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Sustained Release Anti-Psychotic Drug Patent Invalid

A long-standing and valuable patent, protecting sustained release versions of a market leading anti-psychotic drug, has been declared invalid due to the absence of any inventive steps in formulation that would not have been ‘obvious’ to a skilled pharmacology team more than 20 years ago.

pillsAstraZenaca AB has held the patent in respect of sustained release formulations of the drug quetiapine since a priority date in May 1996. The formulations, marketed under the name ‘Seroquel XL’, are used widely in the treatment of schizophrenia, bipolar disorder and major depressive disorder.

However, the patent came under challenge by six rival pharmaceutical companies who argued that the convenient advantages of such formulations were well known in 1996 and that the use of a gelling agent, enabling patients to take a single daily dose, was straightforward, not inventive and would have been obvious to a skilled professional team at the time.

The patent was declared invalid by the High Court. However, in appealing against that ruling, AstraZenaca argued that the judge had misunderstood the basis of its case and erred in principle. The company submitted, inter alia, that pharmacologists would have been deterred from formulating sustained release versions of quetiapine in 1996 by the then current learning that once-daily dosing of the drug would be unlikely to be efficacious.

Dismissing AstraZeneca’s appeal, the court noted that the issue of obviousness was quintessentially a matter of fact, degree and overall impression for the trial judge. It was not the role of the Court of Appeal to perform a fresh evaluation of the evidence or to hear the rival arguments ‘from scratch’.

Although AstraZeneca had argued that the first instance judge ‘was wrong about practically everything that he decided’, the court paid tribute to his ‘excellent’ judgment and upheld his conclusion that the relevant formulations lacked inventive steps at the priority date and would have been obvious to a notional team skilled in the prior art.