Chapter No 3 : Gastrointestinal Agents

This is chapter No 3 of Pharmaceutical Chemistry - I for Diploma in Pharmacy (D. Pharmacy) Details notes for Diploma in Pharmacy (D.Pharmacy) Students.

1. Chapter 3 Gastrointestinal Agents Pharmaceutical Chemistry-I Chetan V. Jain (M-Pharma)
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CHAPTER 3 GASTROINTESTINAL AGENTS
Introduction
 GIT consist of series of organs starting from esophagus up to the Anus
which is followed by stomach, small intestine & large intestine.
 The pharmaceutical compound used in the treatment of GIT disorder /
disturbance are called as GI agents.

Figure 1 The Stomach
Classification
1) Acidified agent: the drug which increases the formation of acid is
known as acidified agents. e.g. Dil HCl
2) Antacids: The drug which neutralizes the excess of HCl secreted in the
body known as antacids. e.g. Aluminium Hydroxide
3) Protective & Adsorbent: The drug which are used in a treatment of
various GIT disorder like dysentery & diarrhea. e.g. Kaolin
4) Saline Cathartic : this are the agents increases the osmotic load in GIT

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1) Acidified Agent
 The drug which increases the formation of acid in a stomach when
stomach is empty or stomach is fully ingested with food is known as
acidified agents.
 The epithelial cell of stomach will secrete a proper acid in body & soften
of fibrous food & helps in the secretion of photolytic enzymes like
pepsin.
 When there is no secretion of acid (HCl) in the body known as
“Achlorhydria” & its symptoms are
o Sensitivity to spicy food
o Loss of appetite
o Mild Diarrhea
o Abnormal pain
 In this condition there is use of external acid like HCl known as acidified
agents & instead of HCl capsules of glutamic acid to be supplied in the
body

Dil. Hydrochloric Acid [HCl]
o Synonym : Muriatic Acid
o Limit: It contains not less than 35% and not more than 38% of HCl.
o Preparation: 10 ml Conc. HCl + up to 100 ml Water
o Properties:
 Clear Colorless Liquid.
 Pungent Odor.
 Miscible with water and alcohol.
 Fuming liquid.
o Uses:
 As a Pharmaceucal Aid (Acidifying Agent)
 As a solvent in Industry
 As a reagent in Laboratory
 For manufacturing of basic Pharmaceuticals.
o Storage: temp not exceeding 30 C in a glass stopped container.

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2) Antacids
 These are the agent which neutralizes HCl acid in the body.
 If there is excessive secretion of HCl in a stomach is known as
“Hyperchlorhydria” & if there less secretion of HCl in stomach is
known as “Hypochlorhydria” although hyper or hypo it is not
applicable for body mechanism but if there hyperchlorhydria it leads
to minimize acid level & the drugs which neutralizes or minimizes
acid level in the body is called as Antacids.
 E.g. aluminium hydroxide gel I.P.

Requirements for an ideal antacid
 It should be insoluble in water and should have fine particle size.
 The antacid should not be absorbable or cause systemic alkalosis.
 The antacid should not be a laxative or cause constipation.
 The antacid should exert its effect rapidly and over a long period of
time.
 The antacid should buffer in the pH 4-6 range.
 The reaction of the antacid with gastric hydrochloric acid should not
cause a large evolution of gas.
 The antacid should probably inhibit pepsin.

Different antacids
1. Aluminium containing antacids
a. Aluminium hydroxide gel
b. Aluminium Phosphate gel
2. Calcium containing antacids
a. Calcium carbonate
3. Sodium containing antacids
a. Sodium bicarbonate
4. Magnesium containing antacids
a. Magnesium carbonate
b. Magnesium oxide
c. Magnesium trisilicate

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Aluminium Hydroxide Gel I.P. [Al(OH)3]
o Synonym: Aluminium hydroxide powder.
o Limit: It contains not less than 3.5% and not more than 4.4% of Al2O3.
o Preparation: a hot solution of potash alum is added slowly with constant
stirring to a hot solution of sodium carbonate. After complete expulsion
of carbon dioxide the ppt of aluminium hydroxide is filtered, washed
thoroughly with hot water until free from sulphate ion
3Na2CO3 + 2KAl(SO4)2 + 3H2O  3Na2SO4 + K2SO4 + 2Al(OH)3 + 3CO2
o Properties:
 White Emulsion
 Sweet in taste due to sweating agent
 Gel is insoluble in water & alcohol
 Soluble in mineral acid.
o Uses:
 Used as antacid.
o Storage: Aluminium hydroxide should be kept in a tightly closed
container.

Aluminium Phosphate Gel IP [AlPO4]
o Limit: It contains not less than 7 % and not more than 8 % of AlPO4.
o Preparation: It is prepared by interaction between aqs. solution of
aluminium salts (Aluminium Chloride) & alkali phosphate (sodium
phosphate) with a formation of aluminium phosphate, phosphoric acid,
salt (NaCl).
2AlCl3 + 3Na2HPO4  2AlPO4 + 6NaCl + H3PO4
o Properties:
 White Emulsion
 Sweet in taste due to sweating agent
 Gel is insoluble in water & alcohol
 Soluble in mineral acid.
o Uses:
 Used as antacid.
o Storage: Aluminium phosphate should be kept in a tightly closed
container.

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Calcium Carbonate [CaCO3]
o Synonym: Precipitated Chalk
o Limit: It contains not less than 98 % and not more than 100.5 % of
CaCO3.
o Preparation: It is prepared by the interaction of sodium carbonate and
calcium chloride. The resulting precipitate is filtered & washes.
Na2CO3 + CaCl2  CaCO3 + 2NaCl
o Properties:
 White crystalline powder
 Odorless & tasteless compound
 Gel is insoluble in water & alcohol
 Soluble in mineral acid.
o Uses:
 Used as Antacid.
 Used as a cleaning & polishing agent in tooth powder.
o Storage: Calcium carbonate should be kept in a tightly closed container.

Sodium Bicarbonate [NaHCO3]
o Synonym: Backing Soda
o Limit: It contains not less than 99 % and not more than 100.5 % of
NaHCO3.
o Preparation: it is prepare by passing CO2 gas through solution of sodium
hydroxide. The solution is concentrated to obtain the product.
2NaOH + CO2  Na2CO3 + H2O
Na2CO3+ H2O + CO2  2NaHCO3
o Properties:
 White crystalline powder, Odorless & Saline taste compound
 Soluble in water & insoluble in alcohol
 The aqueous solution is alkaline in nature.
o Uses:
 Used as Antacid.
 Expectorant, eye drop, ear drop.
o Storage: Sodium Bicarbonate should be kept in a tightly closed
container.

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Magnesium Carbonate [MgCO3]
o Limit: It contains not less than 40 % and not more than 45 % of MgCO3.
o Preparation: it is prepared by double decomposition of magnesium
sulphate & sodium carbonate where each dissolve separately & mix up
into the ratio 1:1
MgSO4 + NaCO3  MgCO3 + Na2SO4
o Properties:
 White Bulky powder
 Odorless & tasteless compound
 Insoluble in water & alcohol
 Soluble in mineral acid.
o Uses:
 Antacid , mild laxative
 Adsorbent in tablet & capsules as a additives in the prevention of
formation of Eutective mixture.
o Storage: Magnesium Carbonate should be kept in a tightly closed
container.

Magnesium Oxide (MgO)
o Synonym: Magnesium Powder
o Limit: It contains not less than and not more than 98 % of MgO.
o Preparation: it is preparation by heating respective magnesium carbonate
to red hot to get formation of magnesium oxide with the expulsion of
CO2
MgCO2 MgO + CO2
o Properties:
 White powder, odorless & Slightly alkaline in taste
 Insoluble in water & alcohol
 Soluble in mineral acid.
o Uses:
 Antacid, mild laxative, in dentifrices.
 Used in formation of tablet as an additives.
 Storage: Magnesium oxide should be kept in a tightly closed container.

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Magnesium Trisilicate (MgSiO3)
o Synonym: Magnesium Powder
o Limit: It contains not less than 29% and not more than 32% of MgO &
Not less than 65% and not more than 68% of SiO2.
o Preparation: By using sodium silicate solution with magnesium sulphate
will give magnesium trisilicate.
MgSO4 + Na2SiO3  MgSiO3 + Na2SO4
o Properties:
 White slightly hydroscopic powder
 Odorless & tasteless
 Insoluble in water & alcohol
 Soluble in mineral acid.
o Uses:
 Antacid , mild laxatives
 Used in treatment of peptic ulcer.
 Storage: It should be kept in a tightly closed container.

3) Protective & Adsorbent
 The drug which are used in a treatment of various GIT disorder like
dysentery & diarrhea.
 Dysentery: It is disease marketed by frequent elimination of watery fluid
with or without mucus or blood which develops due to amoeba known
as “Entamiba Histolytica” a small protozoa causing infection called as
amoebic dysentery
 Diarrhea: Diarrhea mainly results due to improper digestion &
absorption of food & water& by the bacteria infection. In diarrhea the
frequent discharge of intestinal content in the form of watery fluid. The
loss of fluid is accompanied by loss of electrolytes, which frequently
leads to dehydration. They also causes electrolyte imbalance.

Different Protective & Adsorbent
1. Bismuth sub-carbonate
2. kaolin

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Bismuth Sub-carbonate [(BiO2).CO3]2.H2O
o Synonym: Basic Bismuth Carbonate
o Limit: It contains not less than 90% and not more than 92% of BiO2.
o Preparation: Bismuth Nitrite solution can be added with hot solution of
soda ash i.e. sodium carbonate with continuous stirring. Wash the ppt
with water & dry it in atm air
2Bi(NO3)3 + 3Na2CO3 + H2O  [(BiO2).CO3]2.H2O
o Properties:
 White or pale yellowish powder.
 Odorless & tasteless.
 Stable in air but affected by light.
 Soluble in water, alcohol & mineral acid.
o Uses:
 Antidysentric & Anti-diarrheal
 Mild astringent
 Antiseptic & Antacid.
o Storage: It should be kept in a tightly closed container.

Kaolin
o Synonym: China Clay
o It is a hydrated aluminium silicate with variable composition of calcium,
magnesium & iron.
o Preparation: it is prepared by grinding natural china clay & pass through
sieve to get very fine kaolin powder.
o Properties:
 White soft powder.
 Odorless & Clay like taste.
 Insoluble in water.
 Soluble in mineral acid.
o Uses:
 Antidysentric & Anti-diarrheal
 Used in pediatric in the form of “Kaolin Poultice”.
 As a filter.
 As a dusting powder.
o Storage: It should be kept in a tightly closed container.

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4) Saline Cathartic
 These are the agent which decreases the rate of constipation & increases
the osmotic load in GIT.
 Cathartic divided into 4 classes on the basis of its mechanism
1. Stimulant
2. Bulk purgatives
3. Lubricants
4. Saline cathartics

1. Stimulant: These are the agents which acts on directly on intestine &
stimulates peristaltic activity (movement). E.g. Senna , Castor oil
2. Bulk purgatives: They are act by increasing the bulk of intestinal
contents & stimulate peristaltic activity (movement). E.g. Methyl
Cellulose, Sapgol
3. Lubricants: They act as a smooth disposal of lubricated fecal matter
through anus. E.g. Liquid Paraffin, Glycerine.
4. Saline cathartics: These are the agents which increases the osmotic load
in GIT. E.g. Magnesium Sulphate & Sodium Potassium Tartarate.

Different Saline cathartics
1. Magnesium Sulphate
2. Sodium Potassium Tartarate

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Magnesium Sulphate (MgSO4)
o Synonym: Epsom Salt
o Limit: It contains not less than 99% and not more than 100.5% of
MgSO4.
o Preparation: it is prepared by addition of magnesium carbonate with
sulphuric acid with continuous agitation (stirring) till to remove carbon
dioxide gas.
MgCO3 + H2SO4  MgSO4 + H2O + CO2
o Properties:
 Colorless Crystalline powder
 Odorless
 Soluble in water, saline bitter taste.
o Uses:
 Saline cathartics.
 Antidote metal poising.
o Storage: It should be kept in a tightly closed container in a cool place.

Sodium Potassium Tartarate (C4H4O6.Na.K.H2O)
o Synonym: Rochelle Salt
o Limit: It contains not less than 99% and not more than 104% of
C4H4O6.Na.K.H2O.
o Preparation: It is prepared by boiling solution of sodium carbonate with
potassium bitartarate to get a salt with full expulsion of CO2.
Na2CO3 + 2KHC4H4O6  C4H4O6.Na.K.H2O + CO2
o Properties:
 White crystalline powder.
 Odorless & Saline bitter taste.
 Soluble in water & insoluble in alcohol.
o Uses:
 Saline Cathartics
 Preservatives
 Active ingredients of “Effervasant Powder”.
o Storage: It should be kept in a tightly closed container.

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Question Bank
 Define & Classification of Gastrointestinal agent.
 Describe about acidified agent & give monograph of Dilute HCl.
 Write note on Antacid with ideal requirement.
 Give monograph of aluminium, sodium, calcium & magnesium
containing antacids.
 Write note on Protective & adsorbents.
 Give monograph of Protective & adsorbents.
 Define & Classification of Cathartic.
 Give monograph of saline cathartic.