PHA 6114C Micromeritics and Flow Properties of Solids (Lecture 16)

Micromeritics

science of small particles

0.5-10 uM

suspension and fine dispersion

10-50 uM

course emulsion

50-100 uM

fine powder range

150-1000 uM

course powder range

1000-3360

average granule size

2.2 uM

how large is the average particle size?

Standard

normal particle size distribution follows a _______ distribution symmetrical around the mean

Optical Microscopy

a slow and tedious, yet simple method of determining particle size that is used for particles between 0.2-100 uM in size

Martin Diameter

the length of a line bisect the particle image

Feret's Diameter

the distance between two tangents on opposite sides of the particle parallel to some fixed direction

Projected Diameter

a circle with the same area as that of the particle observed

Sieving

separating particles of different sizes by allowing the smaller particles to fall through holes in a container, and used for particles between 50-5000 uM in size

Humidity and Electrostatic Charges

two issues with sieving particles is that ________ and ________ can cause particle aggregation or sticking that will affect how they fall through the mesh filters

Mesh Number

the number of openings per inch

Simple and Fast

why is sieving used the most in pharmaceutical preparations despite its disadvantages?

Sedimentation

measures the terminal settling velocity of particles through a liquid medium using Andreasen apparatus and tests suspension's stability; used for sizes between 0.8-300 uM

Spherical Particles and Deflocculating Agent

disadvantages of using sedimentation to measure particle size is that it is only useful for _______ particles and may need a ____________ to prevent aggregation

Stoke's Equation

equation used to identify particle size measuring the particle settling

Particle Volume Measurement

this method makes use of a coulter counter in determining the particle volume distribution of material suspended in an electrolyte-containing solution, and is useful for measuring particles between 1-500 uM in size

Amplitude

the ________ of the peak generated by the particle resistance in particle volume measurement is proportional to its size

Fast, Reproducible, and Confident

advantages of using particle volume measurement

Cost, Blockages, and Specific Electrolytes Needed

disadvantages of using particle volume measurement

Non-Uniform Distribution

non-uniformity in particle size during manufacturing will lead to _________ of API in the dosage form

Stability

particle size and distribution affects the ________ of suspensions, emulsions, and tablets during storage and handling

Route of Administration

knowledge of the particle size is important for choosing the ___________

Increases

as the particle size decreases, the solubility of the drug ________ and causes faster onset of action

Duration

a decrease in solubility of a drug due to larger particle size can lead to a longer ________ of action

Adverse Effects

decreasing solubility by increasing particle size can lead to decrease in ________, which is typically better for the patient

Adsorption and Air Permeability Methods

two methods for determining surface area of a particle

Adsorption Method

the amount of a gas or liquid solute that is adsorbed on the samples of powder to form a monolayer is the direct function of the surface area of the sample

Air Permeability Method

the greater the surface area per gram of the powder, the greater is the resistance to flow to air

Compression and Irregularities

for the air permeability method, the flow rate through the plug or bed is affected by the degree of ___________ or ________ of the capillaries

Fisher Subsieve Sizer

surface area determination by the air permeability method is generally carried out with a

Porosity, Density, Bulkiness, Flowability, and Compaction

derived properties of powders

Porosity

arises from the presence of internal capillary spaces between particles

Void Volume

the volume of the space in pores or capillaries

Larger

porosity of uniform particles is _______ (smaller/larger) than the porosity of particles of different sizes

Porosity Equation

1-(bulk density/particle density)

Density

defined as the weight per unit volume

True Density

excludes the volume of the pores and voids within the sample, and is only the density of the actual solid material

Granule Density

the mass of particles divided by the volume as determined by the liquid (mercury) displacement method

Bulk Density

includes the volume of all the pores within the sample, and is the mass of powder divided by the bulk volume

Bulkiness

important consideration in the packaging of powders and increases with a decrease in particle size

Flowability

assess the ability of a powder to flow without sticking with the surface

Tablets

manufacturing problems of _____ often face problems related to stickiness or flowability

Uneven Powder Flow

leads to excess entrapped air within the powders and results in capping or lamination

Excellent Flow

angle of repose less than 20

Good Flow

angle of repose between 20-30

Pass Flow

angle of repose between 30-34

Poor Flow

angle of repose greater than 40

Higher

rough and irregular particle surfaces yield a ________ (lower/higher) angle of repose

Glidants

improves powder flow by reducing adhesion and cohesion

Course, Uniform, and Spherical

if you wanted optimal powder flowability, you would want ______ particles with _______ size and _______ shape