1. PHARMACEUTICAL EXCIPIENTS
Course : Pharmaceutical Technology-I
Course ID: PHR 212

2. Excipients – an overview
Drug products contain both drug substance (commonly referred to as active pharmaceutical ingredient or API) and excipients.
The resultant biological, chemical and physical properties of the drug product are directly affected by the excipients chosen, their concentration and interactions with the API:
Consistency of drug release and bioavailability
Stability including protection from degradation
Ease of administration
Excipients are sub-divided into various functional classifications, depending on the role that they are intended to play in the resultant formulation.
Certain excipients can have different functional roles in different formulation types,
e.g. lactose; widely used as:
a diluent, filler or bulking agent in tablets and capsules
a carrier for dry powder inhalation products.
In addition, individual excipients can have different grades, types and sources depending on those different functional roles….

3. API (Active Pharmaceutical Ingredients)
Active Pharmaceutical Ingredients (API) (or) Drugs (meant for oral administration) are classified into two types based on their solubility:
a). Insoluble drugs.
b). Soluble drugs.
a). Insoluble drugs : The therapeutic action of insoluble drugs ( seen locally in GI tract, Eg: Antacids and adsorbents) depends on the surface properties of the drug particles i.e., fine particle size and larger surface area.
The bioavailability of these drugs in GIT along with its optimal surface is affected by :
( I ) Formulation (composition ) of the tablet.
(II) Granulation method (dry granulation or wet granulation).
(III) Method of tab letting ( compression or compaction).

4. API (Active Pharmaceutical Ingredients)
b). Soluble drugs : The therapeutic action of soluble drug is seen systemically. The disintegration and dissolution time of such tablets depends upon the excipients used in the formulation. Solubility of the drug should be considered at or above the absorption site (i.e., upper GIT or the intestinal tract).
The physical and chemical properties of the drugs must be studied extensively before finalising the tablet formula so as to obtain better tab- letting characteristics. Active pharmaceutical ingredient (API), therapeutic agent Should not produce any toxic effect when it comes in contact with other additives, Should be of accurate quantity as label claim, Should be detected by various methods of analysis. Example: paracetamol, aspirin, diclofenac, metformin,telmisartan, nimesulide , nifedipine etc.

5. Diluents
Diluents : Act as fillers used to make required bulk of the tablet. Diluents are used to increase the bulk content of the dosage form, this is done in a situation where the active constituent to be incorporated in the formulation is of less quantity.
For e.g. if the active ingredient is just 5 mg, is such a case a tablet of just 5 mg is very difficult to manufacture and handle too, thus the bulk content is increased by addition of inactive excipient. Must provide better tablet properties such as improved cohesion, to permit the use of direct compression manufacturing or to promote flow.
A diluent should have following properties:
Non toxic.
Commercially available in acceptable grade.
Low in cost. Physiologically inert.
Physically & chemically stable by themselves & in combination with the drugs.
Free from all microbial contamination.
Should not alter the bioavailability of the drug .
Colour compatible.

6. Commonly used tablet diluents
Diluents Based on Chemical nature Solubility Organic diluents Inorganic diluents Water soluble diluents Water Insoluble diluents. For e.g.
Lactose-anhydrous and spray dried lactose
Directly compressed starch- Sta Rx 1500
Hydrolyzed starch-Emdex and Celutab
Microcrystalline cellulose-Avicel (PH 101 and PH 102)
Dibasic calcium phosphate dehydrate
Calcium sulphate dihydrate
Mannitol
Sorbitol
Sucrose- Sugartab, DiPac, Nutab

7. Characteristics of Diluents
Most of the excipients are dehydrates,i.e. contain certain amount of bound water, this bound water is important during granulation process, it reduces the hygroscopic nature of the formulation making the formulation stable.
For the active ingredients which are sensitive to water anhydrous excipients like anhydrous lactose or anhydrous dibasic calcium phosphate are used .
Spray dried lactose, direct compressible starch and MCC (avicel) are the diluents that can be used when the formulation is prepared by direct compression.
Mannitol is one of the costliest diluents but it is still used due to the refreshing sensation given by it when it is used in the chewable tablets.
Sucrose or sugar based diluents are used for direct compression formulations. Sucrose based diluents include: Sugartab (90-93% sucrose +  7 to 10%invert sugar), Dipac (97% sucrose + 3% modified dextrin) and Nutab( 95%sucrose+4% invert sugar with small amount of corm starch and magnesium stearate)

8. Binders
These are the dry powders or liquid which are added during wet granulation to promote granules or to promote cohesive compact during direct compression.
It provides mechanical strength to the tablet. Binders can be in powder form and liquid form.
Example of binders are
Powder binders : cellulose, methyl cellulose, polyvinyl pyrrolidine,
PEG Solution binders : gelatine, PVP, HPMC, PEG, sucrose, starch
Binders can be added in the following ways to the formulation added as powder before wet agglomerisation so that the binder is evenly distributed. As solution form it is used as agglomerisation liquid in the wet granulation. It is called as liquid binder.

9. Binders
As a dry powder, which is mixed with other ingredients before compaction (slugging or tabletting). It is called as dry binder.
Natural binders like acacia and tragacanth are used in solution form in the concentration of 10-25%, alone (or) in combination for wet granulation and they can be added as powder for the direct compression process.
Gelatine is used along with acacia (or) alone this form a better binding agent than the above two natural polymers.
Polymers like MC, HPMC are used as dry powders in case of direct compaction, they act as good binding agents, in the solution form they act as good adhesives.
Ethyl cellulose and HPMC can be used in alcoholic solutions, they act as anhydrous adhesives.

10. Disintegrants
Disintegrants are added to the formulation as it breaks the dosage form into smaller particles when it comes in contact with the liquid, these smaller fragments have greater surface area which will increase the dissolution of the drug.
Various mechanism of disintegrations are proposed-
By breaking into fragments: When the tablet comes in contact with the liquid, the liquid penetrates into the pores of the tablets and breaks it into fragments. To improve the water uptake into the pores certain hydrophilic polymers are added to the formulation.
By swelling: when the tablet comes in contact with the water it swells and ruptures the tablet into small particles.
Examples of disintegrants are: starch, starch derivatives, clay, cellulose, alginates, PVP, cross linked Na CMC. Starch is used for in the concentration range of 5 to 20% of the tablet weight. Modified starch are also used which like Primogel, Explotab. These are used in the low concentration like 1 to 8%, Pregelatinised starch is also employed in the formulation with 5% concentration. Clay like Veegum HV and Betonite are used in 10% level, Polymers like cross linked PVP, CMC are also used as disintegrants.

11. Superdisintegrants
As day’s pass, demand for faster disintegrating formulation is increased. So, pharmacist needs to formulate disintegrants i.e. Superdisintegrants which are effective at low concentration and have greater disintegrating efficiency and they are more effective intragranularly.
But, they have one drawback i.e., they are hygroscopic. Therefore, they not used with moisture sensitive drugs. And this superdisintegrants act by swelling and due to swelling pressure exerted in the outer direction or radial direction, it causes tablet to burst or the accelerated absorption of water leading to an enormous increase in the volume of granules to promote disintegration.

12. Superdisintegrants
Examples are Crosscarmellose ,Ac-Di- Sol, Nymce ZSX, Primellose, Solutab, Vivasol Cross linked cellulose -Swells 4-8 folds in < 10 seconds. -Swelling and wicking both.
Swells in two dimensions.
Direct compression or granulation.
Starch free Crosspovidone, Crosspovidone M, Kollidon Cross linked PVP
Swells very little and returns to original size after compression but act by capillary action.
Water insoluble and spongy in nature so get porous tablet Sodium starch glycolate Explotab, Primogel Crosslinked starch -Swells 7-12 folds in <30 seconds.
Swells in three dimensions and high level serve as sustain release matrix Alginic acid NF Satialgine Crosslinked alginic acid.
Rapid swelling in aqueous medium or wicking action -Promote disintegration in both dry or wet granulation.

13. Lubricants
Lubricants: Lubricants are used to reduce the friction between the tablet and die cavity when the tablet die cavity is getting ejected from the die. Lack of lubricant can lead to problems like capping, scratch on the sides of the tablet, fragmentation of the tablet, shape out etc.Thus to avoid this lubricants are to be used.
For a lubricant the time of addition, concentration in which it is to be added and the combination are the important parameters.
Concentration: as most of the lubricants are hydrophobic in nature thus the an increased concentration of lubricant would lead to problems like poor wettability, and dissolution and disintegration problem. For this reason they are added in the concentration less than 1%.

14. Lubricants
Time of mixing: It is important as overmixing may lead to reduction in tablet dissolution and disintegration. Combination: If the lubricant is mixed with the disintegrant it will lead to formation of an film of lubricant on the tablet surface which will reduce the disintegration.
Examples of lubricants are: stearic acid, stearic acid salt, stearic acid derivatives, talc, PEG, surfactants, waxes ,etc. Calcium stearate and magnesium stearate (0.25–0.50%w/w) are the most commonly used lubricants followed by talc.
Higher molecular weight poly ethylene glycol and certain polymeric surfactants are used as water soluble lubricants.

15. Lubricants Lubrication can be achieved by two ways-
Fluid lubrication: it is achieved by the addition of liquid paraffin which forms an liquid film over the surface, but this is rarely followed.
Boundary lubrication: in this powder is mixed to the formulation which forms a film on the surface which reduces the friction.
Lubricants can be of two types: Insoluble lubricants: these are added to the formulation at the end before the compression of the tablet.
Examples include: magnesium stearate, stearic acid, glyceryl palmito stearate, etc. Soluble lubricants: these are added to overcome the defects caused by the insoluble lubricants. Examples include: PEG, poly oxy ethylene stearate, lauryl sulphate salt, etc.

16. Glidant
Glidant: Glidants are used to improve the flow property of the formulation, it reduces the friction between the particles and between the hopper and particles and die cavity and particles.
Actually glidant, lubricant and antiadherent have a close relation to each other. They have some functions in common.
Most of the glidants used are hydrophobic thus they are to be carefully added i.e. concentration regulated.
Examples of glidants are talc, colloidal silicone dioxide, corn starch. Glidants should be of small size so that they can retain with in the small pores of the granules that have a greater surface area.

17. Function of coating agents: Examples:
Coating is a process by which an essentially dry, outer layer of coating material is applied to the surface of a dosage form and agents which are used in this coating process is called coating agents.
Types:
Three types of coating agents are used pharmaceutically,
Film coating.
Sugar coating.
Compression coating.
Function of coating agents:
Protection, masking, elegance, ease of swallowing, identification etc..
Examples:
HPMC, MC, HPC etc.

18. Excipients For Suspension Products
Again, excipients are sub-divided into various functional classifications, depending on the role that they play in the resultant formulation.
In Liquid/Suspension products, the possible types of excipients include:
Solvents/co-solvents e.g. Aqueous Vehicle, Propylene Glycol, Glycerol
Buffering agents, e.g. Citrate, Gluconates, Lactates
Preservatives, e.g. Na Benzoate, Parabens (Me, Pr and Bu), BKC
Anti-oxidants, e.g. BHT, BHA, Ascorbic acid
Wetting agents, e.g. Polysorbates, Sorbitan esters
Anti-foaming agents, e.g. Simethicone
Thickening agents, e.g. Methylcellulose or Hydroxyethylcellulose
Sweetening agents, e.g. Sorbitol, Saccharin, Aspartame, Acesulfame
Flavouring agents, e.g. Peppermint, Lemon oils, Butterscotch, etc.
Humectants, e.g. Propylene Glycol, Glycerol, Sorbitol

19. Solvents/Co-Solvents
Water is the solvent most widely used as a vehicle due to:
Lack of toxicity, physiological compatibility, and good solubilising power (high dielectric constant), but
Likely to cause instability of hydrolytically unstable drugs
Good vehicle for microbial growth
Sorbitol, dextrose, etc. are often added as solubilisers, as well as base sweeteners
Similar pros and cons to water alone
Water-miscible co-solvents are used to:
Enhance solubility, taste, anti-microbial effectiveness or stability
Reduce dose volume (e.g. oral, injections)
Or, conversely, optimise insolubility (if taste of API is an issue)
Examples: propylene glycol, glycerol, ethanol, low molecular weight PEGs
Water-immiscible co-solvents, e.g.
Emulsions / microemulsions using fractionated coconut oils

20. Features of buffering agent
These are materials which, when dissolved in solvent will enable the solution to resist any change in pH should an acid or an alkali be added. The choice of suitable buffer depends on the pH and buffering capacity required.
Features of buffering agent
It should have a low toxicity, it should be buffered at the range of 7.4 as the pH of the body is 7.4, it should be non-irritant.
Examples of buffering agent
Most of the buffering system are based on carbonate, citrates, gluconates ,lactates, phosphates, or tartrates etc.

21. Preservatives
Preservatives used in multi-use cosmetic/pharmaceutical products (including paediatric formulations)
prevents an increased risk of contamination by opportunistic microbial pathogens (from excipients or introduced externally), resulting in potential health consequences
Ideally targeted for microbial cells - showing no toxicity/irritancy towards mammalian cells
In reality, the majority of effective GRAS preservatives are active against both microbial and mammalian cells (non-specific cytoplasmic poisons)
There is a limited number of approved preservatives available for multi-use oral products, and options are even more limited for other routes of administration.
This restricted number can be further reduced by dose, pH-solubility profiles, incompatibilities, adsorption, toxicity and other relevant physico-chemical factors.

22. Ideal properties of preservatives:
Preservatives are substances that commonly added to various foods and pharmaceutical products in order to prolong their shelf life.
Ideal properties of preservatives:
In concept, the preservative system protects the product against microbial proliferation but does not compromise product performance. In practice, this means that it must:
Exert a wide spectrum of antimicrobial activity at low inclusion levels.
Maintain activity throughout product manufacture, shelf life and usage.
Not compromise the quality or performance of product, pack or delivery system.
Not adversely affect patient safety or tolerance of the product.
Examples:
Methyl & Ethyl parabens, Propyl paraben, Benzoic acid and its salts, Sorbic acid and its salts.

23. Antioxidant: An antioxidant is a molecule that inhibits the oxidation of other molecules. Oxidation is a chemical reaction that transfers electrons or hydrogen from a substance to an oxidizing agent.
Ideal Properties of Antioxidants:
Effective at a low, nontoxic concentration
Stable and effective under normal conditions of use, over a wide pH and temperature range
Soluble at the required concentration
Compatible with a wide variety of drugs and pharmaceutical excipients
Free from objectionable odor, objectionable taste
Colorless in both the original and oxidized form
Nontoxic both internally and externally at the required concentration
Reasonable cost
Unreactive (does not adsorb, penetrate, or interact) with containers or closures
Examples:
BHT( Butylated Hydroxy Toluene), BHA( Butylated Hydroxy Anisol), Sodium sulfite, Ascorbic acid etc.

24. Anti-Oxidants Used to control oxidation of: API, e.g. lovastatin
Preservative, e.g. potassium sorbate
Vehicle, e.g. oils or fats susceptible to β-oxidation
Sacrificial (more oxidisable than API, preservative, etc). Levels will reduce with time…. need to be monitored by specific assay
Need to assess regulatory acceptability (differs in different countries)
Efficacy can be affected by:
Compatibility with other excipients
Partitioning into micelles (from surfactants)
Adsorption onto surfaces (container, thickening agent and suspended particles)
Incompatibilities, e.g. with metal ions

25. Wetting Agents
To aid ‘wetting’ and dispersion of a hydrophobic API, preservative or antioxidant
Reduce interfacial tension between solid and liquid during manufacture or reconstitution of a suspension
Not all are suitable for oral administration
Examples include:
Surface active agents, e.g.
Oral: polysorbates (Tweens), sorbitan esters (Spans)
Parenteral: polysorbates, poloxamers, lecithin
External: sodium lauryl sulphate
….but these can cause excessive foaming (see anti-foaming agents) and can lead to deflocculation and undesirable physical instability (sedimentation) if levels too high
Hydrophilic colloids that coat hydrophobic particles, e.g. bentonite, tragacanth, alginates, cellulose derivatives. Also used as suspending agents, these can encourage deflocculation if levels are too low.

26. Anti-Foaming Agents
The formation of foams during manufacturing processes or when reconstituting liquid dosage forms can be undesirable and disruptive.
Anti-foaming agents are effective at discouraging the formation of stable foams by lowering surface tension and cohesive binding of the liquid phase.
A typical example is Simethicone (polydimethylsiloxane-silicon dioxide), which is used at levels of 1-50ppm.
Of course, a foam is also a very valid dosage form option for certain situations, e.g. for topical administration and in wound dressings. In addition, granulation using a foam rather than aqueous granulation fluid is gaining popularity.

27. Thickening Agents
Suspension stabilisers: prevent settling/sedimentation (particularly if a wetting agent present)
They usually modify viscosity and are often thixotropic (where viscosity is dependent on applied shear and exhibits ‘shear thinning’)
Easily poured when shaken
Quickly reforms ‘gel-like’ structure
They can impact on flocculation at low levels
Work by entrapment of solid particles, e.g. API, in a viscous or even ‘gel-like’ structure
Can be either water-soluble, e.g. methylcellulose or hydroxyethylcellulose
Or water-insoluble, e.g. microcrystalline cellulose

28. Sweetening Agents Natural sweeteners
Sucrose; soluble in water (vehicle), colourless, stable (pH 4-8), increases viscosity; Arguably the best taste/mouthfeel overall but cariogenic & calorific → avoid in paediatrics?
Sorbitol (non-cariogenic, non-calorific - appropriate for paediatric formulations), but lower sweetness intensity than sucrose (so you need more) & can cause diarrhoea
Artificial sweeteners
Regulatory review required – often restricted territories
Much more intense sweeteners compared with sucrose
As a consequence the levels are much lower (<0.2%)
Can impart a bitter or metallic after-taste (hence used in combination with natural sweeteners), e.g.
Saccharin, and it’s salts
Aspartame
Acesulfam –K
Sucralose – excellent sweetness, non-cariogenic, low calorie, wide & growing regulatory acceptability but relatively expensive
Sweetening agents are employed in liquid formulations designed for oral administration specifically to increase the palatability of the therapeutic agent.
Example:
Sucrouse, Saccarine, Aspertame, Sorbitol etc.
Uses of sweetening agent:
The main sweetening agents employed in oral preparations are sucrose, liquid glucose, glycerol, sorbitol, saccharin sodium and aspartame. Aspartame is an artificial sweetening agent. The use of artificial sweetening agents in formulations is increasing . The use of sugars in oral formulations for children and patients with diabetes mellitus is to be avoided.

29. Flavouring Agents Supplement and complement a sweetening agent
Ensures patient compliance (especially in paediatric formulations – a big issue)
Can be natural, e.g. peppermint, lemon oils,
Or artificial e.g. butterscotch, ‘tutti-frutti’ flavour
Instability can be an issue – combinations can be used to cover intended product shelf-life
Taste appreciation is not globally consistent…
Genetic element: one person’s acceptable taste is another’s unacceptable taste
Territorial (cultural?) differences in preference; e.g. US vs. Japan vs. Europe
Regulatory acceptability of flavours needs to be checked
Different sources, different compositions, different flavour, e.g. there are >30 different “strawberry flavours”!
Flavoring agents:
Flavouring agents are added to increase patient acceptance. The four basic taste sensations are salty, sweet, bitter and sour. It has been proposed that certain flavours should be used to mask these specific taste sensations.
Example:
Clove oil, citric and syrup, glycerin, rose oil, orange oil, menthol etc..

30. It should be colorless or not of too intense color.
Humectant : A humectant attracts and retains the moisture in the nearby air via absorption, drawing the water vapor into and/or beneath the organism/object's surface.
Humectants absorb water vapors from atmosphere till a certain degree of dilution is attained. Aqueous solutions of humectants can reduce the rate of loss of moisture.
Ideal properties of humectants :
It must absorb moisture from atmosphere and retain the same under the normal conditions of atmospheric humidity.
It should be colorless or not of too intense color.
It should have good odor and taste.
It should be nontoxic and nonirritant.
It should be noncorrosive to packaging materials
It should not solidify under normal conditions.
It should not be too costly.

31. Humectants
Hygroscopic excipients used at ~5% in aqueous suspensions and emulsions for external application.
Their function is to retard evaporation of aqueous vehicle of dosage form:
To prevent drying of the product after application to the skin
To prevent drying of product from the container after first opening
To prevent cap-locking caused by condensation onto neck of container-closure of a container after first opening
Examples include:
propylene glycol
glycerol
PEG

32. Overview thoughts for paediatric dosage forms
Technical Challenges:
Good taste and mouth feel (oral liquids, chewable/dispersible/”melt-in-mouth” units, inhaled, intranasal)
Inability to swallow solid dosage forms; needing an alternative option
Constraints of dosage form size and volume related to dose required, e.g. drug solubility in small injection volumes
Dosing flexibility
Physical, chemical and, where appropriate, microbial stability
Accuracy of dosing – potentially more of a challenge with lower doses & dose volumes
Parenterals: needlephobia
Important routes: oral, topical, inhaled Others: rectal, ear / eye / nose drops, injectables
 A wide range of excipients and dosage forms needs to be considered
A key consideration for paediatric dosage forms is to understand
the limitations in the type of excipient that can be used and also the
amounts & concentrations that can be administered.

33. Solvents/Solvent sweeteners
Need for oral liquid preparations (that children typically find easier to swallow) often necessitates:
Taste-masking; which often relies on sweeteners
Addition of co-solvents to improve drug solubility …if a solution is wanted (elegance/mouth feel vs. taste)
Most commonly used solvent sweeteners are
Propylene glycol
Glycerine (Glycerol)
However, note that it was historical adulteration of oral medicine with the orally toxic diethylene glycol (used in anti-freeze, brake and
transmission fluids) that led to tragic consequences:
Impetus for formation of US Food & Drugs Administration
Genesis of cGMP’s

34. Solvents/Preservatives
Propylene Glycol Toxicity
Propylene glycol is a general solvent and antimicrobial preservative used in a wide range of pharmaceutical preparations including oral liquid, topical and parenteral preparations
(The development of multi-dose oral liquid and parenteral preparations necessitates the requirement for preservative(s) to prevent microbial contamination as serious microbial infections in the very young can often be fatal.)
However, it’s use in large volumes in children is discouraged:
PG has been associated with cardiovascular, hepatic and CNS adverse events, especially in neonates (where the biological half-life is prolonged (~17h) compared with adults (5h)).
IV parenterals containing PG must be administered slowly
PG also has a laxative action at high oral doses through osmotic pressure effects.

35. Solvents Ethanol Toxicity Peanut Oil Toxicity
Widely used as a co-solvent to aid solubility
In US, maximum permitted quantities in OTC products:
<0.5% for children under 6-years
<5% for children 6-12-years
<10% for children over 12-years
May cause adverse symptoms of intoxication, lethargy, stupor, coma, respiratory depression and cardiovascular collapse
Peanut Oil Toxicity
Peanut oil is used as a food additive and as a solvent in intra-muscular injections
It has been suggested that the use of peanut oil in childhood (infant formula and topical preparations) can lead to later episodes of hypersensitivity, and therefore should be discontinued

36. Sweeteners Saccharin Aspartame Toxicity Sorbitol
Restricted regulatory acceptability
Poor aftertaste
Hypersensitivity reactions; mainly dermatologic
Paediatrics with allergy to sulphonamides should avoid saccharin
Aspartame Toxicity
Source of phenylalanine – possibly an issue for phenylketoneurics
Aspartame has been blamed for hyperactivity in children but as yet unproven
Sorbitol
Can induce diarrhoea

37. Preservatives
Benzyl Alcohol toxicity in neonates
Widely used as a preservative in cosmetics, foods and pharmaceuticals (including injectables and oral liquids)
Toxic syndrome observed in neonates – it was attributed to the practice of “flushing out” umbilical catheters with solutions containing benzyl alcohol, because of trace levels of benzaldehyde that were present
Dilution of nebulisation solutions with BA-preserved saline led to severe respiratory complications and even death in neonates. Attributed to accumulation of BA due to an immature metabolic capability.

38. Preservatives Sodium Benzoate toxicity Thimerosal toxicity
Widely used as a preservative in cosmetics, foods and pharmaceuticals (including injectables and oral liquids)
Injectable combinations of Na Benzoate and Caffeine should not be used in neonates; found to elicit non-immunological contact reactions, including urticaria and atopic dermatitis
Limitation on dosing of NA benzoate to neonates - ≤10mg/kg/day – due to immature metabolic capability
Thimerosal toxicity
Formerly widely used as a preservative in cosmetics, in soft contact lens solutions and pharmaceuticals (primarily vaccines)
Being phased out from most paediatric vaccines as better options emerge
Possible links with toxicity in paediatric vaccines, e.g. linked with childhood autism but not proven

39. Diluents/Fillers Lactose toxicity (immature metabolism)
Lactose occurs widely in dairy products and is used in infant feed formulae.
In pharmaceutical preparations it is widely used as a diluent in tablets and capsules, in lyophilised powders, as a sweetener in liquid formulations and as a carrier in dry powder inhalation products.
Lactose intolerance occurs when there is a deficiency in the intestinal enzyme lactase, leading to GIT build-up of lactose. There is then the risk of abdominal bloating and cramps.
Lactase is normally present at high levels at birth, declining rapidly in early childhood (4-8 years) . Hypolactasia (malabsorption of lactose) can thus occur at an early age and, furthermore, this varies among different ethic groups.
Significant lactose intolerance can also occur in adults but this is rare.

40. Acidifying and Alkalizing agents
Acidifying agent: Agent that have the capacity to acidify, or confer acidity.
Alkalizing agents: Agent that have the capacity to alkalinize, or confer alkalinity.

41. A surfactant must contain a lipophilic region.
Surfactants : Surfactants are compounds that lower the surface tension (or interfacial tension) between two liquids or between a liquid and a solid and increase the solubility. They are also known as surface active agents.
Properties of surfactants : A surfactant must fulfill two structural requirements:
A surfactant must contain a lipophilic region.
A surfactant must contain a hydrophilic region.
In a surfactant both hydrophilic and lipophilic region must be balanced because then both the regions will be concentrated at an interface and therefore surface tension will be lowered.
Types of surfactants :
There are of four types of surfactants based on the charge of the hydrophilic region :
1. Anionic surfactant ( here the hydrophilic region is negatively charged i.e. an anion)
Sodium lauryl sulphate -  It is used as an excipient on some dissolvable aspirins and other fiber therapy caplets.

42. 2. Cationic surfactant (here hydrophilic region is positively charged i.e. a cation)
Cetyl trimethyl ammonium bromide ( cetrimide ) - is an effective antiseptic agent against bacteria and fungi.
3. Non-ionic surfactants :
Tween 80 ( polyoxyethylene sorbitol monooleate)- Polysorbate 80 is an excipient that is used to stabilize aqueous formulations of medications for parenteral administration
Span ( sorbitan ester of lauric acid )
4. Amphoteric surfactant :
Lecithin- it acts as a wetting, stabilizing agent and a choline enrichment carrier, helps in emulsifications and encapsulation, and is a good dispersing agent.
N-dodecyl alanine.

43. Reference Book Handbook of Pharmaceutical Excipients, Fifth Edition.
Edited by: Raymond C Rowe, Paul J Sheskey
and Siân C Owen.