What does a preclinical PK study plan need?
The objective comes first: a first look at exposure, oral bioavailability, dose proportionality, or exposure to support a toxicology study. It decides the routes, dose levels, sampling schedule and parameters. Oral bioavailability (F), for example, needs an intravenous reference group, so the planner adds a check if you ask for F without an IV route.
Sampling time points must describe the absorption phase, the peak and the elimination phase. A reliable half-life needs several samples in the terminal phase. As a quality benchmark, the EMA bioequivalence guideline expects AUC(0-t) to cover at least 80% of AUC(0-infinity), meaning no more than 20% extrapolated, with three to four samples in the terminal phase. Preclinical studies are not bound by that guideline, but it is a sensible check on whether the last time point is late enough.
Serial, sparse or composite sampling?
Serial sampling takes every time point from the same animal, giving a full profile per animal. Composite or sparse designs take fewer samples per animal and combine animals to build the profile, which is common in mice where blood volume is limited. Blood volume sets the limit: as a guide from Diehl et al. (2001), a single sample of about 7.5% of circulating blood volume needs about a week to recover and about 10% needs two weeks, and circulating blood volume differs by species (about 72 mL/kg in mice, 64 mL/kg in rats). Always follow your institution's limits.
Microsampling, typically 50 µL or less, is supported by the ICH S3A questions and answers on toxicokinetics, and can reduce the need for satellite animals.
How many samples will the bioanalytical lab receive?
The planner multiplies groups x animals per group x time points, assuming serial sampling of every animal at every time point and one matrix. Pre-dose samples, repeats and incurred sample reanalysis add to that. Take the number straight into the Bioanalytical Study Planner to plan the method and its validation.
Which PK parameters should you ask for?
The usual non-compartmental parameters are Cmax, Tmax, AUC to the last time point, AUC to infinity, terminal half-life, clearance, volume of distribution and, with IV and oral data, bioavailability. Ask for only what answers the objective, and agree the software and the person who reports them.
Frequently asked questions
What time points should a mouse or rat PK study use?
Enough to cover absorption, the peak and elimination, with several points in the terminal phase for half-life. The exact schedule depends on route and expected half-life, so set it with the study team. The planner counts the time points you list and the samples they produce.
What is the difference between serial and composite sampling?
Serial sampling takes all time points from each animal; composite sampling combines fewer samples from more animals into one profile. Composite designs are common in mice because blood volume limits how much can be taken from one animal.
How much blood can be taken from a mouse or rat?
As a guide from Diehl et al. (2001), about 7.5% of circulating blood volume as a single sample needs about one week to recover. Circulating volume is about 72 mL/kg in mice and 64 mL/kg in rats. Your institution's limits apply.
How do you calculate oral bioavailability?
Bioavailability (F) compares dose-normalized exposure after oral dosing with exposure after intravenous dosing: F = (AUC oral / dose oral) / (AUC IV / dose IV). That is why an IV group is needed.
What is non-compartmental analysis?
A standard way to derive PK parameters such as Cmax, AUC, half-life and clearance directly from the concentration-time data, without fitting a compartmental model.
What is the difference between PK and PD studies?
Pharmacokinetics describes what the body does to the drug (exposure over time); pharmacodynamics describes what the drug does to the body (the effect). Many studies collect both to relate exposure to effect.
Is anything I type stored or shared?
No. The planner runs entirely in your browser. Nothing you enter is saved, sent to BioBridgeX, put in the page address or passed to analytics or AI services. Closing or refreshing the page clears it, so copy or print the plan before you leave.
Is the generated plan a protocol?
No. It organizes the requirements you entered into a structured outline and lists what is still undecided. It is not a validated protocol, it does not recommend sample sizes, and it does not establish GLP, GMP or regulatory compliance. Have the plan reviewed by qualified scientific, statistical, ethical and regulatory experts.
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Sources
- Diehl KH et al. A good practice guide to the administration of substances and removal of blood, including routes and volumes. J Appl Toxicol 2001;21(1):15-23
- NC3Rs: Blood sampling, general principles
- ICH S3A Q&As: Focus on microsampling (2017)
- EMA Guideline on the Investigation of Bioequivalence, CPMP/EWP/QWP/1401/98 Rev. 1 (2010)
- ICH M3(R2): Nonclinical safety studies for the conduct of human clinical trials (2009)
This planner organizes requirements. It is not a validated protocol, does not recommend sample sizes, and does not establish GLP, GMP or regulatory compliance. Review every plan with qualified scientific, statistical, ethical and regulatory experts. Facts on this page last checked 27 October 2026.
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