Study Set Content:
Uses: A mixture of Calcium hydroxide and sodium hydroxide or potassium
hydroxide or both intended for metabolism tests, anesthesia, oxygen therapy
SODA LIMES
Other names:
o Potassium hydrogen carbonate
o Potassium acid carbonate
POTASIUM BICARBONATE
Other names: sodium hydrogen carbonate
SODIUM BICARBONATE(NaHCO3)
Use:
o Buffering agent for pharmaceutical preparations
POTASIUM BICARBONATE (KHCO3)
Use: preferred in preparation of effervescent mixtures containing sodium
bicarbonate and organic acids such as tartaric or citric
- These additives react to liberate carbon dioxide CO2 that acts as a disintegrator
producing effervescence when in water
SODIUM BICARBONATE (NaHCO3)
a solution of a weak acid and its salt or the salt of its conjugate base
or a weak base and its salt or the salt of its conjugate acid that resists drastic
changes in pH when small amounts of acid or base are added to it
buffer
Buffer control the pH of pharmaceutical products within certain specified limits for
these reasons:
Chemical stability
o Solubility of the drug
o Patient’s comfort
Some factors which can produce alteration in pH include:
Alkali in certain inexpensive containers
o Gases present in air such as carbon dioxide and ammonia (CO2 and
NH3)
The selected buffer should not:
▪ Participate in oxidation-reduction reaction
▪ Alter the solubility of other component
▪ Form complexes with active ingredient
Advantage: it contains dihydrogen and monohydrogen phosphate
ions which are found normally in the body
▪ Disadvantage: the insolubility of the phosphate salts of such metals
as Silver, Zinc, and Aluminum support microbial growth (Ag, Zn,
and Al)
Phosphate buffer system
Contains metals that would precipitate in the presence of
phosphate. They are toxic and it is suitable in external preparation,
ophthalmic, and nasal solutions but is contraindicated in parenteral
solutions
Borate buffer system
pH of 7.6 – 8.2
▪ consists of: Boric Acid, Sodium chloride NaCl (to make it isotonic),
and Sodium Borate
Feldman’s buffer system
pH of 7.6-11
▪ consists of Sodium carbonate, boric acid, and sodium chloride NaCl
Atkins and pantin buffer system
pH of 6-7.6
▪ similar to Feldman/s buffer system but sodium chloride is replaced
by Potassium chloride to make it hypotonic
▪ NaCl is replaced by KCl to make it hypotonic
Gifford buffer system
designed to provide a solution having a
specific pH for analytical purpose
Standard buffer systems
designed to maintain pH limit in
drug preparations
Actual pharmaceutical buffers
Acts as a primary solvent for most substances due to its properties:
Small size
o String permanent dipole
o High dielectric constant and availability of protons for hydrogen bonding
Acts as a primary solvent for most substances due to its properties:
Water
usually contain appreciable quantities of sodium and
magnesium sulfates
Alkaline water:
charged with carbon dioxide under pressure while in
earth
Carbonated water:
