T 0777/08 (Atorvastatin polymorphs/WARNER-LAMBERT) vom 24.05.2011

1. At the priority date of the patent in suit, the skilled person in the field of pharmaceutical drug development would have been aware of the fact that instances of polymorphism were commonplace in molecules of interest to the pharmaceutical industry, and have known it to be advisable to screen for polymorphs early on in the drug development process. Moreover, he would be familiar with routine methods of screening. Consequently, in the absence of any technical prejudice and in the absence of any unexpected property, the mere provision of a crystalline form of a known pharmaceutically active compound cannot be regarded as involving an inventive step.

2. When starting from the amorphous form of a pharmaceutically active compound as closest prior art, the skilled person would have a clear expectation that a crystalline form thereof would provide a solution to the problem of providing a product having improved filterability and drying characteristics. The arbitrary selection of a specific polymorph from a group of equally suitable candidates cannot be viewed as involving an inventive step.

3. The skilled person in the field of drug development would not be dissuaded from attempting to obtain a crystalline form by the prospect of a potential loss of solubility and bioavailability when compared to the amorphous form, but would rather regard this as being a matter of trade-off between the expected advantages and disadvantages of these two classes of solid-state forms.