A 64-year-old m an w ith term inal cancer had been su ering from continuous pain and started treatm ent w ith m orphine. After a few days of treatm ent, the initial dose was no longer e ective, and the physician gradually increased the dose, know ing that pharm acodynam ic tolerance m ost likely had occurred. Which of the follow ing best explains the m echanism of tolerance in this patient? A. Accelerated m orphine m etabolism B. Increased a nity of receptors to m orphine C. Decreased binding of m orphine to plasm a proteins D. Decreased m orphine receptor densit y E. Decreased concentration of m orphine in the brain
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A 64-year-old m an w ith term inal cancer had been su ering from continuous pain and started treatm.