neuromuscular blocking agents

neuromuscular blocking agents

1. Dr.charulatha Neuromuscular blocking drugs

2. Need for neuromuscular blocking drugs Improve intubating conditions Providing immobility Better surgical conditions

3. Structure of neuromuscular junction Motor neuron Axon Nerve terminals Synaptic cleft Post synaptic membrane

4. Action potential Electrical potential inside the cell is negative Depolarization Sodium and calcium channels All or none response

5. acetylcholine Acetylcholine synthesis Receptors Vesicles Anticholinesterases Synaptic cleft Calcium and magnesium

6. Post synaptic events Ach receptor Ligand gated ion channel Structure of the receptor Adult , fetal , extrajunctional acetylcholinesterase

7. Presynaptic events Presynaptic receptor Preventing mobilisation of acetylcholine vesicles

8. Pharmacologic characteristics Potency Onset duration

9. atracurium Hoffman reaction Nonspecific ester hydrolysis Dose 0.5 mg/kg Onset 3 -5 min Duration 30 – 45 min

10. Specific points Histamine release Intubating dose Maintenance of anaesthesia Can be used in patients with hepatic or renal failure

11. cisatracurium Dose 0.1 mg/kg Duration 30 -45 min Devoid of histamine releasing properties

12. mivacurium Short acting Degraded by plasma esterases 0.3. mg/kg Ambulatory and laprascopic surgery

13. pancuronium Increase heart rate,blood pressure and cardiac output Sympathomimetic effect Duration of action 1 hr Higher incidence of muscular weakness after cardiac surgery than rocuronium

14. rocuronium 0.6 mg/kg intubating dose Duration 30 -40 min No hemodynamic effects Rapid sequence induction sugammadex

15. vecuronium Intubating dose 0.1 mg/kg No cardiovascular effects Excreted by the kidney Intermediate duration of action Precipitates with thiopentone

16. neostigmine Reversible anticholinesterase inhibitor 50 -70 mcg/kg Increased acetylcholine in the receptor Profound vagal stimulation Administered with glycopyrrolate or atropine

17. sugammadex Gamma cyclodextrin Steroid nucleus – rocuronium and vecuronium No cardiovascular adverse effects 16 mg/kg dose required

18. Special considerations Myasthenia gravis Myotonia Burns Muscular dystrophy UMN lesions