Tardive dyskinesia is least commonly associated with which of the following drugs?
**Core Concept**
Tardive dyskinesia is a side effect of long-term use of antipsychotic medications, characterized by involuntary movements of the face, trunk, and limbs. It is thought to be caused by dopamine receptor blockade, particularly D2 receptors in the basal ganglia.
**Why the Correct Answer is Right**
Tardive dyskinesia is a well-documented side effect of typical antipsychotics, such as haloperidol and chlorpromazine, which are potent D2 receptor antagonists. These drugs can cause long-term dopamine receptor blockade, leading to the development of tardive dyskinesia. In contrast, atypical antipsychotics, such as risperidone and quetiapine, have a lower risk of causing tardive dyskinesia due to their partial agonist activity at D2 receptors and higher affinity for serotonin 5-HT2A receptors.
**Why Each Wrong Option is Incorrect**
**Option A:** Haloperidol is a typical antipsychotic known to cause tardive dyskinesia due to its potent D2 receptor blockade.
**Option B:** Chlorpromazine is another typical antipsychotic that has been associated with tardive dyskinesia.
**Option C:** Clozapine is an atypical antipsychotic that has a lower risk of causing tardive dyskinesia, but it is not entirely free of this side effect.
**Clinical Pearl / High-Yield Fact**
When treating patients with antipsychotics, it is essential to weigh the benefits of treatment against the risk of tardive dyskinesia, particularly in older adults and those with a history of long-term antipsychotic use.
**Correct Answer: C. Clozapine.**