Which of the following is earliest and shortest acting skeletal muscle relaxant?
## **Core Concept**
The question tests knowledge of skeletal muscle relaxants, specifically their onset and duration of action. Skeletal muscle relaxants are drugs that inhibit muscle contraction by affecting the nervous system or muscle directly. They are used in surgical procedures to facilitate endotracheal intubation and provide muscle relaxation during surgery.
## **Why the Correct Answer is Right**
Succinylcholine (Option C) is known for its rapid onset of action, typically within 30 seconds to 1 minute, and short duration of action, lasting approximately 5-10 minutes. This is because it acts as a depolarizing agent at the nicotinic acetylcholine receptor, initially causing muscle contraction followed by prolonged depolarization and muscle relaxation. Its short duration of action is due to its rapid hydrolysis by plasma cholinesterase.
## **Why Each Wrong Option is Incorrect**
- **Option A:** Although specific drugs are not mentioned, other depolarizing or non-depolarizing muscle relaxants have longer onset and duration of action compared to succinylcholine. For example, rocuronium has a faster onset than some non-depolarizing agents but is not as rapid as succinylcholine.
- **Option B:** This option would be incorrect because, similar to Option A, unspecified but likely refers to longer-acting agents.
- **Option D:** This option is incorrect because it likely refers to an even longer-acting agent compared to the others.
## **Clinical Pearl / High-Yield Fact**
A key point to remember is that succinylcholine is the only depolarizing muscle relaxant and is used for rapid sequence induction due to its quick onset. However, its use is limited by potential side effects such as hyperkalemia, especially in patients with burns or certain neuromuscular diseases.
## **Correct Answer:** . Succinylcholine.