Bioequivalence and Bioavailability Forum

Dear Helmut,

❝ Are you sure? I know only liposome-encapsulated formulations (i.e., containing no free doxorubicin).

Sure - but in practice, "trauma" from the peristaltic IV pump and the narrow gauge needle can release drug. Further, the biphasic PK profile of unbound dox following liposomal infusion is supportive of an effective 5% IV bolus and 95% liposomal input.

However, it is very cool to hear that this may be an artifact!

❝ IMHO, encapsulated, free, and total doxorubicin are not relevant from a clinical perspective – only nice to know.

I agree. I believe the free is only clinically relevant. Imposing tests on the bound form is like measuring the amount of drug in the gut (i.e. the "liposome") and in the blood (i.e. unbound in blood).

I am not sure what I would do if I found that total had a much different PK profile, but resulted in same free fractions. Probably explode.

May I add, that I have not found any other forum even tangentially related to clinical pharmacology, pharmacometrics, or drug development that is anywhere as active.
Thanks for the great discussion.

Cheers,
BF