1) The document discusses various drugs acting on the GI system including emetics, antiemetics, purgatives, antacids, and others. 2) It focuses on emetics and antiemetics, describing the mechanisms of vomiting and the phases of vomiting. Various types of emesis are discussed. 3) Several classes of antiemetics are described including antihistamines, neuroleptics, 5-HT3 antagonists, and prokinetic drugs. Individual drugs from each class are explained along with their mechanisms of action and side effects.

1. PRESENTED BY :
VKSK PRIYANKA KAVULURU
M.Sc. N(OBSTETRICS & GYNAECOLOGICAL NURSING)
CLINICAL INSTRUCTOR , SMVDCoN
UNIT-IV
DRUGS ACTING ON GI SYSTEM

2. COMMONLY USED DRUGS
• EMETICS
• ANTIEMETICS
• PURGATIVES
• ANTACIDS
• CHOLINERGICS
•ANTICHOLINERGICS
•FLUID AND ELECTROLYTE THERAPY
• ANTIDIARRHOEALS
•HISTAMINES

3. EMETICS
AND
ANTI EMETICS

4. EMETICS
The drugs that produce/ induce vomiting
are called
“EMETICS””

5. NAUSEA & VOMITING :
VOMITING: Expulsion of gastric contents through mouth due to mass antiperistalsis.
NAUSEA: Uneasy feeling of vomiting.
RETCHING: Series of weaker and unproductive vomiting movements.
PHASES OF VOMITING • Vomiting is a complex process that consists of :
• PRE-EJECTION PHASE: Gastric relaxation and retro peristalsis.
• RETCHING: Rhythmic action of respiratory muscles preceding vomiting and consis
t of abdominal & intercoastal muscles and diaphragm against a closed glottis.
• EJECTION: Intense contraction of abdominal muscles and relaxation of upper
Oesophageal sphincter.
• Followed by multiple autonomic phenomena: Salivation, Shivering, Vasomotor
changes
ACT OF EMESIS

6. MECHANISM OF VOMITING
WHAT IS VOMITING?
• It is the forceful expulsion of the contents of the stomach via the mouth or sometime
s through the nose.
• The vomiting reflex is stimulated by two centers in the medulla oblangata
1 . Vomiting centre
2 .Chemoreceptor trigger zone(CTZ)
• Tactile stimulation of the back of the throat,
• Excessive stomach distension
• Increasing intracranial pressure by direct stimulation
• Stimulation of the vestibular receptors in the inner ear
• Intense pain fibre stimulation
• Direct stimulation by various chemicals, including fumes, certain drugs, and debris
from cellular death

8. TYPES OF EMESIS
MOTION SICKNESS : Result during space flights, taking off and landing of an aeropla
ne etc. It is a labyrinthine vomiting via stimulation of vestibular nuclei
MORNING SICKNESS (VOMITING DURING PREGNANCY) : During 1st trimester
of pregnancy due to effect of increased oestrogen levels on CTZ.
CHEMOTHERAPY/ RADIATION INDUCED NAUSEA AND EMESIS (CIE) : An
ti-cancer drugs induce emesis by direct activation of 5HT3 receptors in CTZ / may activate
vagal and splanchnic 5HT3 receptors to send emetogenic signals to vomiting center through
neurotransmitters.
POST OPERATIVE EMESIS : Complications in patients receiving general anaesthesia.
VOMITING OF VARIED ORIGIN & ADJUVANT ANTI-EMETIC: Drug induced vo
miting. Increased intra-cranial pressure induces emesis. Vomiting in patients due to brai
n injury, cerebral tumour, hydrocephalous- increases CSF pressure. - Activates receptors on
CTZ.

9. Classification of emetics:
Emetics According to site of action:
a. Centrally acting : Apomorphine & Morphine
b. Peripherally acting: Mustard, Potassium tartrate (tartar emetic) and
hypertonic sodium chloride
c. Both : Ipecacuanha
Emetics –centrally acting
Apomorphine:
Given SC/IM -6mg
Causes vomiting within 15 min
In hypersensitive individuals, however, even a sub therapeutic dose may elicit sever
e emesis and collapse
Vomiting is often accompanied by sedation
It should not be used if respiration is depressed
Large doses often produce restlessness, tremors, occasionally convulsions
Sometimes may cause hypotension, syncope and coma

10. Emetics –peripherally acting
Mustard: Volatile oil Formed as a result of a reaction between a glycoside and an
enzyme in the presence of water It is safe and easily available Dose -1 tsp in wat
er
Sodium chloride: Given orally Withdraws fluid from the cells lining the stomach
thus causes irritation which causes reflex emesis.
Salt water • Warm water – mild emetic • 2 spoonful of common salt in 1 pint of
warm water
Emetics –both centrally and peripherally
Ipecacuanha (Emetine)
Acts by irritating gastric mucosa as well as through CTZ Dried root of Cephalis i
pecacuanha contains emetine (alkaloid used in both anti-protozoal and to induce vomiting)
Used as syrup ipecac (15-20ml adults,10-15ml children, 5ml in infants) for inducing
vomiting Takes 15 min or more for the effect
Although apomorphine is highly effective emetic, syrup ipecac is safer.

11. Cephalis ipecacuanha अंतमूल

12. Corrosive (alkali, acid) poisoning
CNS stimulant drug poisoning
Kerosene (petroleum) poisoning
Unconscious patient
All emetics contraindicated in
Contraindication of emetics:

13. ANTIEMETICS

14. DEFINITION

15. ANTI-EMETIC MECHANISM

18. CLASSIFICATION OF
ANTIEMETICS

19. CLASSIFICATION OF ANTI-EMETIC DRUGS
SL
NO
CATEGORY DRUGS
1. Anticholinergic
( Muscarinic receptor antagonist):
Hyoscine (scopolamine)
Dicyclomine
2. Histamine (h1) receptor antagonist/
H1 Antihistainics
cyclizine, promethazine, diphenhydramine, hydro
xyzine,dimenhydrinate,doxylamine, meclozine
(meclizine, cinnarizine.)
3. Neuroleptics (D2 blockers) chlorpromazine, triflupromazine,
prochlorperazine, haloperidol, etc
4. Prokinetic Drugs/
Centrally acting Dopamine receptor antago
nist
Metoclopramide, Domperidone, cisapride, mosapr
ide, itopride, levosulpride.
5. 5-HT3 antagonists Ondansetron, Granisetron, Dolansetron, Palonoset
ron, Ramosetron, Tropisetron.
6. NK 1 /Neurokinine receptor antagonist Aprepitant , Fosaprepitant
7. Other Anti-emetic drugs / Adjuvant antiem
etics
•CORTICOSTEROIDS: Betamethasone, Dexamet
hasone • VITAMIN B6 (PYRIDOXINE): • Phosp
hated carbohydrate solution, benzodiazepines, can
nabinoids

21. 1. ANTI-CHOLINERGIC DRUGS
Antiemetic action is exerted by blocking conduction of nerve
impulses from the vestibular apparatus to vomiting centre
(which involves cholinergic link )
•Hyoscine
•Dicyclomine

23. Orally.
It is used as an antispasmodic agent.
The most common adverse effects are dry mouth and
sedation

24. 2. H1 ANTIHISTAMINICS
The antiemetic action is due to
atihistminic, anticholinergic and weak
antidopaminergic action.
These drugs are useful to prevent
motion sickness, morning sickness and
post operative vomiting.
The main side effects are dry mouth,
sedation, confusion, dizziness, and
urinary retention.

25. Commonly used Antihistaminic
S
L
N
O
Drug Dose and route Main uses
1 Promthazine 25mg, oral and iv Motion sickness, Chemotherapy induce
vomiting
2 Diphenhydramine 25-50mg oral Motion sickness, Chemotherapy induce
vomiting
3 Dimenhydrinate 25-50mg oral -do-
4 Doxylamine 10-20mg oral Morning sickness
5 Mecozine (Meclizine) 25-50mg oral Sea sickness
6
.
Cinnarizine 25-50mg oral Vertigo, labrynthitis

26. 3. NEUROLEPTICS (D2 blockers)
 Neuroleptics act as potent antiemetic also.
 They act by blocking d2 receptors in CTZ.
These are less effective in motion sickness as the
vestibular pathway does not involve d2 receptors
They are mainly used in
 Postopeative /drug induced / radiation sickness, nausea
and vomiting.
Vomiting due to uremeia, liver disease, migraine etc.
Malignancy associated and cancer chemotherapy
(mildly emetogenic) induced vomiting.
The major side effects are acute muscle dystonia and extra
pyramidal side effects.

27. NEUROLEPTIC DRUGS
PROCHLORPERAZINE :
MODE OF ACTION: Blocks postsynaptic mesolimbic dopaminergic D1
and D2 receptors in the brain, including the chemoreceptor trigger zone .
DOSE / ROUTE:
5-10mg bd/tds oral adn/or 12.5-25mg by deep IM injection and is indiac
ted in vertigo and some cases of che motherapy induced vomiting.
Note: These drugs are least preferred as antiemetics due to availability of
better ad safer antiemetics.

28. 4. Prokinetic Drugs/
Centrally acting Dopamine receptor antagonist
The drugs which promote gastric emptying by enhancing the coordinat
ed propulsive motility of upper gastrointestinal tract are called
“Prokinetic drugs”
Commonly used “Prokinetic drugs” :
Metoclopramide
Domperidone
Cisapride,
Mosapride,
Itopride,
Levosulpride

29. Drug Name/
Category
Mode of
action
Dose/route Indications
Adverse
effects
METOCLOPRA
MIDE
Category:
Prokinetic
drug
It is also called as “gas
tric hurrying agent.” It
acts both
Centrally: It blocks the
d2 receptors in CTZ.
Peripherally: it has m
ore prominent effect on
upper git ; increases ga
stric peristalsis while re
laxing the pyloric sphin
cter and the first part of
duodenum. It also incre
ases the tone of lower e
sophageal sphincter (L
ES)
Adults: 10mg
TDS oral or
IM
Children: 0.2
-0.5mg/kg T
DS Oral or I
M
•Chemoptherap
y induced vomi
ting
•Post-operative
vomiting
•Dyspepsia
•GERD
•It is used as ga
strokinetic agen
t.
•Dyspepsia and
persistent hiccu
ps
•Restlessn
ess
•Dry mout
h
•Headache
•Long term
use can ca
use Parkin
soian symp
toms, gala
ctorrhea an
d gynecom
astia

30. Drug Name/
Category
Mode of
action
Dose/route Indications
Adverse
effects
DOMPERIDONE
Category:
D2 receptor
inhibitor
It acts as Metoclop
ramide but has che
mical structure lik
e haloperidol.
Adults: 10-40m
g TDS oral or I
M
Children: 0.3-0.
6mg/kg in three
e divided doses
•Chemoptherap
y induced vomi
ting
•Post-operative
vomiting
•Dyspepsia
•GERD
•It is used as ga
strokinetic agen
t.
•Dyspepsia and
persistent hiccu
ps
•Restlessn
ess
•Dry mout
h
•Headache
•Loose sto
ols

31. Drug Name/
Category
Mode of
action
Dose/route Indications
Adverse
effects
MOSAPRIDE
Category:
D2 receptor
inhibitor
It acts as Metoclop
ramide but has che
mical structure lik
e haloperidol.
Adults: 10-40m
g TDS oral or I
M
Children: 0.3-0.
6mg/kg in three
e divided doses
•Chemoptherap
y induced vomi
ting
•Post-operative
vomiting
•Dyspepsia
•GERD
•It is used as ga
strokinetic agen
t.
•Dyspepsia and
persistent hiccu
ps
•Restlessn
ess
•Dry mout
h
•Headache
•Loose sto
ols

32. Drug Name/
Category
Mode of
action
Dose/route Indications
Adverse
effects
DOMPERIDONE
Category:
D2 receptor
inhibitor
It acts as Metoclop
ramide but has che
mical structure lik
e haloperidol.
Adults: 10-40m
g TDS oral or I
M
Children: 0.3-0.
6mg/kg in three
e divided doses
•Chemoptherap
y induced vomi
ting
•Post-operative
vomiting
•Dyspepsia
•GERD
•It is used as ga
strokinetic agen
t.
•Dyspepsia and
persistent hiccu
ps
•Restlessn
ess
•Dry mout
h
•Headache
•Loose sto
ols

33. Drug Name/
Category
Mode of
action
Dose/route Indications
Adverse
effects
ITOPRIDE
Category:
D2 receptor
inhibitor
It acts as Metoclop
ramide but has che
mical structure lik
e haloperidol.
Adults: 10-40m
g TDS oral or I
M
Children: 0.3-0.
6mg/kg in three
e divided doses
•Chemoptherap
y induced vomi
ting
•Post-operative
vomiting
•Dyspepsia
•GERD
•It is used as ga
strokinetic agen
t.
•Dyspepsia and
persistent hiccu
ps
•Restlessn
ess
•Dry mout
h
•Headache
•Loose sto
ols

34. Drug Name/
Category
Mode of
action
Dose/route Indications
Adverse
effects
LEVOSULPRIDE
Category:
Selective antagonis
t of dopamine d2 re
ceptorD2 receptor .
It acts on both cent
ral and peripheral l
evels
It is usually giv
enin combinati
on with PPI (ra
beprazole) (rab
eprazole 20mg
+ levosulpiride
75mg).
•Anxiety diosrd
ers
•Dyspepsia
•Irritable bowel
syndrome(IBS)
etc.
•It can be given
safely to cardia
c patients.
•Common
sideeffects
are:
•Diarrhoea
and consti
pation(dos
e dependen
t)
•It should
not be advi
sed to stim
ulate the gi
motility in
presence o
f GI haem
orrhage,
obstruction
and perfor
ation

35. 5-HT3 antagonists
These antiemetic drug were developed to control can
cer chemotherapy or radiotherapy induced vomiting.
They block the depolarizing action of 5-HT exerted t
hrough 5-HT receptors.
Commonly used drugs are:
•Ondansetron
•Granisetron
•Palonosetron
•Ramosetron

36. Mode of action:
Cytotoxic drugs/radiation produce nausea and vomiting
Causes cellular damage
Release of mediators including 5-HT receptors from intestinal mucosa
activation of vagal afferents in the gut
Emetogenic impulses to the STN and CTZ
VOMITING
5-HT3 antagonists block
the depolarizing action of
5-HT exerted

37. Drug Name/
Category
Mode of
action
Dose/route Indications
Adverse
effects
ONDANSETRON
Category:
5-HT3
Antagonist
-do- More than 12 years an
d Adults (I.V.)
Prevention of chemoth
erapy induced emesis:
0.15 mg/ kg 3 times/da
y beginning 30 minutes pr
ior to chemotherapy or
0.45mg/kg once daily o
r
8-10mg 1-2 times/day
24mg or 32 mg once da
ily
Treatmnet of hypereme
sis gravidarum:
8 mg administered over
15 minutes every 12 hour
s or 1mg/hour infused con
tiuously for up to 24 hour
s I.M., I.V.
• Cancer Chemotherapy
(highly emetogenic dru
gs) induced vomiting
•Delayed emesis
•Prevent postoperative n
ausea and vomiting
•For radiotherapy and le
ss emetogenic drugs
•Confusion
•dizziness
•fast heartbe
at
•fever
•headache
•shortness of
breath
•weakness

38. Drug Name/
Category
Mode of
action
Dose/route Indications
Adverse
effects
GRANISETRON
Category:
5-HT3
Antagonist
-do- More than 12 years and
Adults (I.V.)
Prevention of chemothe
rapy induced emesis:
1-3mg diluted in 20-50m
l saline and infused IV over
5 min before to chemothera
py, repeated after 12 hour.
0.45mg/kg once daily or
For radiotherapy and le
ss emetogenic drugs:
• 2mg oral 1 hr before c
hemotherapy or 1mg be
fore and 1mg 12hr after
it.
To Prevent postoperativ
e nausea and vomiting:
• 1mg diluted in 5ml sal
ine and injected IV over
30 sec before starting an
esthesia or 1mg orally e
very 12 hours.
• Cancer Chemotherapy
(highly emetogenic dru
gs) induced vomiting
•Delayed emesis
•Prevent postoperative n
ausea and vomiting
•For radiotherapy and le
ss emetogenic drugs
•headache,
weakness;
•diarrhea, co
nstipation;
•stomach pai
n, indigestio
n, loss of ap
petite;
•sleep proble
ms (insomni
a); or
•fever, flu sy
mptoms.

39. Drug Name/
Category
Mode of
action
Dose/route Indications
Adverse
effects
PALONOSETR
ON
Category:
5-HT3
Antagonist
-do- It is given both oral a
nd IV routes
chemotherapy induce
d emesis:
• 250mcg by slow IV
injection 30 min befor
e chemotherapy. Do n
ot repeat before 7 day
s.
To Prevent postoperat
ive nausea and vomiti
ng:
• 75mcg IV as a single
injection just before in
duction.
• Cancer Chemother
apy (highly emetoge
nic drugs) induced v
omiting.
• it is effective in su
ppressing delayed v
omiting
•Prevent postoperati
ve nausea and vomit
ing
In addition to
common side e
ffects
• It also causes
Q-T prolongati
on, when co-a
dministered wi
th erythromyci
n, moxifloxaci
n, anti-psychot
ics, anti-depres
sans etc.
•It should alwa
ys be given by
slow IV infusi
on as rapid IV
injection may
cause blurring
of vision.

40. Drug Name/
Category
Mode of
action
Dose/route Indications
Adverse
effects
RAMOSETRON
Category:
5-HT3
Antagonist
-do- It is given both oral a
nd IV routes
Cancer chemotherapy
induced emesis:
• 0.3mg injected IV b
efore chemotherapy, a
nd repeated once daily
.
To Prevent postoperat
ive nausea and vomiti
ng:
• ramosetron 0.3mg I
V equally effective as
ondansetron 8mg IV.
-do-
It is also indicated fo
r diarrhea predomina
nt IBS as it has sho
wn potential to norm
alize disturbed colon
ic function.
• Fatigue
• Headache
• Injection site
allergic reactio
n
• Flushing (sen
se of warmth i
n the face
• ears
• neck and trun
k)
• Constipation

41. 6. NK1 RECEPTOR ANTAGONISTS
•The substance-P released due to emetogenic chemotherapy activates neurokini
n (NK1) receptors in CTZ and NTS and plays a role in the causation of vomitin
g.
• common NK1 receptor antagonist drugs are:
• APREPITANT
• FOSAPREPITANT

42. Drug Name/
Category
Mode of
action
Dose/route Indications
Adverse
effects
APREPITANT
Category:
NK1 receptor
Antagonist
-do- It is given both oral and I
V routes
Cancer chemotherapy indu
ced emesis:
• oral aprepitant (125mg +
80mg+ 80mg over 3 days)
combined with standard IV
ondansetron/ palonosetron
+ dexamethasone regimen
significantly enhances the
antiemetic efficacy against
highly emetogenic cisplatin
based chemotherapy.
To Prevent postoperative n
ausea and vomiting:
• a single (40mg) oral dose
of aprepitant is well effecti
ve in PONV
• Cancer chem
otherapy
• Post operativ
e nausea and v
omiting
Less common:
•black or tarry stools
•chills
•cough
•fever
•lower back or side
pain
•painful or difficult
urination
•pale skin
•shortness of breath
•sore throat
•ulcers, sores, or wh
ite spots in the mout
h
•unusual bleeding or
bruising
•unusual tiredness o
r weakness

43. Drug Name/
Category
Mode of
action
Dose/route Indications
Adverse
effects
FOSAPREPITA
NT
Category:
NK1 receptor
Antagonist
-do-
It is a parente
rally administ
eerd produrg
of aprepitant.
It is given in a d
ose of 150mg in
conjuction with s
tandard IV ondan
setron/palonosetr
on+dexamethaso
ne regimen.
• Cancer chemothera
py
• Post operative naus
ea and vomiting
•tiredness,
•hiccups
•nausea,
•vomiting,
•heartburn
•stomach pain,
•diarrhoea,
•constipation,
•loss of appetite
•increased thirst
•hot and dry skin,
•weakness

44. ADJUVANT
ANTIEMETICS
Corticosteroids
Benzodiazepines
Cannabinoids

45. Corticosteroids
• Corticosteroids (Dexamethasone, Methylprednis
olone) have antiemetic properties, but exact mech
anism of action is unknown.
• These agents enhance the efficacy of 5-HT3 rece
ptor antagonists.
• The commonly used corticosteroid is dexametha
sone, which is given in a dose of 8-20mg IV befor
e chemotherapy, followed by 8mg/day orally for
2-4 days.

46. Benzodiazepines(BZDs)
 BZDs have sedative action and relieve the psychogenic c
omponent of vomiting; thereby used as adjuvant to antiem
etics.
 they also suppress dystonic side effects of Metoclopram
ide.
 the commonly used BZDs are diazepam, Lorazepam (or
al/IV), and Alprazolam (oral only).

47. Cannabinoids
•They are obtained from cannabis indica and possess good
antiemetic activity. Tetrahydrocannabinol (THC) is the acti
ve principle.
• they act by agonistic action on cannabinoid receptors (CB
-1) which are located in vomiting centre and CTZ.
• they are also good appetite stimulants.
•They are not commonly used due to availability of better
drugs.
• they are used only in those patients, who do not respond t
o other antiemetics.
• common side effects are: - euphoria, dysphoria, sedation,
hallucinations, and dry mouth.

49. Thank you