Illegal sales of prescription ADHD medication to students have been on the rise in South Korea recently, and government data Friday showed that such distribution soared before the crucial Suneung mock test.

The local authorities spotted 669 cases of illegal sales of such medications to students from Aug. 4-14 in a special illegal drug distribution inspection targeting college applicants, according to the Ministry of Food and Drug Safety data submitted to Rep. Han Ji-ah of the ruling People Power Party.

The government inspection held shortly before last year's college entrance exam caught 200 illegal sales of these drugs, which was significantly lower than the latest figure.

In the August inspection, 486 cases involved the sale of Adderall, a combination drug containing amphetamine as a treatment for ADHD. While it is a prescription drug approved by the US FDA, its distribution, manufacturing and sale are not allowed in Korea.

Drugs Concerta and Penid, both prescription drugs using methylphenidate, accounted for 142 and 41 cases, respectively.

The Narcotics Control Act bans the use, distribution and possession of what it defines as narcotics, along with the unregulated use of what it defines as psychotropic drugs. All three drugs are defined as psychotropic drugs by Korean authorities.

While therapeutic doses of these drugs are used to treat ADHD, they are also known to induce side effects such as insomnia and loss of appetite. Some illegal sellers have been targeting Korean students and parents online by promoting the cognitive effects of these drugs as academic performance-enhancing effects.