Neuromuscular blocking agents

Neuromuscular blocking agents
pharmacology

1. PHARMACOLOGY-I Session 2020-21 Submitted by – Mr. Suyash Jain Department Of Pharmaceutical Sciences Dr. Harisingh Gour Vishwavidyalaya , Sagar (M.P.) Neuromuscular blocking agents ( A Central University )

2. INTRODUCTION Neuro-muscular junction/ Myoneural junction/Motor end plate. Junction between Motor neuron & Muscle fibre. Action potential from nerve is transmitted to muscle through this junction.

3. DRUGS AFFECTING NEUROMUSCULAR JUNCTION . Neuromuscular Blockers – this block neuromuscular transmission at junction. Curare Bungarotoxin Succinylcholine and carbamylcholine Botulinum toxin

4. NEUROMUSCULAR BLOCKERS Curare – active principle D- Tubocurarine (Cobra) Block by combine with Ach-receptors . So Ach cannot act on receptors & No End Plate Potential develop So these are receptor blockers.

5. NEUROMUSCULAR BLOCKERS Bungarotoxin – Venom of deadly snake. Krait. Also block N-M junction by combining with acetylcholine receptors .

6. NEUROMUSCULAR BLOCKERS    Succinylcholine & Carbamylcholine – act like acetyl choline & Depolarizes post synaptic membrane But these are not destroyed by cholinesterase – so muscle remain in depolarized state for a long time. So these block Myoneural junction by keeping the muscle in depolarized state.

7. NEUROMUSCULAR BLOCKERS Botulinum Toxin – derived from bacteria Clostridium Botulinum. Block the junction by preventing the Release Of Acetyl Choline from terminal button.

8. N E U R O M U S CULAR STIMULATORS Drugs having acetylcholine like action- Methacholine, Carbachol & Nicotin But these are either not destroyed or destroyed very slowly by acetylcholinesterase so causes repeated stimulation & continuous action of muscle – Muscle spasm.

9. N E U R O M U S CULAR STIMULATORS  Drugs that Inactivate the enzyme Cholinesterase ( Anticholinesterase ) – Neostigmine, Physostigmine & Disopropylflurophosphate (DFP )  So it leads to repeated stimulation & continuous action of muscle. E.g – Laryngeal Spasm.

10. DISORDERS OF NEUROMUSCULAR JUNCTION. Myasthenia Gravis Auto Immune disease. Anti bodies are produced against Acetylcholine Receptors & destroy these channels

11. DISORDERS OF NEUROMUSCULAR JUNCTION. So acetyl choline released will not produce adequate end plate potential & excite muscle fibre So patient dies of paralysis of Respiratory Muscles .

12. DISORDERS OF NEUROMUSCULAR JUNCTION. L am b e r t - E a t o n syndrome. Anti bodies are produced against calcium channels present on pre-synaptic membrane – so Ca influx decrease & decreases release of acetyl choline

13. Thank You