Cliffоrd, а 36-yeаr-оld, Cаucasian male, is referred tо the PMHNP by his PCP due to chronic low back pain that was being managed with oxycodone. Clifford's pain has become so severe, he reports feeling suicidal. Clifford states he becomes very anxious, irritable, restless, and begins to perspire if he is late taking his next dose of oxycodone. He reports that he's so concerned about his pain worsening between doses, that much of his day is spent waiting to take the next dose. When he runs out of medication between visits, he will buy some from his friends. Which of the following best described Clifford's condition?