Pharmaceutical Dosage Forms-Powders

Pharmaceutical Pharmaceutical Dosage Forms Dosage Forms PowderPowder

Powders as Dosage Powders as Dosage FormsForms

DefinitionDefinition

Powders are intimate mixtures of Powders are intimate mixtures of dry, finely divided drugs and/or dry, finely divided drugs and/or chemicals that may be intended chemicals that may be intended for internal or external use.for internal or external use.

Advantages of Powders as Advantages of Powders as Dosage FormDosage Form

1.1. Flexibility of compounding-easy Flexibility of compounding-easy to prepareto prepare

2.2. Good chemical stabilityGood chemical stability

3.3. Rapid dissolution due to small Rapid dissolution due to small particle sizeparticle size

4.4. Fast action and better Fast action and better bioavailabilitybioavailability

Disadvantages of Disadvantages of Powders as Dosage FormPowders as Dosage Form

1.1. Time consumingTime consuming

2.2. Inaccuracy in doseInaccuracy in dose

3.3. Unsuitable for many unpleasant Unsuitable for many unpleasant tasting, volatile, oxidizing, tasting, volatile, oxidizing, hygroscopic and deliquescent hygroscopic and deliquescent drugs.drugs.

ClassificationClassification

Based on UsageBased on Usage

-powders for external use.-powders for external use.

-powders for internal use.-powders for internal use. Based on quantityBased on quantity

-bulk powders-bulk powders

-divided powders-divided powders

GranulesGranules

Agglomerates of powdersAgglomerates of powders Used as such as dosage form or Used as such as dosage form or

used to prepare tabletsused to prepare tablets

e.g. effervescent granules- to mask e.g. effervescent granules- to mask unpleasant taste of drugs.unpleasant taste of drugs.

Pharmaceutical Technology Pharmaceutical Technology involved in the involved in the Manufacturing of PowdersManufacturing of Powders

Comminution of Drugs (Particle Comminution of Drugs (Particle Size reduction of drugs)Size reduction of drugs)

Blending of PowdersBlending of Powders

Comminution of DrugsComminution of Drugs

TriturationTrituration -Grinding with mortar and pestle. -Grinding with mortar and pestle. Mills and pulverizers e.g. FitzMillMills and pulverizers e.g. FitzMill LevigationLevigation- a paste is formed by combining - a paste is formed by combining

the powder and a small amount of liquid the powder and a small amount of liquid (levigating agent) in which the powder is (levigating agent) in which the powder is insoluble. The paste is then triturated to reduce insoluble. The paste is then triturated to reduce particle size. The levigated paste may be mixed particle size. The levigated paste may be mixed with base well with help of a spatula and tile. with base well with help of a spatula and tile. Mineral oil and glycerin are generally used Mineral oil and glycerin are generally used levigating agent.levigating agent.

Pulverization by intervention-Pulverization by intervention- size size reduction using a solvent and which is removed reduction using a solvent and which is removed after size reduction. Suitable for resins and after size reduction. Suitable for resins and gummy substance. E.g. camphor.gummy substance. E.g. camphor.

Blending or Mixing Blending or Mixing PowdersPowders

a. Spatulationa. Spatulation-Mixing is done using spatula and tile or -Mixing is done using spatula and tile or

sheetsheet-useful for solid substances that liquefy or -useful for solid substances that liquefy or

form eutectic mixtures (i.e., mixtures that form eutectic mixtures (i.e., mixtures that melt at a lower temperature than any of melt at a lower temperature than any of their ingredients; when in close, their ingredients; when in close, prolonged contact with one another) prolonged contact with one another)

-not suitable for potent drug-not suitable for potent drug-lack of homogenous mixing-lack of homogenous mixing

Blending or Mixing Blending or Mixing PowdersPowdersb. Trituration b. Trituration It is used both to comminute and to mix It is used both to comminute and to mix

powders.powders. If comminution is desired, a porcelain If comminution is desired, a porcelain

or ceramic mortar with a rough inner or ceramic mortar with a rough inner surface is preferred to a glass mortar surface is preferred to a glass mortar with a smooth working surface.with a smooth working surface.

A glass mortar is preferable for A glass mortar is preferable for chemicals that stain a porcelain or chemicals that stain a porcelain or ceramic surface as well as for simple ceramic surface as well as for simple admixture of substances without admixture of substances without special need for comminution. A glass special need for comminution. A glass mortar cleans more readily after use.mortar cleans more readily after use.

Blending or Mixing Blending or Mixing PowdersPowdersc. Geometric dilution c. Geometric dilution It is used when potent substances must be It is used when potent substances must be

mixed with mixed with a large amount of diluent.a large amount of diluent. The potent drug and an approximately equal The potent drug and an approximately equal

volume of diluent are placed in a mortar and volume of diluent are placed in a mortar and thoroughly mixed by trituration.thoroughly mixed by trituration.

A second portion of diluent, equal in volume to A second portion of diluent, equal in volume to the powder mixture in the mortar, is added, the powder mixture in the mortar, is added, and trituration is repeated. The process is and trituration is repeated. The process is continued; equal volumes of diluent are added continued; equal volumes of diluent are added to the powder mixture in the mortar until all of to the powder mixture in the mortar until all of the diluent is incorporated.the diluent is incorporated.

Blending or Mixing Blending or Mixing PowdersPowdersd. Sifting. Powders are mixed by passing d. Sifting. Powders are mixed by passing

them through sifters similar to those them through sifters similar to those used to sift flour. This process results used to sift flour. This process results in a light, fluffy product. Usually, it is in a light, fluffy product. Usually, it is not acceptable for incorporating potent not acceptable for incorporating potent drugs into a diluents base.drugs into a diluents base.

e. Tumbling is the process of mixing e. Tumbling is the process of mixing powders in a large container rotated by powders in a large container rotated by a motorized process. These blenders a motorized process. These blenders are widely used in industry, as are are widely used in industry, as are large-volume powder mixers that use large-volume powder mixers that use motorized blades to blend the powder motorized blades to blend the powder in a large mixing vessel.in a large mixing vessel.

Use and Packaging of Use and Packaging of

PowdersPowders

Depending on their intended use, Depending on their intended use,

powders are packaged and powders are packaged and dispensed asdispensed as

1. bulk powders or 1. bulk powders or

2. divided powders.2. divided powders.

a. Bulk Powdersa. Bulk Powders

They are dispensed in bulk containers. A They are dispensed in bulk containers. A perforated, or sifter, can is used for external perforated, or sifter, can is used for external dusting, and an aerosol container is used for dusting, and an aerosol container is used for spraying onto skin. A wide-mouthed glass jar spraying onto skin. A wide-mouthed glass jar permits easy removal of a spoonful of powder. permits easy removal of a spoonful of powder. E.g. of bulk powders are as followsE.g. of bulk powders are as follows

(a) Antacid and laxative powders (a) Antacid and laxative powders (b) Douche powders (b) Douche powders (c) Medicated and non medicated powders for (c) Medicated and non medicated powders for

external use external use (d) Dentifrices or dental cleansing powders are (d) Dentifrices or dental cleansing powders are

used for oral hygiene.used for oral hygiene.(e) Powders for the ear, nose, throat, tooth (e) Powders for the ear, nose, throat, tooth

sockets, or vagina are administered with an sockets, or vagina are administered with an insufflator, or powder blower.insufflator, or powder blower.

b. Divided Powdersb. Divided Powders

These are dispensed in individual doses, These are dispensed in individual doses, usually in folded papers.usually in folded papers.

They may also be dispensed in metal foil, small They may also be dispensed in metal foil, small heat-sealed or resealable plastic bags, or other heat-sealed or resealable plastic bags, or other containers.containers.

After the ingredients are weighed, After the ingredients are weighed, comminuted, and mixed, the powders must be comminuted, and mixed, the powders must be accurately divided into the prescribed number accurately divided into the prescribed number of doses.of doses.

Depending on the potency of the drug Depending on the potency of the drug substance, the pharmacist decides whether to substance, the pharmacist decides whether to weigh each portion separately before weigh each portion separately before packaging or to approximate portions by the packaging or to approximate portions by the block-and-divide method.block-and-divide method.

Papers Used to Pack Papers Used to Pack Individual PowdersIndividual Powders

Four basic types are used:Four basic types are used: (a) Vegetable parchment is a thin, semi opaque, (a) Vegetable parchment is a thin, semi opaque,

moisture-resistant paper.moisture-resistant paper. (b) White bond is an opaque paper that has no (b) White bond is an opaque paper that has no

moisture-resistant properties. moisture-resistant properties. (c) Glassine is a glazed, transparent, moisture-(c) Glassine is a glazed, transparent, moisture-

resistant paper.resistant paper. (d) Waxed paper is a transparent waterproof (d) Waxed paper is a transparent waterproof

paper.paper. Hygroscopic and volatile drugs are best Hygroscopic and volatile drugs are best

protected with waxed paper that is double protected with waxed paper that is double wrapped and covered with a bond paper to wrapped and covered with a bond paper to improve the appearance. Parchment and improve the appearance. Parchment and glassine papers are of limited use for these glassine papers are of limited use for these drugs.drugs.

Special Problems Associated Special Problems Associated with Powderswith Powders

Powders with volatile substances, eutectic Powders with volatile substances, eutectic mixtures, liquids, and hygroscopic or mixtures, liquids, and hygroscopic or

deliquescent deliquescent substances present problems substances present problems 1. Volatile substances 1. Volatile substances e.g., camphor, menthol, essential oils) can e.g., camphor, menthol, essential oils) can

be lost by volatilization after they are be lost by volatilization after they are incorporated into powders. incorporated into powders.

It is prevented by using heat-sealed It is prevented by using heat-sealed plastic bags or double wrapping with plastic bags or double wrapping with waxed or glassine paper inside white bond waxed or glassine paper inside white bond paper.paper.

Special Problems Associated Special Problems Associated with Powders: 2. Incorporation with Powders: 2. Incorporation of Liquidsof Liquids

Liquids are incorporated into divided Liquids are incorporated into divided powders in small amounts.powders in small amounts.(1) Magnesium carbonate, starch, or (1) Magnesium carbonate, starch, or

lactose can be added to increase the lactose can be added to increase the absorbability of the powders by absorbability of the powders by increasing the surface area.increasing the surface area.

(2) When the liquid is a solvent for a (2) When the liquid is a solvent for a nonvolatile heat-stable compound, it is nonvolatile heat-stable compound, it is evaporated gently in a water bath. evaporated gently in a water bath. Some fluid extracts and tinctures are Some fluid extracts and tinctures are treated in this way. treated in this way.

Special Problems Associated Special Problems Associated with Powders: 3. Hygroscopic with Powders: 3. Hygroscopic and deliquescent substancesand deliquescent substances

Hygroscopic and deliquescent substances that Hygroscopic and deliquescent substances that become moist because of an affinity for moisture in become moist because of an affinity for moisture in the air.the air.

Substance which absorb moisture are called Substance which absorb moisture are called hygroscopic hygroscopic

If high qty of water is absorbed to make the If high qty of water is absorbed to make the material liquid then it is called as deliquescent. material liquid then it is called as deliquescent.

E.g. Potassium citrate, ammonium chloride, citric E.g. Potassium citrate, ammonium chloride, citric acid, tartaric acid, sodium iodide.acid, tartaric acid, sodium iodide.

It can be prepared as divided powders by adding It can be prepared as divided powders by adding inert diluents/ absorbents. inert diluents/ absorbents.

Double wrapping is desirable for further protection.Double wrapping is desirable for further protection. Prepared as granules to minimize the exposure to Prepared as granules to minimize the exposure to

moisture.moisture.

Special Problems Associated Special Problems Associated with Powders: 4. Eutectic with Powders: 4. Eutectic MixturesMixtures

Some of the drugs when mixed together tend Some of the drugs when mixed together tend to liquefy due to formation of new compound to liquefy due to formation of new compound (due to decrease in melting point). e.g. (due to decrease in melting point). e.g. menthol, thymol, phenol, aspirin, camphor and menthol, thymol, phenol, aspirin, camphor and mentholmenthol

One of the ingredient added in a powder may One of the ingredient added in a powder may reduce the melting point of other ingredient reduce the melting point of other ingredient and forms a liquid. and forms a liquid.

Methods to Overcome:Methods to Overcome:1. Can be minimized by using inert diluents 1. Can be minimized by using inert diluents

/absorbent like magnesium carbonate, kaolin, /absorbent like magnesium carbonate, kaolin, starch, lactose, light magnesium oxide.starch, lactose, light magnesium oxide.

2. They can be dispensed in separate sets of 2. They can be dispensed in separate sets of powders and labelled with suitable directionpowders and labelled with suitable direction

Special Problems Associated Special Problems Associated with Powders: 5. Efflorescent with Powders: 5. Efflorescent powderspowders

Crystalline substance liberates Crystalline substance liberates water of crystallization due to water of crystallization due to change in humidity are called change in humidity are called efflorescent substances.efflorescent substances.

e.g. caffeine, cocaine, codeine e.g. caffeine, cocaine, codeine phosphate, Sodium carbonate, phosphate, Sodium carbonate, sodium phosphate.sodium phosphate.

Methods to overcome: Use Methods to overcome: Use anhydrous saltanhydrous salt

Special Problems Associated Special Problems Associated with Powders: 6. Explosive with Powders: 6. Explosive substancessubstances

When some oxidizing and reducing When some oxidizing and reducing substances are mixed in mortar, substances are mixed in mortar, there are chances of explosion.there are chances of explosion.

Very rare combinations.Very rare combinations.

e.g. Potassium chlorate and tannic e.g. Potassium chlorate and tannic acid.acid.

Method to overcome: separately Method to overcome: separately powder and dispense.powder and dispense.

Packaging and Labeling of Packaging and Labeling of PowdersPowders

Hygroscopic, deliquescent, or volatile Hygroscopic, deliquescent, or volatile powders- packed in glass jars rather powders- packed in glass jars rather than pasteboard containers. than pasteboard containers.

Amber or green glass for light-Amber or green glass for light-sensitive components. sensitive components.

Should be stored in tightly closed Should be stored in tightly closed containers.containers.

Products for external use must indicate Products for external use must indicate “For External Use Only” on the label“For External Use Only” on the label

GranulesGranules

Has some advantage over powderHas some advantage over powder Free flowingFree flowing More stableMore stable Better dose measurementsBetter dose measurements Used in the manufacture of Used in the manufacture of

tablets and capsulestablets and capsules

Effervescent Effervescent Granulated SaltsGranulated Salts Effervescent salts are granules or coarse to very Effervescent salts are granules or coarse to very

coarse powders containing a medicinal agent.coarse powders containing a medicinal agent. It is a dry mixture composed of sodium It is a dry mixture composed of sodium

bicarbonate, citric acid, and tartaric acid. When bicarbonate, citric acid, and tartaric acid. When added to water, the acids and base react to added to water, the acids and base react to liberate carbon dioxide, resulting in liberate carbon dioxide, resulting in effervescence. effervescence.

The resulting carbonated solution masks The resulting carbonated solution masks undesirable taste of any medicinal agent. undesirable taste of any medicinal agent.

Using granules or coarse particles of the mixed Using granules or coarse particles of the mixed powders rather than small powder particles powders rather than small powder particles decreases the rate of solution and prevents decreases the rate of solution and prevents violent and uncontrollable effervescence. violent and uncontrollable effervescence.

Preparation of Preparation of Effervescent granules Effervescent granules Prepared by two general methods: Prepared by two general methods: (a)(a) the dry or fusion method : Ingredients the dry or fusion method : Ingredients

are mixed and heated to release water are mixed and heated to release water of crystallization from citric acid. of crystallization from citric acid. Release of water will produce CORelease of water will produce CO22. The . The mixture will become spongy while mixture will become spongy while heating at 40heating at 400 0 C. Then the spongy C. Then the spongy mass passed through sieve to produce mass passed through sieve to produce granules.granules.

(b) the wet method- water/alcohol used to (b) the wet method- water/alcohol used to prepare wet mass which is passed prepare wet mass which is passed through sieve to produce granulesthrough sieve to produce granules