Drug of choice in intractable hiccups is :
**Core Concept**
Intractable hiccups are a condition characterized by persistent and unrelenting episodes of hiccups, often resistant to conventional treatments. The pathophysiology of hiccups involves the sudden contraction of the diaphragm and other inspiratory muscles, which is usually triggered by irritation of the phrenic nerve or other nerves innervating the diaphragm.
**Why the Correct Answer is Right**
The drug of choice in intractable hiccups is chlorpromazine, a typical antipsychotic medication that has a unique ability to suppress the activity of the central nervous system. Chlorpromazine acts by blocking dopamine receptors in the brainstem, particularly in the area responsible for regulating breathing and hiccup generation. This blockade of dopamine receptors helps to calm the diaphragm and other inspiratory muscles, thereby stopping the hiccup spasms. Chlorpromazine's effectiveness in treating intractable hiccups is thought to be related to its ability to modulate the activity of the brainstem's respiratory centers.
**Why Each Wrong Option is Incorrect**
**Option A:** Metoclopramide is incorrect because, although it can help in some cases of intractable hiccups, it is not considered the first-line treatment and has a higher risk of side effects compared to chlorpromazine.
**Option B:** Baclofen is incorrect because, while it can be effective in treating certain types of muscle spasms, it is not typically used for intractable hiccups and may have more side effects than chlorpromazine.
**Option C:** Ondansetron is incorrect because it is primarily used to treat nausea and vomiting, and has no established role in the treatment of intractable hiccups.
**Clinical Pearl / High-Yield Fact**
Chlorpromazine is a versatile medication that can be used off-label for a variety of conditions, including intractable hiccups, and is often considered a "last resort" treatment option due to its potential side effects.
**Correct Answer: C. Chlorpromazine**