Patent No. EP2168974 (titled "Drospirenon (6Ss, 7Ss; 15Ss,16Ss-Dimethylene-3-Oxo-17Alpha-Pregn-4-Ene-21,17-Carbolactone, Drsp) With Less Than 0.2 % Impurity") was filed by Bayer on Aug 11, 1997. The application was issued on Jul 2, 2014.

Patent oppositions filed by competitors challenge the validity of a granted patent. These oppositions are typically based on claims of prior art, lack of novelty, or non-obviousness. They are a key part of the process for determining a patent's strength and enforceability.
The dossier documents provide a comprehensive record of the patent's prosecution history - including filings, correspondence, and decisions made by patent offices - and are crucial for understanding the patent's legal journey and any challenges it may have faced during examination.