MSACL 2025 Abstract

Development and Validation of a UPLC-MS/MS Method for Analyzing Drugs Commonly Used in Children with Attention-Deficit/Hyperactivity Disorder in Urine

Ching-Mei Chen (1), Liang-Jen Wang (2), Huey-Ling You (1), Wan-Ting Huang (1)
(1) Department of Laboratory medicine, (2) Department of Child and Adolescent Psychiatry, Chang Gung Medical Foundation Kaohsiung Branch, Kaohsiung, Taiwan

Ching-Mei Chen, Master (Presenter) Chang Gung Medical Foundation >> POSTER (PDF)

Relevant Financial Disclosures (within past 24 months, reported on Mar 19, 2025) No relevant financial relationship(s) to disclose. Conflict mitigation NOT REQUIRED.

INTRODUCTION:
Attention Deficit Hyperactivity Disorder (ADHD) is a prevalent neurobehavioral disorder, particularly among school-age children. This condition not only impacts children's daily lives and learning but may also persist into adolescence and adulthood. In Taiwan, the prevalence of ADHD is approximately 9%. The primary medications currently used to treat ADHD include central nervous system stimulants, such as methylphenidate, and norepinephrine reuptake inhibitors, such as atomoxetine. Additionally, because individuals with ADHD often experience manic symptoms, doctors may prescribe aripiprazole, a serotonin 5-HT2A receptor antagonist. While these medications are effective, they can also lead to various psychiatric side effects. Furthermore, individual differences in drug metabolism necessitate precise dosage adjustments to achieve optimal therapeutic effects while minimizing adverse reactions, particularly in the vulnerable populations of children and adolescents. These medications typically have a short half-life and are primarily excreted in the urine as metabolites.

OBJECTIVE(S):
The objective of this study is to develop a rapid and non-invasive method for determining the concentrations of methylphenidate, atomoxetine, aripiprazole, and their metabolites in urine. Furthermore, the study aims to compare the consistency between individual plasma drug concentrations and their corresponding metabolite concentrations with urine drug concentrations.

METHODS:
100 μL of urine was treated with glucuronidase and subjected to HLB solid-phase extraction. The urine was then directly analyzed using UPLC-MS/MS quantification. The three drugs and their metabolites were detected via electrospray ionization in positive mode, and the analytes were monitored in multiple reaction monitoring mode. The total analysis time for each sample was 3.5 minutes.

RESULTS:
We conducted method validation in accordance with the CLSI C62-A guidelines, establishing a detection limit of 1 ng/mL. The standard curve demonstrated linearity within a concentration range of 1-1000 ng/mL, with a linear correlation coefficient exceeding 0.999. Intra-batch and inter-batch imprecision were assessed using quality control samples, yielding values of less than 2.9% (n = 40) and 5.2% (n = 40), respectively. Accuracy was evaluated through recovery studies, with average recoveries for the six analytes ranging from 96.6% to 103.7%. This method exhibited no ion suppression or enhancement phenomena, and the presence of proteinuria and hematuria in samples did not impact the test results. Additionally, we analyzed the concentrations of three drugs and their metabolites in plasma and urine samples from 417 ADHD patients, confirming significant differences in drug concentrations among individuals receiving the same dosage.

CONCLUSION:
This study established an accurate, simple, and non-invasive UPLC-MS/MS method for the quantitative detection of ADHD medications in urine. It also demonstrated the significance of monitoring ADHD medication concentrations for personalized treatment and dosage adjustments, ensuring that each patient receives optimal treatment outcomes.