True statements about Neostigmine are: a) It is a quarternary ammounium compound b) It is metabolised by liver c) It can cross the blood brain barrier d) Prominent effect on cardiac muscle e) It possess agonistic action on NM receptors

**Core Concept**
Neostigmine is a synthetic cholinesterase inhibitor used to treat myasthenia gravis, reverse the effects of non-depolarizing muscle relaxants, and improve gastrointestinal motility. It works by inhibiting the enzyme acetylcholinesterase, thereby increasing the concentration of acetylcholine in the synaptic cleft.

**Why the Correct Answer is Right**
Neostigmine is a quaternary ammonium compound, which allows it to act peripherally without crossing the blood-brain barrier. This property makes it ideal for treating myasthenia gravis and reversing muscle relaxation without central nervous system side effects. Neostigmine is primarily metabolized by the liver and excreted in the urine. Its agonistic action on nicotinic receptors at the neuromuscular junction enhances muscle contraction and is the primary mechanism of its therapeutic effect. However, it does not have a prominent effect on cardiac muscle.

**Why Each Wrong Option is Incorrect**
**Option B:** Neostigmine is not metabolized by the liver primarily; it is excreted in the urine. While the liver does play a role in its metabolism, the primary route of elimination is renal excretion.
**Option C:** Neostigmine cannot cross the blood-brain barrier due to its quaternary ammonium structure, making it a peripheral-acting drug.
**Option D:** Neostigmine does not have a prominent effect on cardiac muscle. Its primary action is at the neuromuscular junction, enhancing muscle contraction.
**Option E:** While Neostigmine is an agonist at nicotinic receptors, it also has a significant effect on muscarinic receptors, which contributes to its side effects such as salivation, sweating, and bradycardia.

**Clinical Pearl / High-Yield Fact**
Neostigmine's quaternary ammonium structure makes it a peripheral-acting drug, which is essential for its therapeutic effects and minimal side effects profile.

**Correct Answer:** a) It is a quarternary ammonium compound.