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55 Cards in this Set
- Front
- Back
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Definition of Powder
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1. physical form of a material: a dry subtance composed of finely divided particles
2. a pharmaceutical prep: a medicated powder intended for internal or external use |
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Particle Size Impacts...
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dissolution
suspendability of suspensions uniformity of mixtures in liquids penetrability of particles for inhalation nongrittiness for ointments, creams, gels |
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Particle Size
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if uniform, will aid in mixing and distribution
finer particles may migrate to bottom (in tablets) larger particles may migrate to top (in tablets) differences in particle size may change the color intensity of a powder expecially important in dermatologicals |
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characterization of powders
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Micromeritics: the study of small particles
particle size & particle distribution (narrow vs wide distribution) uniformity morphology flow porosity volume density compatibility with other formulation components |
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Particle size and Analysis
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purpose of particle size analysis is to obtain quantitative data on size, distribution, and morphology of powders
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Particle size and Analysis
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pharmaceutical powders may range in size from extremely coarse, = 10mm to extremely fine = 1 micron or less
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USP descriptive terms
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very coarse
coarse moderately coarse fine very fine |
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Analysis of PS
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Very coarse......#8 sieve......2,360 micrometer
Coarse.............#20 sieve.....850 micrometer Mod. Coarse.....#40 sieve.....425 micrometer Fine.................#60 sieve.....250 micrometer Very fine..........#80 sieve.....180 micrometer |
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Methods of Particle size Analysis
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sieve analysis
microscopy sedimentation rate laster light scattering or diffraction cascade impaction |
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Sieve analysis
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Particles are passed (mechanically shaken) through a series of sieves of known and successively smaller size
proportion of powder passing through or being withheld on each sieve is determined |
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Microscopy
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particle size is determined by visual observation with the use of a calibrated grid background or other measuring device
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Powder Flow
Impacts Characterization |
Impacted by: size, shape, porosity
Characterized by: angle of repose, carr index |
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Angle of repose
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estimates flow properties
measure the angle formed when powder is allowed to flow freely from a known height Tan0 = h/r powders with low angles of repose flow freely |
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Tapped and bulk density
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method to determine powder flow and compressibility
useful in determining storage needs weigh known volume of powder and mechanically drop from given height and determine volume |
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Particle size reduction
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Comminution: process of reducing the particle size of a solid substance to a finer state of subdivision
Objectives: facilitate crude drug extraction increase the dissolution rates of drugs aid in the formulation process enhance absorption |
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Extemporaneous Particle Size Reduction
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Trituration: to rub to pieces (done with mortar and pestle)
Pulverization: comminution by utilizing a SOLVENT that can be easily removed Levigation: triturating while moistened with a liquid in which the powder is INSOLUBLE |
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Industrial Particle Size Reduction
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Milling
Ball Mills Closed Continuous Roller Mills Cutter Mills Hammer Mills Colloid Mills Fluid Energy Mills Lyophilization (Freeze-Drying) Spray Drying |
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Blending of Powders
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Spatulation—mixing of powders on an ointment slab or pad using a spatula; no particle size reduction
Trituration—continued rubbing of a solid in a mortar with a pestle to reduce the particle size Tumbling—uses clear glass or plastic bottles and zipper sealed plastic bags to mix powders Specialized equipment—mixers, sifters, etc. Geometric dilution—used when blending two or more powders of unequal quantities to ensure that small quantities of usually potent drugs are uniformly distributed throughout the powder mixture |
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Blending of Powders
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TUMBLERS
Double Cone Blender Twin Shell Blender PADDLE BLENDERS Blade and Paddle Blender |
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Factors in Blending
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Size
Shape Density Electrostatic Forces Limits of Blend Segregation Mechanisms |
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Uses of Powders
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Medicated Powders
Aerosol Powders Bulk and Divided Powders Preparation of other dosage forms |
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Uses of Powders – medicated Powders
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Dentifrices:
Powders used to clean the teeth Insufflations: Intended for application to the body cavities (e.g., tooth sockets, ears, nose, throat, vagina) Powder Aerosols: Antiperspirants, deodorants, feminine hygiene sprays, body sprays, insufflations, dry lubricants |
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Uses of Powders – medicated Powders
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Aerosol Powders:
Inhalation Dry-powder inhalers Micronized powders External application and nose, throat, lung, and vagina Insufflators Powder blowers Bulk Powders: Intended to be administered in dosage quantities that are safe for the patient to measure Should pass through a 100 mesh sieve Dusting powders, aerosols, dentifrices, antacids, laxatives, dietary nutrient supplements, douches |
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Uses of Powders - Bulk and Divided Powders
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Must be homogenous, free from potential of causing local irritation
Should flow easily, spread uniformly, and cling to the skin upon application Generally dispensed in sifter-top containers |
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Uses of Powders - Bulk and Divided Powders
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Divided Powders (chartulae, charts, powder papers, powders)
Single doses of the powdered drug mixture individually enclosed in paper, cellophane, or metallic foil wrappers or packets Sufficiently potent to require premeasured doses |
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Advantages of Divided Powders
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1. Allows physicians to prescribe a precise amount of the drug.
2. More stable than the liquid form of many drugs. 3. Dissolve more rapidly than compressed solid dosage forms. 4. Rapid dissolution leads to faster blood levels and possibly less GI irritation |
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Disadvantages of Powders
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1. Not suitable for bitter, nauseating, or corrosive drugs.
2. Preparation is time-consuming, therefore more costly. 3. Exposure of powder to atmospheric conditions. |
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Powder Types Requiring Special Handling
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Hygroscopic
Deliquescent Efflorescent Water of Imbibition Eutectic Mixtures Explosive Mixtures |
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Hygroscopic and Deliquescent Powders
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HYGROSCOPIC
Substances that absorb moisture from the air DELIQUESCENT Substances that absorb moisture from the air to the extent that they liquefy by partially or wholly forming a solution |
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Examples: Hygroscopic and Deliquescent Powders
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Ammonium Bromide/Chloride/Iodide
Calcium Bromide/Chloride Ephedrine Sulfate Hyoscyamine HBr/Sulfate Lithium Bromide Phenobarbital Sodium Potassium Acetate/Citrate Sodium Bromide/Iodide/Nitrate Physostigmine Sulfate/HCl/HBr Pilocarpine |
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Uses of Powders
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Medicated Powders
Aerosol Powders Bulk and Divided Powders Preparation of other dosage forms |
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Uses of Powders – medicated Powders
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Dentifrices:
Powders used to clean the teeth Insufflations: Intended for application to the body cavities (e.g., tooth sockets, ears, nose, throat, vagina) Powder Aerosols: Antiperspirants, deodorants, feminine hygiene sprays, body sprays, insufflations, dry lubricants |
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Uses of Powders – medicated Powders
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Aerosol Powders:
Inhalation Dry-powder inhalers Micronized powders External application and nose, throat, lung, and vagina Insufflators Powder blowers Bulk Powders: Intended to be administered in dosage quantities that are safe for the patient to measure Should pass through a 100 mesh sieve Dusting powders, aerosols, dentifrices, antacids, laxatives, dietary nutrient supplements, douches |
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Uses of Powders - Bulk and Divided Powders
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Must be homogenous, free from potential of causing local irritation
Should flow easily, spread uniformly, and cling to the skin upon application Generally dispensed in sifter-top containers |
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Uses of Powders - Bulk and Divided Powders
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Divided Powders (chartulae, charts, powder papers, powders)
Single doses of the powdered drug mixture individually enclosed in paper, cellophane, or metallic foil wrappers or packets Sufficiently potent to require premeasured doses |
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Advantages of Divided Powders
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1. Allows physicians to prescribe a precise amount of the drug.
2. More stable than the liquid form of many drugs. 3. Dissolve more rapidly than compressed solid dosage forms. 4. Rapid dissolution leads to faster blood levels and possibly less GI irritation |
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Disadvantages of Powders
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1. Not suitable for bitter, nauseating, or corrosive drugs.
2. Preparation is time-consuming, therefore more costly. 3. Exposure of powder to atmospheric conditions. |
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Powder Types Requiring Special Handling
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Hygroscopic
Deliquescent Efflorescent Water of Imbibition Eutectic Mixtures Explosive Mixtures |
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Hygroscopic and Deliquescent Powders
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HYGROSCOPIC
Substances that absorb moisture from the air DELIQUESCENT Substances that absorb moisture from the air to the extent that they liquefy by partially or wholly forming a solution |
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Examples: Hygroscopic and Deliquescent Powders
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Ammonium Bromide/Chloride/Iodide
Calcium Bromide/Chloride Ephedrine Sulfate Hyoscyamine HBr/Sulfate Lithium Bromide Phenobarbital Sodium Potassium Acetate/Citrate Sodium Bromide/Iodide/Nitrate Physostigmine Sulfate/HCl/HBr Pilocarpine |
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Efflorescent Powders
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Crystalline substances that become powdery and liberate their water of hydration when they are manipulated or stored under conditions of low relative humidity
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Examples: Efflorescent Powders
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Alums
Atropine sulfate Caffeine Calcium lactate Citric acid Cocaine Codeine phosphate/sulfate |
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Examples: Efflorescent Powders
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Ferrous sulfate
Morphine acetate Scopolamine HBr Sodium acetate Sodium carbonate Sodium phosphate Strychnine sulfate Terpin hydrate |
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Water of Imbibition
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Colloidal substances may absorb large amounts of water and retain the appearance of dry powders. This may cause problems in weighing. The water content varies with the humidity.
Cellulose, starch, agar, gelatin |
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Eutectic Mixtures
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A proportion of components that will give the lowest melting point
A mixture of components with a melting point less than room temperature Aspirin, betanaphthol, camphor, chloral hydrate, menthol, phenol, salol, thymol |
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Avoiding Eutectics
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1. Dispense powders separately.
2. Add an absorbent powder (talc, starch, lactose, calcium phosphate). 3. Keep ingredients separated as much as possible. 4. Make the eutectic, then add absorbent to incorporate the liquid. |
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Explosive Mixtures
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When triturating an oxidizing agent with a reducing agent (using a mortar and pestle)
OXIDIZING AGENTS Potassium chlorate/nitrate/permanganate, sodium peroxide, silver nitrate, silver oxide REDUCING AGENTS Charcoal, hypophosphites, sulfur, sulfides, tannic acid, volatile oils |
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Granules
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Prepared agglomerates of powdered materials ranging from 4 to 10 mesh in size
Reduced surface area compared to powders Not intended for use with potent drugs because of inherent error when a patient measures the dose with a teaspoon, scoop, etc. Good for unstable drugs Example: antibiotics for reconstitution |
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Granule Preparation
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Prepared by moistening blended powders and by passing this mass through a screen or a granulator
Granules are then air or oven dried. Flavors can be sprayed on the granules and then dried. |
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Effervescent Granules
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Contain mixtures of citric acid, tartaric acid, or sodium biphosphate with a bicarbonate and a medicinal agent
The carbonated solution is a pleasant vehicle and lessens the bitter and salty taste of salts (e.g., magnesium sulfate). |
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Effervescent Granules (cont’d)
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Dispense in:
Packets Wide-mouth bottles Do not want them to effervesce too quickly as they will overflow the container during mixing Examples: Lactinex, Bassoran, Zantac |
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Packaging/Dispensing
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Oral Administration
Wide-mouth containers Powder papers Topical Administration Sifter containers Puffer units |
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Storage/Labeling
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Store in dry places.
Protect from light in some cases. Keep out of reach of children. |
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Stability
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Dry
USP <795>: 6 months if prepared from USP/NF ingredients 25% of expiration date remaining if prepared from commercial product |
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Patient Counseling
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Dose measuring technique?
Mix with liquid or food? Premix and store? Quantity of powder to apply? Rub or pat into skin? Safe to apply where children are playing? Should skin be dry? Sweaty? |
