Table of Contents
What are Medicinal Gases?
Medicinal gases are preparations intended for patient diagnosis and treatment, especially in emergency conditions. Therapeutic gases include oxygen, carbon dioxide, nitrous oxide, helium, and nitrogen. They are administered pre-operatively, intra-operatively, post-operatively, and in emergency situations.
OXYGEN
Formula: O₂ | Molar Mass: 32 g/mol
Oxygen forms 46.6% by mass of the earth’s crust and 20.946% by volume of dry air. In the body it is transported by the blood and participates in metabolism.
Laboratory preparation:
2H₂O₂ → 2H₂O + O₂ (with MnO₂ catalyst)
2KClO₃ → 2KCl + 3O₂ (on heating)
Industrial preparation: Air is liquefied after removing CO₂ and water vapour, then fractionally distilled to yield nitrogen and oxygen.
| Property | Description |
|---|---|
| Color & State | Colourless diatomic gas |
| Odour & Taste | Odourless and tasteless |
| Solubility | Easily soluble in water |
Uses:
- Used in surgical and emergency conditions to fulfil the body’s oxygen demand
- Widely used in hospitals and nursing homes for critically ill patients
Storage:
- Stored in oxygen cylinders made of steel and aluminium alloys
- Keep away from flammable materials — oxygen is highly reactive towards them
CARBON DIOXIDE
Formula: CO₂ | Molar Mass: 44.01 g/mol
Laboratory/Commercial preparation: Heating limestone — CaCO₃(s) → CaO(s) + CO₂(g)
| Property | Description |
|---|---|
| Color & State | Colourless gas; solid form is dry ice |
| Odour & Taste | Odourless; slightly sour taste |
| Solubility | Less soluble in water |
Uses:
- Replacement solvent in the pharmaceutical industry (supercritical fluid chromatography)
- Insufflation gas in minimally invasive surgery (endoscopy) — enlarges and stabilises body cavities
- pH control in wastewater treatment
- Used in preparation of soft drinks
Storage:
- Store in cool, well-ventilated place
- Do not exceed 52°C (125°F) storage temperature
NITROUS OXIDE
Formula: N₂O | Molar Mass: 44.03 g/mol Also known as: Laughing gas, Dinitrogen oxide
Preparation: Heating ammonium nitrate — NH₄NO₃ → N₂O + 2H₂O
| Property | Description |
|---|---|
| Color & State | Colourless gas |
| Odour & Taste | Sweet smell; tasteless |
| Solubility | Insoluble in water |
Uses:
- Used as anaesthesia during surgical processes — provides sensation of pleasure and euphoria
- World’s most widely used inhaled anaesthetic — works as a quick pain reliever
- Used as an oxidant for organic compounds
- In small amounts causes mirth and euphoria; at higher concentrations can cause narcotic effects
Storage: Away from direct sunlight; dry, cool, well-ventilated area; away from incompatible materials
D.Pharma 1st Year — All Subjects Notes
D.Pharma 2nd Year — All Subjects Notes