Pharmaceutical Aids – a Review Study


Hafsa1*, Asfa1, Nuha Rasheed2, Abdul Saleem Mohammad3

1Department of Pharma. D, Nizam Institute of Pharmacy, Deshmukhi (V), Pochampally (M), Behind Mount Opera, Yadadri (Dist)-508284, Telangana, India.

2Department of Pharmaceutics, Nizam Institute of Pharmacy, Deshmukhi (V), Pochampally (M), Behind Mount Opera, Yadadri (Dist)-508284, Telangana, India.

3Department of Pharmaceutical Analysis and Quality Assurance, Nizam Institute of Pharmacy, Deshmukhi (V), Pochampally (M), Behind Mount Opera, Yadadri (Dist)-508284, Telangana, India.

*Corresponding Author E-mail:



Pharmaceutical aids are the drugs and substances which have no or little pharmacological effect but they are essentially used in the preparation of pharmaceutical dosage form (like tablet, injection, emulsion, ointments etc). In this article we will be studying about the substances needed in the preparation, preservation and storage of pharmaceutical products and how are they classified into different categories and why are they necessary in preparation and does that help to the pharmacist?


KEY WORDS: Excipient, vehicles, pharmacopoeia, antiadherents, binders, diluents, ingredient, Indian pharmacopoeia, United States pharmacopoeia, buffering agents, ointments, dosage etc.




A large number of inorganic as well as organic chemicals are known which find extensive as well as valid application in the processing of pharmaceuticals. These are having very little or no therapeutically value but are necessary in the manufacture of various dosage forms such as ointments, orals, tablets, liquids, injectables etc. Such substances are known as pharmaceutical aids. These may be required for such purposes as preservations, stabilization, acidification, alkalization, suspending, excipient, adsorption, absorption, filtration, prevention of oxidation, stabilization, complexation etc.


Pharmaceutical aids may remain in the final product in which case they do not exert any specific action on the body when the product is administrated or they may get removed during processing but come in close contact with the product at some stage. Many times pharmaceutical aids are referred to as “pharmaceutical necessities”. It is essential that pharmaceutical aids should be of same quality as therapeutic agent and are subject to similar quality controls. [1-3]



It is possible to classify the various pharmaceutical aids into various categories which are given as follows:

1.    Acidifiers and alkalisers.

2.    Buffers.

3.    Absorbents and adsorbents.

4.    Antioxidants and preservatives.

5.    Desiccants.

6.    Excipients.

7.    Suspending agents.

8.    Filter aids.

9.    Colorants.

10. Tonicity adjusting agents.

11. Solvent and vehicle.

12. Coloring, flavoring and sweetening agents.

13. Ointments and suppository bases.

14. Diluents, binders, disintegrating agents and lubricants




These are the substances which are used for changing the reaction of a liquid product or maintaining the pH of the product. Only such acids, alkalis and their salts are to be used which do not exert any harmful effects on the body.

Alkalising agents are also called alkaniser.

Example: Sulphuric acid.

Formula: H2SO4.



It has been regarded as one of the most important mineral acids, because it is widely used in the manufacture of sulphates and sulphonates. Industrially it is obtained by the

1. Lead chamber process or

2. The contact process.


More recently it is prepared by first oxidizing sulphur dioxide to sulphur trioxide in presences of vanadium pentaoxide as catalyst. The sulphur trioxide is then dissolved in sulphuric acid to pyrosulphuric acid which on careful reaction with calculated amount of water yields very high concentrated sulphuric acid.



It is a colorless, corrosive liquid having oily consistency. When it is added to water much heat is evolved. It is specific gravity at 25 degree Celsius is about 1.84



These are solutions consisting of a mixture of an acid and on or more of its salt, in a suitable proportion and having a definite pH. The system is able to resist change in pH hen small quantity of acidic or basic substances are added. In other words solutions of drugs in buffers are able to retain their pH and remain stable longer. It is possible to prepare buffers either by mixing stock solutions of the ingredients or by dissolving a solid mixture (powder, pellets or tablets) of these in definite amount of water. In the pharmacopoeia these are the following buffers, in addition to few others not mentioned below:

1. Hydrochloric acid buffer.

2. Acid phthalate buffer.

3. Neutralized phthalate buffer.

4. Phosphate buffer

5. Alkaline borate buffer

6. Ammonia buffer



Excipients are inactive ingredients used as carriers for the active ingredients in a pharmaceutical product. These may be classified into the following categories:





Fillers and Diluents

Coloring Agents






·      Antiadherents are used to keep the powder from sticking to the tablet punch face during the manufacturing of tablets.

·      The most common is Magnesium Stearate.


The Pharmaceutical Ingredients must be Stabilized Towards:

·      Environmental factors (air, water vapor, sunlight).

·      Interactions between different ingredients in the drug or different functionalities in the same molecule.

·      Manufacturing stress (sterilization, compaction etc) [4-7]





Polyethylene glycol (PEG):


·      Binders add mechanical strength to the tablet or granules.


Monomeric glucose exists as a mixture of α and β-anomers.


However, once the glucose is polymerized into starch or cellulose, the anomeric carbon is no longer in equilibrium.


Starch (100 to 6000 glucose units) starch has 1, 4-alpha linkages


Cellulose (1800 to 3000 glucose units). Cellulose has 1,4-beta linkages.


Starch coil



Fig. 1. The structure and the inter- and intra-chain hydrogen bonding pattern in cellulose 1. Dashed lines: inter-chain hydrogen bonding. Dotted lines: intra-chain hydrogen bonding.


·      Cellulose has an extended and rather stiff conformation and is much less soluble and less digestible than is starch.


Antioxidants and preservatives:

There are many substances which are added to the pharmaceutical dosage forms for preventing microbial growth and spoilage of the preparation. Such substances are called preservatives.




Proportions used


1. Benzoic acid (IP)


It finds use as an antibacterial preservative ingredient of compound Camphor tincture IP.

2. Benzalkonium chloride (USP)


It finds use as an antimicrobial preservative

3. Butyl paraben (USP)

0.01% in water

0.15% in oils and creams

It finds use as an antifungal preservative.

4. Centrimide (IP)


It finds use as a bactericide.

5. Chlorobutanol (IP, USP)


It finds use as an antibacterial preservative.

6. Chlorocresol (IP)


It finds use as a bacteriostatic.

7. Cresol (IP)


It is used as a disinfectant.

8. Ethyl paraben (USP)

0.5% in water

0.15% in oils and creams

It is used as an antifungal Preservative.

9. Methyl paraben (IP, USP)

0.1% in water

0.2% in oils and creams

It is used as an antifungal Preservative.

10. Propyl paraben (IP)


It is used as an antifungal Preservative.

11. Phenol (IP, USP)


It is used as a preservative.

12. Phenyl mercuric nitrate (IP)


It finds use as local antibacterial.

13. Sodium benzoate (IP, USP)


It is used as an antifungal Preservative.

14. Mixture of methyl and Propyl hydroxy benzoate

0.06% and 0.03%

It is used as an antifungal Preservative.


The phenolic antioxidants are frequently employed in smaller amounts, together with a large amount of an ascorbic acid derivatives, which serves to provide a hydrogen atom to the phenolic radical, thus regenerating the antioxidant species. Both antioxidant and preservatives are widely used in the preparation of emulsions, mucilages, ointents bases, sterile preparations etc. Some important preservatives are given in table 1.


Other commonly used preservatives have been as follows:

Benzyl alcohol                                                0.9%

Ethyl alcohol                                                   15.0%

Glycerol                                                                           50.0%



The pH of the preparation will need to be adjusted to maintain optimum effect and stability of the pharmaceutical.


Coloring, Flavoring and Sweetening Agents:

Coloring Agents:

In order to increase the aesthetic appearance of pharmaceutical preparations, certain coloring agents are added to the preparations. The minimum concentration prescribed by the “Drug and cosmetic act and rule” may be 0.0001% w/v.


Flavouring Agents:

A flavouring agent is a complex mixture of aromatic compound to improve the palatability of dosage forms.


Diluents, binders, disintegrating agents and lubricants:

Diluents: If a single dose of active ingredient has been small inert substances have been added to increase the bulk



These are the substances which are used for imparting cohesive properties to powdered materials. They are used for granulation.


Disintegrating Agents:

A mixture of substances which tends to facilitate the breakup of a tablet.



These are the substances which are added to improve the rate of flow of granules and prevent adhesion and cohesion during the tablet manufacturing. [7-10]


Solvents or Vehicles:

There are several substances which are used in pharmaceutical formulation as solvents and vehicles. Some of these are given as in the following table.



Other uses

1. Alcohol (IP)

It is used as a preservative

2. Glycerine (IP)

It is used as a sweetening and thickening agent and also as humitant.

3. Oils (Arachis, sesame etc)

These are used specially for oily injections.

4. Propylene glycol (IP)

It is used as a solublising agent.

5. Syrup (IP)

It is used as a sweetening agent.

6. Water, aromatic water and elixir.

These are used as vehicles.



Pharmaceutical aids are the drugs which have no or little pharmacological effects but they are essentially used in the preparation of pharmaceutical dosage form like tablets, Injections, emulsions, ointments. They include solvents, diluenting agents, suspending agents, antioxidants, preservatives, coloring agents, flavoring agents, excipents, ointments, bases. A pharmaceutical drug is a drug used to diagnose, cure, treat or prevent disease. Indian pharmacopoeia prescribes the standards for drugs produced and marketed in India and thus contributes in the control and assurances of the quality of medicines. In the given topic “Pharmaceutical aids” we have discussed about various pharmaceutical aids and its classification, their procedure for the preparation of various pharmaceutical drugs, their dosage prescribed by Indian pharmacopoeia, limits in IP, test for various compounds etc.


Miscellaneous Substances:



1. Agar

It is used in paste and also as a laxative.

2. Alum

It is used as an astringent and clarifying agent

3. Benzyl alcohol

It is used as a preservative in some injections and  Also as a local anesthetic.

4. Castor oil

It is used as an ingredient in paste and cream and  Also as a laxative.

5. Flexible collodion

It is used as a protective on wounds and cuts.

6. Linseed oil

Ingredient of cresol with soap (IP).



Omission and inaccuracy of drug labeling information on pharmaceutical excipents may expose susceptible individuals to adverse reactions caused by preservatives and dyes. Complications of inadvertent intake of sugar containing medicines by diabetics or aspartame intake by patient with PKU may also occur. Excipients being an indispensible component of medicinal product must be evaluated for their safety and stability. The safety assurance of excipient helps the formulator to design an effective and safe dosage form with the use of efficient and safe excipient. Thus, for an excipient to be in a formulation it must be highly stable, safe, and efficacious and above all it must comply with the expected performance in the formulation.



1.     A.H. Beckett and J.B. Stenlake, Practical Pharmaceutical Chemistry, Part-I. The Athtone Press, University of London, London.

2.     P. Gundu Rao, Inorganic Pharmaceutical Chemistry; Vallabh Prakashan, Delhi.

3.     Advanced Inorganic Chemistry by Satya Prakash,  G.D. Tuli

4.     Jolly-Modern Inorganic Chemistry

5.     Pharmaceutical Inorganic Chemistry Textbook by Alagarsamy.

6.     L.M. Atherden, Bentley and Driver’s Textbook of Pharmaceutical Chemistry Oxford University Press, London.

7.     Indian Pharmacopoeia 1996, 2006.

8.     J.H Block, E. Roche, T.O Soine and C.O. Wilson, Inorganic Medical and Pharmaceutical Chemistry Lea and Febiger Philadelphia PA.

9.     Pharmaceutical Inorganic Chemistry by S. Chand, R.D. Madan, Anita Madan

10.   Pharmaceutical Inorganic Chemistry by Soma Shekar Rao




Received on 08.12.2016       Accepted on 08.01.2017     

© Asian Pharma Press All Right Reserved

Asian J. Pharm. Tech.  2016; 7(1): 1-6.

DOI: 10.5958/2231-5713.2017.00001.0