Solid Dosage Forms (Powders & Granules)

Drug Delivery Systems

Methods and technologies used to deliver a drug to the body in a way that ensures safety, efficacy and optimal therapeutic effect.

Drug Delivery Systems

These are designed to control the rate, site, and duration of drug release. Among solid dosage forms are powders and granules.

Powders and Granules

Widely used dosage forms, as final products and as intermediates in the manufacture of tablets, capsules, and suspensions.

Powders

It consist of finely divided solid particles

Granules

Are aggregates of powder particles that are usually larger and free-flowing

Particle size distribution

It influences dissolution rate, flowability, content uniformity, and bioavailability.

Particle size

Determine using a variety of methods, depending on the nature and size range of the particles.

(extremely coarse)10 mm (1cm)—1 um or less (extremely fine)

range of particle size distribution

USP

According to….uses the descriptive terms:

Very coarse, Coarse, Moderately coarse, fine, and very fine. Which are related to the proportion of powder that is capable of passing through the openings of standard sieves

Very coarse, Coarse, Moderately coarse, fine, and very fine.

USP uses descriptive terms

Very fine

<_ 125

Fine

125-180

Moderately fine

180-355

Coarse

>355

Dry Sieving (Mechanical Sieving)

Involves placing a powder sample on a stock of sieves and subjecting it to manual or mechanical shaking using a sieve shaker.

Dry Sieving (Mechanical Sieving)

The shaking motion allows particles to orient themselves and pass through sieve openings according to their size.

Dry Sieving (Mechanical Sieving)

Advantage:

Inexpensive, easy to perform, uses usp standard sieves, good reproducibility for coarse particles

Dry Sieving (Mechanical Sieving)

Limitations:

Not suitable for particles below 40 um

Air Entrainment Method

Uses a stream of air to assist in separating particles, where fine and lightweight particles become suspended in the air, while larger and heavier particles settle or are retained

Air Entrainment Method

Advantages:

Improved separation of fine particles, minimizes aggregation, more effective for powders with poor flow

Limitations

Limitations:

Requires specialized equipment, air velocity must be carefully controlled, less commonly used than dry sieving in routine labs.

Optical Microscopy

Electron Microscopy

Under Microscopy

Optical Microscopy

Uses visible light and a compound microscope to observe and measure particles that are visually observed using calibrated ocular micrometer or grid.

Optical Microscopy

Individual participles are measured, and a number of is usually not fewer than 200 particles for more reliables results. Suitable for powders approximately 0.2 to 100 um

Optical Microscopy

Advantages:

Simple and relatively inexpensive, allows assessment of particle shape and aggregation, useful for irregularly shaped particles.

Optical Microscopy

Limitations:

Time consuming, labor intensive e, limited sample size, results depend on operator skill.

Electron Microscopy

Uses a beam of electrons, instead of visible light to achieve a much higher magnification and resolution.

Electron Microscopy

It used for measuring very fine and submicron particles that cannot be accurately measured using optical microscopy.

Electron Microscopy

Advantages:

Extremely high magnification and resolution, accurate measurement of very fine particles, useful for advanced research and formulation studies

Electron Microscopy

Limitations:

Expensive equipment, complex sample preparation, not suitable for routine quality control.

Sedimentation

particle size analysis method based on the rate at which particles settle in a liquid under gravity, where larger and denser particles settle faster.

Sedimentation

The settling velocity depends on particle size e, density, and viscosity of the medium

Stoke’s law

What law did the sedimentation used on the settling velocity that depends on particle size, density, and viscosity of the medium

Sedimentation

Advantages:

Simple, inexpensive, and is suitable for fine particles

Sedimentation

Limitations:

Time consuming, affected by particle shape and density

Light scattering techniques

Determine particle size by analyzing the intensity and angle of light scattered when a light beam passes through a particle dispersion.

Light scattering techniques

The _ pattern varies with particle sizes allowing estimation of particle size distribution

Light scattering techniques

Advantages:

Rapid, wide size range, small sample needed

Light scattering techniques

Limitations:

Expensive, assumes spherical particles, affected by agglomeration

Adsorption Study

Indirect method of particle sizes analysis that measures the malnutrition of gas or vapor adsorbed on the surface of solid particles.

Adsorption Study

The extent of adsorption is related to surface area, which increases as particle size decreases.

Adsorption Study

Advantages:

Sensitive, suitable for very fine particles

Adsorption Study

Limitations:

Time consuming, indirect method, needs special equipment

Electron Resistivity

measures particle size by determining changes in electrical resistance of a powder bed or particle system.

Electron Resistivity

These changes are influenced by particle sizes allowing estimation, shape, and the way particles are packed together.

Electron Resistivity

Advantages:

Useful for fine powders, sensitive to size changes

Electron Resistivity

Limitations:

Limited use, affected by moisture and packing

Permeametry

a technique that estimates particle size by measuring the resistance to airflow through a packed bed of powder.

Permeametry

Smaller particles create narrower spaces between them, which slow down the airflow, while larger particles allow air to pass more easily.

Permeametry

Advantages:

Simple, fast, and useful for quality control

Permeametry

Limitations:

Affected by powder packing, assumes uniform particle size

Coulter counter

Is a particle size analysis method that counts and measures particles individually as they pass through a small opening filled with an electrolyte solution.

Counter counter

Each particle temporarily blocks the flow of electric current, causing a change in electrical resistance that is proportional to the particle’s volume

Counter counter

Advantages:

Accurate, counts individual particles, rapid

Counter counter

Limitations:

Expensive p, requires liquid medium, aperture blockage

Light Blockage

is a particle size analysis method in which particles passing through a light beam partially block the relight, causing a measurable reduction in light intensity

Light Blockage

The magnitude of light blockage is proportional to the size of the particle

Light Blockage

Advantages:

Simple, fast, suitable for large particles

Light Blockage

Limitations:

Poor for very small particles, affected by transparency

Shape Determination

Commonly performed using Optical microscopy, where individual particles are visually examined under magnification

Shape Determination

Because powder particles are irregular and non-uniform, direct measurement alone is insufficient, therefore, morphological classification is used manufacturing processes like tablet compression and capsule filling.

morphological classification

is used manufacturing processes like tablet compression and capsule filling.

Shape Determination

An essential step in pre-formulation studies to ensure product quality and manufacturing efficiency

Density Determination

A fundamental study under micromeritics that describes the packaging and consolidation behavior of Pharmaceutical powders

Density of powders

Influences their flow properties, mixing uniformity, capsule filling, and tablet compression.

Bulk density

Tapped density

2 densities

Density Determination

These properties are essential in predicting powder flow, compressibility, and handling during pharmaceutical processing

Bulk density

The mass of a powder divided by the bulk volume it occupies, including the void spaces between particles, before tapping.