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Antiemetics in anaesthesia


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Antiemetics in anaesthesia

  1. 1. 1)Anticholinergics – hyoscine, dicyclomine 2)H1 antihistaminics – promethazine diphenhydramine cyclizine cinnarizine etc 3)D2 receptors antagonists – droperidol metoclopramide chlorpromazine 4)Prokinetic drugs - metoclopramide domperidone cisapride mosapride
  2. 2. 5)5HT 3 receptors antagonists – ondensetron granisetron dolasetron palonosetron 6)Adjuvants - dexamethasone benzodizepines
  3. 3. Anticholinergics - Inhibits muscurinic receptors in vestibular apparatus -Blocks the conduction of impulses from vestibular apparatus to vomitting centre -More effective against motion sicknes - Side effects : dry mouth , blurred vision constipation urinary retention
  4. 4. Hyoscine : also known as scopolamine most effective for motion sickness transdermal patch which works for 3 days can be useful for prevention of postdischarge nausea and vomiting in an ambulatory patient Atropine : not a primary antiemetic less incidence of post operative nausea and vomiting when used with neostigmine to reverse neuromuscular blockade than glycopyrrolate probably because of its central action
  5. 5. -Effective in motion sickness -Highly sedative -May delay the recovery when given before the end of anaesthesia -More useful in treating allergic rhinitis And chronic urticaria e.g. promethazine, diphenhydramine cinnarazine , cyclizine
  6. 6. -D2 Receptors are located in CTZ and in the gut wall -Morphine induces vomiting through these receptors -Antagonists more useful for opioid induced vomiting -Less effective in motion sickness as vestibular pathway does not involve dopaminergic link
  7. 7. METOCLOPRAMIDE : - Antidopaminergic and prokinetic actionc -prokinetic action more helpful during emergency anaesthesia for patient with inadequate starvation -Dose more than 10mg is avoided – can cause dystonia -Dystonia can be prevented by adminstration of benzodizepine during anaesthesia
  8. 8. Droperidol : - Highly sedative - short half life of 3 hrs - supplimentation with morphine loaded PCA (patient controlled analgesia) pump highly effective in preventing opioid induced vomitting - anticonvulsive property
  9. 9. SIDE EFFECTS : -Extra pyrimidal – dystonia, restlessness, dyskinesia etc. -Galectorrhorea - Dysphorea - QT prolongation ( droperidol)
  10. 10. -Antagonism of D2 receptors in the gut wall -Enhancing Ach release from myentric motor neurons -Increases gastric persistalsis and LES tone -This action is helpful in patient who is full stomach and to be induced in emergency -Enhances gastric emptying in diabetic patients with autonomic neuropathy
  11. 11. METOCLOPROMIDE : -central as well as GI action DOMPERIDONE : - blocks D2 receptors in upper GI - no central action - less extrapyrimidal side effects CISAPRIDE : - Prokinetic action mainly through Ach release from myentric neurons - no extrapyrimidal side effects - prolong QT syndrome
  12. 12. -5HT3 receptors in the gut are linked with CTZ via afferent vagus -cytotoxic drugs , radiation release serotonin from enterocromaffin cells which acts on 5HT3 receptors -triggers CTZ via vagus causing emesis -5HT3 antagonists most effective against chemotherapy induced vomiting -Also effective against PONV -Advantages : no extrapyrimidal or sedative side effects like previous antiemetics
  13. 13. ONDENSETRON: -1ST drug introduced in this group -Dose 0.1 mg/kg -Plasma half life of 4hrs -metabolism by cyto P450 enzyme -genetic polymorphism of this enzyme leads to decreased efficacy due to ultrarapid metabolism -Effective when given at the end of the surgery -- effective in treatment of pruritus caused by neuraxial opioid adminstration
  14. 14. GRANISETRON : -Half life twice as that of ondensetron -Requires less frequent dosing -Dose 20 mcg/kg OTHER 5HT3 antagonists : dolasetron palanosetron ( longest acting)
  15. 15. These drugs enhances antiemetic property of Primary drugs DEXAMETHASONE: -Supposedly has action on nucleus tractus solitarius -Onset of action is slow , better to be given at the begining of surgery during general anaesthesia - Dose : 4mg is effective
  16. 16. BENZODIZEPINES: -They help by relieving anxiety, anticipatory vomiting -produce amnesia for unpleasant procedure -also supress dystonic side effects of metoclopramide PROPOFOL: Antiemet -ic dose : 10-15 mg