Zolpidem, a sleeping pill called “entertainers’ drug,” has resurfaced as a social issue, as K-pop star BoA has come under prosecution’s probes on charges of drug smuggling.

The 34-year-old singer is suspected of illegally bringing antipsychotic drugs prescribed in Japan, including zolpidem, in Korea under the name of an employee of her Korean entertainment agency.

Zolpidem, short-term treatment for insomnia, is one of the most frequently prescribed sleeping medicines. The drug is also called the “second propofol” because of its side effects, making its users lose their memory of what happened in the previous day.

There are also clinical reports about some positive effects, such as recovering people in coma and improving cognitive impairment of people attacked by stroke. However, it has long become a social problem in Korea.

The sleeping pill was classified as a psychotropic medical drug as it can induce side effects such as hallucination when taken for a long time. It can also cause headaches, nausea, vomiting, dizziness, memory loss, sleepwalking, and withdrawal symptoms, including insomnia and damages to the central nervous system when the administration is cut off.

There have also been reports of accidents while driving or operating risky machines or feeling suicidal impulses after taking zolpidem.

In 2014, Son Ho-young, a member of the first-generation Korean idol group g.o.d, was investigated by the prosecutors on suspicion of using zolpidem without prescription. He attempted to kill himself by taking the sleeping pills in May 2013, days after his girlfriend's death.

Singer Amy also confessed that she took zolpidem and propofol with her male colleague, Wheesung.

Other Korean celebrities, including some who committed suicide -- actress Choi Jin-sil, her brother Choi Jin-young, and actor Park yong-ha – were also known to have problems with zolpidem suffering from its side effects.

A greater danger is that the drug can be used for crimes, including murder and date rape.

A case in point was the infamous husband-killer Koh Yuh-jeong.

When the murder case surfaced, people wondered how a skinny, 5-feet 2 inches-tall woman could kill a 5-foot-9 man weighing 180 pounds. Police said later they detected zolpidem from the stained blood on blankets loaded in Koh's vehicle and found that she obtained zolpidem before meeting her husband.

Zolpidem is also widely used as a date rape drug. Former Hanwha Eagles catcher Uhm Tae-yong lured a teenage girl he met on the internet in 2018 and raped her after giving the medicine.

The Ministry of Food and Drug Safety said that about 523 million tablets of appetite suppressants and 346 million zolpidem-based drugs were prescribed to 3.32 and 4.43 million people from May 2018 to the first half of 2020.

The ministry has been operating Narcotics Information Management System since May 2018 and received reports on the production, distribution, and use of narcotics from importers, pharmaceutical companies, distributors, hospitals, clinics, and pharmacies.

Regarding suspicion on BoA's drug smuggling, SM Entertainment said, "It was not the intention of BoA or the agency to smuggle narcotics, but a mistake due to our ignorance of customs regulations concerning drugs."

The entertainment agency explained that its employee in Japan got the drug in legal procedure at a local hospital. However, he did not know formally prescribed drugs abroad can cause problems in Korea.

"The employee made a mistake of sending the drug to Korea, based on Japanese medical workers’ assurance that he could send them abroad,” the agency. "The employee and BoA cooperated sincerely to investigators.”