This document discusses antacids and their preparation. It defines antacids as alkaline substances used to neutralize excess stomach acid. Ideal antacids should be absorbable, raise stomach pH to 3-4.5, maintain pH for an adequate time, and not cause constipation. Antacids are classified as systemic (absorbable) like sodium bicarbonate, or non-systemic (non-absorbable) like aluminium hydroxide, calcium carbonate, and magnesium hydroxide. The document provides details on the preparation, properties, and uses of various common antacid substances and combination preparations.

1. PHARMACEUTICAL INORGANIC CHEMISTRY
B PHARMACY 1ST SEM
ANTACID AND ITS PREPARATION
SURAJ KUMAR SHRIVASTAVA
ASST PROF
SSCPS BHILAI

3. These are the drugs which usually alkaline
substances and used for neutralizing excess acid in
the stomach of patients suffering from Hyper-
chlorhydria (hyperacidity).

4. It should be absorbable or cause systemic alkalosis.
Ability to raise the pH of the stomach to values in the range
of pH 3-4.5.
ability to maintain the desired pH for an adequate length of time.
It should not cause constipation.

5.  SYSTEMIC (ABSORBABLE) ANTACID : e.g. Sodium bicarbonate
NON SYSTEMIC(NON ABSORBABLE)ANTACID: Further classified
as
a.Aluminium containing antacids:e.g. Aluminium hydroxide,
Aluminium phosphate, Basic aluminium carbonate.
b.Calcium containing antacids:e.g. Calcium carbonate, tribasic calcium
phosphate.
c. Magnesium containing antacids: e.g. magnesium carbonate,
magnesium citrate , magnesium hydroxide.
d.Combination antacid preparation: e.g. Aluminium hydroxide gel and
magnesium hydroxide.

6. SODIUM BICARBONATE : NaHCO3 Mol wt - 84.01
It contain not less than 99% not more than 100.5% of NaHCO3.
SYNONYM - Sodium hydrogen carbonate, Baking soda , Mitha soda
PREPARATION :
2NaOH + CO2 → Na2CO3 + H2O
Na2CO3 + H2O + CO2 → 2 NaHCO3
PROPERTIES : Occurs as white crystaline or amorphous powder
saline taste. Freely soluble in water bt practicaly insoluble in alcohol
USES: It is mainly used as an electrolyte replenisher. it is mainly used
for its acid neutralizing properties , Antacid .

7. Aluminium hydroxide gel - Al(OH)3 Mol wt 77.7
It is aqueous white viscous suspension of hydrated aluminium oxide having
varying amount of basic aluminium carbonate. Contain not less than 3.5% and not
more than 4.4 % w/w of aluminium oxide.
SYNONYM - Aluminium hydrated powder
PREPARATION :
Aluminium chloride is treated with Ammonium hydroxide then ppt aluminium
hydroxide is formed
AlCl3 + 3NH4OH  Al(OH)3 + 3NH4Cl
PROPERTIES : White viscous suspension. A clear liquid gets separated
when it is kept standing for some time. Al (OH)3 gel gives astringent AlCl3
when react with gastric HCl. Nausea, Vomiting and constipation.
USES: Very effective slow acting antacid. Not absorbed in
alimentary canal and not produce carbon dioxide. Widely used in
intestinal toxemia and hyperchlor hydria. Dos not cause gastric
alkalosis

8. CALCIUM CARBONATE - CaCO3 Mol wt – 100.
SYNONYM Precipitated chalk ppt calcium carbonate
PREPARATION
Alternatively, calcium carbonate is prepared from calcium oxide. Water is added
to give calcium hydroxide then carbon dioxide is passed through this solution to
precipitate the desired calcium carbonate, referred to in the industry as
precipitated calcium carbonate
CaO + H2O → Ca(OH)2
Ca(OH)2 + CO2 → CaCO3↓ + H2O
PROPERTIES : It is a white odourless tasteless microcrystalline powder
USES : It is used as fast acting antacid , In calcium deficiency , It is used as
Dentrifrices

9. MAGNESSIUM CARBONATE – MgCO3 Mol wt - 84.03
It is hydrated basic magnessium carbonate containing 40-50% of magnessium oxide
SYNONYM - Magnesium carbonate
PREPARATION
Magnesium carbonate can be prepared in laboratory by reaction between any
soluble magnesium salt and sodium bicarbonate:
MgCl2(aq) + 2NaHCO3(aq) → MgCO3(s) + 2NaCl(aq) + H2O(l) + CO2(g)
PROPERTIES : It is a light white friable mass or as bulky white powder , odourless ,
Practically insoluble in water and alcohol it exist in two forms heavy and light form
USES : It is used as antacid , It is used as Pharmaceutical aid

10. COMBINATION ANTACID
Preparations:
Aluminium hydroxide magnesium carbonate co dried gel: It is a co
precipitate of aluminium hydroxide and megnesium carbonate to
contain critical proportion of water for antacid activity.
 Simeco tablets: contain aluminium hydroxide magnesium carbonate
co dried gel(282mg), magnesium hydroxide (85 mg) and activated
dimethicone(25mg)
 Aluminium hydroxide gel Magnesium trisilicate combination: This is a
one of more common combination . It has laxative, constipative and
protective
 Calcium carbonate containing antacid mixture: Calcium carbonate
with aluminium hydroxide gel yield product which have rapid onset with
prolonged action.
 Magaldrate

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