Dosage Lec - Module 2

Powders

Mixtures of finely divided drugs and/or chemicals used internally or externally

Latin Name of Powder

Pulvis

Divided Powder

Powder dispensed in individual doses, generally in folded papers (chartula)

Types of Powders

Oral powders, dentifrices, douche powders, dusting powders, insufflations, triturations

Dusting Powders

For external use on skin; must be impalpable, free flowing, and passed through at least 100-mesh sieve

Insufflated Powders

Finely divided powders applied to body cavities (ears, nose, vagina, tooth socket, throat)

Adherent in Insufflated Powders

Polyethylene oxide polymer that forms viscous, mucoadhesive gel with moisture

Classes of Powders

Simple, Compound, Bulk, Divided

Eutectic Mixture

Mixture of substances that liquefy when mixed or triturated (melting point below room temp)

Hygroscopic Substances

Absorb moisture from air

Deliquescent Substances

Absorb moisture until liquefaction occurs

Efflorescent Substances

Crystalline powders that lose water of hydration on exposure to low humidity; may liquefy or become sticky

Explosive Powder Mixtures

Powder combinations that react violently when mixed

Coarse Powder

All particles pass through sieve No. 8 and not more than 20% pass through sieve No. 60

Moderately Coarse Powder

All particles pass through sieve No. 20 and not more than 40% pass through sieve No. 60

Moderately Fine Powder

All particles pass through sieve No. 40 and not more than 40% pass through sieve No. 80

Fine Powder

All particles pass through sieve No. 60 and not more than 40% pass through sieve No. 100

Very Fine Powder

All particles pass through sieve No. 80

Sieve Analysis

Separating particles into size ranges using sieves of successively smaller openings

Microscopy Method

Uses calibrated grid to size particles under microscope

Sedimentation Method

Measures terminal settling velocity of particles in liquid

Light Obscuration

Method where dispersed particles reduce light reaching a sensor

Laser Holography

Pulsed laser photographs aerosolized particle spray in 3D

Cascade Impaction

Separates particles into size ranges by air velocity

Comminution

Process of reducing particle size

Trituration

Grinding powders in mortar and pestle

Levigation

Reducing particle size in small-scale ointments/suspensions by forming paste with levigating agent

Common Levigating Agent

Glycerin

Pulverization by Intervention

Reducing particle size of gummy substances using volatile solvent

Common Solvent for Pulverization

Alcohol

Geometric Dilution

Mixing potent substances with large diluent by gradual addition

Spatulation

Blending powders on paper/tile using spatula

Sifting

Mixing powders by passing through sifters

Tumbling

Mixing powders in rotating chamber

Bulk Powders

Packed in wide-mouth containers

Dusting Powders Packaging

Sifter-top container or shaker

Divided Powders Packaging

Wrapped in folded papers

Dusting Powder Label

“FOR EXTERNAL USE ONLY”

Douche Powder

Powder dissolved in warm water for vaginal use

Nutritional Powder

Powder containing vitamins (e.g., B-complex)

Headache Powder

Divided powder for headache relief

Dentifrices

Powders containing mild abrasive, soap/detergent, anticariogenic agent

Powder Wrapping – White Bond Paper

Thin, semi-opaque, limited moisture resistance

Powder Wrapping – Glassine Paper

Glazed transparent paper, limited moisture resistance

Powder Wrapping – Waxed Paper

Transparent, waterproof; used for double-wrapping hygroscopic/deliquescent powders

Granules

Dry aggregates of powder particles, irregular or spherical, usually 4–12 sieve size range

Granule Characteristics

Free-flowing, stable, less hygroscopic, easily wetted, used in tablets and capsules

Effervescent Granules

Contain sodium bicarbonate, citric acid, tartaric acid; liberate CO₂ in water

Effervescent Granules with Tartaric Acid

Brittle granules form

Effervescent Granules with Citric Acid

Sticky granules form

Dry/Fusion Method (Effervescent)

Water of crystallization from citric acid acts as binding agent

Wet Method (Effervescent)

Moistening agent (water + alcohol) forms pliable mass for granulation

Advantages of Powders

Flexible dosing, rapid onset, useful in clinical studies, stable compared to liquids

Disadvantages of Powders

Inconvenient to carry, poor taste masking, unsuitable for low-dose potent drugs, hygroscopic instability

Steps in Powder Preparation

(1) Comminution → (2) Blending → (3) Packaging

Comminution Techniques

Trituration, Levigation, Pulverization by intervention

Mixing Methods

Spatulation, Geometric dilution, Sifting, Tumbling

Methods of Dividing Powders

Weighing each dose, Block-and-divide

Wet Granulation Steps

(1) Weighing/blending → (2) Binder solution prep → (3) Wet massing → (4) Screening → (5) Drying → (6) Screening → (7) Lubricant blending → (8) Compression

Dry Granulation Steps

(1) Weighing/blending → (2) Compaction → (3) Screening → (4) Lubricant blending → (5) Compression

Direct Compression Steps

(1) Weighing/blending → (2) Lubricants added → (3) Compression