Prescribing Safety Assessment (PSA) Practice Exam

Which dopamine antagonist is known to cross the Blood Brain Barrier?

1. Domperidone

2. Prochlorperazine

3. Metaclopramide

4. Haloperidol

The correct answer is: Metaclopramide

The correct choice is based on the pharmacological properties of the drugs listed. Metoclopramide is a dopamine antagonist that crosses the blood-brain barrier effectively. This characteristic allows it to act on the central nervous system (CNS), which is particularly relevant when considering its use for treating nausea and vomiting. Metoclopramide's ability to penetrate the blood-brain barrier enables it to block dopamine receptors in the vomiting center of the brain, leading to its antiemetic effects. This central action differentiates it from some other dopamine antagonists that may not reach the CNS effectively. In contrast, while other options like prochlorperazine and haloperidol are also known to act on dopamine receptors and are used for their CNS effects, their potency and primary use can vary. Domperidone, on the other hand, is distinct as it does not adequately cross the blood-brain barrier, making it less effective for CNS-related issues, although it is still a dopamine antagonist used primarily for gastrointestinal conditions. Overall, the unique ability of metoclopramide to cross the blood-brain barrier supports its use in treating conditions where central dopamine receptor antagonism is desired.