veterinary pharmacology

1. PHARMACOLOGY OF
DRUGS
ACTING ON GIT
Submitted to;
Dr Ravikumar
Head of dept VPT

2. Gastrointestinal Tract
Continuous tube extending from the
mouth to the anus.
Major function: convert complex
compounds into simpler compounds
that can be absorbed and used by
cells.

3. GI Transit Time
Time it takes for material to pass from
one end of the GI tract to the other
end.
Subdivided into gastric emptying and
small intestine and colon transit time.
Speeding up transit time = less
absorption
Slowing transit time = more
absorption.

4. Stomach
Composed of layers of smooth muscle
lined with glands.
Glands secrete
Enzymes
Hydrochloric acid
Mucus
Food moves from the stomach to the
small intestine where most absorption
takes place.

5. Gastrointestinal System

6. DRUGS AFFECTING
SALIVARY SECRETION
 Saliva is watery & froathy substance
produced in mouth of human and animals.
 Regulation of salivary secretion is via
salivary nuclei located in brain stem, which
are excited by taste and tactile stimuli from
tongue and other areas of mouth.
 Saliva contains amylase which helps in
breakdown of starch to sugar, salivary
lipase helps in fat digestion.

7. SALIVARY
STIMULANTS/SIALICS
CLASSIFICATION
1. Indirect acting sialics- e.g. Gentian,
Nuxvomica & Quassia.
2. Direct acting sialics- e.g. Carbacol
and Arecoline.

8. INDIRECT ACTING SIALICS
 These are mainly vegetable drugs.
 They stimulate taste buds by mild irritant
action which inturn enhances salivary
secretion.
 GENTIAN- Obtained from Gentiana Lutea.
 Active principle present is Amarogentin
&Getiopicrin.
 Works as stomachic for increasing appetite.

9. DOSE OF GENTIAN
POWDER
DOG-0.3-1.2g.
CATTLE-30-60g.
SHEEP AND PIGS-4-8g .
 ROUTE OF ADMINISTRATION PER
ORAL.

10. NUX VOMICA
Obtained by strychnus nux vomica
Active principle strychnine and
Brucine.
It posses stomachic action
DOSECATTLE;4-8g TOTAL
HORSES;1.3-4g TOTAL
ROUTE OF ADMINISTRATION PER ORAL.

11. QUASSIA
Obtained from dried stem of Picraena
excelsa.
It has antihelminthic and fly repellent
property.
In small dose it act as appetite
stimulant but in large dose it induces
vomition due to irritation.

12. DIRECT ACTING SIALICS
Directly stimulates salivary gland.e.g
Cholinergic sialics like carbachol and
arecoline.
 MOA Carbachol and arecoline
stimulate salivary gland directly via
muscuranic receptor and lead to
copious flow of saliva .
Ptyalism is seen in intoxication of
organophosphorous ,carbamates and
pyrethroid poisoning.

13. ANTISIALICS
Decrease the flow of saliva .
1. Used in oral surgery and as
preanasthetics.
2. Inhibition of saliva is seen as side
effect of several drugs.
3. Theraupetically antimuscuranic drugs
like ( Atrophine,
hyoscine,glycopyronium) used as anti
sialics.

14. ATROPINE & HYOSCINE
Occurs naturally & used as
preanaesthetic ,primarilly to reduce
salivary & bronchial secretions.
These are non selective anti
muscuranic drugs.
Contraindicated in Horse as it causes
CNS excitation.
 HYOSCINE has greater central
effects .

15. GLYCOPYRRONIUM
 Its longer acting synthetic quaternary
compound( highly water soluble
cannot cross BBB ) to atrophine
sulphate.
 Safe in horse.
DOSE
HORSE-0.001-0.003mg/kg IV
DOG – 0.01-0.02mg/kg s/c, IM,IV

16. GERD
 It’s long term condition where
stomach contents come back upto
esophagus.
 Symptoms include-Heartburn,
vomition, halitosis, chest pain etc..

19. Factors Contributing to GERD
 Pregnancy.
 Overeating.
 Eating on the run.
 Eating late at night.
 Drinking alcohol.
 Smoking cigarettes.
 Consuming various foods (high fat content,
caffeine, citrus, spices)

20. Therapy for GERD
Preventative behavior.
Preventative dietary changes.
Avoiding medications or other
substances that promote reflux.
Using combination of medications.

21. Agents used as Antacids
aluminum hydroxide (ALternaGel)
aluminum hydroxide-magnesium
carbonate (Gaviscon ES)
aluminum-hydroxide-magnesium
hydroxide-simethicone (Maalox Max)
magnesium hydroxide (Milk of
Magnesia)

22. Agents for GERD H2 Antagonists
Cimetidine (Tagamet, Tagamet HB)
Famotidine (Pepcid, Pepcid AC)
Nizatidine (Axid, Axid AR)
Nanitidine (Zantac, Zantac 75)

23. Histamine2 Receptor
Antagonists
Block gastric acid and pepsin
secretion.
Competitive inhibition on gastric
parietal cells.
Bedtime dose is most important.

24. Therapeutic Uses of
ranitidine (Zantac, Zantac 75)
 Active duodenal ulcers.
 Benign gastric ulcers.
 Long-term prevention of duodenal ulcers.
 Gastric hypersecretory states.
 GERD.
 Postoperative ulcers.
 Upper GI bleeding.
 Preventing stress ulcers.

25. Proton Pump Inhibitors
Blocks acid secretion by inhibiting the
hydrogen-potassium ion pump in
parietal cells.

26. omeprazole (Prilosec)
Indicated for short-term treatment.
Take before meals.
Also indicated for helicobacter pylori .
Diarrhea is primary side effect.

27. lansoprazole (Prevacid)
Indicated for short-term therapy of
ulcers and esophagitis.
Indicated for long-term treatment of
hypersecretory disorders and
Zollinger-Ellison syndrome.

28. esomeprazole (Nexium)
Very similar to Prilosec, but is
metabolized slower which increases the
duration of action.
Taken empty stomach.

29. pantoprazole (Protonix)
Less expensive than others in this
class.
Drug of choice in many hospitals due
to IV dosage form availability.

30. Agents for GERD Combinations
calcium carbonate-famotidine-
magnesium hydroxide (Pepcid
Complete)
lansoprazole-naproxen (Prevacid
NapraPAC)

31. Agents for GERD
Coating Agent:
Sucralfate (Carafate)-It’s sucrose sulfate-
aluminium complex that binds to ulcer
creating physical barrier protecting GIT
from stomach acid.
Prostaglandin E Analog:
Misoprostol (Cytotec)
Cholinergic Agent:
Bethanechol (Urecholine)

32. Prostaglandin E Analog:
Misoprostol (Cytotec)
Cholinergic Agent:
Bethanechol (Urecholine)

33. Peptic Disease
Includes:
Mucosal injury.
Erythema.
Erosions.
Ulceration.

34. Ulcer
Local defect or excavation of the
surface of an organ or tissue.
3 common types:
Gastric.
Duodenal.
Stress.

35. Gastric Ulcers
Local excavation in the gastric
mucosa.
Have malignant potential.
Occur more in men than women.
Prevalent in smokers and populations
in the Western Hemisphere.
H. pylori is a common contributing
factor.

36. Duodenal Ulcers
Peptic lesion in the duodenum.
Occur more in hypersecretors.
More difficult to treat than gastric
ulcers due to the difficulty in getting
the medication to the duodenum.

37. Rx for H. pylori
H. pylori is the cause of most peptic
ulcers.
H. pylori secretes enzymes that
neutralize stomach acid.
Antibiotics are the mainstay of
therapy, mixed with an antacid or
proton pump inhibitor.

38. Gastrointestinal Disease
Crohn’s disease: inflammatory bowel
disease
Can affect any portion of tubular GI tract
Cannot be cured with surgery

39. EMESIS
Emesis is complex process occurs due
to stimulation of vomition centre located
in medula oblangata , & due to visual &
olfactory stimuli.
 Apparent emetic impulse originating
from semicircular canal of vestibular
apparatus are transmitted by 8th cr
nerve to vestibular nuclei via
cerebellum and induces vomition.

40. Contd..
--Peripheral efferent pathway include
stimulation arising from various
visceral organs and tissues.
Blood borne emetic substance include
drugs, hormones ,endotoxic
substance induce vomition via CTZ.

41. EMETICS
Drugs which are used to evoke
vomiting.
Clinically emesis is induced to empty
anterior portion of GIT, Prior to
induction of general anaesthesia.
Mainly employed in dogs and cats.

44. Classification
LOCALLY ACTING EMETICS
e.g Ipecacuanha,luke warm
water,sodium chloride,copper
sulphate,zinc sulphate, hydrogen
peroxide.
CENTRALLY ACTING EMETICS
e.g Apomorphine and xylazine.

45. LOCALLY ACTING
 Vomition is induced by irritating the
epithelium of oropharynx,
oesophagus, stomach and duodenum.
 IPECACUANHA contains active
ingredient emetine and cephaline
thus irritating gastric mucosa
stimulating CTZ .
 Pharmacological effect it takes 15-30
mis to induce emesis in dogs and cats
.

46. SIDE EFFECTS cardiotoxicity.
NO SPECIFIC ANTIDOTE IS THERE
activated charcoal may be given.
DOSE
 Dogs & Cats ; 1-2ml/kg PO. Total
dose more than 15 ml for dog.

47.  LUKE WARM WATER
 Administered by stomach tube for
inducing vomition.
 Used in non corrosive poisoning .
 SODIUM CHLORIDE
 Induce vomition by irritating GI
mucosa
 In DOG 30-60ml PO

48. Centrally acting anti emetics
 APOMORPHINE –It acts on vomiting
centre and CTZ , its semi synthetic
derivative of morphine ,dopamine
agonist acts on D2 receptors present on
CTZ inturn induce vomition.
 CONTRAINDICATED in cats because of
CNS excitation.
 DOSE in DOG ; 0.04mg/kg IV
 XYLAZINE alpha 2 adrenoreceptor
agonist its reliable emetic in CATS.
 DOSE IN CATS ;0.4-1mg/kg IM

49. ANTI EMETICS
 Drugs which prevent vomition.
 LOCALLY ACTING ANTI EMETICS
1. Demulcants and protectants e.g. kaolin,
pectin, bismuth salts
2. Gastric antacids and local anaesthetics
e.g. magnesium hydroxide, aluminium
hydroxide and benzocaine.
3. Anticholinergics e.g. glycopyronneum,
methscopalamine, propantheline.
4. Prokinetics e.g. domperidone and
cisapride

50. CENTRALLY ACTING ANTI
EMETICS – directly act on emetic
centre
1. H1 receptor antagonist used in case of motion
sickness e.g meclozine 2-6g/kg PO in dogs
,cyclizine,cinnerazine. these are administered
30-60 min before journey .
2. D2 receptor antagonist- phenothiazine
derivative, e.g. Chlorpromazine in dogs 0.25-0.5
mg/kg .Benzamides e.g. Metachlopromide D2
blocker acts on CTZ dose in dogs 0.1-0.3 mg/kg
po.
3. 5HT3 receptor antagonist acts centrally e.g.
Ondansetron dogs and cats 0.1-0.2mg/kg.
4. Muscuranic receptor antagonist e.g.hyoscine
dogs 0.03mg/kg.

51. MISCELLANEOUS DRUGS
1. GLUCOCORTICOIDS e.g.
Dexamethasone, Methyl
prednisolone.
2. BENZODIAZEPINES e.g. Diazepam,
lorazepam and midazolam.
3. CANNABINOIDS e.g. Dronabinone
and Nabilone.

53. DRUGS AFFECTING
APPETITE
 Appetite is regulated by hunger & satiety
centre in hypothalamic nuclei & other
component of limbic system.
 Neurotransmitter are alpha 2
adrenoreceptor,D1 dopamine
receptor,seretonine are involved in controll of
appetite.
 Appetite stimulants are also called as
orexigenics/ Appetisers.
 Inhibition of satiety centre increase in
appetite.
 Stimulation of satiety centre –decrease in
appetite.

54. CLASSIFICATION OF
APPETISERS
1. BENZODIAZEPINES – inhibit satiety
centre via nor adrenaline/D1 receptor.
eg, Diazepam – 0.05-0.15g in Dog PO,
Oxazepam 0.3-0.4 mg PO in dogs.
2. CYPROHEPTADINE- is H1 blocker it
inhibits seratogenic receptors thus
inhibition of satiety centre. 5-20mg PO
in dogs.
3. GLUCOCORTICOIDS-steroids induced
euphoria results in increase feed intake.
E.g.0.25-0.5mg prednisolone in dogs
PO once a day.

55. 3)GLUCOCORTICOIDS-steroids
induced euphoria results in increase
feed intake. E.g.0.25-0.5mg
prednisolone in dogs PO once a day.
4) ANABOLIC STEROIDS-Synthetic
analogue of testosterone , they
promote appetite ,increase weight
gain.e.g.Stanozolol-0.25-3mg/kg PO
once daily.

56. contd
5) PROGESTERONE –e,g Megesterol
acetate – 5mg/kg PO in dogs.
6) MISCELLANEOUS DRUGS –e,g,
Vitamin B preperations.

57. APPETITE SUPPRESENTS
These are the agents which suppress
the appetite by stimulation of satiety
centre.
 These are used in management of
obesity due to excessive food intake.
 These are not used in veterinary
medicine.
 E,g, AMPHATAMINE used in case of
obesity.

58. Sumitted by,
C.P Sahithya
Dept of VPT