Powders and Granules

PHARDOSE PRELIMS CHAPTER 6  – POWDERS AND GRANULES POWDERS - Used to describe the physical form of a material, which is a dry substance composed of finely divided particles. - Used to describe a type of pharmaceutical preparation, that is, a medicated powder inte nded for internal or external use. Ways how medicated powders are used in therapeutics: 1.) Powdered drugs maybe blended with powdered fillers and other pharmaceutical ingredients to fabricate solid dosage forms as tablets and capsules. 2.) They may be dissolved or suspended in solvents or liquid vehicle to make various liquid dosage forms. 3.) They may be incorporated into semisolid bases in the preparation of medicated ointments and creams. GRANULES - Are prepared agglomerates of powdered materials. - May be used per se for the medicinal value of their content, or they may be used for pharmaceutical purposes, as in making tablets. PARTICLE SIZE AND ANALYSIS Powders of Vegetable & Animal Origin Drugs Very coarse (No. 8)  Coarse (No. 2)  Moderately coarse (No. 40)  Fine (No. 60)  Very Fine (No. 80)  * Granules typically fall within the range of 4- to 12sieve size. * The purpose of particle size analysis in the pharmacy is to obtain quantitative data on the size distribution, and  shapes of the drug and other components to be used in  pharmaceutical formulations. formulations.

FACTORS WHICH ARE INFLUENCED BY PARTICLE SIZE 1. Dissolution rate of particles intended to dissolve; Drug micronization can increase the rate of drug dissolution and its bioavailabity. 2. Suspendability of particles intended to remain undissolved but uniformly dispersed in a liquid vehicle

Distribution of a drug substance in a 3. Uniform Distribution powder mixture or solid dosage form to e nsure dose-dose content uniformity. 4. Penetrability of particles intended to be inhaled for deposition deep in the respiratory tract. 5. Lack of grittiness of solid particles in dermal ointments, creams, and ophthalmic preparations.

METHODS WHICH DETERMINES PARTICLE SIZE 1. SEIVING - in which particles are passed by m echanical shaking through a series of sieves. sieves . 2. MICROSCOPY - in which sample particles are sized through the use of a calibrated grid background or background  or other measuring devices. 3. SEDIMENTATION RATE - in which particle size is determined deter mined by measuring the terminal settling velocity of  velocity  of  particles through a liquid medium in a gravitational or centrifugal environment. 4. LIGHT ENERGY DIFFACTION/LIGHT DIFFACTION/LIGHT SCATTERING - in which particle size is determined deter mined by the reduction in light reaching the sensor  as the particle, dispersed in a liquid or gas, passes through the sensing zone. 5. LASER HOLOGRAPHY - in which pulsed which pulsed laser is fired fired through an aerosolized particle spray and spray  and is photographed in three dimensions with holographic camera. 6. CASCADE IMPACTION - This is based on the principle that a particle driven by an air-stream will hit the surface in its path. 7. Online Methods MICROMERETICS - The science of small particles. COMMINUTION OF DRUGS 1. TRITURATION or COMMINUTION - Grinding a drug in mortar and pestle to reduce its particle size; mills & pulverizers for large amount of powder to reduce particle size. 2. LEVIGATION - is commonly used in small-scale preparation of  ointments and suspensions to reduce the particle size and grittiness of the added powders.

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BLENDING POWDERS 1. SPATULATION - is blending small amounts of powders by movement of a spatula through them on a sheet of paper or an ointment. 2. TRITURATION - may be employed both to comminute and mix powders. 3. GEOMETRIC DILUTION - is used when a small amount of a potent substance is to be mixed with a large amount of  diluent - To ensure the uniform distribution of the potent drug. 4. TUMBLING - Putting the powder mixture in a rotating chamber. 5. SIFTING or PERCOLATION - segregation of air entrapment (fluidization) and particle entrapment (dusting). MEDICATED POWDERS Routes of Administration: Internally (oral)  Externally (dusting)   Inhalation of local and systemic effects Commercially packaged of constitution  Vaginal douche  Injection  AEROSOL POWDERS - Administered by inhalation with the aid of dry powder inhalers, which deliver micronized particles of  medication in metered quantities. BULK POWDERS - Bulk powders are available in packaged amounts  Antacids  Douche powders  Medicated powders of external application  Brewer’s yeast powder   DIVIDED POWDERS - Are divided into individual dosing units based on the amount to be taken or used at a single time.

GRANULES - are prepared agglomerates of smaller particles of  powder.

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BASIC WET METHOD - is to moisten the powder of powder mixture and the pass the resulting paste through a scree n of the mesh size to produce the desired size of granules. Placed on a drying tray and are dried by air or under heat. * Fluid bed processing – powders – powders are placed in a conical   piece of equipment  DRY GRANULATION - dry powder is passed through a roll r oll compactor (roll   press) and the through a granulating machine. * Slugging – is – is the compression of a powder or powder  mixture into large tablets of slugs on a compressing machine under 8,000 to 12,000lb of pressure. * Granules flow well compared t o powders * Granules are less likely to cake or harden upon standing. * Granules also are more easily wetted by liquids that  are certain light and fluffy powders (which tend to float  on the surface) and are often preferred for dry products intended to be constituted into solutions or suspensions.

EFFERVESCENT EFFERVESCENT GRANULATED SALTS - Are granules or coarse coar se powders containing a medicinal agent in a dry mixture usually of sodium of sodium bicarbonate, citric acid and tartaric acid  (2) General Methods of Preparation: 1) Dry or Fusion Method  - the one molecule of water present in each molecule of citric acid acts as the binding agent for the powder mixture. 2) Wet Method  - That the source of binding agent is not the water of crystallization but the water added to alcohol as the moistening agent, forming the pliable mass for granulation