D2 occupancy of 50-75% is associated with which effect?

D2 occupancy of 50-75% is associated with which effect?

• A. EPS
• B. Clozapine monitoring
• C. Hyperprolactinemia
• D. Maintenance dosing

Answer: (C)

D2 receptor occupancy determines which side effects antipsychotics are likely to cause. When occupancy falls in the 50-75% range, blockade in the tuberoinfundibular pathway reduces dopamine’s inhibition of prolactin release, leading to hyperprolactinemia. Extrapyramidal symptoms are more strongly tied to higher occupancy in the nigrostriatal pathway, especially around or above 70-80%, so this range is more characteristic of prolactin elevation than EPS. Clozapine monitoring relates to agranulocytosis and other risks, not this occupancy window, and maintenance dosing refers to continuing treatment to sustain control rather than a distinct side effect. Hyperprolactinemia best fits the occupancy level described.

D2 receptor occupancy determines which side effects antipsychotics are likely to cause. When occupancy falls in the 50-75% range, blockade in the tuberoinfundibular pathway reduces dopamine’s inhibition of prolactin release, leading to hyperprolactinemia. Extrapyramidal symptoms are more strongly tied to higher occupancy in the nigrostriatal pathway, especially around or above 70-80%, so this range is more characteristic of prolactin elevation than EPS. Clozapine monitoring relates to agranulocytosis and other risks, not this occupancy window, and maintenance dosing refers to continuing treatment to sustain control rather than a distinct side effect. Hyperprolactinemia best fits the occupancy level described.