Practical and Efficient Strategy for Evaluating Oral Absolute Bioavailability with an Intravenous Microdose of a Stable Isotopically-Labeled Drug Using a Selected Reaction Monitoring Mass Spectrometry Assay

Abstract

A strategy of using selected reaction monitoring (SRM) mass spectrometry for evaluating oral absolute bioavailability with concurrent intravenous (i.v.) microdosing a stable isotopically labeled (SIL) drug was developed and validated. First, the isotopic contribution to SRM (ICSRM) of the proposed SIL drug and SIL internal standard (IS) was theoretically calculated to guide their chemical synthesis. Second, the lack of an isotope effect on drug exposure was evaluated in a monkey study by i.v. dosing a mixture of the SIL and the unlabeled drugs. Third, after the SIL drug (100 μg) was concurrently i.v. dosed to humans, at T(max) of an oral therapeutic dose of the unlabeled drug, both drugs in plasma specimens were simultaneously quantified by a sensitive and accurate SRM assay. This strategy significantly improves bioanalytical data quality and saves time, costs, and resources by avoiding a traditional absolute bioavailability study or the newer approach of microdoses of a radio-microtracer measured by accelerator mass spectrometry.

Deuterium‐ und tritiummarkierte Verbindungen: Anwendungen in den modernen Biowissenschaften

“…[241] ¾hnliche Ansätze mit stabil isotopenmarkierten Fettsäuren, Glukose oder D 2 Oa ls Vorstufen [242] kçnnen für die dynamische Lipidomik [243] herangezogen werden, z. [252] Bei dieser neu entwickelten Methode kçnnen Kosten-und Zeitaufwand erheblich reduziert werden, aufgrund verringerter Sicherheitsanforderungen, [253] der Vermeidung radioaktiver 14 C-Tracer gefolgt von teurer Auswertung mittels AMS (beschleunigte Massenspektrometrie) [254] und der Mçglichkeit, durch ein Doppeltracerdesign die Bestimmung der absoluten Bioverfügbarkeit mit einer konventionellen ADME-Analyse in einer einzigen Studie zu kombinieren. [245] Eine selektivere und daher häufiger verwendete Strategie zur Untersuchung des Phospholipidstoffwechsels in vivo ist der Einbau stabil markierter Kopfgruppen in Phosphoglycerid durch den Einsatz von D 9 -Cholin und/ oder D 4 -Ethanolamin.…”

Approaches to intravenous clinical pharmacokinetics: Recent developments with isotopic microtracers

“…Without having to conduct intravenous toxicology and with a streamlined formulation, significant cost and time saving can be made, although the technique is still not fully adopted by the industry in favor of the crossover design . The majority of intravenous microtracer studies reported so far have used 14 C and AMS (see Tables and ), but advances in the sensitivity of LC‐MS/MS since the 1970s has also allowed stable isotopes to be used . The choice between using a 14 C microtracer (with HPLC followed by AMS analysis) and a 13 C microtracer (with LC‐MS/MS) depends mostly on the required assay sensitivity.…”

“…The same principles apply to any isotope depending on its natural abundance. For example, 15 N has been used as a microtracer, which has a natural abundance of 0.37% . On the other hand, 14 C has a natural abundance of approximately 10 −10 percent, and therefore its background levels do not present a limitation on the LOQ until the concentrations are extremely low, typically in the attomole range .…”

“…Microtracer studies designed to obtain intravenous PK conducted to date published in the peer‐reviewed literature are summarized in Tables and . Over time, the design of the microtracer study as evolved so that the intravenous dose is administered typically as an infusion to coincide with the t max of the extravascular dose.…”

Synthesis of isotopically labeled daclatasvir for use in human clinical studies

“…This paper describes the synthesis of [ 14 C]‐ daclatasvir under c‐GMP guidelines to support non‐human developmental studies, as well as ADME studies. With improvements in the sensitivity of triple quadrapole mass spectrometers and the ability to mitigate isotopic interferences, one can employ selected reaction monitoring liquid chromatography–tandem mass spectrometry (LC‐MS/MS) assay to determine absolute oral bioavailability . This strategy significantly improves bioanalytical data quality and saves time, costs, and resources by avoiding a traditional absolute bioavailability study or the newer approach of micro‐dosing of a radio‐microtracer measured by accelerator mass spectrometry.…”