Students sometimes use ADHD medicines that have not been prescribed to them in order to study more effectively. It is suspected that they obtain these medicines from other people, who do have a prescription. Sewage research conducted by RIVM supports this theory. The medicines are not being imported from other countries or purchased online at a large scale.

ADHD medicines are available only with a prescription from a doctor. Nearly 1 out of every 20 students has taken one of these medicines without a prescription at some point. This was shown by an earlier survey under students by the Trimbos Institute, RIVM and the Netherlands Municipal Public Health Services and Medical Assistance in Accidents and Disasters. The most well-known and commonly used ADHD medicine is methylphenidate, which is marketed under the brand names Ritalin and Concerta.

Use of these medicines without a prescription is illegal and undesirable, because they can have serious side effects. Examples are nausea, palpitations, insomnia and – less commonly – anxiety disorders and depression. When people take medicine that has not been prescribed to them, physicians are unable to keep an eye out for side effects and their potential causes.

Sewage sampling

Methylphenidate is broken down into ritalinic acid, which ends up in sewage. Every day for a period of one week, RIVM took samples to measure the amount of ritalinic acid at three sewage treatment plants: Utrecht, Amsterdam and Eindhoven. Based on the prescriptions for ADHD medicines issued by doctors, RIVM estimated how much ritalinic acid should be present in the sewage from the three cities. This estimate was then compared to the quantities found at the sewage treatment plants. The results of RIVM’s samples were in agreement with the estimate. This means that no additional amounts were being ingested after being ordered online or purchased in other countries.

One possible way to reduce improper use is for doctors to prescribe  a smaller quantity of methylphenidate tablets. It is also important that they monitor each patient sufficiently to assess whether the medicine is working and whether they need to keep using it. Pharmacists may report signs of improper use to physicians.