According to the USPTO Official Gazette, Glaxo Group has filed a disclaimer that dedicates its Patent No. 5,290,815 to the public. The ‘815 patent involves a method of treating a late asthmatic reaction and reportedly covered the use of Advair Diskus and Serevent. The patent was apparently de-listed from the Orange Book in 2003.
MPEP 1.321 provides for statutory disclaimers:
A patentee owning the whole or any sectional interest in a patent may disclaim any complete claim or claims in a patent. In like manner any patentee may disclaim or dedicate to the public the entire term, or any terminal part of the term, of the patent granted. Such disclaimer is binding upon the grantee and its successors or assigns.