Which phenomenon is linked to high D2 occupancy around 78%?

Which phenomenon is linked to high D2 occupancy around 78%?

• A. Acute and manic symptoms
• B. Hyperprolactinemia
• C. EPS
• D. Clozapine monitoring

Answer: (C)

High D2 receptor occupancy in the nigrostriatal pathway leads to extrapyramidal symptoms. When occupancy nears about 78% or higher, most of the dopamine D2 receptors in this motor pathway are blocked, disrupting normal motor control and producing EPS such as dystonia, parkinsonism, and akathisia. This occupancy level is a practical marker for when EPS risk becomes prominent, reflecting the balance between therapeutic dopamine blockade in the mesolimbic system and adverse motor effects from the nigrostriatal system. Hyperprolactinemia, by contrast, stems from D2 blockade in the tuberoinfundibular pathway and can occur with various levels of occupancy, not specifically tied to this 78% threshold. Clozapine monitoring relates to the risk of agranulocytosis and metabolic effects, not to a particular D2 occupancy level. Acute manic symptoms are not the direct product of approaching this high occupancy threshold.

High D2 receptor occupancy in the nigrostriatal pathway leads to extrapyramidal symptoms. When occupancy nears about 78% or higher, most of the dopamine D2 receptors in this motor pathway are blocked, disrupting normal motor control and producing EPS such as dystonia, parkinsonism, and akathisia. This occupancy level is a practical marker for when EPS risk becomes prominent, reflecting the balance between therapeutic dopamine blockade in the mesolimbic system and adverse motor effects from the nigrostriatal system.

Hyperprolactinemia, by contrast, stems from D2 blockade in the tuberoinfundibular pathway and can occur with various levels of occupancy, not specifically tied to this 78% threshold. Clozapine monitoring relates to the risk of agranulocytosis and metabolic effects, not to a particular D2 occupancy level. Acute manic symptoms are not the direct product of approaching this high occupancy threshold.