Group name: MEDS PREDATORS

Topic: Powders and Granules

TOPIC CONTENTS:

Powder: a)Introduction b) Classification c) Mixing of powders d)Method of preparation e)Advantages and disadvantages f)Shelf life and storage g)Containers h)Packaging i)Labeling j)Pharmaceutical uses

Introduction:

Defination: Powders may be defined as a solid material in a finely divided state. A powdered drug on its own can be a dosage form for taking orally (called simple powder) when they are usually mixed with water first, or for external application as a dusting powder.

Classification of Powders:

(a)Classification on the basis of use:1)Bulk powder for internal use2)Bulk powder for external use3)Divided or unit doses powder

1).Bulk powder for internal use

• They are mixture of finely divided drugs and\ or chemicals in a dry form that may be intended for internal use (oral powders)

• Types:• a)Oral powder• b)Powder spray• c)Dry powder inhalers• d)Effervescent powders

2).Bulk powder for external use• They are mixtures of finely divided drugs

and/ or chemicals in a dry form that may be intended for external use available in multiple doses (dusting powder)

• Types:• a)Dusting powders• b)Insufflations• c)Dentifrices

3)Divided powder

• Divided powder are similar formulation to bulk powder but individual doses are separately wrapped.

• Types• a)Douche powders• b)Powder for injection• c)Effervescent powders

Size classification of powders

Mixing of powders

• Ingredients of powder should be mixed thoroughly using the technique of doubling-up to insure an even distribution(some times called geometric dilution).

• This process involves starting with ingredient which has smallest bulk.

• The other ingredients are added progressively in approximately equal parts by volume.

• In this way the amount in the mortar is approximately doubled at each addition.

Mixing of powders

• Mixing in b/w additions continues until all the ingredients are incorporated.The powder can then be packed.

Method of preparation

• 1- Reduction of particle size of all ingredients to the same range to prevent stratification.

• 2- Sieving.• 3- Weighing of each ingredient.• 4- Mixing.• 5- Packaging.

(a)General method for preparation of bulk powders:

(1)Weigh the powder present in smallest volume(powder A) and placed in mortar.(2)Weigh the powder present in the next largest volume(powder B) and placed on labeled weighing paper.(3)Add approximately same amount of powder B as powder A in the mortar.

(a)General method for preparation of bulk powders:

• Mix well with pestle.• Continue adding amount of powder B that is

approximately the same as that in the mortar and mix with the pestle,i.e doubling the amount of powder in the mortar at each addition.

(b)General method for preparation of divided powders:

1)The minimum weight of individually wrapped powder is 120mg.Dilution of drug with a diluent usually lactose is often necessary to produce this weight.2)Usually tablets or capsules may be used to prepare oral powders . This involves either crushing the tablets in a mortar and pestle,or emptying the contents of the capsule and adding a suitable diluent.

(b)General method for preparation of divided powders:

3)Lactose is most commonly used diluent because it is colourless,odourless,soluble,is generally harmless and has good flow properties.4)Some patients may be unable to tolerate lactose and a suitable inert alternative diluent,for instance light kaolin,would then be used.

Powder calculations:

• While dealing powders calculations

–Always calculate for at least 1 extra powder to compensate loss of powder during manipulations.– If amount of active ingredient is less than

minimum weighable qty than dilutions (triturations) are to be made.–Min. weighable qty is diluted over several time to

obtain req. dose.

Powder calculations:

A. Doubling up method

B. Calculations involving powder volumes

Example:• E.g.• Rx • Hyoscine HBr 300 mcg• mitte 4 powders• one to given 30minutes before journey

• (Remember: minimum powder weight for divided powder = 120mg)• • Calculate for 5 doses• Active req. = ?• Diluent (lactose) req. = ?

Powder calculations:• Step-1• Hyoscine HBr =100mg• Diluent =900mg

• Step-2• Triturate A=100mg• Diluent =900mg

• Step-3• Triturate B =?• Diluent =?

Folding of paper

It involves following steps:(A)The long edge away from the dispenser should be turned over to about one-7th of the paper width.(B)The powder should be weighed accurately and placed on the paper towards the folded edge of the centre of the paper.(C)The unfolded long edge should then be brought over the powder to meet the crease of the folded edge and the flap closed over it.

Folding of paper

(D)The folded edge should then be folded over(towards the dispenser)so that it covers about half the powder packet.(E)The short edges of the powder packet should be folded over. using a powder cradle if available,so that flaps are of equal lengths and the folded powder fits neatly into a box a jar.Before making these folds ensure that there is no powder in the ends to be folded,otherwise it may fall out and be lost.

Folding of paper

Advantages of powders:

• Good chemical stability compared with fluids• useful for bulky drugs with large dose, e.g.

indigestion powder. • Easy to swallow even in large bulk, especially if

mixed with drink food (useful for stomach- tube feeding)

• The smaller particle size of powders causes more rapid dissolution in body fluids, increases drug bioavailability, and decreases gastric irritation compared with tablets.

Advantages of powders:

.Faster dissolution rate/Bioavailability

Increase S.A ------- increase dissolution Rapid onset of action

. Can be taken orally by some patients who are unable to swallow other solid dosage forms such as capsules and tablets.

Disadvantages of powders:

• Not suitable for drugs unstable in atmospheric conditions

• Not suitable for bitter, nauseating, deliquesnt and corrosive drugs.

• Inaccuracy of dose in case of bulk powder• Inconvenient to carry.

Shelf life and storage of internal powders

(1)Shelf life of internal powders is 2-4 weeks.(2)Proprietary powders often have a longer shelf life because of protective packaging.(3)Storage for these powders should be moisture proof and airtight.

Shelf life and storage of external powders

• Shelf life of external powders is 4 weeks.• Dry powders should remain stable for long

period of time if packaged and protected from atmosphere.

• Store in a cool and dry place.

Containers for internal powders

• Extemporaneously prepared individualy wrapped powders are often dispensed in a paperboard box.

• It is preferable to use a screw-top glass or plastic container which provides an air tight seal and protection against moisture.

• Bulk powders are packed in an airtight glass or plastic jar.

Containers for internal powders

Containers for external powders

• Powders for external use may be packed in glass,metal or plastic containers with a sifter-type cap. Some are also available commercially in pressurized containers,containing other excipients such as propellant and lubricants.

Containers for external powders

Labels and advice for internal powders

• Powders are usually mixed with water or another suitable liquid before taking,depending upon their solubility.

• Powders for babies can be placed directly into mouth followed by a drink to wash down the powder.

• Bulk powders should be shaken and measured carefully before dissolving in a little water and taking.

Labels and advice for internal powders:

Labels and advice for external powders

• For external use only.• Store in cool ,dry place.

Labels and advice for external powders:

Uses of powders:

• Powders are used as counter-irritant e.g /camphor starch dusting powder.

• Rhubarb powder is used in dyspepsia.• Chlorhexidine dusting powder is used as

antimicrobial.• Dover’s powder( ipecacuanha and opium) is

used as antipyretic.• Magnesium trisilicate powder is used as antacid

and anti-flatulent.

Uses of powders:

• Powders are also used as antiseptics.

Uses of powders:

• Ibuprofen powder is used to treat juvenile arthritis.

• Rumford is used as aluminium free baking powder.

Uses of powders:

• Powders are also used in cosmetics as face powders.

Uses of powders:

• Prickly heat powders are used to relief skin burn.

Uses of powders:

• Baby powders are used to protect skin and nappy rashes.

TOPIC CONTENTS:

• Granules:• a)Introduction• b) Classification• c)Method of preparation• d)Advantages and disadvantages • e)Shelf life and storage• f)Containers• g)Packaging• h)Labeling• i)Pharmaceutical uses

Introduction• Granules are powder agglomerated to produce large

free flowing particles.• Granules are particles ranging in size from about 4 to

10 mesh.• They are irregularly shaped but may be prepared to

be spherical.• Granulation are also used as intermediates in the

preparation of capsule and tablets,since they flow more smoothly and predictably than do small powder particles.

Granules

Why we prepare granules when we have powders?

• To avoid powder segregation.• To enhance the flow of powder.• Granules have higher porosity than powders.• To improve the compressibility of powders.• Materials, which are slightly hygroscope, may

adhere & form a cake if stored as a powder.

Classification

Granules are classified into following categories:1)Effervescent granules.2)Coated granules.3)Gastro-resistant granules.4)Modified release granules.

1:Effervescent granules

• Effervescent granules are uncoated granules generally containing acid substances and carbonates or hydrogen carbonates which react rapidly in the presence of water to release carbon dioxide.

• They are intended to be dissolved or dispersed in water before administration.

Effervescent granules

2:Coated granules

• Coated granules are usually multi-dose preparations consist of granules coated with one or more layers of mixtures of various excipients.

• The substances used as coatings are usually applied as solution or suspension in conditions in which evaporation of the vehicle occur.

Coated granules

3:Gastroresistant granules

• These are delayed release granules that are intended to resist the gastric fluid and to release the active substance in intestinal fluid

• These properties are achieved by covering the granules with the gastro-resistant material or by other suitable means.

Gastro-resistant granules

4:Modified release granules

• They are coated or uncoated granules which contain special excipients or which are prepared by special procedure are both , designed to modified the rate , the place or the time at which the active substance or substances are released.

• Modified release granules include prolonged release granules and delayed release granules.

Modified release granules

Advantages and Disadvantages of granules

Advantages• Granules are more flowable

compared to powder.• Segregation of the constituents

of the powder mixture could be avoided by granulation.

• Granules are more stable against humidity and atmosphere.

• Granules are more easily wetted by liquids than light and fluffy powders.

Disadvantages

.The masking of bitter tastes may be a problem with this type of preparation.• Granules are not a good

method of administering potent drug with low dose.

• Instability in presence of moisture.

• Problems in packaging and storage.

Methods of preparation

Granules are generally prepared by two methods.1)Wet method2)Dry method

Wet method:

• wet method is to moisten the powder or powder mixture and then pass the resulting paste through a screen of the mesh size to produce the desired size of granules.

• The granules are placed on drying trays and are dried by air or under heat.

• The granules are periodically moved about on the drying trays to prevent adhesion into a large mass.

Wet method:

• Another type of wet method is fluid bed processing, in which particles are placed in a conical piece of equipment and are vigorously dispersed and suspended while a liquid excipient is sprayed on the particles and the product dried, forming granules or pellets of defined particle size.

Fluid bed processing:

Dry method:

• Dry granulation is performed by two ways.• a) Roll compactor• b) Slugging

a) Roll compactor:• Dry powder is passed through a roll compactor and

then through a granulating machine. • A roll compactor, also called a roll press or roller

compactor, processes a fine powder into dense sheets or forms by forcing it through two mechanically rotating metal rolls running counter to each other .

• The surface of the compacting rolls may be smooth or may have pocket indentations or corrugations that allow compaction of different forms and textures.

a) Roll compactor:

• The compacted powder is granulated to uniform particle size in a mechanical granulator. Powder compactors are generally combined in sequence in integrated compactor–granulation systems.

a) Roll compactor:

b)Slugging:

• Slugging, is the compression of a powder or powder mixture into large tablets or slugs on a compressing machine under 8,000 to 12,000 lb of pressure, depending on the physical characteristics of the powder.

• The slugs are generally flat-faced and are about 2.5 cm (1 inch) in diameter.

b)Slugging:

• The slugs are granulated into the desired particle size, generally for use in the production of tablets. The dry process often results in the production of fines, that is, powder that has not agglomerated into granules. These fines are separated, collected, and reprocessed.

Preparation of effervescent granules:

• These granules are prepared by two methods:

• A)Fusion method• b)Wet method

A)Fusion method:• In the fusion method, the one molecule of water

present in each molecule of citric acid acts as the binding agent for the powder mixture.

• Before mixing the powders, the citric acid crystals are powdered and then mixed with the other powders of the same sieve size to ensure uniformity of the mixture.

• The sieves and the mixing equipment should be made of stainless steel or other material resistant to the effect of the acids.

A)Fusion method:• The mixing of the powders is performed as rapidly as is practical,

preferably in an environment of low humidity to avoid absorption of moisture and a premature chemical reaction.

• After mixing, the powder is placed on a suitable dish in an oven at 34°C to 40°C.

• During the heating process, an acidresistant spatula is used to turn the powder.

• The heat releases the water of crystallization from the citric acid, which, in turn, dissolves a portion of the powder mixture, setting the chemical reaction and consequently releasing some carbon dioxide.

A)Fusion method:• This causes the softened mass of powder to become

somewhat spongy, and when it has reached the proper consistency (as bread dough), it is removed from the oven and rubbed through a sieve to produce granules of the desired size.

• A No. 4 sieve produces large granules, a No. 8 sieve prepares medium size granules, and a No. 10 sieve prepares small granules.

• The granules are dried at a temperature not exceeding 54°C and are immediately placed in containers and tightly sealed.

B)Wet method:

• The wet method differs from the fusion method in that the source of binding agent is not the water of crystallization from the citric acid but the water added to alcohol as the moistening agent, forming the pliable mass for granulation.

• In this method, all of the powders may be anhydrous as long as water is added to the moistening liquid.

• Just enough liquid is added (in portions) to prepare a mass of proper consistency; then the granules are prepared and dried.

Example:

• Sodium citrate and tartrate B.P.• Ingredients Quantity1) Sodium bicarbonate 510gm2) Tartaric acid 270gm3) Citric acid 180gm4) Sucrose 150gm

Shelf life and storage:

• Shelf life of granules is 2-3 weeks.• Granules should be stored in airtight

containers.• Granules should be placed at cool and dry

place.

Container

• Granules should be kept in air tight container.

Container:

Label and advice

• Dissolve or mix with water before taking.• A normal dose is 1-5 g of the powder taken in

liquid, when required.• Antacids are usually taken b/w meals and at

bedtime.

Label and advice:

pharmaceutical uses:

• Effervescent granules are used as an antacid.

pharmaceutical uses:

• Methylcellulose granules are used as a laxative.

Uses of granules:

• Granules are also used in fertilizer industry.

Uses of granules:

• Granules are used for instant preparation of solutions and suspensions.

Uses of granules:

• Lactinex granules are use in uncomplicated diarrhea.

Uses of granules:

• Granules are also used as animal foods.

Powders Granules

• Comparatively poor flow properties • Flow well compared to tablets, good choice for compressing tabs

• Relatively less stable (physically and Chemically) due to inc. S.A & Atm. Effect

• Has less surface area, more stable to atm. effect

• More likely to hardening / cake formation on long storage

• Less likely

• For some powders, drugs float on the surface, difficult to make solution

• More easily wetted by the solvents, good choice reconstitution liquids

• Relatively poor compressibility • Good compressibility

• Chances of non uniform dosing are more • Relatively more uniformity of contents in case of granules

• More dust due to small particle size • Generate less dust on handling

• Comparatively less appealing • Have a more elegant appearance

• Relatively simple method of processing/formulation

• It involves more processing, exposure to heat and contact with solvents

Powders VS Granules