The Ministry of Food and Drug Safety and the Korea Customs Service have designated tapentadol, a narcotic painkiller, as a banned substance in imported foods after it was found in a diet product called TAWON LIAR brought into the country through international mail, the two agencies said. The two agencies jointly pursued the move as a preemptive step to block narcotics from entering the country through direct overseas purchases of food products — a booming channel of e-commerce in which Korean consumers buy items directly from foreign retailers and have them shipped into the country. Tapentadol works by inhibiting the reuptake of norepinephrine and serotonin and can cause life-threatening or fatal respiratory depression; it is classified as a narcotic under Korea's Narcotics Control Act. The substance was found by the Incheon International Airport Customs analysis office in a shipment of TAWON LIAR mailed from France. The office reported the finding to the ministry, which designated tapentadol as a blocked ingredient to swiftly stop it from entering the country. As of this month, Korea