Expectorants - Pharmaceutical Inorganic Chemistry B. Pharma 1st Semester

Expectorants

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