LLOQ ≤5% Cmax [Bioanalytics]

posted by Helmut Homepage – Vienna, Austria, 2019-05-02 12:20  – Posting: # 20265
Views: 283

Bonjour chimiste!

» hello sir helmutz,

Not interested in opinions of other members of the forum?

» […] i would like to know how to calculate my LIQ frome un infernal Cmax, without taking into account the formula of 5%, is there any other mathematic relation between Cmax as pk parrameter and LIQ as analytical parrameter.

You should be able to quantify 5% (or lower) of Cmax in order to demonstrate that there are no residual concentrations of previous administrations in periods >1. In a crossover study you have to avoid carry-over which requires a sufficiently long washout.
It is the job of the pharmacokineticist (not yours) to design the study. Hint: Never plan with the average half-life from the literature. Always assume longer ones (see this presentation, slides 65/66).
The bioanalytical method should be reliable and reproducible for the intended use. Sometimes people forget the last part and reach too far. It’s not necessary to come up with a “perfect” method – it must only be fit for purpose. Goalposts:
» 2/ i would like to know how can i calculate the internal standard concentration used in validation from an ULOQ ?

Not sure what you mean. Can you reword/explain?

» 3/IAM working acctually on hplc and lc ms ms dosage methode of amoxicilline in human plasma , iam juste in begining and i need some of your precious recommandations if it is possible ?

Some hints from the method we used in my CRO (250 ng/mL – 31 µg/mL):Good luck in developing/validating your method!

» N//B excuse me for my english iam doing my best because i usually communicate in frech.

No problem. Few native speakers here. Google translate is not that bad. ;-)

Helmut Schütz

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