Longitudinal study on the seasonal variation in methylphenidate consumption in the South African private healthcare sector.

Background: A steady growth in the consumption of medicine for Attention-Deficit/Hyperactivity Disorder (ADHD) has been evident over the past two decades. The Coronavirus disease 2019 (COVID-19) pandemic is reported to have had an effect on stimulant consumption. Methylphenidate is the main active ingredient used in the treatment of ADHD, both in children and adults. Objective: The primary aim was to analyze the consumption patterns of methylphenidate in the private healthcare sector in South Africa by means of a drug utilization study using the Defined Daily Dose (DDD) methodology to establish trends, detect seasonal variations and to compare the results with international studies. Methods: A retrospective descriptive drug utilization study was conducted. IQVIA sales data from the South African private healthcare sector from 2013 to 2023 were analyzed. Consumption patterns were expressed as the number of Defined Daily Doses (DDDs)/1000 inhabitants/day and DDDs/1000 inhabitants/month. Ethical approval for the study was granted. Results: Methylphenidate consumption showed a steady increase in the years around the pandemic period, from 9.07 (in 2018) to 9.88 DDDs/1000 inhabitants/day (in 2023), with a notable lower consumption in 2020 when the COVID-19 pandemic started. Consumption in 2013 was only 6.01 DDD/1000 inhabitants/day, which indicates an increase of 64.39 % over the 11-year period. Seasonal peaks in consumption were observed in February, May, August and November, coinciding with times before assessment periods in schools and universities. Conclusions: There was a clear visible upward trend in the consumption of methylphenidate, with a decrease during 2020, as was also observed in other countries. Similar studies are recommended for other central nervous system drug classes.