plasma protein binding

[chromeleon]

I want to quantify the amount of unmetabolised drug after injecting into mice - unfortunately it would seem that most of the drug is binding to plasma proteins, therefore when I filter the sample the drug is lost along with the protein

is there a way to "unbind" my drug, e.g. changing pH? I'm going to try this but thought I should post on here first to see if anyone has any experience of this issue.

thanks in advance.

[danko]

Is the mechanism of binding known – e.g. hydrogen bonding, charge (ion) attraction, hydrophobic interactions etc. ?
Is the drug ionizable at all and if so do you know the pKa?

Best Regards