Pharmaceutical excipients

1. PHARMACEUTICAL EXCIPIENTS
An Excipient is usually an inert substance
added to the drug to give suitable
consistency or definite form to the drug. It
is also called pharmaceutical necessity or
aid.

2. PHARMACEUTICAL EXCIPIENTS
 There are various types of pharmaceutical
excipients used in the compounding of the
pharmaceutical dosage forms. We will discuss
about chemistry, Physical properties and uses
of them.
 Lists of the important excipients:
1. Antioxidants
2. Preservatives
3. Humectants
4. Ointment bases

3. PHARMACEUTICAL EXCIPIENTS
5. Acidifying agents
6. Air displacement agents
7. Alkalizing agents
8. Antifoaming agents
9. Buffering agents
10. Chelating agents

4. PHARMACEUTICAL EXCIPIENTS
11. Coloring agents
12. Flavouring agents and Perfumes
13. Stiffening agents
13. Wetting and Solubilizing agents
15. Complexing agents, Emulsifying agents
16. Solvents.

5. Antioxidants
 An antioxidant is a substance capable of
inhibiting oxidation and that may be added for
this purpose to pharmceutical products subject to
detereoration by oxidative processes as, for
example , the development of rancidity in oils and
fats or the inactivation of some medicinals in the
environment of their dosage form.
E.g. BHA (Butylated Hydroxyanisole)
BHT (Butylated Hydroxytoluene)
Ascorbic acid, Alpha Tocopherol (Vit-E) e.t.c

6. Antioxidants
 Mechanism of action:
Most antioxidant function by providing
electron or labile H+ which will be
accepted by any free radical to
terminate the chain reaction.

7. The selection of Antioxidants
The following criteria’s should be brought into
consideration while selecting a suitable
antioxidant for pharmaceutical purposes:
o It should be capable of ensuring desired
redox reaction when used in pharmaceutical
preparations.
o It should be chemically compatible i.e. it
should not react with other chemicals in the
preparations.

8. The selection of Antioxidants
oIt should not alter the solubility of other
components.
oIt should also exhibit reasonable chemical
stability.
o It should be effective at a very low
concentration.
oIt should be physiologically inert.
o It should be safe and nontoxic.

9. Ascorbic Acid
 Chemistry: Ascorbic acid is an organic acid.
It is also called Vitamin C.
Chemical formula: C6H8O6
Structure:

10. Ascorbic Acid
 Physical Properties:
Description: It’s appearance is white
to slightly yellow crystals or powder.
Solubility: Water soluble.
 Use: It is used as an antioxidant to
retard oxidative degradation of
various pharmaceuticals.

11. BHA (Butylated Hydroxyanisole)
 Chemistry :
1,1-dimethylethyl-4-methoxy phenol
 Physical Properties:
Description: White or slightly
yellow, waxy solid having a
faint, characteristic odor.

12. BHA (Butylated Hydroxyanisole)
 Solubility: Insoluble in water, soluble
in alcohol, chloroform or ether.
 Uses: it is used as an antioxidant in
pharmaceutical products containing
fats and oils.

13. BHT ( Butylated Hydroxytoluene )
 Chemistry:
1,1-dimethylethyl-4-methyl phenol.
 Physical properties:
Description: White, tasteless crystals with a
mild odor, stable in light or air, melting point
700C.
Solubility: Insoluble in water, soluble in
alcohol, chloroform and water.
 Uses: It is used as an antioxidant to retard
oxidative degradation of oils & fats in various
pharmaceuticals.

14. Preservatives
A preservative is a substance that prevents or
inhibits the growth of microorganisms and is
added to pharmaceutical preparation to avoid
consequent spoilage of the preparation by
microorganism.
e.g. Methyl paraben
Ethyl Paraben
Propyl paraben
Benzoic acid

15. Preservatives
e.g. Sodium benzoate
Benzalkonium chloride
Benzyl alcohol
Chlorobutanol
Phenol
Thiomerosal

16. Preservatives
 Desirable features of a preservative suitable
for use in pharmaceutical formulation:
1. A wide spectrum of activity against all
bacteria, yeasts and moulds.
2. Bactericidal rather than Bacteriostatic .
3. Freedom from toxic, irritant or sensitizing
activity.
4. Compatibility with other ingredients and
with the container.
5. High water solubility.
6. Stability and effectiveness over a wide
range of pH and Temp.
7. Freedom from color and odor.

17. Potassium Benzoate
 Chemistry: Potassium salt of benzoic
acid.
Structure:
COOK . 3H2O

18. Potassium Benzoate
 Physical Properties:
Description: Crystalline powder
Solubility: Soluble in water
 Use: It is used as an antimicrobial
preservative in pharmaceutical preparation.

19. Phenol
 Chemistry: It is also called carbolic acid.
Structure:
OH
 Physical Properties:
Description: Colorless to light pink, needle
shaped crystals, characteristic odor.

20. Phenol
Solubility: 1g in 15 ml water, very
soluble in alcohol, glycerin, chloroform
& ether.
 Use: It is used as a preservative for
injectable preparations at 0.5% w/v.

21. Chlorobutanol
 Chemistry: 1,1,1-trichloro-2-methyl-2-propanol
Structure: (CCl3)C(CH3)2OH
 Physical Properties:
Description: Colorless to white
crystals, camphoraceous odor and
taste, anhydrous melts at 950C ; hydrous melts
at 760C.

22. Chlorobutanol
Solubility: 1g in 125 ml water; 1 ml alcohol or
10 ml glycerin; freely soluble in
chloroform, ether or volatile oils.
 Use: It is primarily used as preservative in
ophthalmic and parenteral preparations as it
has antimicrobial & germicidal properties.

23. Methyl Paraben
 Chemistry: It is the
methyl ester of
parahydroxybenzoic
acid.
Structure:
CH3
 Physical properties
Description: Colorless crystals or white powder.
Solubility: soluble in water, ethanol, slightly
soluble in benzene and acetone.
 Uses: It is used as preservative in pharmaceutical
formulation to inhibit the growth of
microorganisms.

24. Acidifying agents
 Substances that are used in liquid preparation
to provide acidic media for product stability.
e.g. Citric acid
Acetic acid
Fumaric acid
Hydrochloric acid
Nitric acid

25. Citric Acid
 Chemistry: 2-hydroxy-1,2,3-propane
tricarboxylic acid.
 Structure:
HOCCOOH
CH2COOH
CH2COOH

26.  Physical Properties:
Description:
Colorless, Translucent crystals or a white
granular to fine crystalline powder. Strongly
acid taste & odorless.
Solubility: Very soluble in water, freely
soluble in methanol, soluble in ether.
 Use: It is used as an acidifying agent to stable
the product providing appropriate pH.
Citric Acid

27. Acetic acid
 Chemistry: It is also called ethanoic
acid or methane carboxylic acid.
Structure:

28. Acetic acid
 Physical properties:
Description: Colorless liquid
or crystals. Molecular mass-60 g/mol
Solubility: Completely miscible with
water, ethanol, acetone.
 Use: It is used as an acidifying agent to
stable the product providing appropriate
pH.

29. Alkalizing Agent
 Alkalizing Agent are substances that are used
in liquid preparation to provide alkaline media
for product stability.
e.g. Ammonia solution
Ammonia carbonate
Diethanolamine
Potassium Hydroxide
Sodium Borate
Sodium carbonate
Trolamine

30. Sodium Borate
 Chemical Formula: Na2B4O7.10H20
 Physical Properties:
Description: colorless, transparent crystals or
a white crystalline powder, odorless. pH-9.5
Solubility: soluble in water & glycerin but
insoluble in alcohol.
 Use: It is used as an Alkalizing Agent in liquid
preparation to provide appropriate pH for
product stability.

31. Sodium Carbonate
 Chemistry: Sodium carbonate (also known as
washing soda or soda ash), Na2CO3, is a sodium
salt of carbonic acid. It is decomposed by weak
acids forming salts of the acid and liberate CO2
Chemical formula: Anhydrous Na2CO3
Na2CO3.2H2O

32. Sodium Carbonate
 Physical Properties:
Description: Colorless crystals or a white
crystalline powder. Aqueous solution is
alkaline to litmus, pH-11.5.
Solubility: Soluble in water but insoluble in
alcohol.
 Use: It is used as an Alkalizing Agent in
liquid preparation to provide appropriate pH
for product stability.

33. Sodium Bicarbonate
 Chemistry: Sodium bicarbonate NaHCO3, or
sodium hydrogen carbonate, also known as
baking soda, bread soda, or bicarbonate of
soda.
Chemical structure:

34. Sodium Bicarbonate
 Physical properties:
Description: soluble white anhydrous or
crystalline chemical compound, with a slight
alkaline taste resembling that of sodium
carbonate.
Solubility: 1g in 10ml water.
 Use: It is used as an Alkalizing Agent in liquid
preparation to provide appropriate pH for
product stability.