should reach opposite conclusions. As such, he carefully considered the Dutch court’s judgment that held the patent to be valid. Despite the desire for uniformity in judgments, Arnold J could not be persuaded, noting that there were marked differences in the evidence, arguments and prior art cited in the English and Dutch cases. The central difference was that the Dutch court accepted that there were real problems to overcome in the development of a sustained release formulation of quietiapine, namely high first-pass metabolism, high serum protein binding and pH-dependent solubility. The first of these factors was considered by Arnold J to be illusory, while the last two were not advanced as arguments in the English court.


The case hinged on “expectation of success” arguments that are by their very nature highly subjective and so frequently litigated. Only a few days after this decision, the US District Court for New Jersey found Astrazeneca’s US formulation patent for Seroquel XR to be valid. As future decisions emerge, it will be interesting to see whether this determination of invalidity resulted from the choice of arguments and evidence advanced, or whether it is a consequence of English courts having a less liberal attitude in relation to obviousness.