Particle Size in Medicine Formulation
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Questions and Answers

Why is the appropriate size of particulate solids important in medicine formulation?

  • It only affects the physical performance of the drug product
  • It impacts the physical performance and pharmacological effects of the drug product (correct)
  • It only affects the pharmacological effects of the drug product
  • It has no impact on the drug product

    • What is determined when a drug is synthesized and formulated?

  • Taste of the drug
  • Chemical composition of the drug
  • Particle size of the drug and other powders in the formulation (correct)
  • Color of the drug

    • How does particle size impact medicine formulation?

  • It only affects the physical performance of the medicine
  • It affects the physical performance and pharmacological effects of the medicine (correct)
  • It only affects the pharmacological effects of the medicine
  • It has no impact on the medicine

    • Why is interference with the uniformity of fill volumes in tablets and capsules a concern?

    <p>It may alter the mass of drug incorporated, affecting content uniformity</p> Signup and view all the answers

    How do powders with different particle sizes impact encapsulation or tablet compression?

    <p>They alter the volumes of powder during each event</p> Signup and view all the answers

    Why is it important to define and control the particle sizes of drugs and powders during formulation?

    <p>To avoid problems during production</p> Signup and view all the answers

    What is the impact of reducing the particle size of a drug on its dissolution rate?

    <p>It generally increases the rate of dissolution</p> Signup and view all the answers

    How does reducing the particle size of a low solubility drug like griseofulvin affect its dissolution rate?

    <p>It increases the rate of dissolution</p> Signup and view all the answers

    What impact can an increased rate of dissolution due to reduced particle size have on drug handling by the body?

    <p>It can have a direct impact on bioavailability</p> Signup and view all the answers

    Why is reducing the particle size of nitrofurantoin not always beneficial?

    <p>It may lead to more rapid absorption and adverse effects</p> Signup and view all the answers

    What is the impact of reducing particle size to improve dissolution rate?

    <p>It can increase bioavailability but may lead to adverse effects in some cases</p> Signup and view all the answers

    Why is knowledge and control of particle size important for drug products?

    <p>It affects both the production of drug products and their efficacy/safety post-administration</p> Signup and view all the answers

    What is the median size for fine powder?

    <p>125 μm to 180 μm</p> Signup and view all the answers

    What is the median size for micronized powder?

    <p>Less than 10 μm</p> Signup and view all the answers

    What is the median size for very fine powder?

    <p>125 μm or less</p> Signup and view all the answers

    Coarse powder has a median size greater than 355 μm.

    <p>True</p> Signup and view all the answers

    The median size for very fine powder is 125 μm or less.

    <p>True</p> Signup and view all the answers

    Micronized powder has a median size less than 10 μm.

    <p>True</p> Signup and view all the answers

    What is the term used to describe the diameter of a hypothetical sphere representing an approximation to the true size and shape of a particle?

    <p>Equivalent sphere diameter</p> Signup and view all the answers

    Why is the dimension representing the size of a particle referred to as the equivalent sphere diameter?

    <p>Because it is based on a hypothetical sphere that approximates the true size and shape of the particle</p> Signup and view all the answers

    What property of a particle is measured and related to a sphere to determine its equivalent diameter?

    <p>Some property of the particle</p> Signup and view all the answers

    What is the projected area diameter based on?

    <p>A circle of area equivalent to the projected image of a particle</p> Signup and view all the answers

    What is the perimeter diameter based on?

    <p>A circle with the same perimeter as the particle</p> Signup and view all the answers

    What is the purpose of generating more than one sphere equivalent to an irregular particle shape?

    <p>To account for different aspects of the particle's geometry</p> Signup and view all the answers

    What does Feret’s diameter measure?

    <p>Mean distance between two parallel tangents to the projected outline of the particle</p> Signup and view all the answers

    What does Martin’s diameter represent?

    <p>Mean chord length of the projected particle perimeter</p> Signup and view all the answers

    What factors influence Feret’s and Martin’s diameters?

    <p>Orientation and shape of the particles</p> Signup and view all the answers

    Particle size can be determined based on factors such as volume, surface area, sieve aperture, and sedimentation characteristics.

    <p>True</p> Signup and view all the answers

    Equivalent sphere diameter is based on factors such as volume, surface area, sieve aperture, and sedimentation characteristics.

    <p>True</p> Signup and view all the answers

    It is not possible to determine the equivalent sphere diameters of particles based on factors such as volume, surface area, sieve aperture, and sedimentation characteristics.

    <p>False</p> Signup and view all the answers

    What is the term used to describe a particle population with spheres of the same diameter?

    <p>Monodisperse</p> Signup and view all the answers

    What is the term for particles with a range of different equivalent diameters?

    <p>Polydisperse</p> Signup and view all the answers

    How are particles with a range of different equivalent diameters described?

    <p>Polydisperse or heterodisperse</p> Signup and view all the answers

    What can be presented in the form of a histogram plotted from data to interpret particle size distribution?

    <p>Size distribution breakdown</p> Signup and view all the answers

    What does a histogram enable to be determined about particles with a given equivalent diameter?

    <p>Percentage of particles</p> Signup and view all the answers

    What does a histogram allow to be compared?

    <p>Different particle size distributions</p> Signup and view all the answers

    What is the alternative to a histogram for representing particle size distribution?

    <p>Cumulative percent frequency distribution</p> Signup and view all the answers

    What does a cumulative percent undersize value represent in particle size analysis?

    <p>Cumulative percent frequency undersize</p> Signup and view all the answers

    How can two or more particle populations be compared?

    <p>By means of the cumulative distribution representation</p> Signup and view all the answers

    Mode and median are measures of central tendency used to represent a single value near the middle of the size distribution.

    <p>True</p> Signup and view all the answers

    The mode represents the most frequently occurring particle size in the distribution.

    <p>True</p> Signup and view all the answers

    The median is the arithmetic average of all the particle sizes in the distribution.

    <p>False</p> Signup and view all the answers

    Is the three point size distribution based on the diameters below which 90%, 50% and 10% of the particles lie?

    <p>True</p> Signup and view all the answers

    The values for the diameters may be written as X90, D90, d 90, or D [ X50, D50, d 50, or D [0.50]; and X10, D10, d 10, or D [

    <p>True</p> Signup and view all the answers

    Is the median size for very fine powder 125 μm or less?

    <p>True</p> Signup and view all the answers

    True or false: The IQCS can take any value between −1 and +1. If the IQCS is 0, then the size distribution is practically symmetrical between the quartile points.

    <p>True</p> Signup and view all the answers

    True or false: A median size of 125 μm or less is considered very fine powder.

    <p>True</p> Signup and view all the answers

    True or false: The median size for micronized powder is less than 10 μm.

    <p>True</p> Signup and view all the answers

    Arithmetic means are obtained by summation of a particular parameter for all the individual particles in a sample and division of the value obtained by the total number of particles.

    <p>True</p> Signup and view all the answers

    Means can be related to the diameter, surface area, volume or mass of a particle.

    <p>True</p> Signup and view all the answers

    The median is the arithmetic average of all the particle sizes in the distribution.

    <p>False</p> Signup and view all the answers

    What is the most widely used technique for powder classification?

    <p>Sieving</p> Signup and view all the answers

    What property does sieving method rely on for particle size analysis?

    <p>Size of particles</p> Signup and view all the answers

    What is the typical range of analysis achievable using sieves?

    <p>5 μm to 125000 μm</p> Signup and view all the answers

    Sieving analysis is usually performed with powders in the dry state only.

    <p>False</p> Signup and view all the answers

    Wet sieving can be used for powders in liquid suspension or those which agglomerate during dry sieving.

    <p>True</p> Signup and view all the answers

    Sieving analysis cannot be used for powders in liquid suspension or those which agglomerate during dry sieving.

    <p>False</p> Signup and view all the answers

    What material is often used to make the mesh for sieve analysis?

    <p>Stainless steel</p> Signup and view all the answers

    How many sieves does a typical sieve stack usually comprise?

    <p>Six to eight sieves</p> Signup and view all the answers

    What is the arrangement of mesh sizes from top to bottom in a sieve stack?

    <p>Progressively finer towards the top</p> Signup and view all the answers

    Mesh size refers to the number of openings in one linear inch of a screen.

    <p>True</p> Signup and view all the answers

    A 36 mesh screen will have 150 openings.

    <p>False</p> Signup and view all the answers

    Sieves can only be referred to by their aperture size.

    <p>False</p> Signup and view all the answers

    What is the diameter of a particle measured by a sieve?

    <p>Length of the side of the minimum square aperture it has passed through</p> Signup and view all the answers

    What type of plot is used to analyze particle size distribution after sieving?

    <p>Cumulative undersize plot</p> Signup and view all the answers

    What happens to the powder during sieving analysis?

    <p>Mechanical agitation is applied to the assembled stack</p> Signup and view all the answers

    What is the recommended sieving time for dry sieving?

    <p>5-30 minutes</p> Signup and view all the answers

    When using standard sized sieves (200 mm diameter), when is it recommended to stop sieving?

    <p>When the mass on any sieve does not change by more than 5% or 1 g of the previous mass on that sieve</p> Signup and view all the answers

    Why is it important to define and control the sieving times?

    <p>To ensure accurate particle size analysis</p> Signup and view all the answers

    What is a key advantage of the sieving technique?

    <p>Precise and reproducible results in a comparably short time</p> Signup and view all the answers

    Why is the sieving technique considered an accepted alternative to other analysis methods?

    <p>It can separate particle size fractions</p> Signup and view all the answers

    What type of materials is the sieving technique well adapted for?

    <p>Bulk materials</p> Signup and view all the answers

    Is the sieving technique well adapted for bulk materials?

    <p>True</p> Signup and view all the answers

    Is the possibility to separate the particle size fractions an advantage of the sieving technique?

    <p>True</p> Signup and view all the answers

    Are the investment costs for the sieving technique high?

    <p>False</p> Signup and view all the answers

    Is it problematic if the material has much fine material below 100 μm, unless specialized micro sieving equipment is available?

    <p>True</p> Signup and view all the answers

    Is it problematic if the particles are fragile?

    <p>True</p> Signup and view all the answers

    Is it problematic if the particles are in the form of elongated needles?

    <p>True</p> Signup and view all the answers

    What makes the sieving technique problematic for particles in the form of elongated needles?

    <p>They can get stuck in the sieve apertures</p> Signup and view all the answers

    Why is the sieving technique problematic for materials that easily acquire an electrostatic charge?

    <p>The powder particles cling to the sieve</p> Signup and view all the answers

    What is a disadvantage of the sieving technique when dealing with hygroscopic materials?

    <p>The material adheres to the sieve or forms clumps</p> Signup and view all the answers

    What is a problematic characteristic for particles when using the sieving technique?

    <p>Fragility</p> Signup and view all the answers

    Why is the sieving technique problematic for materials that easily acquire an electrostatic charge?

    <p>It causes clumping of the material</p> Signup and view all the answers

    What is a known problem of reproducibility associated with the sieving technique?

    <p>Irregular/agglomerated particles</p> Signup and view all the answers

    Is the sieving technique problematic if the material easily acquires an electrostatic charge?

    <p>True</p> Signup and view all the answers

    Is the sieving technique problematic for particles in the form of elongated needles?

    <p>True</p> Signup and view all the answers

    Is the sieving technique labor-intensive?

    <p>True</p> Signup and view all the answers

    What distinguishes air jet sieving from conventional mechanically vibrated sieve analysis?

    <p>Individual sieves are used instead of a complete nest of sieves</p> Signup and view all the answers

    What is a potential advantage of air jet sieving over conventional mechanically vibrated sieve analysis?

    <p>It is often more efficient and reproducible</p> Signup and view all the answers

    What issue can arise with finer particles in air jet sieving?

    <p>Agglomeration can become a problem</p> Signup and view all the answers

    Air jet sieving is often more efficient and reproducible than conventional mechanically vibrated sieve analysis.

    <p>True</p> Signup and view all the answers

    Agglomeration is not a problem with finer particles in air jet sieving.

    <p>False</p> Signup and view all the answers

    Air jet sieving uses a complete nest of sieves.

    <p>False</p> Signup and view all the answers

    Light microscopy is relatively inexpensive and requires small sample sizes

    <p>True</p> Signup and view all the answers

    Light microscopy can only detect 3D shapes of particles

    <p>False</p> Signup and view all the answers

    Light microscopy provides a permanent record photograph of the examined particles

    <p>True</p> Signup and view all the answers

    What is an advantage of light microscopy for particle examination?

    <p>Ability to analyze particle aggregates in 2D shape</p> Signup and view all the answers

    What is a benefit of light microscopy in terms of sample size requirement?

    <p>Small sample sizes required</p> Signup and view all the answers

    What is a feature of light microscopy that aids in record-keeping?

    <p>Ability to produce permanent photographic records</p> Signup and view all the answers

    What is a disadvantage of the sieving technique when dealing with particle shape?

    <p>No information on 3D shape</p> Signup and view all the answers

    What is a potential issue associated with the sieving technique's throughput?

    <p>Very low throughput, so may be non-representative</p> Signup and view all the answers

    What is a concern related to sizing operator bias when using the sieving technique?

    <p>Certain amount of subjectivity associated with sizing operator bias</p> Signup and view all the answers

    What is a key advantage of scanning electron microscopy (SEM)?

    <p>Particles are individually examined</p> Signup and view all the answers

    What is a disadvantage of scanning electron microscopy (SEM)?

    <p>Very expensive</p> Signup and view all the answers

    When is scanning electron microscopy (SEM) particularly appropriate?

    <p>When a three-dimensional particle image is required</p> Signup and view all the answers

    What is the lower limit of particle sizing by the gravitational sedimentation method?

    <p>5 µm</p> Signup and view all the answers

    What is the particle size range mostly applied to centrifugal sedimentation?

    <p>0.001 μm to 1 mm</p> Signup and view all the answers

    What are the effects that can be overcome by centrifuging the suspension in sedimentation techniques?

    <p>Convection, diffusion, and Brownian motion</p> Signup and view all the answers

    What is the Andreasen Pipette Technique primarily known for?

    <p>Quick sedimentation analysis for particles of increasingly finer sizes</p> Signup and view all the answers

    What distinguishes the Andreasen Pipette Technique from beaker decantation?

    <p>Samples are taken off successively throughout the test</p> Signup and view all the answers

    What is the key advantage of the Andreasen Pipette Technique over beaker decantation?

    <p>Quicker analysis for increasingly finer particle sizes</p> Signup and view all the answers

    What is the method used to determine size distribution?

    <p>Sieve analysis</p> Signup and view all the answers

    What happens to particles greater than a critical size during the settling process?

    <p>They settle below the level of the sampling point</p> Signup and view all the answers

    What type of sample does each collected suspension sample represent, except for particles greater than a critical size?

    <p>Representative sample of the entire suspension</p> Signup and view all the answers

    How is the concentration of solid in a sample expressed as a percentage?

    <p>As a percentage of the initial concentration</p> Signup and view all the answers

    What does the concentration expressed as a percentage of the initial concentration give?

    <p>The percentage (w/w) of particles whose falling velocities are equal to or less than x/t</p> Signup and view all the answers

    How is the corresponding Stokes' diameter obtained?

    <p>By substitution in the equation using the percentage (w/w) of particles whose falling velocities are equal to or less than x/t</p> Signup and view all the answers

    What is a disadvantage of sedimentation analysis for particle size measurement?

    <p>Concentration effects can interfere with measurements</p> Signup and view all the answers

    Why is careful temperature control necessary for sedimentation analysis?

    <p>To suppress convection currents</p> Signup and view all the answers

    What is an advantage of the sieving technique for particle size analysis?

    <p>Can measure a wide range of sizes with considerable accuracy</p> Signup and view all the answers

    Is sedimentation analysis relatively simple and inexpensive to perform?

    <p>True</p> Signup and view all the answers

    Is it necessary to carefully control temperature to suppress convection currents during sedimentation analysis?

    <p>True</p> Signup and view all the answers

    Are particles required to be completely insoluble in the suspending liquid for sedimentation analysis?

    <p>True</p> Signup and view all the answers

    Is the Coulter Counter method used to measure particle volume based on the diameter of a sphere that has the same volume as the particle?

    <p>True</p> Signup and view all the answers

    Does the Coulter Counter method determine the number and size of particles suspended in an electrolyte by causing them to pass through an orifice immersed with an electrode?

    <p>True</p> Signup and view all the answers

    Do changes in electric impedance as particles pass through the orifice in the Coulter Counter method generate voltage pulses proportional to the volumes of the particles?

    <p>True</p> Signup and view all the answers

    What does the Coulter Counter method measure?

    <p>Particle volume by causing particles to pass through an orifice immersed with an electrode</p> Signup and view all the answers

    What does the diameter of a sphere representing the volume of a particle indicate?

    <p>The size of a hypothetical sphere with the same volume as the particle</p> Signup and view all the answers

    What generates voltage pulses in the Coulter Counter method?

    <p>Changes in electric impedance as particles pass through the orifice</p> Signup and view all the answers

    What is the Coulter Principle (Electrical Sensing Zone method) used for?

    <p>Measuring particle size and counting particles</p> Signup and view all the answers

    What does the voltage pulse measured in the Coulter method represent?

    <p>Volume of the particle</p> Signup and view all the answers

    What property of particles does the Coulter method of sizing and counting particles NOT depend on?

    <p>Electrical charge</p> Signup and view all the answers

    True or false: The Coulter Principle is based on measurable changes in electrical resistance produced by conductive particles suspended in an electrolyte?

    <p>False</p> Signup and view all the answers

    True or false: The Coulter method of sizing and counting particles is dependent on particle shape, color and density?

    <p>False</p> Signup and view all the answers

    True or false: The Coulter method allows the system to count and size particles for an exact reproducible volume?

    <p>True</p> Signup and view all the answers

    Is the Coulter method suitable for measuring particle diameter from approximately 0.5-400μm?

    <p>True</p> Signup and view all the answers

    Does the Coulter method require the medium to be an electrolyte?

    <p>True</p> Signup and view all the answers

    Is the Coulter method suitable for measuring high particle concentration?

    <p>False</p> Signup and view all the answers

    What is a disadvantage of the sedimentation method for particle size analysis?

    <p>Errors with porous particles</p> Signup and view all the answers

    What is a challenge associated with the Coulter method for particle size measurement?

    <p>Orifice blocking troublesome</p> Signup and view all the answers

    What is a key advantage of the sieving technique for particle size analysis?

    <p>True volume distribution</p> Signup and view all the answers

    What method relates obscuration of light source to particle size?

    <p>Optical sensing zone method</p> Signup and view all the answers

    Which technique involves particles passing through a laser beam and the light scattered by them being collected over a range of angles in the forward direction?

    <p>Laser Diffraction Particle Size Analysis</p> Signup and view all the answers

    What is the advantage of laser diffraction technique over sedimentation analysis?

    <p>Particle size range 0.02-2000µm</p> Signup and view all the answers

    Particle size range for Laser Diffraction Particle Size Analysis is 0.02 - 2000µm

    <p>True</p> Signup and view all the answers

    Laser Diffraction measures the distribution of scattered light intensity to yield particle size distribution

    <p>True</p> Signup and view all the answers

    The angles of diffraction in Laser Diffraction are directly related to the particle size

    <p>False</p> Signup and view all the answers

    Is laser diffraction a non-intrusive technique?

    <p>True</p> Signup and view all the answers

    Is laser diffraction a fast technique?

    <p>True</p> Signup and view all the answers

    Is laser diffraction typically uses a low power laser beam?

    <p>True</p> Signup and view all the answers

    What is a key advantage of laser diffraction for particle size analysis?

    <p>Non-intrusive and fast</p> Signup and view all the answers

    Why is careful temperature control necessary for sedimentation analysis?

    <p>To minimize the effect of thermal expansion</p> Signup and view all the answers

    What is a potential advantage of air jet sieving over conventional mechanically vibrated sieve analysis?

    <p>Reduced particle attrition and agglomeration</p> Signup and view all the answers

    What should govern the choice of particle size analysis method?

    <p>The properties of the sample being investigated and the type of size information required</p> Signup and view all the answers

    What might constrain the selection of a particle size analysis method?

    <p>Instruments available in a laboratory</p> Signup and view all the answers

    What is a key factor in selecting a particle size analysis method?

    <p>Properties of the sample being investigated</p> Signup and view all the answers

    Study Notes

    Importance of Particle Size in Medicine Formulation

    • Appropriate particle size is crucial for ensuring the effectiveness and stability of drug formulations.
    • Particle size influences drug synthesis and formulation decisions, affecting bioavailability and therapeutic efficacy.

    Impact of Particle Size on Medicine Formulation

    • Uniformity in fill volumes of tablets and capsules is essential to maintain dosage accuracy and consistency.
    • Variability in powder particle sizes can lead to inconsistent encapsulation or compression during tablet manufacturing.

    Advantages and Disadvantages of Reducing Particle Size

    • Reducing particle size typically enhances drug dissolution rates, increasing bioavailability.
    • For low solubility drugs like griseofulvin, smaller particle sizes significantly improve dissolution rates.
    • However, reducing the size of certain drugs, such as nitrofurantoin, may not always lead to better outcomes due to potential challenges like aggregation.

    Particle Size Measurement Terms

    • Equivalent sphere diameter represents the diameter of a sphere that approximates the particle's shape.
    • The median size for fine powders is typically less than 125 μm, while micronized powders are less than 10 μm.
    • Very fine powder is defined as having a median size of 125 μm or less, while coarse powders exceed 355 μm.

    Distribution and Analysis of Particle Size

    • Histograms can represent particle size distribution, allowing for visual analysis of size distribution ranges.
    • Cumulative percent undersize values allow for comparison of particle populations.
    • Mode and median provide central tendency measures of particle sizes, with mode being the most frequently occurring size.

    Sieve Analysis Technique

    • Sieving is the most commonly used technique for powder classification, relying on physical separation based on size.
    • Typical analysis ranges can be achieved with standard sieves, primarily in dry form, although wet sieving is possible for some applications.
    • Separation of particle size fractions is a key advantage of the sieving technique, which is more economical compared to other methods.

    Challenges in Sieve Analysis

    • Fine materials below 100 μm can be challenging without specialized equipment.
    • Sieve analysis may be problematic for fragile particles or elongated needle-like shapes due to their physical characteristics.
    • Electrostatic charge accumulation in hygroscopic materials complicates accurate sieving results.

    Air Jet Sieving vs Conventional Sieving

    • Air jet sieving improves efficiency and reproducibility compared to conventional mechanically vibrated sieving.
    • It utilizes a nest of sieves, preventing agglomeration of fine particles, which can enhance analytical outcomes.

    Light Microscopy for Particle Examination

    • Light microscopy is advantageous for particle shape analysis and requires small sample sizes.
    • This technique provides permanent photographic records of particle shapes, aiding in documentation and further analysis.

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    Description

    Learn about the importance of particle size in medicine formulation and production for safe and effective drugs. Understand how particle size impacts the physical performance and pharmacological effects of drugs.

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