The interchangeable use of these 2 terms bothers me, especially as a scholar of psychology and neuroscience.
A diabetic depends on their insulin. Someone with hbp depends on medication to keep their blood pressure stable. A person with a seizure disorder depends on anti-convulsants, etc. But no one ever says "he's addicted to insulin, he needs it to manage his illness"
Granted, not all of us take our pain medication everyday. But many need to. Chronic pain is an illness, an illness that is managed with medication.
Thus, to be dependent on medication is not to be addicted to it. Addiction comes in when a person seeks out the effects of abusing the substance. I'm sure most of you know this, but I just want to spread awareness.