Overview of pharmaceutical excipients used in tablets

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The pharmaceutical industry is ever thirsty to satisfy patient’s therapeutical needs and apart from active ingredients, inactive excipients play a major role in formulation development. Pharmaceutical excipients are substances other than the logically active drug or prodrug which are included in the manufacturing process or are contained in a finished pharmaceutical product dosage form.
In addition to transporting the active drug to the site in the body where the drug is intended to exert its action, excipients play an important part in the manufacturing process. They may also be important for keeping the drug from being released too early in the assimilation process in places where it could damage tender tissue and create gastric irritation or stomach upset. Others help the drug to disintegrate into particles small enough to reach the blood stream more quickly and still others protect the product’s stability so it will be at maximum effectiveness at time of use. In addition, some excipients are used to aid the identification of a drug product.
Last, but not least, some excipients are used simply to make the product taste and look better. This improves patient compliance, especially in children. Although technically “inactive” from a therapeutic sense, pharmaceutical excipients are critical and essential components of a modern drug product. In many products, excipients make up the bulk of the total dosage form (1). Apart from the drug’s active ingredient, other essential components include diluent s or fillers, binders, disintegrants, lubricants, coloring agents and preservatives (3). Diluents or fillers are inert ingredients that can significantly affect the chemical and physical properties of the final tablet thus affecting the biopharmaceutical profile.
One classic example of this are calcium salts, which can be utilized as fillers, which interfere with the absorption of tetracycline from the gastrointestinal tract. (4) This example emphasizes that excipients may not always be inert, as they may be perceived. Usually tablets are designed so that the smallest tablet size which can be conveniently compressed is formed. Thus, if the dose is small more diluents are required and if the dose is high less diluents are required as not to increase the tablet size, which might size, which might make it difficult to swallow.
Diluents selection should be made carefully as physical chemical changes might render the product unstable and might cause problems in manufacturing. Binders are added to tablet formulations to add cohesiveness to powders thereby providing the necessary bonding to form granules which under compaction form a compact mass as tablet. In other words, binders are essential to achieve the “hardness” of the tablet.
Binders are usually selected on basis of previous experience, particular product needs, literature or vendor data or the preference of individual scientists or manufacturing unit. The primary criterion when choosing a binder is its compatibility with other tablet components.
It must add sufficient cohesion to the powders to allow for normal processing yet allow the tablet to disintegrate and the drug to dissolve upon ingestion, releasing the active ingredients for absorption. Disintegrants facilitate the breakup of a tablet after oral administration.
They can be added prior to granulation or during the lubrication step prior to compression or at both processing steps. The effectiveness of many disintegrants is affected by their position within the tablet. Since disintegration is the opposite operation to ranulation (agglomeration) and the subsequent formation of strong compacts, one must carefully weigh these two phenomena when designing a tablet. Lubricants prevent sticking of the tablets to the tablet punches during the compression phase of the tablet nufacturing process.
When lubricants are added to a powder mass, they form a coat around individual particles which remains more or less intact during compression. Lubricants are mostly hydrophobic. The presence of lubricant coating may cause an increase in the disintegration time and a decrease in drug dissolution rate. The choice of a lubricant may depend upon the type of tablet being manufactured, dissolution, flow characteristics and requirements of the formulation in terms of hardness, friability and compatibility. Glidants are the materials that have good flow properties and poor lubrication properties.
Glidants improve the flow of powder into the tableting machines for compaction. They act to minimize the tendency of a granulation to separate or segregate due to excessive vibration.
High speed tablet machine require smooth even flow of material to die cavities (tablet mold). The uniformity of tablet weights directly depends on how uniformly the die cavity is filled. Ingeneral many materials commonly referred to as lubricants possess only a minimal lubricating activity and are better glidants or anti-adherents.
Thus a blend of two or more materials may be necessary to obtain these properties. Pharmacists should be familiar with the
components of pharmaceuticals products, beyond their active ingredients. In order to educate pharmacists on excipients that are routinely used in the pharmaceutical industry, we decided to examine the top 200 prescription tablets and capsules products of 2003 (2) and find out how many or which excipients are used in each product.
The selection will cover both brand and generic drugs. Out of the 200 prescription drugs, the total numbers of inactive excipients used except for coating and coloring Although the list is composed on the top 200 drugs of 2003, very few blockbusters has been launched since then and still the excipients in all remains the same.
StartFragment

NoExcipientNumber of times
excipients used in
tablets out of 200
Use
1Acacia2Emulsifying agent; stabilizing agent;
suspending agent; tablet binder;
viscosity-increasing agent
2Alginate1Binder
3Alginic Acid1Stabilizing agent; suspending agent; tablet binder, tablet disintegrant;
viscosity-increasing agent.
4Aluminum Acetate1Antiseptic
5Benzyl Alcohol2Antimicrobial preservative; disinfectant; solvent
6Butyl Paraben1Antimicrobial preservative
7Butylated Hydroxy
Toluene
.
1Antioxidant
8Citric acid1Disintegrant
9Calcium carbonate1Tablet and capsule diluent; therapeutic agent
10Candelilla wax4Binder
11Croscarmellose sodium22Tablet and capsule Disintegrant
12Confectioner sugar1Sugar coating adjunct; sweetening agent; tablet and capsule diluents
13Colloidal silicone
Dioxide
22Adsorbent; anticaking agent; emulsion stabilizer; glidant; suspending agent; tablet disintegrant; thermal stabilizer; viscosity-increasing agent
14Cellulose19Adsorbent; suspending agent; tablet and capsule diluent; tablet disintegrant (cellulose microcrystaline) Adsorbent; glidant; suspending agent; tablet and capsule diluent; tablet disintegrant (cellulose powdered) Tablet and
capsule diluent.(cellulose Silicified)
15Plain or anhydrous
calcium phosphate
3Diluent
16Carnuba wax12Binder
17Corn starch17Binder
18Carboxymethylcellulose
Calcium
3Stabilizing agent; suspending agent; tablet and capsule disintegrant; viscosity-increasing
19Calcium stearate5Tablet and capsule Lubricant
20Calcium disodium
EDTA
1Chelation
21Copolyvidone1Film-former; granulating agent; tablet binder
22Castor oil hydrogenated4Extended release agent; stiffening agent; tablet and capsule lubrican
23Calcium hydrogen
phosphate dihydrate
1Diluent
24Cetylpyridine chloride1Antimicrobial preservative; antiseptic; cationic surfactant; disinfectant; solubilizing agent; wetting agent
25Cysteine HCL
.
1Reducing Agent
26Crosspovidone20Tablet disintegrant
27calcium phosphate di or
tri basic
7Tablet and capsule diluent Anticaking agent; buffer, nutrient; dietary supplement; glidant; tablet and capsule diluent and clouding agent( for calium phosphage tribasic)
28Dibasic Calcium Phosphate9Diluent
29Disodium hydrogen phosphate1Buffering agent
30Dimethicone1Antifoaming agent; Emollient
31Erythrosine Sodium2Color
32Ethyl Cellulose3Coating agent; flavoring fixative; tablet binder; tablet filler; viscosity-increasing agent.
33Gelatin14Coating agent; film-former; gelling agent; suspending agent; tablet binder; viscosity-increasing agent
34Glyceryl monooleate2Nonionic surfactant
35Glycerin3Antimicrobial preservative; emollient; humectant; plasticizer; solvent; sweetening agent; tonicity agent
36Glycine1Tonicity
37Glyceryl monostearate1Emollient; emulsifying agent; solubilizing agent; stabilizing agent; sustained-release ingredient; tablet and capsule lubricant
38Glyceryl behenate1Coating agent; tablet binder; tablet and capsule lubricant
39Hydroxy propyl cellulose25Coating agent; emulsifying agent; stabilizing agent; suspending agent; tablet binder; thickening agent; viscosity-increasing agent.
40Hydroxyl propyl methyl
Cellulose
45Coating agent; filmformer; rate-controlling polymer for sustained release; stabilizing agent; suspending agent; tablet binder; viscosity-increasing agent.
41Hypromellose7Coating agent; filmformer; rate-controlling polymer for sustained release; stabilizing agent; suspending agent; tablet binder; viscosity-increasing agent.
42HPMC Pthalate1Coating agent.
43Iron oxides or ferric oxide15Color
44Iron oxide yellow5Color
45Iron oxide red or ferric Oxide6Color
46Lactose hydrous or anhydrous or monohydrate or spray dried77Binding agent; diluent for dry-powder inhalers; lyophilizationaid; tablet binder; tablet and capsule diluent.(lactose anhydrous) Binding agent; diluent for dry-powder inhalers; tablet binder; tablet and capsule diluent(lactose monhydrate) Binding agent; diluent for drypowder inhalations; tablet and capsule diluent; tablet and capsule filler.(lactose spray dried)
47Magnesium stearate108Tablet and capsule Lubricant
48Microcrystalline
Cellulose
61Adsorbent; suspending agent; tablet and capsule diluent; tablet disintegrant same as cellulose see above it is just that mcc is usp
49Mannitol4Sweetening agent; tablet and capsule diluent; tonicity agent; vehicle (bulking agent) for lyophilized preparations
50Methyl cellulose3Coating agent; emulsifying agent; suspending agent; tablet and capsule disintegrant; tablet binder; viscosityincreasing agent
51Magnesium carbonate2Tablet and capsule Diluent
52Mineral oil3Emollient; lubricant;oleaginous vehicle; solvent
53Methacrylic acid copolymer5Coating
54Magnesium oxide2Tablet and capsule Diluent
55Methyl paraben5Antimicrobial Preservative
56Povidone or PVP36Disintegrant; dissolution aid; suspending agent; tablet binder.
57PEG40Ointment base; plasticizer; solvent; suppository base; tablet and capsule lubricant
58Polysorbate 8019Solubilizer
59Propylene glycol10Antimicrobial preservative; disinfectant; humectant; plasticizer; solvent; stabilizer for vitamins; watermiscible cosolvent.
60Polyethylene oxide3Mucoadhesive; tablet binder; thickening agent.
61Propylene paraben4Antimicrobial Preservative
62Polaxamer 407 or 188 or Plain3Dispersing agent; emulsifying and coemulsifying agent; solubilizing agent; tablet lubricant; wetting agent.
63Potassium bicarbonate1Alkalizing agent; therapeutic agen
64Potassium sorbate1Antimicrobial Preservative
65Potato starch1Binder
66Phosphoric acid1Acidifying agent
67Polyoxy140 stearate1Emulsifying agent; solubilizing agent; wetting agent
68Sodium starch glycolate20Tablet and capsule disintegrant
69Starch pregelatinized21Tablet and capsule diluent; tablet and capsule disintegrant; tablet binder (starch pregelatinized Glidant; tablet and capsule diluent; tablet and capsule disintegrant; tablet binder.( starch, potato, corn , wheat, rice) so check the above and make the changes
70Sodium crossmellose1Disintegrant
71Sodium lauryl sulfate13Anionic surfactant; detergent; emulsifying agent; skin penetrant; tablet and capsule lubricant; wetting agent
72Starch19Glidant; tablet and capsule diluent; tablet and capsule disintegrant; tablet binder.( starch , potato, corn , wheat, rice) combine all the starches
73Silicon dioxide14Same as colloidal silicon dioxide
74Sodium benzoate2Antimicrobial preservative; tablet and capsule lubricant
75Stearic acid12Emulsifying agent; solubilizing agent; tablet and capsule lubricant.
76Sucrose9Base for medicated confectionery; granulating agent; sugar coating adjunct; suspending agent; sweetening agent; tablet and capsule diluent; viscosityincreasing agent.
77Sorbic acid3Antimicrobial preservative
78Sodium carbonate1Carbonating agent
79Saccharin sodium1Sweetening agent
80Sodium alginate1Stabilizing agent; suspending agent; tablet and capsule disintegrant; tablet binder; viscosity-increasing agent.
81Silica gel1Adsorbant
82Sorbiton monooleate1Solubilizer
83Sodium stearyl fumarate4Tablet and capsule lubricant.
84Sodium chloride3Tablet and capsule diluent; tonicity agent
85Sodium metabisulfite1Antioxidant.
86Sodium citrate dihydrate1Alkalizing agent;buffering agent; emulsifier;sequestering agent.
87Sodium starch1Binder
88Sodium carboxy methyl cellulose1Coating agent; tablet and capsule disintegrant; tablet binder; stabilizing agent; suspending agent; viscosity-increasing agent; waterabsorbing agent.
89Succinic acid1Acidity
90Sodium propionate1Antimicrobial preservative
91Titanium dioxide49Coating agent; opacifier; pigment
92Talc20Anticaking agent;glidant; tablet and capsule diluent; tablet and capsule lubricant.
93Triacetin6Humectant; plasticizer;solvent
94Triethyl citrate3Plasticizer

EndFragment
From the table above we see that most of the commonly used ingredients have not been changed in making a tablet from generations and might follow the same trends for many generations to come.
CONCLUSION: Lot of time and effort are still needed in field of excipients. However till then a formulation scientist is entrusted with the limited amount of excipients and will have to deal with 94 excipients or now maybe 104. Rutesh H. Dave, PhD, Assistant Professor, Division of Pharmaceutical Sciences, Long Island University
The author would like to thank Dr. Joseph Nathan and Dr. Jack Rosenberg for their valuable input in preparing this manuscript.


Overview of pharmaceutical excipients used in tablets and capsules Overview of pharmaceutical excipients used in tablets and capsules Overview of pharmaceutical excipients used in