Drug Pharmacokinetics Determined by Real-Time Analysis of Mouse Breath
In this study, Drug Pharmacokinetics Determined by Real-Time Analysis of Mouse Breath by Xue Li, Pablo Sinues, Robert Dallmann, Lukas Bregy, Maija Hollmén, Steven Proulx, Steven A. Brown, Michael Detmar, Malcolm Kohler and Renato Zenobi. SUPER SESI-HRMS was used to non-invasively and in real-time monitor the pharmacokinetics of ketamine, propofol, and valproic acid, along with their metabolites in mice. This approach allowed for obtaining real-time pharmacokinetic curves without the need to sacrifice the animals, representing a significant advance in terms of animal welfare and time and cost savings.
Conventional methods usually require sacrificing multiple animals to obtain low-resolution pharmacokinetic curves, whereas this approach allows for high-resolution curves with a temporal resolution of 10 seconds.
The pharmacokinetic profile of a drug influences its efficacy and toxicity, as it determines the exposure time and levels. The study focused on ketamine and its metabolites, simultaneously determining the pharmacokinetics after the administration of various subanesthetic doses of ketamine.
👉🏻After administration of the drug, animals were placed in an acrylic chamber flushed with a constant flow of air, which was then directly analyzed by SESI-HRMS. Shortly after the administration of Ket to the mice, we observed an increase in a cluster of signals in the m/z range of 238-240, which perfectly matched the isotopic distribution of the protonated molecule ([M+H]+) of Ket.
➕Additionally, the fragmentation ions formed from the [M+H]+ ion of Ket matched those previously reported, as did the fragments obtained from the Ket standard. Not only Ket but also its major metabolites could be detected with this setup.
a) Schematic of the experimental setup. b) SESI mass spectrum recorded from mouse breath, showing the isotope pattern in the m/z region of protonated Ket. c) Fragment-ion (SESI MS/MS) spectrum produced using m/z 238 as the precursor ion.
🔁 A nearly linear correlation was found between the maximum signal intensity and the injected drug's concentration. However, the maximum signal intensity was found to be delayed compared to values in plasma obtained from the literature. This could be attributed to the partitioning of Ket and its metabolites between blood and respiration. Similar to Ket, it´s four metabolites showed a linear trend in response to dose for maximum signal intensity. The primary metabolites (NK and HK) peaked after Ket, which is consistent with results reported for NK in rat serum samples.
a) Time-dependent Ket signal for four Ket doses:15, 30, 45, and 60 mgkg-1.Each dose was injected in adifferent mouse (n=4). Black dots represent the raw data and solid curves are smootheddata. b) Dependence of the maximum Ket signal on the amount injected (r2=0.9563; p-value=0.0221). Linear fit and 95% confidence bounds are shown in red.
In conclusion, SESI-HRMS analysis of mouse breath is a promising strategy for real-time pharmacokinetic monitoring. This method provides instant and precise data, saving time and cost. It also allows for repeated measurements of multiple compounds in a single animal. Additionally, the ability to obtain a complete pharmacokinetic curve with a single dose is advantageous in preclinical studies with limited compound quantities. Furthermore, this method enables easy monitoring of drug-drug interactions, even with different dosing schedules and kinetics. We believe that the SESI-HRMS method will be valuable in preclinical programs and may have applications in clinical drug development phases.
