Patents by Inventor Elmar Josef Friederichs

Elmar Josef Friederichs has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Method of preparing the enantiomers of O-dimethyltramadol
    Patent number: 5728885
    Abstract: A method of preparing the enantiomers of O-demethyltramadol and the use of the enantiomers as pain-killing drugs are described.
    Type: Grant
    Filed: January 17, 1997
    Date of Patent: March 17, 1998
    Assignee: Gruenenthal GmbH
    Inventors: Helmut Buschmann, Werner Winter, Ivars Graudums, Peter Jansen, deceased, Wolfgang Werner Alfred Strassburger, Elmar Josef Friederichs