Pharmaceutical Binders

7/29/2019 Pharmaceutical Binders

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BINDERS

PHARMACEUTICAL APPLICATIONSSeshu Kumar Kodati


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INTRODUCTION In the development of tablets, whether manufactured by wet

granulation, dry granulation or direct compression, the key aim is to

ensure that the resultant product achieves satisfactory physical and

performance characteristics throughout its shelf life.

This is achieved, in part, through the selection of an appropriate

binder which may be introduced in the wet granulation stage, via dry

granulation, or by careful selection of directly compressible filler-

binders.


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INTRODUCTION Traditionally, tablets have been manufactured by wet granulation followed by

drying, sizing, blending/ lubrication and compression of the final granulation.

Direct compression, and to a lesser extent dry granulation, are becoming

increasingly popular methods of tablet manufacture. Direct compression requires

only blending and compression. Reducing the number of unit operations requires

less time and energy consumption, and allows for cost advantages both from anoperational and capital investment point of view. However, the inherent

compactibility of raw materials becomes more important in direct compression. In

this regard, direct compression presents a challenge for many poorly compressible

actives. The challenge of achieving desirable tablet mechanical properties, such astablet strength and friability from a poorly compressible high-dose active, can be

overcome by selection of an appropriate tablet binder.


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INTRODUCTION An ideal binder should have good binding properties, as determined by

compressibility under pressure, high plasticity, low elasticity and small particle

size. Small particle size facilitates even distribution of the binder through theinter-particulate void spaces in a tablet. Uniform binder distribution in the tablet

results in decreased pore structure and subsequent enhancement in tablet

crushing strength. To reduce friability, a binder with highly plastic properties (high

deformability) is essential. A further requirement for a good binder is low

hygroscopicity. Excessive uptake of moisture (greater than 5 percent) or high

moisture content can lead to instability and sticking during production.


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INTRODUCTION Commonly used binders include: starch, gelatin and sugars as sucrose, glucose,

dextrose, and lactose.

Natural and synthetic gums which have been used include acacia, sodium

alginate, carboxy- methylcellulose, methylcellulose, polyvinyl pyrrolidone,

Veegum. Other agents which may be considered binders under certain

circumstances are polyethylene glycol, ethylcelulose, waxes, water and alcohol.

There are many excipients used as binders in the direct compression; these

include hydroxypropylcellulose (HPC), methylcellulose (MC), povidone (PVP),

hydroxypropylmethylcellulose (HPMC), and starches and their derivatives, such aspregelatinized and granulated starches.


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INTRODUCTION The quantity of binder used has considerable influence on the characteristics of the

compressed tablets.

The use of too much binder or too strong a binder will make a hard tablet which will

not disintegrate easily and which will cause excessive wear of punches and dies.

Usually materials which have no cohesive qualities of their own will require a

stronger binder than those with these qualities.


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INTRODUCTION Binders are used both as a solution and in a dry form depending on other ingredients and

method of preparation.

The same amount of binder in solution will be more effective than if it were in a dry form

and moistened with the solvent. So it is preferable to incorporate the binding agent in

solution.

If the drug substance is adversely affected by an aqueous binder , a non aqueous binder

can be used or binder can be added dry.

The direct-compression method for preparing tablets requires a material that not only is

free-flowing but also sufficiently cohesive to act as a binder.


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MECHANISM OF BINDERS When binder added to powder diluents mixtures in the form of slurry ,suspension

(or) solution. Liquid bridges are developed between the particles and tensile

strength of their bonds get increased with the amount of liquid present in binder.Surface tension forces ,capillary pressures are primarily responsible for granule

strength and its formation.

After this step the excess of moisture content in binder is removed by drying toappropriate levels.In this stage interparticle bonds are resulted from fusion/re

crystallization and curing of binding agent with vanderwall forces playing a

significant role .


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BINDER SELECTION1. Choosing binder

2. Quantity of binder to be used

3. Mode of use of binder

4. Binders strength

glucose>acacia>gelatin>simple syrup>starch

5. Binders for moisture sensitive drugs

Ex: PVP, HPMC, Polymethacrylates (NE 30 D,Rs 30D) and pregelatinised starch.


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BINDER IN DIFFERENT TYPES OF TABLETS Effervescent tablets:

Effervescence evolving bubbles of gases from liquid due to chemical reaction. Use

of binders in effervescence tablets are limited to i) limited water solubility ii)

disintegration Binders such as natural gum & starch Cellulose derivatives are not

used. Dry binders sucrose, lactose and mannitol are not used. Best to use pvp as dry

binder along with ethanol,isopropanol in water.

Sublingual tablets:

They are intended to be placed beneath the tongue and held there until complete

absorption of medicament takes place. Must use water soluble excipient lactose of

particle size 120mesh . To increase hardness and reduces erosions on edjes use

glucose ,sucrose and acacia gums as binders Eg: GTN tablets


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BINDER IN DIFFERENT TYPES OF TABLETS BUCCAL/VAGINAL TABLETS:

Use of viscous natural gum/ synthetic gums/mix of gums , which absorbs moisture

to form a hydrated surface layer from which medicament diffuses and available for

absorption through buccal mucosa. Eg:HPMC,HPC,EC Muco adhesive polymers are

generally used like Eg:carbopol and PAMA

Chewable tablets: Mainly conceded the chew ability and sweetness. Eg:honey-tab:60% honey + wheat

flour Crystaflo-granular molaris co crystallized with syrup +caramel No specific

binder is required but us e the sugars which are compress able(method : direct

compression) E.g. : Di- pac(97% sucrose+3% dextrin) Nu-Tab(96%sucrose + 4%

invert sugar) E molex(95% dextrin +maltose and other saccarhides for improve

compress ability)


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BINDER IN DIFFERENT TYPES OF TABLETS Rectal tablets:

Tablet will disintegrate to form a paste within few minutes in the presence of

less available water(moisture). So use strong disintegrants like dross

carmellose sodium,crosslinked povidone are used.

Lozenzes:

Flavoured medicated dosage forms intended to sucked and held in mouth /

pharynx. E g : Beet-sugar Cane-sugar Corn-sugar

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Pharmaceutical Binders