Drug used in ameliorative test for myasthenia gravis is
**Core Concept**
The underlying principle being tested is the diagnosis of **myasthenia gravis**, an autoimmune disease characterized by weakness and rapid fatigue of the muscles under voluntary control. This is achieved through an ameliorative test, which assesses the improvement in muscle strength after administering a specific drug. The drug used should effectively increase the concentration of **acetylcholine** at the neuromuscular junction.
**Why the Correct Answer is Right**
The correct answer is a drug that inhibits **acetylcholinesterase**, the enzyme responsible for breaking down acetylcholine. By preventing the breakdown of acetylcholine, this drug increases the amount of acetylcholine available to bind to receptors at the neuromuscular junction, thereby improving muscle strength in patients with myasthenia gravis. This mechanism is crucial for the ameliorative test.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it does not specifically address the neuromuscular junction or increase acetylcholine levels.
**Option B:** Incorrect as it may not be directly related to increasing acetylcholine concentration at the neuromuscular junction.
**Option C:** Incorrect because, although it might have some effect on muscle strength, it is not the primary drug used for the ameliorative test in myasthenia gravis.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that the drug used in the ameliorative test for myasthenia gravis, such as **edrophonium**, acts quickly and has a short duration of action, making it ideal for diagnostic purposes. This test can help differentiate myasthenia gravis from other causes of muscle weakness.
**Correct Answer:** D. Edrophonium