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Digestive Pharmacology/ Drug acting on GIT
1.
2. DRUG ACTING ON ALIMENTARY CANAL
Dr. YOUSUF ALI SARKER
Department of Pharmacology
Faculty of Veterinary Science, BAU
3. TALK PLAN
Introduction
Drug acting on mouth and pharynx
Drug acting on esophagus
Drug acting on stomach
Drug acting on intestine
References
4. INTRODUCTION
The digestive system process food/drugs into molecules
that can be absorbed and utilized by the cells of the body and
elimination
A long continuous tube that extends from the mouth to the
anus.
Epithelial layer:
1. Mucosa
2. Submucosa
3. Muscular layer
4. Adventatia or serosa
Site of drug interaction
5. Salivary stimulant or Sialogogue
Direct sialogogue
Carbamoylcholine, arecoline, pilocarpine
Indirect sialogogue or reflex sialogogue
Simple bitter
Alkaloid bitter
Aromatic bitter
Antisialogogue
Atropine, hyoscine, hyosciamine, kaolin
Appetizing and stomachic
DRUG ACTING ON MOUTH AND PHARYNX
6. Salivary stimulant or Sialogogue
Mechanism of action
Incase of reflex sialogogue salivation causes by stimulating taste bud
of tongue
Salivary aciner cell
Activation of cAMP or Ca2+ dependent pathway
Intracellular increases Ca2+Regulate secretory granules
Depolarization occursActivation of receptors (M3)
cAMP pathway Ca2+ pathway
Secretion occurs (Melvin, 2005)
7. Antisialogogue
Mechanism of action
Competitive antagonist for the receptors which are
responsible for salivation
e.g.: Muscarinic (M1. M2, M3, M4), adrenergic receptors
Reduce flow and fluidity of saliva
Used to limit the flow of excess saliva, which often
occurs secondary to anesthetic drug use
Atropine, hyoscine etc
8. Appetizing and Stomachic
Appetite is primarily controlled by ventral and lateral
nuclei of hypothalamus.
Several neuro-transmitter, glucocorticoids and B-
vitamins can non-specifically stimulate/ control appetite
Ammonium bicarbonate
Sodium bicarbonate
Pulv. nux vomica
Pulv. ginger
Pulv. gentian
9. DRUG ACTING ON ESOPHAGUS
Parasympathomymetics drugs: (arecoline or pilocarpine)
Stimulate salivation and increase esophageal peristalsis for the relief
of choke in animals
Phenothiazine derivative tranquilizers relief choke by relaxing
esophagus
Metoclopramide
Increases esophageal motility
Improve gastrooesophageal sphincter function
Accelerate gastric emptying
H2-antagonists
For gastroesophagel reflex disease(GERD)
Proton-pump inhibitors
10. Emetics
Antiemetics
Antacids
Proton Pump Inhibitors (PPI)
H2 blockers
Demulcents
Carminatives and
Antizymotics
DRUG ACTING ON STOMACH
11. Drugs are those causes emesis or vomition
Changes in GI muscle; rapid oral or rectal expulsion of GI contents
Treatment of toxic ingestion, acute indigestion
Morphine, Apomorphine, NaCl solution, Ipecacuanha
Emetics
(Stewart, 2010)
Classification
Centrally acting Peripherally acting Both
Morphine
Apomorphine
Nikethamide
Mustard
Antimony and K+ tartrate
Hypertonic NaCl solution
Salts of heavy metals
Ipecacuanha
(emetine &
cephaeline)
(Hornby, 2001)
13. Drugs which assist in suppressing emesis
Several neurotransmitters are responsible for stimulating
the vomiting center
Successful therapy involves blocking one or more
receptor for these neurotransmitter.
Antiemetics
Antiemetic drugs based on receptor antagonism
5-HT1, HT3 M1, M3 D2 H1 NK1
Apomorphine HCl
Dolasetron
Scopolamine Chlorpromazin
Metclorpromide
Promethazine
Doxylamine
Aprepitant
Fosaprepitant
(Riviere & Papich, n.d.)
14. Antiemetic (cntd)
Mechanism of action (Metclorpromide)
Increases peristalsis of the jejunum and duodenum
Inhibit the action of dopamine (D2 receptor)
Increases tone and amplitude of gastric contractions
Relaxes the pyloric sphincter and duodenal bulb
Pre- anesthetic medication
Motion sickness
Drug induced vomition
Morning sickness
Radiation sickness
Drowsiness
Dry mouth
Blurred vision
Constipation
Euphoria
Therapeutic Uses Adverse Effects
21. Histamine H2 receptor blockers
Inhibit secretion of gastric acid through competitive inhibition of
Histamine H2 receptors
Prevention & treatment of PUD, Esophagitis, GI bleeding,
stress ulcers
May alter the effects of other drugs through interactions with
CYP450 (especially cimetidine)
e.g.: Ranitidine, Cimetadine, Famotadine, Nizatidine,
Roxitidine
23. Coat, protect, lubricate and sooth gastric mucosa of GIT
Liquid paraffin, Vegetable oil, glycerol, Sugar
Demulcents
Agents
Mechanism of action
Coat lining of GIT
Inhibit irritation to lining
Protection & soothing
24. Expulsion of gases from the stomach (eruction)
Volatile oil, NaHCO3, MgCO3,Fennel, Peppermint
Carminatives
Correct dosage
Mechanism of action
Mild irritation to gastrointestinal mucosa
Release gas from stomach
Vasodilatation
Relaxation of gastro-intestinal musculature
(cardiac sphincter)
25. Prevent or decrease bacterial or enzymatic fermentation
Prevent further gas production during bloat or tympany
Volatile oil (liq. paraffin), chloroform, chloral hydrate, ethyl
alcohol
Antizymotics
Methyl group can increase surface tension of fluid/foam
Decrease foam stability
Mechanism of action
26. Emollient Laxative
Liquid Paraffin
Anionic Surfactant
Bulk Laxative
Stimulant Laxative
Osmotic Laxative
DRUG ACTING ON INTESTINE
Classification
Laxative are the agent that evaquate Soft formed
stool without griping and lose of water
Laxative
Di Palma, 2007
27. Mechanism of Action of Laxative
Little amount is absorbed
Increase the bulk of feces
Increase water content of the feces
Promote evacuation of feces
Polyethylene glycol (PEG3350) is a modern laxative designed to act
without the use of metabolizable or irritating substances
Di Palma, 2007
28. Purgative
Bulk Purgative
Methyl cellulose
Ispaghula husk
Osmotic Purgative
MgSO4
Lactulose
Faecal Softners (Emoliants)
Liquid paraffin
Stimulant Purgative
Glycerol
Purgative are the agent that promote defaecation as
a result of muscle contraction
Classification
29. Mechanism of Action of Purgative
They absorb water and swell and an emollient gel formation
The increased volume or bulk leads to distention with reflex
contraction producing peristaltic activity
Feces remain soft and hydrate
Defecation occurs
30. Cathertics
Oral administration of MgSO4
↓
Slow and incomplete absorption from GIT
↓
Water retained in the intestinal lumen by peristaltic movement
↓
Indirectly increased peristaltic movement, Semi-fluid and watery
evacuation
Evacuate More Fluid Feces
Osmotic Cathartics
Irritant Chathartics
Mechanism of Action
(Toxicologists, 2004)
31. Mechanism of Action
Astringent
↓
Protein precipitation
↓
Covers the surface of the cell or tissue
↓
Tissue remain impermeable to the passage of fluid in
either direction
↓
No water lose
Antidiarrhoeal
Astringent
Antispasmodic
32. Enema
GIT surgery
Radiological examination
Endoscopy
Before delivery
Rectal suppository
Uterine suppository
Vaginal suppository
Indication
33. REFERENCES
Abdel-Aziz, H., Windeck, T., Ploch, M., & Verspohl, E. J. (2006). Mode of action
of gingerols and shogaols on 5-HT3 receptors: Binding studies, cation uptake by
the receptor channel and contraction of isolated guinea-pig ileum. European
Journal of Pharmacology, 530(1-2), 136–143.
http://doi.org/10.1016/j.ejphar.2005.10.049
Di Palma, J. a, Cleveland, M. V., McGowan, J., & Herrera, J. L. (2007). A
randomized, multicenter comparison of polyethylene glycol laxative and
tegaserod in treatment of patients with chronic constipation. The American
Journal of Gastroenterology, 102(9), 1964–1971. http://doi.org/10.1111/j.1572-
0241.2007.01365.x
Lundell, L. (2015). The physiological background behind and course of
development of the first proton pump inhibitor. Scandinavian Journal of
Gastroenterology, (January), 1–5. http://doi.org/10.3109/00365521.2015.1013981
34. Najm, W. I. (2011). Peptic Ulcer Disease. Primary Care - Clinics in Office
Practice, 38(3), 383–394. http://doi.org/10.1016/j.pop.2011.05.001
Riviere, J. E., & Papich, M. G. (n.d.). Veterinary Pharmacology & Therapeutics
(pp. 1247–1270). WILEY-BLACKWELL.
Scully, C. (2003). Drug effects on salivary glands: dry mouth., 44(10), 165–176.
Retrieved from http://discovery.ucl.ac.uk/157676/
Toxicologists, C. (2004). Position paper: cathartics. Journal of Toxicology.
Clinical Toxicology, 42(3), 243–253. http://doi.org/10.1081/CLT-120039801
REFERENCES (CNTD)
Release ingredients(mucilage), These gummy, slimy chemicals have a clear and direct action on the lining of the intestines that soothes and reduces irritation by direct contac