In the United States, provided that maintenance fees are timely paid, the life of a utility patent is determined as follows:
You can extend the life of your patent if you qualify in any of the below circumstances:
A patent expires either because its term has come to an end or you haven’t paid the maintenance fees. After a patent “expires,” the invention covered by the patent is then in the public domain. That means that anyone can freely use or make the invention without your permission.
It is still possible to patent improvements to the original patented item. The drug companies are experts at patent extension strategies. For example, one common way drug companies extend a patent is by reformulation or repositioning a drug. Reformulation is the process of applying different formulations for the same drug, whereas repositioning is the process of finding a new therapeutic use for the drug. Often, new advances are focused on how to simplify dosing or how the drug is administered. Extended-release versions of drugs are common ways companies reformulate products, for example. New methods of administering drugs may mean taking an injectable drug and creating a nasal spray version. Patent extension can be achieved by providing dissolvable tablets that don’t have to be taken with water, as another example. Thus, reformulating a drug so it can be administered in a different form can confer longer patent protection. Repositioning the drug can also extend patent life. For example, the discovery of new uses for the drug can earn the drug company an additional three years of protection under FDA rules.