Why Would the Nurse Anticipate an Adverse Reaction in an Older

Why would the nurse anticipate an adverse reaction in an older adult who is taking the protein-bound drug warfarin (Coumadin) ?

A) Unbound active drug molecules continue to circulate in the bloodstream.
B) The bleeding and clotting times will decrease.
C) The drug becomes ineffective and does not deliver its intended therapeutic action.
D) Renal damage can occur from the altered drug molecules.