PharmChem1

1. ANTIOXIDANTS

2. • Compunds capable of functioning as REDUCING
AGENTS
• Pharmaceutical necessity- addition prevents oxidative
decomposition in the products.

3. • Either the antioxidant oxidizes in place of the active
constituent or inversely, the antioxidant reduces the
already oxidized active constituent back to its normal
oxidation state.
• In selecting a suitable antioxidant, the following factors
should be considered:
a) An antioxidant in a pharmaceutical preparation should be
PHYSIOLOGICALLY INERT
MECHANISM OF ACTION OF
ANTIOXIDANTS

4. b) The possible TOXICITY of both the reducing agent
and its oxidized product must be assessed
c) One should consider possible SOLUBILITY problems
between the reducing agent and the drug
d) VERY STRONG reducing agent will form explosive
mixtures when combined in dry form or in concentrated
solution with strong oxidizing agents

5. HYPOPHOSPHOROUS ACID (HPH2O2)

6. • The formation of free iodine is prevented in diluted
hydriodic acid and syrup.
• Its presence in ferrous iodide syrup ensures the non-
formation of both ferric ions and molecular iodine.
• Salts of hypophosphorus acid are antioxidants.
• Sodium hypophosphite is a preservative in certain foods.
• Ammonium hypophosphite is likewise a preservative in
many preparations.
USES:

7. SYNONYM : Sulfurous anhydride
SULFUR DIOXIDE (SO2)

8. • It will protect many susceptible compounds from
oxidation by reducing oxidized forms back to their
original compounds or by reacting with oxygen before the
susceptible compounds do.
• It is usually in injectable preparations in ampules or vials.
• It is used in industry to bleach wood pulp, to fumigate
grains and to arrest fermentation.
USES:

9. SYNONYMS: SODIUM HYDROGEN SULFITE,
SODIUM ACID SULFITE AND LEUCOGEN
SODIUM BISULFITE (NaHSO3) or SODIUM
METABISULFITE(Na2S2O5)

10. • It prevents oxidation of the compounds of phenol or
catechol nucleus to quinones.
• Bisulfite may also be found in ascorbic acid injections as a
reducing agent.
• It prepares water-soluble derivatives of normally insoluble
drugs.
• Metabisulfite is an ascorbic acid injections as reducing
agent.
USES:

11. NITROGEN(N2)

12. • As an inert atmosphere, it retards oxidation in oxidation-
sensitive products, and replaces air in containers for
parenterals and solutions for topical applications.
USES:

13. SODIUM THIOSULFATE

14. • Contains sulfur in two different oxidation states.
• The oxidized sulphur atom is in a +6 state resisting
further oxidation, whereas the remaining sulphur atom is
in a zero oxidation state. This oxidation polarity allows
the compound to act as a reducing agent. Also, sodium
thiosulfate acts as an antidote for cyanide poisoning.
USES:

15. SODIUM NITRITE

16. • Nitrites can act as both a reducing and oxidizing agent.
Reduction of compounds with sodium nitrite results in
formation of nitrates.
• It is an antidote for cyanide poisoning.
• Nitrites in brine solutions are curing ingredients of meats
and fish for they are excellent color developer, enhance
flavor production, and prevent microbial growth.
However, nitrite ions remain in cured meats and react
with organic amines to form potentially carcinogenic N-
nitrosamines.
USES:

17. GLASS

18. • Glass is the container material of choice for most small
volume infusions. It is composed chiefly of silicon
dioxide, with varying amounts of other oxides like
sodium, potassium, calcium, magnesium, aluminum,
boron and iron.
• The following are added to imaprt color to the glass:

19. Substance added Color imparted
Copper(I) oxide Opaque red, green, blue
Tin (IV) oxide Opaque
Calcium Fluoride Milky white
Manganese (IV) oxide Violet
Cobalt (II) oxide Blue
Finely divided gold Red, Purple, Blue
Uranium compounds Yellow, Green
Iron (II) compounds Green
Iron (III) compounds) Yellow
Chromium Green
Cadmium sulfide Yellow
Selenium Red or Pink

20. • Glass is formed by the silicon oxide tetrahedron. Though
boric oxide will enter into this structure, most of the
other oxides do not.
• Glass types are determined from the result of two USP
tests: the powdered glass test and water attack test. The
latter is used for type II glass.

21. • Selecting the appropriate glass composition is critical
facet of determining the overall specifications for each
parenteral formulation.
• Glass can be a source or cause of
leachables/extractables, adsorption formulation
components, especially proteins, and cracks or scratches.
• Leachability- is a property in which ions from the glass
container will leach out and interact with the product,
thereby reducing the stability of the product.

22. • Delamination or glass particulate formation- is caused by
the chemical attack on the glass matrix by the
formulation solution, resulting in the weakening of the
glass and eventual dislodgement of flakes from the glas
surface.

23. GLASS TYPES

24. • Composed principally of silicon dioxide and boric oxide,
with low levels of the non-network-forming oxides, it is
a chemically resistant glass (low leachability) with low
thermal coefficient of expansion.
• This type of container is suitable for all products
although sulfur dioxide treatment sometimes is added to
further increase its resistance.
1. TYPE I – BOROSILICATE GLASS

25. • The relatively high proportions of sodium oxide and
calcium oxide makes this glass type chemically less
resistant.
• Type II melts at lower temperature, rendering it easier to
mold into various shapes; and has a higher thermal
coefficient of expansion than Type I.
• It has a lower concentration of the migratory oxides than
Type III.
2. TYPE II – SODA-LIME TREATED GLASS

26. • This type is treated under controlled temperature and
humidity conditions with sulfur dioxide or other
dealkalizers to neutralize the interior surface of the
container.
• Type II glasses may be suitable for a solution that is
buffered, has a pH below 7, or is not reactive with glass.

27. • These glasses are composed of relatively high proportions of
sodium oxide and calcium oxide, a combination that renders
the glass chemically less resistant.
• They melt at lower temperature, are easier to mold into
various shapes, and have a higher thermal coefficient of
expansion than Type I.
• Type III glasses are suitable principally for anhydrous liquids
or dry substances.
• 4. NP – Soda- lime glass not suitable for containers
for parenterals
3. TYPE III – SODA-LIME GLASS

29. Special addition/Composition Desired Property
Large amounts of PbO with
SiO2 and Na2CO3
Brilliance, Clarity, Suitability for
optical structures; crystals or
flint glass
SiO2, B2O3, and small amounts
of Al2O3
Small coefficient if thermal
expansion; borosillicate glass
One part SiO2 and four parts
PbO
Ability to stop (absorb) large
amounts of X-rays and gamma
rays: lead glass
Large concentrations of As2O3 Transparency to infrared
radiation
REAGENTS ADDED TO MODIFY THE
CHARACTERISTICS/APPEARANCE OF GLASS