Pharmacokinetics describes how a drug’s concentration changes in the body over time, providing information about its systemic exposure. PK studies measure the drug levels in the blood and help determine the optimal dosing schedule. By tracking how the drug moves through the body, these studies enable predictions regarding the onset, duration, and intensity of its effects.
ADME refers to the underlying biological processes that influence the journey of a drug through the body. The “A” stands for Absorption and describes how the drug enters the bloodstream. The “D” stands for Distribution and describes how the drug spreads across tissues. The “M” stands for Metabolism and describes how the drug is transformed into active or inactive breakdown products. Finally, the “E” stands for Excretion, and describes how the drug is eliminated from the body, mainly through urine and faeces. Taken together, the ADME parameters determine the pharmacokinetic profile and, ultimately, how the drug’s concentration in the blood changes over time.

Tracking a drug’s concentration over time provides essential data. This informs key decisions on dosage optimisation, ensuring effective and safe outcomes in both preclinical and clinical applications.
MOUSE PK SETUP
In early in vivo pharmacokinetic (PK) studies, rats or mice are commonly used as model animals. In mouse studies, C57BL/6 mice are commonly selected for their well-characterised genetic background and broad availability. To ensure accuracy and reliability of the data, each sample is typically collected in biological replicates. A study involving 12 mice is generally sufficient for obtaining biological triplicate concentration measurements at 8 time points. Compounds can be compared within a single study using cassette testing. Various formulations or routes of administration can be tested in parallel by adding more groups to the study. Each compound under investigation is tested using the intended route of administration and is most often compared with an alternative route to assess its bioavailability.
Serum or plasma is collected from each mouse at various time intervals, such as 0.25, 0.5, 1, 2, 4, 6, 8, and 24 hours post-dose. Depending on the expected values for clearance and half-life (T½), the study duration may need to be adjusted accordingly. The sampling schedule should allow for a thorough evaluation of pharmacokinetic parameters, including the elimination of the test article. Therefore, it is generally recommended to collect samples for at least three to five times the drug’s expected half-life.
Following the collection of plasma or serum (and other samples, when applicable), the materials are stored at -80°C pending analysis. At BioXpedia, we use liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) for the quantification of small molecule drugs.
RAT PK SETUP
For studies in rats, the overall setup is similar to that of mice, but the physiology of rats allows for some flexibility in the sampling schedule. Rats have larger blood volumes, which often permits multiple samples to be collected from the same animal at different time points, thus reducing the number of animals required for a full pharmacokinetic profile. However, the larger size of rats requires a higher dose of the test article to achieve serum concentrations comparable to those in mice. In general, a rat PK study requires two to four times more of the test drug than a mouse study.
Like with mice, cassette dosing can be employed in rat studies, allowing the evaluation of multiple compounds in a single study.
RAPID PK TURNAROUND
At Biotest Facility, we understand the urgency that surrounds the drug development process. When it comes to pharmacokinetics, our streamlined processes enable us to deliver high-quality PK data on short notice. The most important requirement is that the test drug demonstrates a well-tolerated profile in rodents.
We offer a standard setup for our studies but can adjust based on specific scientific rationale to meet your particular research needs. For small studies involving a single compound or a few compounds, our turnaround time can be as brief as two weeks.
We deliver reliable data efficiently, ensuring timely and flexible service without unnecessary delays. You can receive our standard PK pricing by filling out the contact form below.
PK STUDY PRICE REQUEST
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