The document discusses various gastrointestinal agents used to treat disorders of the gastrointestinal tract. It describes acidifying agents and antacids which are used to alter gastric pH. Antacids work by neutralizing excess stomach acid through chemical reactions. Common antacids discussed include aluminum hydroxide, calcium carbonate, and sodium bicarbonate. The document also examines how antacids are prepared, their properties, uses, and side effects.

1. GASTROINTESTINAL AGENTS
REVATHI.G
M.PHARM
PHARMACEUTICAL CHEMISTRY
ASSISTANT PROFESSOR,SVCP

2. Gastrointestinal Agents or GIT tract
➢ One of the Vital organ Present in the body.
➢ Responsible for;
1. Consuming and digesting foodstuffs,
2. Absorbing nutrients and expelling waste.
➢ Effected by Enzymatic breakdown of complex food molecules into;
➔ Monosaccharides, Amino acids and glycerides.
➢ Dysfunction of any one of the GIT system → Human illness
➢ The tract consists of the stomach and intestines, and is divided into the upper and lower
Gastrointestinal tracts.

3. GIT AGENTS
Agents used to treat gastrointestinal disturbance are known as gastrointestinal agents.
For the treatment of gastrointestinal disorder of more serious conditions, the various inorganic
agents used to treat GIT disorders include/ classififed as:
1. Acidifying agents and antacids → Products for altering gastric pH
2. Protectives → intestinal inflammation
3. Adsorbents → intestinal toxins
4. Saline cathartics or laxatives → constipation

4. CONTENTS
ACIDIFYING AGENTS ANTACIDS PROTECTIVES AND
ADSORBENTS
SALINE CATHARTICS
Dilute Hydrochloric Acid Sodium Bicarbonate,
Aluminium Hydroxide,
Aluminium Phosphate,
Calcium Carbonate,
Magnesium Carbonate,
Magnesium Oxide,
Magnesium Trisilicate
Bismuth Sub carbonate
and
Kaolin
Sodium Potassium
Tartarate
Magnesium Sulphate

5. ACIDIFYING AGENTS
• In Digestion of Food → important constituent of gastric juice are PEPSIN (proteolytic enzyme) and Hydrochloric
acid (Hcl)
• Always there is a small quantity of gastric juice present in stomach, even it contains no food → Fasting juice
• Pepsin → most effective in acidic environment (pH 2.0) and becomes inactive at higher pH (alkaline)
• Hydrochloric acid present in gastric juice acts as;
➢ Acidifies food and stops the action of ptyalin
➢ Kills microbes which acts against to our body
➢ Provides acid environment needed for effective digestion by pepsin
• Pepsinogens → activated to pepsin by Hcl

6. HCL
Secreted By Oxyntic (parietal) Cells
Secretion under the control of;
Acetylcholine Histamine Gastrin

7. GASTRIC ACID SECRETION
GOVERNED BY
HISTAMINE MUSCARINIC GASTRIN
Mast cells post ganglionic G cells
vagal neurons

8. GASTRIC ACID SECRETION

9. PARIETAL CELLS (Oxyntic Cells)
➢Are Epithelial Cells
➢ Secrete Hydrochloric Acid (Hcl) And Intrinsic Factor.
➢Located In The Gastric Glands
➢Found In Lining Of The Fundus And Body Regions Of The Stomach.
LINK → HTTPS://YOUTU.BE/ZADJ0K0WAFY
BILE CANALICULUS (Bile Capillaries)
➢Is A Thin Tube That Collects Bile Secreted By Hepatocytes.
➢Bile Canaliculi Empty Into A Series Of Progressively
➢ Larger Bile Ductules And Ducts,
➢Which Eventually Become Common Hepatic Duct

10. ACHLORHYDRIA
Patients Suffering From Achlorhydria
1. Respond to stimulation by Histamine phosphate
• ( Release of gastric acid Increases)
2. Lack of gastric HCl even after stimulation of Hp
• 10% w/w Dil.HCl recommended to releive from achlorhydria
• Note→ Hypochlorhydria – low gastric acid content

12. DEFINITION
• Chemical Substances Which Remove The Excess Acid And Raise the pH To An Appropriate
Level In Stomach Are Called “Antacid”.
• Antacids Are the Drugs acts as a basic salt Used To Neutralize the Hydrochloric Acid Secreted in
the Stomach In Gastric Juice.
• They raise the pH of the gastric contents to above 3.5 and give the symptomatic relief of pain
( in gastric and duodenal ulcers )
• By lowering the acidity and consequently relieving the muscle spasm.
• They do this by acting as weak bases

13. ANTACID COMPOUNDS
Antacids are weak bases → used to neutralize excess stomach acid
Most antacids are weak inorganic bases
Common examples include;
1. SODIUM BICARBONATE
2. ALUMINIUM HYDROXIDE GEL
3. ALUMINIUM PHOSPHATE
4. CALCIUM CARBONATE
5. MAGNESIUM CARBONATE
6. MAGNESIUM TRISILICATE
7. MAGNESIUM OXIDE AND COMBINATION OF ANTACID PREPARATIONS

14. REACTION OF ANTACID
 Antacids react with HCl in the stomach
 Some common antacid reactions include:
CaCO3 + 2 HCl → CaCl2 + H2O + CO2
NaHCO3 + HCl → NaCl + H2O + CO2
Al(OH)3 + 3 HCl → AlCl3 + 3 H2O
Mg(OH)2 + 2 HCl → MgCl2 + 2 H2O
MgO + 2 HCl → MgCl2 + H2O

15. MECHANISM OF ANTACID
• Antacids perform a neutralization reaction, in the stomach and by inhibiting pepsin, which is a proteolytic
enzyme.
• They buffer gastric acid, raising the pH to reduce acidity in the stomach.
• When gastric hydrochloric acid reaches the nerves in the gastrointestinal mucosa, they signal pain to the central
nervous system. This happens when these nerves are exposed, as in peptic ulcers.
• The gastric acid may also reach ulcers in the esophagus or the duodenum.
• Link → https://youtu.be/d3X0gurRdhg

16. ANTACID MECHANISM

17. HOW ANTACID WORKS ?

18. CAUSES OF EXCESSIVE RELEASE OF ACIDS IN THE STOMACH

19. AVAILABLE ANTACIDS
SUSPENSION

20. SOME FAMOUS BRANDS OF ANTACIDS
1. ALKA-SELTZER – NAHCO3 AND/OR KHCO3
2. EQUATE –AL(OH)3 AND MG(OH)2
3. GAVISCON –AL(OH)3
4. MAALOX (LIQUID) –AL(OH)3 AND MG(OH)2
5. MAALOX (TABLET) – CACO3
6. MILK OF MAGNESIA – MG(OH)2
7. PEPTO-BISMOL – HOC6H4COO
8. PEPTO-BISMOL CHILDREN’S – CACO3
9. ROLAIDS – CACO3 AND MG(OH)2
10. TUMS – CACO3
11. MYLANTA

21. USES OF ANTACIDS
 It Bring Down the Percentage Of Acidity In Our Stomach And Prevent Mucus Lining In The
Stomach.
 It Prevent From Heart Burn (Acid From Stomach Rising Into Esophagus) that Can To Our Stomach
Lining.
 It Also Prevent From The Ulcer (damage To Lining Of Stomach Wall, Resulting In Loss Of Tissues
And Inflammation).

22. SIDE EFFECTS
 Magnesium Compounds May Cause Diarrhea
 Aluminum Compounds May Cause Constipation And They Also May Interfere With The
Adsorption Of Phosphates In The Formation Of Bones. This Is More Likely To Be True If They
Are Taken For An Extended Period Of Time
 Carbonates May Generate Carbon Dioxide Leading To Bloating And Flatulence.
 Calcium Compounds Containing MayAlso Increase Calcium Output In The Urine, Which
Might Be Associated With KidneyStones.
 Sodium : Increased Intake Of Sodium May Be Deleterious ForArterial Hypertension,
Heart Failure And Many Renal Diseases.

23. WHO CANNOT TAKE ANTACID
• Patient With Kidney Failure Or Heart Burn Diseases Sodium Bicarbonate Has High Sodium
Content And Is Not Appropriate For People Who Are On Salt Restricted Diet Or Have
Congestive Heart Failure High Blood Pressure Or Kidney Problem .In Pregnant If A Lady Is
Pregnant Antacid Are Safetous For Heart Burn Symptoms But Do Not UseAntacid.

24. INDICATIONS WHEN WE TAKE ANTACID
 When Heart Burn Is There Then We Take Antacid To Reduce The Heartburn.
 Treatment With Antacids Alone Is Symptomatic And Only Justified For Minor Symptoms.
 The Utility Of Many Combinations Of Antacids Is Not Clear, Although The Combination Of
Magnesium And Aluminium Salts May Prevent Alteration Of Bowel Habits.
 ATypical Feeling Of Restlessness.
 Indigestion.
 Feeling Of Nausea (Wanting To Throw Up) And Actual Vomiting.

25. CLASSIFICATION OF ANTACIDS
Non-
systemic
• Directly neutralize the acid in stomach and give
relief to gastric and duodenal ulcers.
Aluminum hydroxide gel,
Aluminum Magnesium carbonate,
Magnesium phosphate & trisilicate,
Calcium carbonate
Magnesium oxide
Systemic
• Absorbed from gut into blood circulation → cause alkalosis.
• Also called systemic alkalisers
• Injection to relieve acidosis in blood, especially diabetic coma
Sodium bicarbonate

26. COMBINATION OF ANTACID
• 3 complications are seen, when antacids used;
1. Exerts an action on the bowel with some mild laxative (MgOH) & constipation Al(OH)3 effect
2. If the Cation (metallic ion) is absorbed →systemic alkalosis (NaHCO3) produced
3. Calcium ions → hypercalcemia & mg and Al → precipitation of PO4 in GIT and Phosphorous gets
depleted
4. Affects the absorption of other drugs which are administered along with antacids such as
anticholinergics and antibiotics, due to its adsorption by antacids → alter pH and delays absorption
5. Dyspepsia → gas formation in gut – use of methylpolysiloxane ( dimethicone / simethicone )
necessary.
6. In order to minimize this defects → combination of antacids are to be used
(MgOH) + Al(OH)3 combination → Balancing the laxative and constipation effect

27. ANTACID COMBINATIONS IN CLINICAL USE
Magnesium And Aluminium
Hydroxide ( Magaldrate )
Magnesium And Aluminium
Hydroxide, Dimethicone ( Dioval
Forte Tablets )
Magnesium And Aluminium Hydroxide,
Methylpolysiloxane (Gelusil Mps)
Aluminium Hydroxide Gel And
Magnesium Trisilicate (Gelusil)
Aluminium Hydroxide Gel,
Magnesium Hydroxide And
Magnesium Trisilicate (Gelusil M)
Magnesium And Aluminium
Hydroxide, Methylpolysiloxane,
sodium Carboxy Methyl Cellulose
(Digene Gel)

28. SYSTEMIC ANTACIDS
1. SODIUM BICARBONATE (NaHCO3)
❑ Synonym : Baking soda
❑ Molecular Formula : NaHCO3
❑ Molecular weight : 84.01 gm
❑ Category : Antacid
❑ Standard : It contains 99 – 100.5 % equivalent of sodium bicarbonate calculated with reference to
dried compound.
❑ Preparation : LABORATORY METHOD
I) It is prepared by passing CO2 gas through NaOH solution
2 NaOH + CO2
Na2CO3 + H2O
Sodium hydroxide carbondioxide sodium carbonate water

29. II) Further, Addition Of CO2 Produces Sodium Bicarbonate Will Precipitate Out Of Solution
❑INDUSTRIAL METHOD
➢SOLVAY PROCESS
✓Brine Solution (Nacl) Is Saturated With Ammonia (To Remove Impurities).
✓The Solution Is Filtered, CO2 Is Passed Through The Solution.
✓Precipitate → Filtered And Dried.
Na2CO3 + H2O + CO2 2NaHCO 3
sodium carbonate water carbondioxide Sodium bicarbonate
H2O + CO2 → H2CO3
NH3 + H2CO3 → NH4HCO3
NaCl + NH4HCO3 → NaHCO3 + NH4Cl

30. ❑Physical properties:
✓Its is a white, odourless and crystalline powder
✓Stable in dry air and Saline Taste.
✓In moist air → decomposes to sod.co3, water, co2
✓Soluble in water
✓Insoluble in alcohol
❑ Chemical Properties:
1. When heated with water → loses water and carbondioxide and forms carbonate

31. 2. CO2 is again liberated when it is heated with any acid
3.Reacts with mercury chloride → forms Reddish brown precipitate of mercury oxide (HgO)
NaHCO3 + HCl = NaCl + H2O + CO2
Sodium bicarbonate Hydrochloric acid Sodium chloride water Carbondioxide
HgCl2 + 2NaHCO3 Hg(HCO3)2 + 2NaCl
Hg(HCO3)2
HgO + H2O + CO2
Mercury chloride Sodium bicarbonate Mercury bicarbonate Sodium chloride
Mercury bicarbonate Mercury oxide Water Carbondioxide

32. ❑ Test For Identity:
Solution of a substance + CO2 free water + Phenolphthalein
Pale pink colour is produced ( due to alkalinity of NaHCO3 )
On heating
Evolution of CO2 gas
Solution becomes Red ( due to formation of Na2CO3 )

33. ❑ Test For Purity:
✓ Arsenic
✓ Calcium
✓ Heavy metals
✓ Chloride
✓ Sulphate
❑ Assay :
Acid - base titration
Weighed amount is dissolved in water + titrated with sulphuric acid using methyl orange as indicator.
2NaHCO3 + H2SO4 → Na2 SO4 + 2CO2 + 2H2O
❑Storage condition :
✓ It should be stored in a well –closed container.
✓ Since, it slowly decomposed when exposed to moist air

34. ❑Dosage:
1 to 4 gm per day
❑Medicinal And Pharmaceutical Uses:
✓Used As An Antacid
✓Used In Systemic Acidosis, Especially In Diabetic Coma
✓Used As A Electrolyte Replinisher
✓Used As Local Application For Burns, Insect Bites Etc.
✓Used As A Constituent In Ear Drops To Soften And Remove Wax.

35. NON - SYSTEMIC ANTACIDS
1. ALUMINIUM HYDROXIDE GEL
❑Description:
✓It is an aqueous suspension of hydrated aluminium oxide together with varying amounts of basic
aluminium carbonate.
✓It contains aluminium oxide, glycerin, sucrose or saccharin as a sweetening agent, peppermint oil as a
flavouring agent and sodium benzoate as a preservative.
❑Synonym : Aluminic acid
❑ Molecular Formula : Al(OH)3
❑ Molecular weight : 78 gm
❑ Category : Antacid
❑ Standard : It contains not less than 3.5 % and not more than 4.4 % w/w Al2O3

36. ❑ Preparation :
1. Prepared by the reaction of an aluminium sulphate or aluminium chloride with sodium carbonate or
sodium bicarbonate.
2. The precipitate of aluminium hydroxide is collected, washed and resuspended in water and finally
homogenized.
3Na2 CO3 + 3H2O → 3NaHCO3 + 3 NaOH
Alcl3 + 3NaOH + H2O → 3 NaCl + Al(OH)3. 3H2O
2NaHCO3 → Na2CO3 + H2O + CO2

37. HOW TO PREPARE ALUMINIUM HYDROXIDE ?

38. ❑Physical Properties :
1. It is a white viscous suspension.
2. A clear liquid gets separated when it is kept standing for sometime.
3. pH between 5.5 to 8.0
4. Amphoteric in nature and
5. Dissolves readily in acids or alkalis → forming aluminium salts and aluminates
❑Chemical properties:
❑When heated strongly → decomposes into Aluminium oxide and water
❑It reacts with HCl → forms Aluminium Chloride
Al(OH)3 + 3HCl = AlCl3 + 3H2O

39. ❑Assay:
Complexometric titration
❑Test for Purity
✓ pH
✓ Arsenic
✓ Heavy metals
✓ Chloride
✓ Sulphate
❑Storage
Stored in a tightly closed container in a cool place. Avoid freezing.
❑Uses:
1. As an antacid.
2. Since aluminium salts produce constipation, and are therefore generally administered along with magnesium salts
to counteract this effect.
3. Used in cases of acute hyper acidity
4. Acts as a Protective in treating Peptic ulcers.

40. 1. DRIED ALUMINIUM HYDROXIDE GEL
❑ Synonym : Aluminic acid
❑ Molecular Formula : Al(OH)3
❑ Molecular weight : 78 gm
❑ Category : Antacid
❑ Standard : It contains not less than 47% and not more than 60% of Al2O3
❑Properties:
✓White, light, amorphous powder
✓Odourless and tasteless
✓Consists of;
1. hydrated aluminium oxide
2. small quantities of basic aluminium carbonate and bicarbonate
✓Insoluble in water and alcohol
✓Soluble in mineral acids

41. ❑Chemical properties:
❑When heated strongly → decomposes into Aluminium oxide and water
❑It reacts with HCl → forms Aluminium Chloride
Al(OH)3 + 3HCl = AlCl3 + 3H2O
❑Assay:
Complexometric titration
❑Test for Purity
✓ pH
✓ Arsenic
✓ Heavy metals
✓ Chloride
✓ Sulphate
❑Storage
Stored in a tightly closed container

42. ❑Medicinal and Pharmaceutical Uses:
1. As an antacid.
2. Used in cases of acute hyper acidity
3. Acts as a Protective in treating Peptic ulcers.
4. Since aluminium salts produce constipation, and are therefore generally administered along with
magnesium salts to counteract this effect.

43. 3. ALUMINIUM PHOSPHATE ( AlPO4)
❑Synonym : Dried aluminum phosphate gel
❑ Molecular Formula : AlPO4
❑ Molecular weight : 122 gm
❑ Category : Antacid
❑ Standard : It consists mainly 80% of hydrated aluminium ortho phosphate (AlPO4).
❑ Preparation :
1. By interaction between aqueous Aluminium chloride and sodium phosphate
AlCl3 + Na3PO4 AlPO4 + 3NaCl

44. HOW HCL GETS LIBERATED ?

45. 2. Solution of dried dibasic sodium phosphate in water is added slowly to solution of AlCl3 → AlPO4 is formed
along with NaCl and HCl
3. HCl formed is neutralized by adding diluted ammonia.
Mixture is filtered and washed with water to free it from soluble salts
Sufficient water is added to get a gel with Con. About 4% AlPO4
All the water is removed and product gets dried under suitable condition
To get a dried ALPO4
AlCl3.6H2O + Na2HPO4 = AlPO4 + 2NaCl + HCl + 6H2O
HCl + NH4OH = NH4Cl + H2O

46. ❑ Physical Properties :
1. It is a white powder or suspension having friable aggregates.
2. Insoluble in ethanol, water, NaOH solutions
3. Soluble in Dilute mineral acids
3. Gel → pH between 6.0 to 7.2
❑ Chemical properties:
❑ Undergoes Acid neutralizing capacity is based on the release of trivalent phosphate ion due to its
Strongly basic nature
AlPO4 Al+3 + PO4
-3

47. ❑Assay:
Complexometric titration
❑ Dosage: 5 – 15 ml ( 1 teaspoonful – 1 tablespoon )
❑Test for Purity
✓Acidity and alkalinity
✓Arsenic
✓Heavy metals
✓Phosphate
❑ Storage
Stored in a well closed container

48. ❑ Medicinal and Pharmaceutical Uses:
✓Used as a Mild slow acting antacid having half the acid neutralising capacity of aluminium
hydroxide gel
✓It is better than aluminium hydroxide gel in the sense that it doesn’t interfere with the absorption
of phosphates from the intestine

49. 4. CALCIUM CARBONATE (CaCO3)
❑Synonym : Precipitated Chalk
❑ Molecular Formula : CaCO3
❑ Molecular weight : 100 gm
❑ Category : Antacid
❑ Standard : It contains not less than 98% and not more than 100.5% CaCO3
❑ Preparation :
1. Prepared by mixing solution of calcium chloride and sodium carbonate
CaCl2 + Na2CO3 CaCO3 + 2NaCl

50. Reaction B/W Calcium Chloride And Sodium Carbonate

51. 2. Prepared by passing CO2 through lime water
❑Physical Properties :
1. It is a white, odourless, tasteless microcrystalline powder
2. Insoluble water and slightly soluble in water containing CO2.
3. In Soluble in alcohol and soluble in some acids
4. Stable in Air
Ca(OH)2 + CO2 CaCO3 + H2O
Calcium hydroxide Carbondioxide Calcium carbonate

52. HOW CO2 PASSED THROUGH LIME WATER?

53. ❑Chemical properties:
It decomposes back to CaO and CO2 when heated beyond 830c. Its solubility is enhanced in presence of CO2
❑Assay :
Complexometric titration
❑Test for Purity:
✓ Arsenic
✓ Heavy metals
✓ Chloride
✓ Sulphide
✓ Barium
CaCO3 + H2O + CO2 Ca(HCO3)2
CALCIUM CARBONATE CARBONDIOXIDE CALCIUM BICARBONATE

54. ❑Storage:
Is stable in air, it may be stored in a well closed container.
❑Medicinal and Pharmaceutical Uses
✓ Used as fast acting non-systemic antacid
✓ As a supplement for calcium deficiency
✓ As Dentrifices due to mild abrasive property and in cosmetics
✓ As a precipitated chalk used in Tooth powder.
✓ Also used in treatment of some forms of diarrhoea, due to its non-irritating nature.
✓ Limestone → used in manufacture of cement, lime, washing soda and glass.

55. 5. MAGNESIUM CARBONATE (MgCO3)
(Heavy and light magnesium carbonate)
❑Synonym : Mineral magnesite
❑ Molecular Formula : MgCO3.Mg(OH)2.5H2O (Heavy) OR MgCO3.Mg(OH)2.3H2O (light)
❑ Molecular weight : 485 gm
❑ Category : Laxative
❑ Standard : It is hydrated basic MgCO3 containing 40-45% MgO
❑ Preparation :
1. Is prepared by mixing hot solutions of MgSO4 and sodium carbonate
MgSO4 + Na2CO3 MgCO3 + Na2SO4

56. 2. Is Precipitated by the addition of sodium carbonate to an aqueous solution of a Mg salt and saturating it
with CO2
MgCl2 + 2NaHCO3 + CO2 + H2O MgCO3 2NaCl + 2H2CO3
Heavy magnesium carbonate - MgCO3.Mg(OH)2.5H2O (40- 45% OF CaO)
Hot solutions of
Magnesium sulphate (125 parts) + Sodium carbonate (150 parts) in Water (250 parts)
Mixed
Evaporated → dryness
Dried Residue → treated with water
Insoluble carbonate is filtered
Washed and dried in oven

57. Light magnesium carbonate - MgCO3.Mg(OH)2.3H2O (40- 45% OF CaO)
Mixing solutions of
Magnesium sulphate (125 parts) + Sodium carbonate (150 parts) in Water (1000 parts)
Mixed
Boiled for 15 Minutes
Precipitate is obtained
filtered
Washed and dried in oven

58. MAGNESIUM CARBONATE PREPARATION

59. ❑Physical Properties : (Heavy & Light MgCO3)
1. Hydrated MgCO3 → contains 40-45 % of MgO
2. White, odourless powder or light, white and friable masses
3. In Soluble in water and alcohol but dissolve in dilute acids
4. Stable in Air
❑Chemical properties:
1. It reacts with dilute acids → strong effervescence. At 7000C, converted into MgO
MgCO3 MgO + CO2

60. 2. When heated to redness → give MgO
3[MgCO3.Mg(OH)2.5H2O] 4MgO + 3CO2 + 6H2O
❑Assay :
Complexometric titration
❑Test for Purity:
✓Arsenic
✓Heavy metals
✓Chloride
✓Sulphide
✓Copper and Lead

61. ❑Storage:
Stored in a well closed container.
❑Medicinal and Pharmaceutical Uses
✓Used as a Cathartic and laxative
✓Also used in food additive, in tooth and face powders
✓Used as a mild non-systemic Antacid

62. 6. MAGNESIUM TRISILICATE
❑Synonym : Epsom salt, Hydrated magnesium silicate
❑ Molecular Formula : 2MgO.3SiO2.3H2O
❑ Molecular weight : 261 gm
❑ Category : Adsorbent and Antacid
❑ Standard : It is hydrated basic MgCO3 containing 40-45% MgO
❑ Preparation :
1. Is prepared by mixing hot solutions of MgSO4 and sodium carbonate
2MgSO4 + 4NaSiO2 + excess 3H2O 2MgO.3SiO2.3H2O + 2Na2SO4 + SiO2

63. HOW MAGNESIUM TRISILICATE FORMULATED ?

64. ❑Physical Properties :
1. Odourless, tasteless, white grainy powder
2. Slightly hygroscopic in nature
3. Insoluble in water and alcohol
❑Chemical Properties :
1. When Treated With any acid such as dil.HCl → forms MgCl2 and gelatinous trisilicic
acid
Mg2Si3O8 + 4HCl = 2MgCl2 + H4Si3O8
Magnesium trisilicate Trisilicic acid

65. 2. It neutralises gastric acid
MgO + 2H3O Mg(OH)2 + 2H2O
MgO + 2HCl MgCl2 + H2O
❑Assay :
Complexometric titration
❑Test for Purity:
✓Arsenic
✓Heavy metals
✓Chloride
✓Sulphide
✓Copper and Lead

66. ❑Dose:
I gm four times a day
❑Storage:
Stored in a well closed container.
❑Medicinal and Pharmaceutical Uses
✓ Used as an antacid and adsorbent.
✓ Reduces gastric pain and hyperacidity
✓ Used in larger doses to induce diarrhoea
✓ Due to presence of Silicon dioxide, it acts as a protectant for gastric mucosa in ulcers.

67. 7. MAGNESIUM OXIDE (MgO)
❑Synonym : Magnesia
❑ Molecular Formula : MgO
❑ Molecular weight : 40 gm
❑ Category : Osmotic laxative and dentrifice
❑ Standard : Not less than 98 % MgO
❑ Preparation :
1. Is prepared by gently heating the magnesium carbonate
MgCO3 MgO + CO2
2. When light carbonate is heated → redness, MgO is formed
3MgCO3. Mg(OH).3H2O 4MgO + 3CO2 +4H2O

68. ❑Physical Properties :
1. Very light, bulky, white powder→ light MgO, Dense mass → heavy MgO
2. Odourless, slightly alkaline taste
3. Practically insoluble in water
4. Dissolve with dilute acids → slight effervescence
5. When exposed to air → absorbs moisture and CO2

69. ❑Chemical Properties :
1. Is soluble in carbonic acid solution
MgO + H2O + 2CO2 Mg+2 + 2HCO-3
2. At high temperatures, it reacts with carbon to form Magnesium carbide
CaC2 + MgO MgC + CaO + C
3. MgO reacts with acid → form salts
MgO + 2HCl MgCl2 + H2O
❑Assay :
Complexometric titration

70. ❑Test for Purity:
✓Arsenic
✓Heavy metals
✓Iron
✓Sulphide
✓Copper and Lead
❑Storage:
Stored in a well closed container.
❑Medicinal and Pharmaceutical Uses
• Antacid And Osmotic Laxative
• Used As An Dentrifice And Food Additives

71. COMBINATION OF ANTACID PREPARATIONS
• COMBINATIONS OFANTACID
• PREPARATIONS
• ANTACID PREPARATIONS ARE FORMULATED WITH ONE MORE THAN ONE ANTACID AS COMBINATIONS TO
COUNTERACT THE SIDE EFFECT OF ONE BY ANOTHER OR TO BE USED FOR SPECIFIC CONDITIONS.
• (I) ALUMINIUM HYDROXIDE GEL – MAGNESIUM HYDROXIDE COMBINATION.
• PREPARATION: AVAILABLE AS ORAL SUSPENSION AND TABLETS.
• ADV: SINCE ALUMINIUM SALTS CAUSES CONSTIPATION, THIS EFFECT IS BALANCED BY LAXATIVE EFFECT OF
MAGNESIUM.
• (II) SIMETHICONE CONTAINING ANTACIDS
• IT IS FORMULATED ALONG WITH ALUMINIUM HYDROXIDE GEL AND MAGNESIUM HYDROXIDE.
• IT IS AVAILABLE AS ORAL SUSPENSION AND TABLET.
• ADVANTAGE: SIMETHICONE RELIEVES FLATULENCE.
• (III) ALUMINIUM HYDROXIDE GEL – MAGNESIUM TRISILICATE COMBINATION
• IT IS AVAILABLE AS ORAL SUSPENSION AND TABLET.
• ADVANTAGE:
• MAGNESIUM TRISILICATE HAS PROTECTIVE EFFECT.

72. Magnesium And Aluminium
Hydroxide ( Magaldrate )
Magnesium And Aluminium
Hydroxide, Dimethicone ( Dioval
Forte Tablets )
Magnesium And Aluminium Hydroxide,
Methylpolysiloxane (Gelusil Mps)
Aluminium Hydroxide Gel And
Magnesium Trisilicate (Gelusil)
Aluminium Hydroxide Gel, Magnesium
Hydroxide And Magnesium Trisilicate
(Gelusil M)
Magnesium And Aluminium Hydroxide,
Methylpolysiloxane, sodium Carboxy
Methyl Cellulose (Digene Gel)

73. Magnesium And Aluminium Hydroxide
( Magaldrate )
Magaldrate → product of chemical combination of aluminium hydroxide and magnesium
hydroxide along with the sulphates of aluminium and magnesium
❑Synonym : MAGALDRATUM
❑ Molecular Formula : Al5Mg10(OH)31(SO4)2,xH2O
❑ Molecular weight : 164 gm
❑ Category : Antacid
❑ Standard : Not more than 100.5 % and Not less than 90 % Al5Mg10(OH)31(SO4)2,xH2O
❑Assay: Potentiometric titration

74. ❑Physical Properties :
1. White , crystalline powder
2. Odourless, slightly alkaline taste
3. Practically insoluble in water and water
4. Dissolve with dilute acids
❑Test for Purity:
✓ Arsenic
✓ Heavy metals
✓ Iron
✓ Sulphide
✓ Copper and Lead

75. ❑Storage:
Stored in a well closed container.
❑Medicinal and Pharmaceutical Uses
• Antacid
• Magaldrate used in the formulation of magaldrate oral suspension and oral tablet