Which is not a feature of non depolarizing block?
**Core Concept**
Non-depolarizing muscle blockers, such as rocuronium and vecuronium, work by competitively inhibiting the binding of acetylcholine to nicotinic receptors at the neuromuscular junction, thereby preventing muscle contraction. This results in a prolonged depolarization of the muscle cell membrane, leading to muscle paralysis.
**Why the Correct Answer is Right**
The correct answer will be the feature that is not characteristic of non-depolarizing muscle blockers. Non-depolarizing blockers typically exhibit a gradual onset of action, a prolonged duration of action, and a fade in twitch response with repetitive stimulation. They also exhibit a phenomenon known as "desensitization" or "fade" in twitch response with prolonged stimulation.
**Why Each Wrong Option is Incorrect**
**Option A:** Desensitization or fade in twitch response is a characteristic feature of non-depolarizing muscle blockers.
**Option B:** Gradual onset of action is a characteristic feature of non-depolarizing muscle blockers.
**Option C:** Prolonged duration of action is a characteristic feature of non-depolarizing muscle blockers.
**Clinical Pearl / High-Yield Fact**
Non-depolarizing muscle blockers can cause histamine release, leading to symptoms such as hypotension, tachycardia, and bronchospasm.
**Correct Answer: D.**