Biotechnology Question:

Some drugs bind extensively to plasma proteins (Warfarin binds 99%) whereas others have virtually no binding.

Extraction depends on the type of drug - there are different standard techniques for acidic, basic, and neutral drugs - and, indeed, some drugs need specific extraction techniques.

It is important for you doing bioequivalence studies to know exactly the proportion of drug extracted but such controls are again specific for each drug and use specific marker compounds.