Question

Treatment of Myasthenia Gravis (cholinesterase inhibitor like pyridostigmine) can improve skeletal muscle weakness by stimulating nicotinic receptors -- but cause unwanted muscarinic overstimulation (GI smooth muscle, excessive glandular secretions). Drug of choice?

Answer 1

Myasthenia gravis is treated with cholinesterase inhibitors, which can cause muscarinic side effects. Atropine is used to manage these side effects by blocking muscarinic receptors.

Step-by-step explanation:

Myasthenia gravis is an autoimmune disease where the immune system creates antibodies that block the acetylcholine receptors at the neuromuscular junction. This leads to muscle weakness and fatigue since the muscle cells receive limited signals to contract. Treatment often involves using cholinesterase inhibitors like pyridostigmine to prevent the breakdown of acetylcholine, thereby increasing signaling at the neuromuscular junction. However, these drugs can also cause overstimulation of muscarinic receptors, leading to undesirable side effects like gastrointestinal smooth muscle contraction and excessive glandular secretion.

To manage the muscarinic side effects while treating myasthenia gravis, a drug often used is atropine. Atropine is an antimuscarinic agent that blocks the muscarinic acetylcholine receptors, thus reducing the unwanted effects of cholinesterase inhibitors on organs like the GI tract without affecting skeletal muscle contraction. However, the use of these medications must be carefully balanced to treat the genetic neuromuscular disorder effectively while mitigating potential side effects.