1. Expectorants
Dr. M.Y. Ansari

2. Introduction
Expectorants are ingredients that increase bronchial secretions and make it easier to cough up mucus from the airways and lungs. They are used in the treatment of chesty, wet, productive or phlegmy coughs, which typically occur with a cold.
A medication that helps bring up mucus and other material from the lungs, bronchi, and trachea.
Potassium Iodide stimulates the gastric mucosa and that increases the bronchiole secretion . Ammonium chloride acts like potassium iodide but is less potent Antimony potassium tatrate also used as expectorant.
Eg. Potassium iodide, ammonium Chloride

3. AMMONIUM CHLORIDE
AMMONIUM CHLORIDE  is an acidifying agent that has expectorant and diuretic effects
It is an inorganic compound with the formula NH4Cl and a white crystalline salt that is highly soluble in water. 
Ammonium chloride occurs naturally in volcanic regions, forming on volcanic rocks near fume-releasing vents (fumaroles). The crystals deposit directly from the gaseous state and tend to be short-lived, as they dissolve easily in water.

4. Preparation
Preparation: Ammonium chloride is made by reacting hydrochloric acid with ammonia the solution is evaporated to dryness
NH3 +HCl=NH4Cl
THE PRODUCT IS PURIFIED by re-crystallisation or by sublimation

5. Assay
Weigh accurately about 3 g of Ammonium Chloride, previously dried, and dissolve in water to make exactly 250 ml.
Measure exactly 25 ml of this solution, add 10 ml of sodium hydroxide solution, and immediately equipped with a distilling apparatus connected to a receiver containing 40 ml of 0.1 mol/l sulfuric acid, exactly measured.
Heat to distill the ammonia into sulfuric acid. Titrate the excess sulfuric acid with 0.2 mol/l sodium hydroxide (indicator: 3 drops of methyl red TS).
1 ml of 0.1mol/l sulfuric acid = mg of NH4Cl
A modified Volhard method was used in IP ‘66’.
A solution of the substance acidifies with nitric acid is shaken with a measured volume of n/10 silver nitrate , nitrobenzene being previously added
Nitrobenzene is added to coagulate the precipitate of silver chloride , so that it will not interfere with the titration later of excess of silver nitrate which is determined by titration with N/10 ammonium thiosynate , using ferric ammonium sulphate as indicator.

6. Potassium iodide Molecular formula: KI Molecular weight: 166
KI, when dried, contains not less than 99.0% of KI
Description: Potassium iodide occurs as colour less or white crystals, o a white
Crystalline powder.
It is very soluble in water, soluble in ethanol (95), and practically insoluble in diethyl ether
Identification: A solution of potassium Iodide (1 in 20) responds to the Qualitative Test for potassium salt and for iodide
Purity: 1) Clarity and colour of solution- Dissolve 1.0g of Potassium iodide in 2ml of water: the solution is clear and colourless.
2) Alkaline- Dissolve 1.0g of potassium iodide in 10mL of freshly boiled and cooled water, and add 0.50mL of 0.005mol/L sulphuric acid and 1 drop of phenolphthalein : No colour develops

7. Test of purity Test of purity: Arsenic heavy metals Iron Sulphate
Thiocynate
sulphated ash
loss on drying
Calcium
Storage: Since ammonium chloride is slightly hygroscopic it is stored in well closed containers
Uses: >expectorant >diuretic and >systemic acidifiers

8. Medicinal use
Ammonium chloride is used as an expectorant in cough medicine.
Its expectorant action is caused by irritative action on the bronchial mucosa, which causes the production of excess respiratory tract fluid, which presumably is easier to cough up.
Ammonium salts are an irritant to the gastric mucosa and may induce nausea and vomiting.
Ammonium chloride is used as a systemic acidifying agent in treatment of severe metabolic alkalosis, in oral acid loading test to diagnose distal renal tubular acidosis, to maintain the urine at an acid pH in the treatment of some urinary-tract disorders

9. Thank you