Purpose: The aim of this study was to describe the extent of ă methylphenidate (MPH) abuse and characterize its patterns by following ă several cases involving intravenous administration of crushed MPH ă tablets. Methods: First, a drug reimbursement database (covering 4 ă million inhabitants) was explored to assess the magnitude of MPH abuse ă among the general population, and second, a specific study based on ă individuals with drug dependence was performed to describe abusers' ă characteristics (n = 64), patterns of abuse and clinical implications. ă Results: From 2005 to 2011, the number of patients who were dispensed ă MPH at least once increased by 166%. The patients with `deviant' ă patterns of MPH consumption were mainly male adults with opiate ă maintenance treatment reimbursements. MPH abusers had precarious living ă conditions. Half of them consumed MPH daily by intravenous route and ă reported amphetamine-like effects (cardiovascular events, weight loss, ă psychiatric adverse events). Conclusion: Given the increase of MPH use, ă it is important to warn the scientific community about possible MPH ă abuse, especially in individuals with drug dependence. This study has ă facilitated public health intervention and dissemination of information ă related to MPH abuse among health care professionals at local and ă national levels. (C) 2015 S. Karger AG, Basel