South Korean police apprehended 48 Thai nationals involved in the trafficking and use of yaba, a synthetic drug referred to as “crazy medicine" in Thai. Yaba, typically in the form of pink tablets, is a mix of methamphetamine and caffeine.

According to the North Chungcheong Provincial Police Wednesday, of the 48 suspects, 16 accused of selling the illegal substance were arrested for charges of violating the Narcotics Control Act. The remaining 32 individuals suspected of purchasing the drug were sent to the prosecution without detention.

All the suspects are Thai nationals and the drugs are suspected to have been smuggled from Thailand, concealed within what the police said were traditional Thai bags via international packages.

According to police investigators, once the drugs arrived in Korea, the sellers appeared to have looked for buyers here via social media.

Transactions were believed to have been conducted either through dead drops, where drugs were left in pre-arranged locations so that the buyer could pick them up after the seller left, or through direct, in-person exchanges.

Among the buyers, six individuals working in a factory were found to have used yaba together at home after work. Some workers in a rural greenhouse were also found to have used the drug, the police said.

First manufactured in the early 20th century and used during World War II as a stimulant for soldiers, yaba is now a serious problem in Bangladesh, Cambodia, India, Laos, Myanmar, Thailand, the US, Vietnam and elsewhere.

The authorities seized 9,927 yaba tablets, 38.3 grams of Philopon and 43.6 grams of marijuana, with a total estimated value of over 500 million won ($376,109). The police confiscated 73 million won in criminal proceeds ahead of a formal indictment.

North Chungcheong Provincial Police added that international cooperation is underway to apprehend those involved in this case overseas.