In In re Rajagopalan, the Fed. Cir. affirmed the Board’s conclusion of obviousness of Applicant’s pharmaceutically acceptable composition for deterring illicit manufacture of methamphetamine.  Rajagopalan had discovered certain organoleptic excipients having a structure of pyrazines, pyrimidines, thiazolines, thiazolidines and thiazoles, can inhibit chemical reduction of ephedrine or pseudoephedrine to methamphetamine, the excipients behaving as a competing substrate.  

Giamalva was cited as disclosing a combination of pseudoephedrine and co-distillable additives which can cause difficulty in isolating pseudoephedrine or otherwise interfere with efforts to produce illegal drugs by altering reactants.  Suitable additives would have similar properties to pseudoephedrine to prevent separation during distillation and may have a characteristic unpleasant odor or flavor.  A mechanism of action is discussed by 1) tainting the extracted pseudoephedrine with a strong odor; and 2) competing with pseudoephedrine for the reducing agent.  Conventional flavorants are proposed.  Adams is cited for disclosing acetylpyrazine as a food flavoring agent.  Takakura is cited for disclosing 5-acetyl-2,4-dimethylthiazole as providing a livestock meat stock flavor.

The Fed. Cir. found the Board’s decision to be supported by substantial evidence that Giamalva taught using amine-based odorant to interfere with chemical conversion and that Adams disclosed pyrazine odorants and that there was sufficient motivation to combine.