A patient develops tolerance to a pain medication, requiring increasingly higher doses to achieve the same analgesic effect. Which mechanism explains the reduced drug efficacy despite escalating dosage?

💡 Explanation

Tolerance to medications, especially those affecting the reward system, often involves downregulation of receptors in the postsynaptic neuron. Repeated drug exposure leads to decreased receptor density as a compensatory mechanism to maintain homeostasis, because the neuron attempts to reduce overstimulation; therefore, a higher dose is required to elicit the original effect, rather than an increase in liver metabolism.

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