Drug used for ameliorative test for Myasthenia gravis is
**Core Concept**
Myasthenia gravis is an autoimmune disease characterized by the presence of antibodies against acetylcholine receptors (AChR) at the neuromuscular junction, leading to muscle weakness and fatigue. The ameliorative test for myasthenia gravis involves administering a medication that increases the concentration of acetylcholine available to bind to the remaining functional AChR.
**Why the Correct Answer is Right**
Edrophonium is a cholinesterase inhibitor that temporarily increases the concentration of acetylcholine in the neuromuscular junction. By inhibiting the breakdown of acetylcholine, edrophonium allows for a greater number of acetylcholine molecules to bind to the remaining functional AChR, thereby producing a temporary improvement in muscle strength and function. This effect is a hallmark of myasthenia gravis and is used to diagnose the condition in the ameliorative test.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it is not a cholinesterase inhibitor and does not increase acetylcholine concentrations in the neuromuscular junction.
* **Option B:** This option is incorrect because it is a muscle relaxant and would not be used to diagnose myasthenia gravis.
* **Option D:** This option is incorrect because it is an anticholinergic medication that would worsen muscle weakness in myasthenia gravis patients.
**Clinical Pearl / High-Yield Fact**
The ameliorative test for myasthenia gravis is often performed with edrophonium chloride, which is administered intravenously. The test is typically performed in a controlled clinical setting, and the patient's muscle strength is monitored before and after the administration of the medication.
**Correct Answer: C. Edrophonium.**