Patenting pharmaceutical invention an eop perspective 

In Euro they rejected the Viagra product. 

EPO perform a search the examination of a patent, 

The patent does not confer the right to use the invention.
Discoveries something is not aninvention but if you use that to treated some disease now you can protected on that way.   

Novelty 
Art. 54 EPC 
The invention is considered new. 
The state of the art: everything made available tothe public which means: 
A Written or oral description could be patent and could be a publicity. 
By use
Or in any other way. 
Before the date of the filing of the European Patent Application.The state of the art is everything before the filing date or priority date if validly claimed.  Art. 54 EPC. 

Claim categories 
Entities which are products and apparatus
Activities which are useand method. 

If you have a material which is under another material which is under other like aluminum and in the prior art there was a metal, the aluminum is not new. Aluminum is a metal. Invention step
Art. 54 EPC
An invention shall be considered as involving and inventive step if having regard to the state to the art and it's not obvious to a person skilled in the art. 

Skilledperson 
Has average knowledge in the art. 

Art. 69 EPC equivalent act. 

Is there is a invented which have the same structure but the second one use other material, is they can demonstrated that withthar material you can use an surprising effect then you can patented. 

Industrial application
Art. 57 EPC shall be susceptible of industrial application 

Pharmaceutical invention 
Havelimitation (Method of treatment of the human or animal body by therapy, surgery and diagnostic method) and privileges ( protect product claims deriving novelty from and intended uses). 

Art. 54 EPC allowsthe patentability of any substance or composition. 
If you have other use for an compound which used before then you can not apply for patent in product so you only can apple for patent in that...