Hi Alida, in general, Bioavailability is tested by comparison of the levels of your compound in serum/plasma levels after i.v. injection vs p.o. You'll find plenty of guidelines for this :-) Good luck!

The problem is that our mice are not available for further assays, we only have have plasma that we obtain before the end of the experiment.

Thanks for your answer anyway.

Hi,

You don't need to use exactly the same animals especially when they very small. Sometimes its impossible make blood sampling twice in such animals so you can use two groups. One from your experiment you describe and second group (single IV dose). Please remember that sampling in case of IV is different than in case SC or PO. Directly after drug dosing you need to take first blood sample (1 min after dose for example) to avoid BIAS related to first concentration value.

Finally in this case you need to do additional experiment with single IV dose to get experimental data describing AUC after IV. Unfortunately its only one way to calculate F. In case of problems with sampling you can use sparse sampling method.

Best regards

Tomasz

To my knowledge, these experiments are not done with the very same animal. Use one for po, take blood samples. Use another one for iv, take blood samples immediately afterwards. The plasma level you measure after iv is considered as 100% bioavailability. Compare the AUC of iv and po - there is your absolute bioavailability after oral administration. As Tomasz said, you always need the iv when you want to compare to other ways of administration such as ip, sc etc.

Thanks both of you.

Maybe I should redefine my question, because what we want to know is the existence of that specific drug in mice that were treated with it, on purpose of confirming the results our lab had.

I have read about HPLC tests, but I would like to know if there´s a kit or immunoassay that can confirm the presence of that drug in plasma.

Use another larger species.

are you asking how to confirm if the drug was absorbed at all? I think yours is a bioanalysis issue; you need to refine your assay to detect lower concentrations that are currently quantifiable. Probably you need to share the name/type of compound.

That said if you did have IV data (even from different animals) then you may be able to fit even very sparse oral data simulatneously. Building these models in Phoenix's PML either graphically or textually is quite straight forward and the NLME engine will help you get the most information from your data.

https://support.certara.com/forums/topic/954-lesson-4-multiple-absorption-routes-via-graphical-model-builder/

https://support.certara.com/forums/topic/1248-extravascular-model-bioavailability-clarification-and-pml-code/

No. We just wanna know if the drug that was administered po was correctly administered. I mean, we have two groups, control and treatment. We would like to know if there is presence in plasma of that drug in the treatment group.