Plasma Methylphenidate Levels In Youths with Attention Deficit Hyperactivity Disorder Treated with OROS Formulation (original) (raw)

Therapeutic Drug Monitoring, 2015

Abstract

There are limited studies investigating the relationship between oral release osmotic system-methylphenidate (OROS-MPH) doses and plasma methylphenidate (MPH) concentrations in children and adolescents. The aim of the present study was to investigate the relationship between the doses of OROS-MPH and the plasma levels of the drug. We also examined the effects of the other drugs including aripiprazole, risperidone, fluoxetine, and sertraline on the levels of the MPH in the plasma. The files of 100 ADHD subjects (76 male, 24 female) who were diagnosed as ADHD according to the DSM-IV criteria, were screened. The ages of subjects were between 6-18 years (mean= 11.5±3.8 years). Plasma MPH levels were determined by high-performance liquid chromatography-tandem mass spectrometry assay (HPLC-MS/MS). Daily mean OROS MPH dose used in ADHD children was 0.7±0.2 mg/kg (range: 0.3-1.3 mg/kg). The mean plasma OROS MPH was 11.6 ± 7.3 ng/mL (range: 0.5-43.4 ng/mL). There was no group difference in the mean plasma MPH and dose-related MPH levels between the groups that used any additional drug including aripiprazole (n=25), risperidone (n=10), fluoxetine (n=16) sertraline (n=10) and not used these drugs (p>.05). There was a positive correlation between the OROS MPH doses (mg/kg) and the blood MPH levels (Pearson correlation= 0.40; p<.001). The plasma levels of MPH were found to be less than 13 ng/mL in 65% of the subjects. Our findings point to the fact that plasma levels of MPH show a wide range of changes at similar doses, correlate positively with the doses and, as expected, are not affected by using risperidone, sertraline, fluoxetine, and aripiprazole. Therapeutic drug monitoring (TDM) may help to optimize MPH dose in patients not responding to treatment or in those experiencing serious side effects, but not in routine clinical practice. The presence of intermediate dose formulations such as 45 mg tablets for OROS MPH may contribute to the optimization.

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