A patient on chronic high-dose morphine for cancer pain requires progressively higher doses to achieve the same analgesic effect, and develops diarrhea, piloerection, and cramps if doses are delayed. His physician notes he shows no drug-seeking behaviour beyond legitimate pain control requests. These phenomena are respectively termed:

• A Addiction, pseudoaddiction
• B Physical dependence, addiction
• C Tolerance, physical dependence ✓
• D Tolerance, addiction

Explanation

Tolerance is the need for increasing doses to achieve the same effect, and physical dependence is the emergence of a characteristic withdrawal syndrome on abrupt cessation or dose reduction. Both occur predictably with chronic opioid therapy and do not constitute addiction, which requires compulsive use despite harm plus craving and loss of control. Recognizing that tolerance and physical dependence are expected physiological adaptations is essential, because mislabeling them as addiction leads to unjustified withholding of analgesia.

Reference: Katzung's Basic and Clinical Pharmacology, 16th ed.

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Written and medically reviewed by the StethoPrep medical team.