The document summarizes the gastrointestinal tract (GIT) and various drugs used to treat GIT disorders. It describes the main organs of the GIT including the mouth, esophagus, stomach, small intestine, and large intestine. It then discusses drugs used to treat acidity/hyperacidity conditions like antacids and acidifiers. Other drugs discussed include cathartics to treat constipation and protectives/adsorbents for diarrhea. The mechanisms of several antimicrobial agents are also outlined.

1. Mr. Ashish R. Chaudhari
ASST. PROFESSOR, M.PHARM (QA)
Department of Pharmaceutical Chemistry
Presented by :
P.R.PATIL, INSTITUTE OF PHARMACY, TALEGAON (SP), DIST- WARDHA

2. GASTROINTESTINAL TRACT
 The digestive system is the Gastrointestinal tract (GIT) which is a
group of organs.
 It extends fromAlimentary canal to the anus.
 The entrance to the system is the buccal cavity i.e. mouth.
 The main portions of GIT include-
1. Stomach
2. Small Intestine – i) Duodenum
ii) jejunum
iii)ileum
3. Large Intestine – i) Caecum
ii) Ascending colon
iii) Transverse colon
iv) Descending colon
v) Rectum with the exit anus

3. GASTROINTESTINAL TRACT

4. STOMACH
 In stomach, digestion of proteins in acidic medium takes place
with pepsin enzyme.
 Both HCl & enzyme are secreted in the stomach by specialised
cells.
Small intestine
In small intestines, the following changes takes place –
 Digestion of proteins takes place in alkaline medium in presence
of enzymes.
 Digestion of cabohydrates & lipids takes place in presence of
enzymes & bile salts.
 Absorption of digested foods, vitamins & minerals takes place.

5. EASE OF GIT
 Inadequate secretion of acid takes place in the stomach, causes
Achlorhydria or Hypochlorhydria.
 When excess secretion of acid takes place in stomach, causes
Hyperacidity or Hyperchlorhydria.
 There may occur accumulation of toxic substances or gases.
 There may occur inadequate absorption of fluids and minerals from
large intestine, thereby causing diarrhoea.
 There may occur insufficient peristaltic movement of large intestine
thereby causing constipation.
 There may occur inadequate secretion of saliva, thereby making the
food to swallow with difficulty.

6. A. Acidifying Agents or Acidifiers
1) Gastric acidifiers – eg. HCl
2) Urinary acidifiers
3) Systemic acidifiers
4) Acids
B.Antacids
1) Systemic (absorable) antacids – eg. Sodium bicarbonate
2) Non-systemic (non-absorable) antacids
a)Aluminium containing antacids eg.-Aluminium hydroxide ,
Aluminium phosphate
eg. – Calcium containing antacids,
Tribasic calcium phosphate
b) Calcium containing antacids
c) Magnesium containing antacids eg. – Magnesium carbonate,
Magnesium hydroxide

7. d) Combination antacid preparation –
eg.-Aluminium hydroxide gel & Magnesium hydroxide
Aluminium hydroxide gel & Magnesium trisilicate
C. Protectives andAdsorbents
1. Bismuth compounds- Bismuth subcarbonate, Bismuth subnitrate
D. Cathartics
1. Stimulants -
2. Bulk purgatives –
3. Lubricants
eg. Senna, rhubarb, cascara, podophyllum,
castor oil, etc.
eg. Methylcellulose, sodium
carboxymethylcellulose, gum, isapgol, etc.
- eg. Liquid paraffin, glycerin, etc.
4. Saline Cathartics – eg. Magnesium hydroxide, magnesium
sulphate,etc

8. ACIDIFYING AGENTS/ACIDIFIERS
These are the inorganic chemical substances that either produce
or increase acids.
These chemicals increase the level of acid in the stomach when
ingested, thereby decreasing the stomach PH.
 Gastric acidifiers : These are the drugs which are used to increase
acidity of the stomach in patients suffering from achlorhydria or
hypochlorhydria.
 Urinary acidifiers : These are the drugs which are used to remove
acidic urine from the body or to maintain the PH of urine.
 Systemic acidifiers : These are the drugs which are able to neutralise
alkaline body fluids, specially bloodor to maintain the Ph of all parts
of body.
 Acid : These are used as pharmaceutical aids in preparation of
medicaments.

9. HYDROCHLORIC ACID
Molecular wt. : 36.46
Molecular formula : HCl
Synonyms : Spirit of salt, Muriatic acid
Preparation :
It can be prepared by the action conc. Sulphuric acid on Sodium Chloride and
passing the liberated Hydrogen Chloride through water.
NaCl +H2SO4 NaHSO4 + HCl
Properties:
1. It is nearly colourless clear and fuming liquid.
2. It possesses pungent odour.
3. It is soluble with water and alcohol.
4. It is a strong acid and attacks metals, foaming the hydrochlorides with the
evolution of gas.
Chemical properties :
1. It reacts with sodium metal which results in the formation of sodium
chloride and liberates hydrogen gas.
2Na + 2 HCl 2NaCl + H2
2. It is oxidised by strong oxidising agents liberating chlorine gas.
2 KMnO4 + 16 HCl 2 MnCl2 + 2 KCl + 8 H2O + 5 Cl2

10. Storage :
It is stored in well closed container of glass or other
inert material at a temperature not exceeding 30 c.
Uses :
1. It is used as a pharmaceutical aid or as an acidifying
agents.
2. Used as gastric acidifiers when levels of
hydrochloric acid in gastric juice are low.
3. Externally used as a solvent, catalyst in bais
pharmaceuticals and as acidifiers.
Dose : 0.6- 8 ml

11. ANTACIDS
 These are the drugs or preparations which neutralise excess HCl in the body.
 Antacids are usually alkaline substances & it is given to the patients
suffering from Hyperchlorhydria (hyperacidity)
 It is known that the production of gastric hydrochloric acid is a continual process. It
means that administration of antacids is also a continual process.
 Under the normal physiological conditions, hydrochloric acid is secreted by
epithelial cells of
gastric mucosa.
 The PH of stomach depends upon the intake of food.
 Depending upon the location ulcers can be classified as oesophageal ulcer(affets
oesophagus), gastic ulcer(affects gastric mucosa), duodenal ulcer (affects
duodenum)

12. FOLLOWS :
1) Systemic(absorable) antacids : These are water soluble and cause metabolic
alkalosis.
Eg. – Sodium bicarbonate
2) Non- systemic (non-absorable) antacids : These are not absorbed to a
significant extent. This group is further divided into following :
a) Aluminium containing antacids : eg.- Aluminium hydroxide (AlOH3),
aluminium phosphate(AlPO4), dihydroxyaluminium aminoacetate,
dihydroxyaluminium sodium carbonate, basic aluminium carbonate.
a) Calcium containing anatcids : eg. – calcium carbonate, tribasic calcium
phosphate.
a) Magesium containing antacids : eg.- Magnesium carbonate, Magnesium
citrate, ,magnesium hydroxide, magnesium oxide
a) Combination antacid preparation :Aluminium hydroxide gel & magnesium
hydroxide.
Aluminium hydroxide gel & magnesium trisilicate.

13. Ideal requirements ofAntacids :
I) THE ANTACID SHOULD BE ABSORABLE OR
CAUSE SYSTEMIC ALKALOSIS.
iii)
ii) The antacid should not be laxative or cause
constipation.
The antacid should exert it’s effect rapidly and over a
long period of time.
iv) The antacid should probably inhibit pepsin.
v) The antacid should have buffer in the PH range of 4-6.
vi) The reaction of the antacid with gastric hydrochloric
acid should not cause a large evolution of the acid.

14. TABLE : MARKETEDANATCID
PREPARATION
Brand Name Ingredients
Gelusil Al(OH)3 and Mg(OH)2 with M.P.S.
Digene Al(OH)3 and Mg(OH)2 with M.P.S.
Siloxogene Al(OH)3 and Mg(OH)2 and Simethicone
Almacarb Al(OH)3 with liquorice
Cogel Al(OH)3 with MgCO3
Solacid Al(OH)3, Mg(OH)2 and magnesium trisilicate

15. Cathartics :
These are the drugs which brings about defecation.
They are beneficial in constipation and for expulsion of intestinal
parasites.
In normal habits, peristalsis causes defecation. The peristaltic waves are
able to stimulate bowel and relieve it’s contents.
The peristaltic motion normally takes place about 3-4 times a day.
Constipation can also be due to many factors like weakness of intestine,
intestinal spasm, injury or use of certain drugs & diets, etc.
In constipation fecal material becomes dry & hard.
Cathartics or purgatives generally act by four different mechanisms.

16. Cathartics or purgatives generally act by four different mechanisms.
STIMUL
ANTS
Saline
Cathartics
Lubricants
Bulk
Purgatives
Cathartics

17. Stimulants :
These are the drugs or chemicals which act by local irritation on
intestinal tract and bring about stimulation of peristaltic activity.
As they are directly act on intestine & stimulate peristalsis, they are
termed as stimulants.
Eg.- Senna, Castor oil, rhubarb, etc.
Bulk Purgatives :
These are the agents which are able to increase bulk of intestinal
contents.
These are soluble or non-digestable type of materials.
Eg.- Methylcellulose, sodium carboxymethylcellulose, gum, isapgol, etc.
Lubricants :
In constipation, contents of intestine become hard because of
absorption of water by body, there results in difficulty in clearing
bowels.
Eg.- Liquid paraffin, glycerin, etc.

18. Saline Cathartics :
 These act by increasing the osmotic load of intestine by absorbing
large quantity of water & thereby stimulate peristalsis.
 Poorly absorable cations like calcium, magnesium, & anions like
phosphate, sulphate, tartrate are contributing to this effect.
 Saline cathartics are water soluble and they are taken with plenty of
water.
 This is helpful in restricting excessive loss of body fluid & reduces
nausea and vomitting.
 They may be administered by oral route in the form of suspension,
tablet or in other suitable formulations.
 Eg.- magnesium hydroxide, Magnesium sulphate, etc. & tartrate salts
of Na & K.

19. Protectives andAdsorbents
 Protectives and adsorbents are the chemically inert substances which are used in
the treatment of diarrhoea.
 Diarrhoea is defined as the frequent passage of watery stools or liquid faeces.
 As a result of increased motility in the colon, the stool may contain blood, pus,
mucus, or excess quantity of fats.
 It may be mild or chronic diarrhoea.
 Mild diarrhoea is due to bacterial infections with their toxins, side effects of
some drugs, hypersensitivity, accidental or intestinal poisoning while chronic
diarrhoea is due to the GIT disturbances, absorption and inflammation.
 Excess discharge of intestinal content leads to the loss of electrolyte which give
rise to Dehydration or Electrolyte Imbalance.
 Inorganic compounds such as Bismuth Subcarbonate, Kaolin, Bentonite, etc. are
insoluble salts which are used as protectives and adsorbents.

20. ANTIMICROBIAL AGENTS
 An antimicrobial (disinfectant & Antiseptic) is a substance that
kills or inhibits the growth of microorganisms such as bacteria,
fungi or protozoans.
 Antimicrobial agents either kill microbes (microbiocidal) or
prevents the growth of microbes (microbiostatic).

21. CLASSIFICATION OF ANTIMICROBIAL AGENTS
1. Antiseptics
2. Disinfectants
3. Germicides
4. Bacteriostatics
5. Sanitizers

22. ANTISEPTICS
These are the substances that are able to kill or prevent the growth of
microorganisms.
It acts by inhibiting their activity or destroying them specially by applying
to the living tissues like surface of skin, application of antiseptic dressings
on wounds.
The drugs like phenol, iodine, boric acid, cetrimide are the examples of
antiseptics.
Disinfectants
These are the substances that are used to prevent growth or multiplication
of microorganisms.
It is used to apply on inaminate objects (non-living objects)
Disinfectants are widely used for home & hospital sanitation.
All disinfectant solutions undergo deterioration under storage & elevated
temperature. Ex- cresol, phenol

23. GERMICIDES :
THESE ARE THE SUBSTANCES WHICH KILLS
MICROORGANISMS.
Specific terminology like “ Bactericide”(against bacteria), “ fungicide”
(against fungi), “ virucide”(against virus), etc. denotes exact action.
Bacteriostatics :
These are substances which inhibits the growth of bacteria.
Thus, bacteriostatics drugs or agents do not kill but arrest the growth
of bacteria.
Sanitizers :
Disinfectants that are used to maintain general public health standards, ae termed as
Sanitizers.
Sanitation is mainly concerned with cleaning or washing away the organic matter(saliva,
mucous, etc.)
Sanitation can be achieved only with surfaces & articles that are physically clean.
High concentration of sanitizers also cause local cellular damage.

24. Mechanism of action
 The mechanism of action of antimicrobial agents may range from
a mild astringent to powerful oxidative processes.
 Inorganic compounds are generally not used as antiinfectives for
systemic infections i.e. they are not administered internally like
antibiotics or sulphonamides.
 For topical applications(dermatological, oral, ear, opthalmic,
etc.) they may be used with caution.
 Inorganic compounds exhibits antimicrobial action by involving
either of the following three mechanisms
i) Oxidation
ii) Halogenation
iii) Protein binding or precipitation

25. Oxidation mechanism
 Examples of compounds acting by this mechanism are
peroxides of peroxy acids, oxygen liberating compounds
like potassium permagnate.
 They bring about oxidation of active functional groups
present in proteins and enzymes vital to the growth and
survival of microorganisms.
 This causes a change in the confirmation of the proteins &
thereby alters it’s function.
 For ex- a free sulfhyhydryl group has been essential for
functioning of a variety of proteins & enzymes.
 This free nature of sulfyhydryl group gets destroyed by
oxidation resulting into a formation of a disulfide bond.

26. 2. HALOGENATION
MECHANISM
 Examples of compounds acting by this mechanism are the compounds
which are able to liberate chlorine or hydrochloride or iodine.
 This category of agents act on the peptide linkage & alter it’s potential
& property.
 The destruction of specific function of protein causes death of micro-
organisms.
 Most of the enzymes are proteinous in nature.
 Aprotein molecule is composed of a variety of amino acids connected
through a peptide (--CONH--) linkage.
 As hydrochlorites (Ocl-) are found to chlorinate peptide linkage exert
their antimicrobial activity by chlorination of peptide linkages in
protein molecules.

27. Protein precipitation :
 Examples of compounds acting by this mechanism are metal
ions(eg.-Astringents)
 Polar group of proteins binds with metal ions to form complex.
 The complex formed may be strong chelate leading to
inactivation of proteins

28. Characteristics ofAntimicrobial agents
1. It should possess antiseptic/germicide activity .
2. It should have rapid onset of action.
3. It should not cause local cell damage.
4. It should not interfere with body defence.
5. It should show no systemic toxicity from topical applications.

29. IODINE
Chemical formula : I2 Molecular wt. – 126.9
Iodine compounds are very common in nature.
Sea water is also having traces of combined iodine, which gets absorbed by
some specific plants and sea weeds, like Laminaria digitata.
Iodine also occurs in the form of sodium iodate.
Preparation :
 It is manufactured by extracting kelp(seaweed’s ash) with water.
 When the sulphate and chloride of sodium and potassium gel crystalised
out, the solution is concentrated, leaving freely soluble sodium and
potassium iodide in the mother liquor.
 Sulphuric acid is added to mother liquor, small amount of thiosulphate and
sulphide are allowed to settle down.
 Mother liquor is decanted and to this MnO2 is added and iodine distills over.

30. Various Iodine preparations
1. AQUEOUS IODINE
SOLUTION
2. WEAK IODINE SOLUTION
3. STRONG IODINE SOLUTION
4. POVIDONE IODINE SOLUTION
5. TINCTURE OF IODINE

31. NOTE ON COMPOSITION OF VARIOUS
IODINE PREPARATIONS
1) Aqueous iodine praparation:
Synonym : Lugol’s solution
It is having 5% w/v of iodine and 10% w/v of potassium iodide in purified water.
Composition :
Iodine
Potassium iodide
Purified water
50 g
100 g
1000 ml
2) Weak iodine preparation :
Synonym : Tincture of iodine
It is having 2% w/v of iodine and 2.5 % w/v of potassium iodide.
Composition :
Iodine
Potassium iodide
Alcohol(50%)
20 g
25 g
1000 ml

32. POVIDONE
IODINE
Povidone iodine is an aqueous solution of povidone iodine. It is a complex produced
by the interaction between iodine and povidone (polyvinyl pyrrolidine). The
complex has 10% available iodine.
Description :
 Complex occurs as yellowish brown, amorphous powder and has characteristic
odour.
 Soluble in water and alcohol.
 The solution is transparent in nature, has reddish brown colour and faint smell of
iodine.
Action and uses :
1. It is a powerful bactercidal.
2. Used as disinfectant for the skin, wounds, mouth.
3. Effective in management of burns and cut.
4. Important advantage of this preparations over usual iodine preparations are it’s
water solubility, non-irritation, less toxic, and non staining nature. It could be
easily removed from skin and cuts by washing.

33. Hydrogen peroxide
Chemical formula : H2O2
It is an aqueous preparation of hydrogen peroxide.
Method of preparation :
1. it is obtained by adding a thick paste of Barium peroxide (BaO2
ice cold dilute sulphuric acid. The barium sulpahte will formed.
) in ice cold water to a
BaO2 + H2SO4 -------------- BaSO4 + H2O2
Barium
Peroxide
Sulphuric
acid
Barium
sulphate
Hydrogen
peroxide
2.It is also manufactured by electrolysis of ice cold 50% sulphuric acid.
2H2SO4 ----------- 2HSO4 + 2 H+
Perdisulphuric acid is formed, which on distillation under reduced pressure gives
hydrogen peroxide
2HSO4 + 2 H+ ----------- H2S2O8 (Predisulphuric acid)
H2SO4 + 2H2O ----------- H2SO4 + H2O2
3. Prepared by passing CO2 through Barium peroxide in water.
BaO2 + CO2 + H2O --------- H2O2 + BaCO3

34. PROPERTIES :
 It is colourless and odouless liquid having slightly acidic taste.
 It is a strong oxidising agent.
 The solution decomposes in contact with oxidizable matter or
when made alkaline.
Uses :
 It is a strong oxidising agent and it gives nascent oxygen.
 It is used in cleaning cuts and wounds as it is antiseptic and
germicide.
 It is used as deodorant.
 Used in bleaching the hair.
 Effective antidote in phosphurus and cyanide poisoning.

35. STORA
GE:
 It is stored in a light resistant container with a stopper made up
of glass or plastic resistant to hydrogen peroxide.
 It is kept in cool and dark place.