Contents
• Expectorants:
• The monograph analysis of:
Ammonium chloride
Potassium iodide
Learning
Objectives
At the end of this
lecture, the student will be able to:
• Define: Expectorants:
• Explain the monograph analysis of:
Ammonium chloride
Potassium iodide
Expectorants
Expectorants: help in removing the sputum from respiratory
tract.
Classification of
expectorants:
• Sedative
• Stimulant
The inorganic compound used as expectorant are ammonium
chloride and potassium iodide
Monograph
of Ammonium chloride
Name: Ammonium
chloride
Chemical formula:
NH4Cl
Molecular weight:
53.5
Standard:
Ammonium Chloride contains not less than 99.0 per cent and not more than 100.5
per cent of NH4Cl, calculated on the dried basis
Method of preparation:
CO2 +2NH3 + 2 NaCl + H2O à 2NH4Cl + Na2CO3
Properties of
ammonium chloride:
Description:
Colourless crystals or a white, crystalline powder.
Monograph of Ammonium chloride contd—
Test for
purity:
Appearance of solution
Sulphates
pH
Thiocyanate
Sulphated ash
Arsenic
Heavy metals
Loss on drying
Iron
Calcium
Assay:
Principle Acid/Base
titration
NH4Cl + H2O à NH4OH + HCl
4NH4OH + 6HCHO à (CH2)6N4 + 10 H2O
NaOH + HCl à NaCl +H2O
Indicator:
phenolphthalein
Colour change:
colorless to pale pink
Medicinal uses:
• Expectorant
Storage: store
protected from light and moisture
Monograph
of Potassium iodide
Name: Potassium
iodide
Chemical formula:
KI
Molecular weight:
166.0
Standards:
Potassium Iodide contains not less than 99.0 per cent and not more than 100.5
per cent of KI, calculated on the dried basis
Method of
preparation:
Step: I 6 KOH + 3 I2 → KIO3 + 5 KI + 3 H2O
Step: II KIO3 + 3 C → KI + 3 CO
Properties of
potassium iodide
Description:
Colourless crystals or a white powder; odourless
Test for purity
Iodate
Appearance of solution
Alkalinity
Arsenic
Heavy metals
Iron
Barium
Cyanide
Sulphates
Thiosulphate
Loss on drying
Assay: Principle Iodometric
titration
Indicator:
Chloroform
Colour change:
purple to colourless
Storage: store
protected from light and moisture
Summary:
• Expectorants: removes sputum
• Ammonium chloride: Prepared by passing ammonia gas through
a solution of hydrochloric acid, assayed by formal titration method and
medicinally used as an expectorant
• Potassium iodide: Prepared by passing iodine gas through a
solution of potassium hydroxide, assayed by iodometric titration using
chloroform as an indicator