Opinion ID: 804422
Heading Depth: 2
Heading Rank: 1

Heading: Approval of the ‘743 Patent

Text: The patented invention claims a controlled-release dispersible potassium chloride tablet. The ‘743 patent was developed using a technique called “microencapsulation,” a process in which small particles of a drug are coated to make them disperse over time. The research supporting the ‘743 patent built on work that Schering had done for an earlier patent for a controlled-release aspirin tablet, Patent No. 4,555,399 (“the ‘399 patent”). The application for what became the ‘743 patent was initially rejected by the Patent and Trademark Office (“PTO”) as obvious in light of the ‘399 patent and other prior art. In order to circumvent the prior art, Schering amended its application for what became the ‘743 patent to clarify that the controlled release coating in the invention contained ethylcellulose with a viscosity of greater than 40 cp, 3 whereas the ‘399 patent called for the use of ethylcellulose with a viscosity of 9-11 cp. Schering argued that a coating containing ethylcellulose of greater than 40 cp was not obvious under the prior art. After this amendment, the PTO granted the ‘743 patent on September 5, 1989. 3 Centipoise, abbreviated “cp”, is a measure of viscosity. McGraw-Hill Dictionary of Scientific and Technical Terms 354 (6th ed. 2003). 10