Oregon Attorney General Ellen Rosenblum said Thursday she has filed a lawsuit alleging that GNC Corp. GNC, -12.50% sold dietary supplements that include illegal ingredients. The news sent shares of GNC down about 13% in afternoon trade. Rosenblum said various GNC products contain the synthetic chemical picamilon, or the stimulant BMPEA, both of which are not approved for sale in the U.S. The suit also alleges that some products included unlabeled BMPEA. "It is scary to know that certain products sold by GNC contain an ingredient that is not even labeled - let alone approved in the United States," she said. The suit says Picamilon is a prescription drug used in some countries, but not the U.S., to treat neurological conditions. BMPEA is similar to an amphetamine that is banned by the World Anti-Doping Organization, it says. GNC shares are down this 26% year, while the S&P 500 is down 0.5%.