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Muscle relaxants
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- 2. INTRODUCTION • Skeletal musclerelaxant are drugs that reduce muscle tone either by acting peripherally at the neuromuscular junction or centrally at cerebrospinal axis or directly on the contractile mechanisms. • The term muscle relaxant is used to refer to two major therapeutic groups which are neuromuscular blockers and spasmolytic.
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- 4. CLASSIFICATION SKELETALMUSCLE RELAXANTS DRUGD ACTING CENTRALLY DRUGS ACTING PERIPHERALLY DRUGSACTING ON NMJ DRUGS ACTING DIRECTLY ON MUSCLE COMPETITIVE OR NON- DEPOLARISING BLOCKERS NON-COMPETETIVE OR DEPOLARISING BLOCKERS
- 5. PERIPEHERALLY ACTING MUSCLERELAXANT • It acts peripherally at neuromuscular junction or at muscle fiber itself.
- 6. COMPETETIVE OR NON-DEPOLARISING BLOCKERS ISOQUINOLINEDERIVATIVES • Tubocurarine • Gallamine • Atracurium • Alcurium • Doxacurium • Mivrcurium
- 7. STEROID DERIVATIVES • Pancuronium •Vecuronium • Rapacuronium • Pipecuronium • Rocuronium
- 8. MECHANISM OF ACTION •Bind to nicotinic receptors on the motor end plate and block action of acetylcholine by competitive blockade. • These compounds slowly dissociate from receptors and transmission is gradually restored.
- 9. PHARMACOLOGICAL ACTIONS SKELETAL MUSCLE-On IV administer- action, it causes Flaccid paralysis effect on small muscles of eyes and fingers effect on muscles of limbs, neck and trunk effect on intercostal muscles paralysis of diaphragm RESPIRATION STOPS Muscle weakness
- 10. CONT.… • Recovery occursin reverse order i.e., the diaphragm is first to recover. • Its effect last for 30-60minutes. AUTONOMIC GANGLIA- in high doses it can block autonomic ganglia and adrenal medulla and causes hypotension.
- 11. CONT… • HISTAMINE RELEASE-it causes histamine release from mast cells leading to bronchospasm, increased tracheobronchial and gastric secretions. It also results in hypotension. GASTROINTESTINAL TRACT- it may enhance post-operative paralytic ileus after abdominal operations.
- 12. CONT.… CARDIOVASCULAR SYSTEM- itcauses significant fall in B.P. due to • Ganglionic blockade • Histamine release • Reduced venous return
- 13. PHARMACOKINETICS • It isquaternary ammonium compound, hence not absorbed orally. • It is given IV and IM only.
- 14. ADVERSE EFFECTS • Respiratoryparalysis • Prolonged apnea • Hypotension • Flushing • bronchospasm
- 15. TREATMENT OF TOXICITY •NEOSTIGRNINE may be used to reverse the skeletal muscle paralysis and it is the antidote in curare poisoning. • ANTIHISTAMINE should be given to counter the effect of histamine. • SUGAMMADEX is an antidote for overdosage of rocuronium and vecuoronium.
- 16. IMPORTANT FACTS Pancuronium, atracurium,vecuronium, gallimine, doxacurium, mivacurium, pipecuronium, rapacuronium, rocuronium are synthetic neuromuscular blockers, whereas tubocuranine is natural neuromuscular blocker(NMB). Use of synthetic NMBs is preferred over natural NMBs due to following reasons: • Less or no histamine release • Do not block autonomic ganglia hence cause less hypotension.
- 17. CONT… • More potency. •Agents like rapacuronium and rocuronium have rapid onset of action • Atracurium can be safely used in patients with renal impairment because it is degraded by plasma esterases.
- 18. DEPOLARISING OR NON-COMPETIVEBLOCKERS • Succinylcholine • Decanethonium
- 19. MECHANISM OF ACTION •It stimulates nicotine receptors and depolarize skeletal muscle membrane. • Persistent depolarization causes flaccid paralysis. • Its mechanism is not clearly known.
- 20. PHARMACOLOGICAL ACTIONS SKELETAL MUSCLE-on IV administration onset of action is very rapid i.e., within 1minute. • Its initial action is muscular fasciculations and twitchings, mostly in chest and abdominal regions are followed by skeletal muscle paralysis. CARDIOVASCULAR SYSTEM- initially hypotension and bradycardia may results from stimulation of vagal ganglia. It is followed by hypertension and tachycardia due to stimulation of
- 21. CONT… • Higher dosescan cause cardiac arrhythmias. • It can also cause release of histamine if injected rapidly
- 22. PHARMACOKINETICS • It israpidly hydrolyzed by PSEUCDOCHOLINESTERASE enzyme hence it is short acting about 5minutes. • Some people might have abnormal synthesis of this enzyme which is du to hereditary condition. • In such people it doesn’t get hydrolyzed at last for several hours resulting in apnea and paralysis.
- 23. ADVERSE ACTIONS • Postoperativemuscle pain (due to damage to muscle fiber) • Hyperkalemia • Cardiac arrhythmias • Apnea (due to pseuducholinesterase)
- 24. USES OF PERIPHERALLYACTING SKELETAL MUSCLE RELAXANT as have short acting property • ET intubation • Laryngoscopy • Bronchoscopy • Esophagoscopy Orthopedic procedure like reduction of fractures
- 25. CONT.… In electroconvulsive therapy(as it protects pt. from convulsions and trauma) To overcome spasm of tetanus, athetosis and status epilepticus
- 26. DIRECTLY ACTING MUSCLERELAXANT They directly affect skeletal muscle contractile mechanism. E.g. DANTROLENE
- 27. MECHANISM OF ACTION Inhibitscalcium release in muscle Inhibits muscle contraction Skeletal muscle relaxation
- 28. PHARMACOLOGICAL USES • Itis used in spastic disorders like hemiplegia, paraplegia, spinal injuries, multiple sclerosis and cerebral palsy. • Drug of choice in malignant hyperthermia is dantrolene. • Quinine is used as antimalarial drug. • Quinine is also used in myotonia congenital and nocturnal muscle cramps.
- 29. ADVERSE EFFECTS • Drowsiness •Dizziness • Fatigue • Diarrhea • Muscle weakness • Hepatoxicity (rare)
- 30. CENTRALLY ACTING MUSCLERELXANT • These drugs act on higher centres and cause muscle relaxation without loss of consciousness. • They also have seductive properties.
- 31. CONT.… BENZODIAZEPINES • Diazepam • Chlorodiazepoxide •Clonazepam • nitrazepam
- 32. CONT.… GABA ANALOGUES • Baclofenac •Progabide ALPHA 2-AGONIST • trizanidine
- 33. CONT.… OTHERS • Glycine • Meprobamate •Mephenesen • Idrocilamide • Riluzole • Botulinium toxin
- 34. MECHANISM OF ACTION Centralmuscle relaxant Depress spinal polysynaptic reflexes Decrease muscle tone
- 35. PHARMACOLOGICAL USES Can beused as analgesics in cases of • Muscle strains • Sprains • Myalgia • Cervical root syndromes • Low backache
- 36. CONT.… • Arthritis • Fibrosis •bursitis In spastic neurological disorders like ( with use of baclofen and diazepam) • Cerebral palsy • Multiple sclerosis
- 37. CONT.… • Poliomyelitis • Hemiplegia •Quadriplegia Tetanus (IV diazepam) Orthopedic like fracture reduction
- 38. CONT… Botulinum toxin isuseful in: • Dystonia's • Sports or writers cramps • Muscle spasm • Tremors • Cosmetic therapy
- 39. • Drowsiness • Mentalconfusion • Weakness • Ataxia • Hallucinations ADVERSE EFFECTS
- 40. CONT… • Tachycardia • Seizures •Night time insomnia
- 41. NURSING IMPLICATIONS • Respirationshould be monitored while on SMRs. • SMRs should not be withdrawn suddenly after long use (as may cause hallucination, seizures). • Patients should avoid driving after having SMRs due to drowsiness and hallucinations. • Patient vitals should be monitored every half hourly.
- 42. CONT… • In patientwith liver disease lower dose is given first followed by gradual increase in further dose. It is contraindicated in chronic liver disease patient or patient with hepatotoxicity. • Restriction in amount of dose in case patient has developed psychological or physical dependence.
- 43. YOUR TURN!!!!!! • Howmany types of muscle relaxants do we have? 2 i.e., peripheral acting and centrally acting • Which type of muscle relaxant is better natural or synthetic? And why? Synthetic is better. Because it has less side effects like less hypotension, fast acting, no or less histamine release, etc.
- 44. THANK YOU! BY AAYUSHISAJWAN (EN NO 25)