**Core Concept**
Pyridostigmine and neostigmine are both cholinesterase inhibitors used in the management of myasthenia gravis. They work by preventing the breakdown of acetylcholine at the neuromuscular junction, thereby increasing the concentration of acetylcholine available for muscle contraction.

**Why the Correct Answer is Right**
Pyridostigmine has a longer duration of action compared to neostigmine due to its ability to cross the blood-brain barrier and its higher lipid solubility. This results in a longer-lasting effect on the neuromuscular junction, making it more suitable for once- or twice-daily dosing in patients with myasthenia gravis. The longer duration of action of pyridostigmine allows patients to take fewer doses throughout the day, which can improve compliance and reduce the risk of cholinergic side effects.

**Why Each Wrong Option is Incorrect**
**Option A:** Pyridostigmine is not more potent than neostigmine; in fact, neostigmine is generally considered more potent due to its shorter duration of action and faster onset of effect.

**Option C:** Both pyridostigmine and neostigmine can produce muscarinic side effects, such as bradycardia, diarrhea, and salivation. The difference lies in the duration of action, not the severity of side effects.

**Option D:** Both pyridostigmine and neostigmine have direct action on nicotinic receptors at the neuromuscular junction, which is the primary mechanism by which they exert their therapeutic effect.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that pyridostigmine's longer duration of action makes it more suitable for patients with myasthenia gravis who require once- or twice-daily dosing. This can improve compliance and reduce the risk of cholinergic side effects.

**Correct Answer:**
✓ Correct Answer: B. It is longer acting