A Patient Has Taken a Narcotic Analgesic for Chronic Pain

A patient has taken a narcotic analgesic for chronic pain for several months. At a follow-up appointment, the provider notes that the patient has been taking more than the prescribed dosage. The patient has normal vital signs, is awake and alert, and reports mild pain. What does the provider suspect is responsible for the patient's response?

A) This patient exhibits a negative placebo effect with a reduced response to the drug.
B) This patient has developed tachyphylaxis because of repeated exposure to the drug.
C) This patient has developed pharmacodynamic tolerance, which has increased the minimal effective concentration (MEC) needed for analgesic effect.
D) This patient has increased hepatic enzyme production as a result of prolonged exposure to the drug.