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. 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. -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. -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. 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. 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. SIDE EFFECTS :
-Extra pyrimidal – dystonia,
restlessness,
dyskinesia etc.
-Galectorrhorea
- Dysphorea
- QT prolongation ( droperidol)
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. 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. -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. 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. GRANISETRON :
-Half life twice as that of ondensetron
-Requires less frequent dosing
-Dose 20 mcg/kg
OTHER 5HT3 antagonists :
dolasetron
palanosetron ( longest acting)
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. 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
