Pharmaceutical gases

1. Study of important inorganic gases
Ramesh kandel
M. Pharm

2.  Currently there are five gases in the USP.
 Oxygen
 Helium
 Carbon dioxide
 Nitrogen
 Nitrous oxide

3. Oxygen (O2; Mol. Wt. 32)
 Oxygen is necessary in the normal oxidative metabolism
for the production of useful energy.
 Oxygen occurs as a colorless, odorless, tasteless gas,
which supports combustion more energetically than dose
air.
 One liter at 0 degree centigrade and at a pressure of 760
mm of mercury weighs about 1.429 grams.
 One volume dissolves in about 32 volumes of water and in
about 7 volumes of alcohol 20 degrees and at a pressure

4.  Oxygen is stored in cylinders which are usually green-
colored ( WHO: white) or carry a green label.
 Since oxygen supports rapid combustion, there should be
no smoking or open flames nearby
 Precautions should be taken against ignition by sparks
from electrical appliances, clothing, or bedding.

5.  Oxygen is commonly administered by nasal tubes, mask,
or in tents at atmospheric pressure in concentrations
ranging from 30-80 %.
 Occasionally100 % oxygen is administered for short
periods of time.
 Another method of administration is hyperbaric oxygen
therapy in which 100 % oxygen is given at 1.5 to 3
atmospheres absolute pressure.

6.  This technique has been used for air embolism (air
bubbles in blood), carbon monoxide poisoning, gas
gangrene, crush injury, myocardial infraction, and
peripheral and cerebral vascular disease.
 A pressure chamber is required.

7. Carbon dioxide (CO2; Mol. Wt.
44.01)
 Carbon dioxide along with water, is the normal end product
of combustion, whether rapid as found in a burning flame
or very slow as found in the metabolism of all aerobic
organisms.


8.  Carbon dioxide occurs as an odorless, colorless gas. Its
aqueous solutions are acid to litmus.
 One liter at 0 degree centigrade and at a pressure of 760
mm of Hg weighs 1.977 g.
 One volume dissolves in about one volume of water.
 It is supplied in cylinders which are usually of gray metallic
color.
 It is administered in concentrations up ti 7 % in oxygen.
 It is also available as a 5% mixture with oxygen.

9.  Use for medical purposes is limited.
 It is used as respiratory stimulant since carbon dioxide is a
normal respiratory stimulant.
 Carbon dioxide, 5 to 7 % is used in the treatment of carbon
monoxide poisoning as carbon dioxide increases both the
ventilatory exchange rate and the rate of dissociation of
carbon monoxide from carboxyhemoglobin.

10.  The frozen form of carbon dioxide , dry ice, has been used
in the treatment of skin conditions as acne, angiomas (a
tumor made up of blood or lymph vessels), corns and
calluses, eczema, moles,psoriasis, and warts.
 It is used to destroy tissue by freezing it.

11. Helium (He; Mol. Wt. 4.003)
 Helium occurs as a colorless, odorless, tasteless gas,
which is not combustible and dosenot support combustion.
 One liter at 0 degree centigrade and pressure of 760 mm
of Hg weighs not less than 178 mg and not more than 180
mg.
 It is very slightly soluble in water.
 Helium is usually supplied in brown cylinders and also as a
mixture containing 20 % or 40 % oxygen in brown/green
containers.

12.  Helium is second lightest element, is used as a diluent in
oxygen administered during respiratory obstruction
(laryngeal edema, mucous plug abstructions) which cause
turbulent air flow.
 Because helium has a much lower water and fat solubility
than nitrogen, helium-oxygen mixtures are used in high
pressure, underwater diving.

13. Nitrogen (N2; Mol. Wt. 28.01)
 Nitrogen occurs as a colorless, odorless, tasteless gas.
 It is nonflammable and dose not support combustion.
 One liter at 0 degree centigrade and pressure of 760 mm
of Hg weighs about 1.251 g.
 One volume dissolves in about 65 volumes of water and in
9 volumes of alcohol at 20 degrees and a pressure of 760
mm of Hg.
 It is sold in black cylinders.

14.  Nitrogen has little therapeutic use.
 It is used as a diluent for pure oxygen and is official as a
pharmaceutic aid to displace air, usually to increase the
shelf life of an easily oxidized product.
 Nitrogen is an important constituent of plant and animal
tissues, largely as amino acids and as proteins.
 The determination of a patient’s nitrogen balance is an
important diagnostic parameter.

15. Nitrous Oxide (N20; Mol. Wt.
44.01)
 Nitrous oxide is the only inorganic gas used as an
anesthetic.
 It is called ‘laughing gas’ because of the delirium
associated with its use and has been abused.
