This document discusses expectorants, which are drugs that help remove sputum from the respiratory tract by increasing fluidity or volume of fluids coughed up. Expectorants are classified as either sedative or stimulant. Sedative expectorants act through irritating the gastric mucosa to stimulate respiratory secretions, while stimulant expectorants directly or indirectly stimulate secretory cells. Ammonium chloride is discussed as an example sedative expectorant. Its properties, methods of preparation, chemical reactions, assay, storage, and uses are summarized.

1. EXPECTORANTS

2. DEFINITION:
Expectorants are drugs which helps in removing sputum
from the respiratory tract either by increasing the
fluidity(reduce the viscosity) of sputum or increasing the
volume of fluids by coughing .
CLASSIFICATION OF EXPECTORANTS:
According to their mechanism of action classified into two
categories
1.Sedative expectorant
2.Stimulant expectorant

3. SEDATIVE EXPECTORANT
 These type of drugs act with a reflex action by irritating the
gastric mucosa and there by stimulating respiratory tract
secretions.
• Eg. Ipecac syrup , indian squill ,ammonium chloride , potassium
iodide , antimony potassium tartrate.
• STIMULANT EXPECTORANT
• These type of expectorants which bring about a
stimulation of secretory cells of respiratory trsct
directly or indirectly
• Eg. Eucalyptus , lemon , terpin hydrate

4. AMMONIUM CHLORIDE
Molecular Formula-NH4CI
Molecular weight- 53.49g
Method of Preparation-
1. By neutralizing hydrochloric acid with
ammonia
NH3 + HCI NH4CI
2. By ammonium sulphate with sodium chloride
2NaCl + (NH4)2SO4 2NH3+2HCl+Na2SO4
2NH3+ 2HCl 2NH4CI

5. Physical Properties-
1. White, fine crystalline powder
2. Odourless and cooling saline taste
3. Hygroscopic in nature
4. Freely soluble in water but slightly soluble in
Alcohol
Chemical properties-
 In its vapour form, it dissociate in ammonia
and hydrochloric acid
NH4CI NH3+ HCI

6. Assay
 Weighed amount is dissolved in water and treated
with pre-neutralised formaldelyde solution .
 The ammonium chloride is decomposed to
methyleneimine and an equivalent amount of
hydrochloric acid .
 The liberated acid is titrated with standard NaOH
using phenolphthalein indicator .
Storage condition-
 It should be stored in well closed container

7. Uses-
1. As Expectorant
2. As Diuretics
3. As systemic Acidifier

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