Patents are grants by a government to the originators of an invention of the right to exclude others from marketing or profiting from that unique invention. The protection conferred by a patent is limited to the concepts defined by the patent claims. A patent can cover a chemical entity, a pharmaceutical formulation, a method for making a chemical entity or formulation, methods for diagnosing, preventing, or treating a disease, a means for administration of a drug, and many other materials and processes. A government grants only one patent on an invention, but a drug product can be protected by several patents covering different aspects of the product. For example, a new chemical entity can be claimed in one patent, its use in treating a particular disease in a second patent, and a unitary dosage form in a third patent. The term of protection afforded by a patent is limited by law; for modern patents, the term is normally 20 years from the date of filing, subject to the payment of maintenance fees, with extensions being available under limited circumstances. To be judged as patentable, an invention must meet requirements for novelty, utility, and inventiveness. A novel invention is new to the world or, in a few countries, to the particular country, when compared with what was known or used in the past, spoken of as the prior art. Inventiveness is a subjective judgment of whether the item being claimed is unique enough to differentiate it from the prior art or is not obvious to a person of ordinary skill or knowledge in that field. Patent laws vary from country to country, and each country or international patent granting organization issues a patent based on its own laws. As a result, a single invention may receive a number of different patents, which can be grouped into a family of so-called equivalent patents from different countries. Filing of the first application for a patent for a particular invention establishes a priority date under the Paris Convention for the Protection of Industrial Property, permitting the applicant to file equivalent applications in other countries within 12 months and to have the applications treated as though they had been filed on the priority date. The initial steps in filing patent applications in many countries can be simplified by filing a single application through the Patent Cooperation Treaty (PCT). A preliminary search ofthe prior art is performed and the patent specification is published as an international application with the country code write off (WO). The international search and publication take place before the applicant has the specification translated and pays the fees for moving the patent application to the national phase of examination in each of the countries where patent protection is desired, delaying a final decision on the breadth of filing and most of the cost of international filing.
The patent literature consists of much more than granted patents. To obtain a patent, the owner of a new invention must file a patent application with a detailed disclosure of the method for making and using the invention. This disclosure, known as a "specification," is published as part of a patent document. The specification contains a set of claims which are numbered sentences that set forth the limitations of the invention to be protected. Before patent rights are granted, a patent examiner reviews the claims to determine whether they meet the legal requirements for patentability, and a patent is granted only if one or more of the claims meets those requirements. Modern patent applications are published before the examination of the claims is complete, normally 18 months after the priority filing date. The published applications become a part of the patent literature at the time of publication and remain part of the patent literature whether or not an enforceable patent is ever granted. Although many published patent applications are not patents in the true sense of the word, they are usually referred to as patents.
As a legal document, a patent is significant because it identifies the ownership and term of protection of an invention defined by its claims. When a patent covers an approved pharmaceutical entity or dosage form, this information, in combination with the exclusivity period granted by regulatory agencies, defines the exclusivity period for a drug (for a more detailed explanation of market exclusivity, please refer to the chapter on Drug Regulation). Patents that claim products, methods for making them, methods of synthesis, or new medical treatments limit the related research other companies or institutions may perform. Because patent specifications contain information about how to make and utilize chemical compounds and other novel materials and to perform processes such as the production of new dosage forms and the treatment of patients, patents are useful research tools in the same way as the rest of the scientific literature. They remain useful long after patent rights have expired. Most patent databases are comprised of the published patent literature, with bibliographic information and abstracts taken from the first publication of a patent specification rather than the subsequent granted patent that often issues in significantly amended form.
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