True about d–TC is all except – a) Excreted unchanged by kidneyb) Causes hypotension by ganglion blocking actionc) Vagolytic actiond) Effects lasts for 2–3 hours

**Core Concept**
D-Tubocurarine (d-TC) is a non-depolarizing neuromuscular blocking agent that competitively inhibits nicotinic acetylcholine receptors at the neuromuscular junction, leading to muscle paralysis. Its mechanism of action involves the formation of a stable complex with the nicotinic receptor, preventing acetylcholine from binding and initiating muscle contraction.

**Why the Correct Answer is Right**
The correct answer is related to the pharmacokinetics and pharmacodynamics of d-TC. d-TC is indeed excreted primarily unchanged by the kidneys, which is a key factor in its elimination from the body. Additionally, d-TC causes hypotension by ganglion blocking action, which is a result of its effect on nicotinic receptors in the autonomic nervous system. However, d-TC is not vagolytic; in fact, it can cause bradycardia due to its effect on nicotinic receptors in the sinoatrial node. The effects of d-TC typically last for 2-3 hours, which is consistent with its pharmacokinetic profile.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because d-TC is indeed excreted unchanged by the kidneys.
**Option C:** Incorrect because d-TC causes bradycardia due to its effect on nicotinic receptors in the sinoatrial node, not vagolytic action.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that non-depolarizing neuromuscular blockers like d-TC can cause histamine release, leading to hypotension, bronchospasm, and cutaneous flushing.

**Correct Answer:** B.