Pharmaceutical necessities

Pharmaceutical Necessities

Dr. Basavaraj K. Nanjwade M. Pharm., Ph. D

Department of PharmaceuticsFaculty of Pharmacy

Omer Al-Mukhtar UniversityTobruk, Libya.

E-mail: [email protected]

01/04/2015 1Faculty of Pharmacy, Omer Al-Mukhtar University, Tobruk, Libya.

CONTENTS1. Antioxidants.2. Preservatives.3. Colouring Agents.4. Flavouring Agents.5. Diluting Agents.6. Pharmaceutical Solvents.


• A substance that inhibits oxidation is called antioxidants.

• Examples: Ascorbic acid, butylated hydroxyanisole (BHA), butylated hydroxytolluene (BHT), propylgallate

01/04/2015 Faculty of Pharmacy, Omer Al-Mukhtar University, Tobruk, Libya. 3

1. Antioxidants

• An antioxidant is a molecule that inhibits the oxidation of other molecules. Oxidation is a chemical reaction involving the loss of electrons or an increase in oxidation state. Oxidation reactions can produce free radicals. In turn, these radicals can start chain reactions. When the chain reaction occurs in a cell, it can cause damage or death to the cell. Antioxidants terminate these chain reactions by removing free radical intermediates, and inhibit other oxidation reactions.


1. Antioxidants

• The following are some of the qualities of an ideal anti-oxidant

1. It should be readily soluble or dispersible in the medium.

2. It should be effective in low concentration.3. It should be non toxic.4. It should be non irritant.5. It should be compatible with other ingredients of

emulsion.6. It should be colourless, odourless and tasteless.01/04/2015 Faculty of Pharmacy, Omer Al-Mukhtar University,

Tobruk, Libya. 5

1. Antioxidants

• Preservative describes those antimicrobial agents used to protect pharmaceutical preparations.

• Examples: ethanol, alcohol, chlorhexidine, benzoic acid, methyl parabens, ethyl parabens.


2. Preservatives

• A preservative is a substance that is added to products such as foods, pharmaceuticals, paints, biological samples, wood, etc. to prevent decomposition by microbial growth or by undesirable chemical changes. In general preservation is implemented in two modes, chemical and physical. Chemical preservation entails adding chemical compounds to the product. Physical preservation entails refrigeration and drying. They are used in foods, cosmetics, and many other products.


2. Preservatives

2. Preservatives• Antimicrobial preservatives: Emulsions contain

water, which will support microbial growth. Microbes produce unpleasant odours, colour changes and gases and may affect the emulsifying agent, possibly causing breakdown of the emulsion. Other ingredients of emulsions can provide a growth medium for microbes. Examples include arachis oil which supports Aspergillus species and liquid paraffin which supports Penicillium species.


• Preservation of suspension: All pharmaceutical preparations that contain water are therefore susceptible to microbial growth. Water is the most common source of microbial contamination. Also the naturally occurring additives such as acacia and tragacanth may be sources of microbes and spores. Preservative action may be diminished because of adsorption of the preservative onto solid particles of drug, or interaction with suspending agents. Useful preservatives in extemporaneous preparations include chloroform water, benzoic acid and hydroxybenzoates.


2. Preservatives

• Preservation of solutions: Most water-containing pharmaceutical solutions will support microbial growth unless this is prevented. Contamination may come from raw materials or be introduced during extemporaneous dispensing.

• Preservatives may be added to the formulation to reduce or prevent microbial growth. Chloroform is the most widely used in oral extemporaneous preparations.


2. Preservatives

• A substance that gives color to pharmaceutical preparations are called coloring agents.

• Examples: amaranth, caramel, tartrazine.


3. Colouring Agents

3. Colouring Agents• Colouring agents are added to pharmaceutical

preparations to enhance the appearance of a preparation or to increase the acceptability of a preparation to the patient. Colours are often matched to the flavour of a preparation, e.g. a yellow colour for a banana-flavoured preparation. Colour is also useful to give a consistent appearance where there is natural variation between batches. Colours can give distinct appearance to some medicines, e.g. the green colour of the Drug Tariff formula of methadone mixture.


• Colouring agents should be non-toxic and free of any therapeutic activity themselves. Natural colournats are most likely to meet this criterion and include materials derived from plants and animals, e.g. carotenoids, chlorophyllas, saffron, red beetroot extract, caramel and cochineal.

• Colourants are added to tablets to aid identification and patient compliance. Colouring is often accomplished during coating, but a colournat can also be included in the formulation prior to compaction.


3. Colouring Agents

• A substance that gives flavor to the pharmaceutical preparations are called as flavoring agents.

• Examples: raspberry, liquorice, lemon and orange, ginger, anise and cinnamon.


4. Flavouring Agents

4. Flavouring Agents• Flavouring agents are incorporated into a formulation

to give the tablet a more pleasant taste or to mask an unpleasant one. The latter can be achieved also by coating the tablet or the drug particles.

• Flavouring agents are often thermolabile and so cannot be added prior to an operation involving heat. They are often mixed with the granules as an alcohol solution.


• Flavours added to solutions can make a medicine more acceptable to take, especially if the drug has an unpleasant taste.

• Flavours should be chosen to mask particular taste types, e.g. a fruit flavours helps to disguise an acid taste.

• The age of the patient should be taken into account when selecting a flavour, as children will tend to enjoy fruit or sweet falvours.

• The flavour and colour should also complement each other.


4. Flavouring Agents

• A substance that increases the volume of the pharmaceutical preparations are called as diluting agents.

• Examples: Water, alcohol.


5. Diluting Agents

5. Diluting Agents• Diluents are fillers designed to make up the required

bulk of the tablet when the drug dosage amount is inadequate.

• Diluents may also improve cohesion, permit use of direct compression, or promote flow.

• Diluents: These add bulk to make the tablet easier to handle.

• Example include lactose, mannitol, sorbitol and calcium carbonate.


• In order to form tablets of a size suitable for handling, a lower limit in terms of powder volume and weight is required.

• Tablets weight normally at least 50 mg. • Therefore, a low dose of drug per tablet requires the

incorporation of a substance into the formulation to increase the bulk volume of the powder and hence the size of the tablet.

• This excipient, known as the filler or the diluent, is not necessary if the dose of the drug per tablet is high.


5. Diluting Agents

• If a prescriber insists that a manufactured solution is diluted, then a suitable diluent must be selected.

• Information sources to obtain this information are the Medicines Compendium or the National Pharmaceutical Association (NPA) Diluent Directory.

• An indication of the expiry date for the diluted preparation is also given in these references.

• The dilution should be freshly prepared.


5. Diluting Agents

• A substance that is used in the preparation of pharmaceuticals are called as pharmaceutical solvents.

• Examples: water, alcohol.


6. Pharmaceutical Solvents

6. Pharmaceutical Solvents• Solvent usually the component present in greatest

quality.• Materials such as alcohol, glycerol and glycols, which

are water miscible, will reduce the liquid/air interfacial tension.

• The solvent will penetrate the loose agglomerates of powder displacing the air from the pores of the individual particles, so enabling wetting to occur by the dispersion medium.

• The first-choice solvent is obviously water.


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Pharmaceutical necessities