1. Mechanism of Action
1.1. Antimuscarinic
1.1.1. Muscarinic blocking agents bind competitively and prevent acetylcholine from binding to the sites. However, their antagonistic actions can be reduced by increasing the concentration of the muscarinic agonists.
1.2. Antinicotinic
1.2.1. Ganglionic blockers act specifically on the nicotinic receptors present in the sympathetic and parasympathetic nervous systems. As these drugs show no selectivity towards the sympathetic and parasympathetic nervous systems, they are used in experimental pharmacology.
1.3. Neuromuscular Blocking Drugs
1.3.1. Mechanism of action of non-depolarizing blockers
1.3.1.1. At low doses, these drugs compete with ACh at the receptor without stimulating it, thus preventing depolarization of muscle cell membrane and inhibiting muscular contraction.
1.3.1.2. At high doses, these drugs block the ion channel at the motor end plate, reducing neuromuscular transmission. This effect cannot be reversed by cholinesterase inhibitors and electrical stimulation.
1.3.2. Mechanism of action of depolarization agents
1.3.2.1. These drugs act by depolarizing the plasma membrane of the muscle fibers. But their action is not reversed by anticholinesterases, and thus, the depolarization of muscle fiber persistently increases. Succinylcholine is a depolarizing muscle relaxant.
2. Trade Name in Egypt
3. Subclasses
3.1. Antimuscarinic
3.1.1. Examples
3.1.1.1. Atropine
3.1.1.2. Scopolamine
3.1.1.3. Topicamide
3.1.1.4. Pirenzepine
3.1.1.5. Cyclopentolate
3.1.1.6. Glycopyrrolate
3.1.2. Indications
3.1.2.1. Hyper hydrosis Retinal examination Antispasmodic Motion sickness
3.2. Antinicotinic (ganglionic-blocking druds ).
3.2.1. Examples
3.2.1.1. Nicotine
3.2.1.2. Trimethaphan
3.2.1.3. Mecamylamine
3.2.1.4. Hexamethonium
3.2.2. Antinicotinic drugs are classified into two types: - Neuromuscular blocking agents - Ganglionic blockers
3.2.3. Indications
3.2.3.1. High blood preussre
3.2.3.2. Highe motor activity of bowel
3.3. Neuromuscular Blocking Drugs
3.3.1. Example of De polarizing
3.3.1.1. Pancuronium
3.3.1.2. cisatracurium
3.3.1.3. Tubocurarine
3.3.1.4. Atracurium
3.3.2. These are further classified into two classes: - Non-depolarizing Blockers. - Depolarizing Blockers.
3.3.3. These classes of drugs act as antagonists (non-depolarizing type) and agonists (depolarizing type) at the receptors of the end plate of the neuromuscular junction.
3.3.4. At lower doses, they produce complete muscle relaxation, facilitating their use in tracheal intubation during surgery. They also allow fast recovery from anesthesia and decrease postoperative respiratory depression.
3.3.5. Example of polarizing
3.3.5.1. Succinyle choline
3.3.6. Indications
3.3.6.1. Provide muscular relaxation
3.3.6.2. Useful in rapid endotrachal intubation