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Professor & HoD Department of Pharmaceutical Chemistry, JSS College of Pharmacy, (Constituent College, JSS Academy of Higher Education &Research-Deemed to be University, Mysuru) Ooty-643 001, The Nilgiris, Tamilnadu,INDIA The author has about 23 years of teaching and research experience. The Author has more than 110 research publications in reputed National and International journals and has H-index 16 by scopus. He has also published 9 books. He is a recognized research guide for Ph.D in JSS Academy of Health Education and Research and He served as editorial member and reviewer in many reputed National and International journals. He is the winner in Drug Discovery Hackathon-2020 for Covid-19 Drug discovery organized by Govt of India and also received a Research grant of 14.35 lakhs in phase-II research. He is nominated as BOS member in various universities. He has organized many national and International seminar/ workshop/ Conferences etc sponsored by various funding agencies.

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Friday, June 6, 2008

GANGLIONIC BLOCKERS AND NEURO MUSCULAR BLOCKERS

GANGLIONIC BLOCKERS AND NEURO MUSCULAR BLOCKERS
GANGLIONIC BLOCKING AGENTS
The Ganglionic blocking agents are drugs which act by competiting with Acetyl choline (Ach) from the cholinergic receptors present in the autonomic post ganglionic neurons.
Since the ganglia of both the sympathetic and parasympathetic nervous systems are cholinergic, these drugs interrupt the outflow through both system.
They are used mostly for their interruption of the sympathetic outflow in hypertension, vasopastic disorders and peripheral vascular disease. Thus lowering the B.P and increasing the peripheral blood flow.
CLASSIFICATION
Based on the mechanism these are classified as follows.
1.By Interfering with Ach release - Triethyl choline, Hemicholinium
2. By interference with post synoptic action of Ach - Eg : Hexamethonium
3. By prolonged depolarization - Eg : Nicotine


NEURO MUSCULAR BLOCKING AGENTS
Agents which blocks the transmission of Ach at the motor end place are called neuromuscular blocking agents. They are used in surgical anesthesia as adjuvant to relax the skeletal muscle.
CLASSIFICATION
1.Natural Compounds – Eg : Tubocurarine chloride, Metocurarine iodide, Pancuronium bromide.
2. Synthetic Compounds - Eg : Gallamine triethiodide, Decamethonium bromide, Pipecuranium bromide, Vecuronium bromide.
Tubocurarine chloride Synthesis

SAR for Neuro muscular blockers
  1. The drugs have quarternary ammonium group for good activity.
  2. The type of alkyl group present in quarternary ammonium group determines the charge distribution and binding characters.
  3. Non depolarizing drugs are bulky and more rigid than depolarizing drugs.
  4. As the strerric hindrance to receptor increases, the potency decreases. L-tubocurarine is less potent than d-tubocurarine.
  5. The depolarizing agents (Eg-Decamethonium) have a more flexible structure that enable bond rotation.
  6. The distance between quarternary ammonium groups can vary up to the limit of maximal bond distance usually 1.0 ± 0.1 nm.

MECHANISM OF ACTION
Neuro muscular blocking agents can block the neuro muscular transmission by

  • Inhibiting acetyl choline synthesis
  • Inhibiting Ach release and inhibit calcium entry have neuromuscular block.
    Interfering with the post synoptic action of Ach.
  • Non depolarizing blocking agents act by competitive antagonism at Ach receptos of the end plate and these largely accounts for their action.
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