Respiratory Stimulants | Pharmaceutical Chemistry

Respiratory Stimulants, the pharmapedia, Pharmapedia AMMONIUM CARBONATE, Carbon dioxide & Oxygen

These are drugs used to stimulate the respiratory system or restore the normal respiration by to increase the activities of the CNS.

Respiratory stimulant are the class of those drug which is used to stimulate the CNS i.e Central nervous system of the body,hence it is known as CNS stimulator. It Also stimulate the chemo receptor and vasomotor centre of the body.

These agents are used to revive an unconscious person who may have fainted.

Mechanism of Respiratory Stimulants

These drug act as a irritating agent therefore it irritate the epithelial layer of the air passage such as bronchi, trachea and lungs which leads to respiratory stimulation.

Example of Respiratory stimulants

  2. Carbon dioxide(CO2)
  3. Oxygen(O2)


Aromatic spirit of ammonia is used in reflux stimulation. Since Aromatic spirit of ammonia has two active ingredients namely ammonium carbonate & strong ammonia solution.

1. Ammonium Carbonate N.F.

Molecular formula: [(NH4)2CO3]

It contains variable proportion of ammonium bicarbonate and ammonium carbonate to yields 30 to 34 % NH3.

Synonyms: Ammonium sequin carbonate, Hartshorne & Preston’s salt, Sal Volatile

I.P. limit: Ammonium carbonate contains not less than 30% of NH3.


  1. Ammonium carbonate is manufactured by subliming a mixture of ammonium sulphate and calcium carbonate.
    2(NH4)2 SO4 (ammonium sulphate ) + 2CaCO3 ( calcium carbonate) → NH4HCO3 (Ammonium carbonate)+ NH2 COONH4
    It is also prepared by the reaction of CO2 and ammonia in presence of stream.
    3NH3 (ammonia) + 2CO2 + H2O + NH4HCO3 + NH2 COONH4


  1. White powder, alkaline to litmus.
  2. Soluble in water.
  3. On exposure to air, it decomposes into ammonia and carbon dioxide.

Assay: Back Titration Method

Weighed amount is dissolved in excess of sulphuric acid. Excess of sulphuric acid is back titrated with standard sodium hydroxide using methyl orange as indicator.

It should be stored in air tight container.


  • It is used as a respiratory stimulant.
  • It acts as expectorant and Pharmaceutical aid.
  • It is used in preparation of aromatic spirit of ammonia.

Aromatic spirit of ammonia

Aromatic spirit of ammonia contain about 2% w/v free Ammonia and 3% w/v of ammonium carbonate, 64 to 70% w/v of alcohol besides lemon oil and nutmeg oil as a flavouring agent.

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