Patterns and predictors of medication compliance, diversion, and misuse in adult prescribed methylphenidate users

Objectives: To examine patterns and predictors of medication compliance, diversion, and misuse in a sample of adults with prescriptions for the stimulant medication methylphenidate (MPH). Methods: Sixty-six adults currently prescribed MPH (53% male) completed structured interviews and provided details regarding their medication and other substance use histories. Results: On average, participants reported using their medication as prescribed on 14.5 (SD 11.7) of the past 30 days; 44% admitted to diverting it and 29% admitted to inappropriate use. While analyses revealed that medication misuse, diversion, and level of compliance were interrelated and all associated with concurrent illicit substance use, each also had other distinct associations. Specifically, MPH misuse was associated with the use of illicit stimulants such as amphetamine and cocaine, diversion with age and age of MPH prescription, and compliance with participation in an attention deficit hyperactivity disorder (ADHD) support group. Regression analyses revealed that misuse and poor compliance were both best predicted by concurrent illicit substance use, while the model that best predicted diversion included age of first MPH prescription (younger) and MPH misuse. Conclusions: Poor medication compliance, diversion, and misuse are relatively common and interrelated among adult MPH users. MPH prescriptions should be monitored closely in individuals with histories of illicit substance use.