Erin Strickland (Presenter)
Ameritox, Ltd.
Bio: Dr. Erin Strickland is a Research & Development Scientist at Ameritox, Ltd. in Greensboro, NC. Her recent work has focused on rapid sample analysis and accurate mass applications, including use in forensic drug analyses and drug metabolimics. She has presented several posters at the American Society for Mass Spectrometry, Society of Forensic Toxicologists, and MSACL conferences and presented work at the Triangle Area Mass Spectrometry group in North Carolina. Dr. Strickland earned her doctoral degree from Duke University in Chemistry where she worked extensively with mass spectrometers to study drug-protein interactions to elucidate drug mode-of-action. Her undergraduate studies in forensic science were completed at Eastern Kentucky University. She is a member of the American Society for Mass Spectrometry, the American Chemical Society, and the Society for Forensic Toxicologists.
Authorship: Erin C. Strickland (1), Jeffrey R. Enders (1), Ayodele A. Morris (1), Oneka T. Cummings (1), Alexandra Clinkscales (1), and Gregory L. McIntire (1)
(1) Ameritox, Ltd., 486 Gallimore Dairy Road, Greensboro, NC 27409
| Short Abstract Metabolomic studies of drugs in the body customarily focus on blood samples to identify these compounds. Metabolomic studies in urine (e.g, uromics) are less common. Using an exact mass LC-QTOF instrument and enzymatic hydrolysis, as needed for confirmation, work in this lab has identified metabolites of a variety of antipsychotic drugs in urine that were either not previously identified in the literature or were known but thought to be minor metabolic pathways. This work will specifically report on advances in Seroquel®, Haldol®, and Latuda® monitoring demonstrating both new metabolites and increased importance of known metabolites. |
Long Abstract
Introduction
Prompted by previous success with determining a novel clinically relevant metabolite in urine for Abilify® (aripiprazole) and the poor compliance in mental health populations, several antipsychotics were evaluated to determine if improved urine monitoring was possible with alternative metabolites, known or unknown. As metabolomic studies normally focus on blood samples to identify metabolites of drugs in the body and less frequently explored in the urine, we utilized an exact mass LC-QTOF instrument and a dilute-and-shoot paradigm to identify metabolites of a variety of atypical and typical antipsychotic drugs in the urine that were either not previously reported in the literature or were known but thought to be minor metabolic structures. Enzymatic hydrolysis was implemented as needed for confirmation of conjugated metabolites. This work will specifically report on advances in Seroquel®, Haldol®, and Latuda® monitoring demonstrating both novel clinically relevant metabolites for urine drug monitoring and the increased importance of known metabolites.
Methods
Patients that were either prescribed the medication and/or were previously tested in-house as positive for the drug(s) of interest were analyzed on an Agilent LC-QTOF system (Agilent 6230 QTOF with Agilent 1290 LC stack system) using a dilute-and-shoot paradigm. The chromatography was a generic 6 minute method run on a Phenyl-Hexyl column that has been shown to resolve isobars, such as methamphetamine and phentermine. Potential metabolic structures were programmed into the library for searching. These compounds were purchased directly when possible or synthesized by 13C Molecular, Fayetteville, NC, to confirm identifications. Finally, in those cases where glucuronidation was suspected, hydrolysis with β-glucuronidase obtained from IMCS was carried out at 60 degrees C for 60 min (approx. 3,000 units) to confirm the presence of conjugated metabolites.
Results
Seroquel® is typically monitored in urine using the parent drug, quetiapine, and one of two plasma metabolites, 7-hydroxyquetiapine or norquetiapine. These compounds are present at low levels in urine and further investigation was conducted to determine if other known metabolites could be more abundantly found in urine. Indeed, the known carboxylic acid and sulfoxide metabolites of quetiapine are far more prevalent in the urine compared to quetiapine and 7-hydroxyquetiapine. Furthermore, it was noted that after hydrolysis, that large quantities of the parent compound quetiapine and 7-hydroxyquetiapine were liberated.
In the case of Haldol®, the parent drug haloperidol was not thought to be glucuronidated (1). However, upon inspection of the structure and hydrolysis, it was evident that a great deal of haloperidol was liberated indicating that it is primarily excreted in the urine as the conjugated parent drug.
Plasma metabolomics of Latuda® (lurasidone) implicated several small fragment metabolites of lurasidone to be major metabolites in urine. Upon study of urine samples, it was noted that other known metabolites that were modifications of the parent drug (designated as metabolites M8/M9, M21, and M22) were more prevalent in urine than the small fragment metabolites. These metabolites include one or both of the following modifications: hydroxylation of the norborane ring and reductive opening of the isothiazole ring followed by methylation of the free sulfur.
Conclusions
As noted in these examples, using a dilute-and-shoot LC-QTOF paradigm of testing urine samples can indicate a different metabolic profile compared to blood or even urine that is extracted or analyzed by GC-MS. Any drug can be more extensively studied using an accurate mass instrument to identify urine metabolites so that patient monitoring can be more robust and better reflect true-compliance in patients.
References & Acknowledgements:
References
1. R. C. Baselt. Disposition of toxic drugs and chemicals in man, 10th edition. Chemical Toxicology Institute, Foster City, CA, 2014, pp. 980-2, 1179, 1754-7.
Acknowledgements
Dr. Robert A. Millet from Carolina Behavioral Clinic for providing patient positive samples when requested.
| Description | Y/N | Source |
| Grants | no | |
| Salary | yes | Ameritox |
| Board Member | no | |
| Stock | no | |
| Expenses | no |
IP Royalty: no
| Planning to mention or discuss specific products or technology of the company(ies) listed above: | no |