powders and granules Flashcards
Describes the physical state or form of a single
chemical substance
Powder” or “Powdered”
– Mixture of finely divided drugs/chemicals in the dry state intended for internal or external use
– Frequently formulated to exist as fine particulates
• Pharmaceutical Preparation
Consist of primary particles, existing
individually or with some loose agglomeration through
adhesive forces
Powders
consist of large particles formed by
joining or binding together of primary particles whose
identity can still be visible in the final agglomerate
form
Agglomerates
consist of particles formed by the progressive
enlargement of primary particles until their original identity is no longer visible
Granules
They are for pharma applications, they consist of spherical particulates produced during a precise forming and mechanical
handling.
Pellets
fine powders to be dusted
in skin by means of sifter containers
Dusting Powders
Used to prepare solutions to cleanse
the vagina. Some may
contain antibiotics
Douche Powders
Fine powders to be introduced in body cavities (must pass thru #100 mesh
Insufflations
Dispensed under pressure to deliver targeted and
uniform application at site. Tight particle size range
and usually below 50 microns.
Powder Sprays
Single doses of powdered medicinals individually wraped in cellophane, metallic foil, or paper. More accurate dosage from than bulk powders because the patient is not involved in measurement of the dose. – Compounding or commercially available
• Divided Powders
course particles are mainly deposited in the ____; greater than 5microns
throat
fine particles are mainly deposited in the _____; less than 5 microns
lungs
advantages of powders
- chemicals more stale in solid state than liquid (applies to tablets and capsules too)
- no difficulty swallowing
- easy to adjust dose
- drugs could have rapid onset of action
- feasible to be made into other dosage formulations
disadvantages of powders
-misunderstanding of method of use or dose
-bitter taste
-difficulty protecting from decomposition of
-powders containing hygroscopic, deliquescent, and aromatic compounds
-manufacturing expense
-compared to tablets/capsules
– Powders lack convenience of handling
– Powders lack ease of product identification
– Powders lack ease of administration by patient
micromeritics - fundamental properties (5)
– Particle size – Size distribution – Shape (morphology) – Surface Area – Surface description
Micromeritics
Science and technology of small particles
Micromeritics - Derived Properties
– Porosity of powder – Packing arrangement – Density – Flow – Dissolution rate
Methods to Determine Particle Size
- Sieves
- Optical Microscopes
- Electron Microscopes
- Sedimentation Methods (Stokes Law)
- Centrifugation Methods
- Light Scattering Methods
- Common method
- Particles passed through series of screens
- Higher ____ number—finer powder
Sieving Method
sieve
Formulations have ____ average particle size, but
____ size distributions
same
different
Grinding drug in mortar to reduce its particle size
Trituration
Particle size reduction on large scale utilizes ______ and ___
• Mills and pulverizers
Powder shape can affect what two things?
– Surface area of particle
– Behavior when surrounded by other powders (packaging and flow)
the fundamental properties of powders are
– Particle size/distribution/range
– Shape (morphology)
– Surface Area
Derived Properties of Powders are
- Porosity of powder
- Packing arrangement
- Density
- Flow
Measure of the void spaces IN a bulk powder
Porosity
– ____ porosity– little void volume within powder
– ____ porous powder–large void volume
low
Highly
porosity can influence:
– Disintegration and dissolution
– Drug diffusion
– Adsorption
Two types of Ideal Packing Arrangement
A. Closest or Rhombohedral
B. Most open or Cubic Packing
Ideal Packing Arrangement assumes uniform ___, ___ powder
beds
sized
spherical
Three types of Non-Ideal Packing Arrangements
- Powders neither spherical nor uniform size
- Powders with large particle size distribution
- Powders that form aggregates
Powders neither spherical nor uniform size have _____ packing
intermediate packing
In non-ideal packing, Powders with large particle size distribution have ___ particles shift between larger particles
and also have ____ porosity
smaller
Lower
Powders that form aggregates have ____ and arches in packing, as well as ____ porosity
Bridging
Higher
Ratio of mass of sample to volume
Density
Density is Dependent on: (2)
– Type and arrangement of atoms in molecule
– Arrangement of molecules in sample (Crystallinity)
density can influence:
– Flow
– Powder blending
– Tableting/encapsulation
Types of Density:
- Bulk Density
* Tap Density
– ‘Light’ powder–___ bulk density
– ‘Heavy’ powder–___ bulk density
low
high
In Tap Density, one must tap volumetric cylinder until volume is ___
constant
Specific bulk volume
Bulkiness or Bulk
Bulkiness _____ as particle size decreases
increases
Flow Properties of Powders are classified as ‘_____’ or ‘____’
free flowing
sticky
Importance of Flow
– Blending
• Homogeneity of mixture
– Tableting/encapsulation
• Content uniformity
• Weight uniformityFactors Influencing Powder Flow
• Particle Morphology
• Crystallinity
• Bulk and Tap Densities
• Moisture Content
– Hygroscopicity of powders
– Storage humidity
• Particle Density
• Particle Size and Size Distribution
• Surface Area
• Surface Energy
• Electrostatic Charge- Spherical particles generally demonstrate _____ flowability
- Out of round (oblong) shapes with smooth edges are ____ flowable
- ____ ____ with sharp edges do not flow as readily as spherical or oblong particles
- irregularly shaped ___ ____ particles such as flakes generally flow without much difficulty. They may cause bridging
- Irregularly shaped ____ particles show poor flowability and result in bridging
- ____ solids demonstrate very poor flowability and bridge easily
good easily Cubical blocks two dimensional interlocking Fibrous
– Large dry particles above ___ microns generally flow with ease
– As the particle size decreases from 250 microns to about ___ microns, flowability reduces
– Below ___ microns, flow becomes a problem with
most substances
250
75
75
The following are characteristics of ____:
- Powder-like product
- Prepared from powders
- Generally small, irregularly-shaped chunks
- flow better than powders
Granules
Methods to Prepare Granules
- Wet Method
* Dry Method
This method of preparing granules require ‘binder’,
water, and heat
Wet method
This method of preparing granules uses high
compressional pressure
Dry Method
Pharmaceutical Uses of Granules
Tableting
Products for reconstitution
what are some Advantages of Granules for Reconstitution over Powders
Greater physical and chemical stability • Decrease caking • Increased atmospheric stability – Smaller surface area so more stable to humidity • More easily ‘wetted’ by a liquid
Granules Marketed as Bulk
- Senokot (Laxative)
* Bromo Seltzer
