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Lecture 2: Micromeritics

Learning Objectives

After studying this chapter, students should be able to:

1. Define the concept of micromeritics and its significance in pharmaceutical sciences.
2. Identify and describe the fundamental particle characteristics including size, shape,

and distribution.
3. Understand methods for determining and interpreting particle size.
4. Discuss derived properties of powders such as density, porosity, and flow.
5. Relate micromeritic properties to pharmaceutical formulation and performance.
6. Perform basic micromeritic experiments such as angle of repose and tapped density.

2.1 Introduction to Micromeritics

Micromeritics is the science of small particles — focusing on the measurement and
interpretation of the physical properties of particulate matter.
In pharmacy, this field is crucial because most dosage forms (tablets, capsules, suspensions,
aerosols, creams) involve particles whose behavior strongly depends on their micromeritic
characteristics.

Micromeritics encompasses two main classes of properties:

• Fundamental properties: particle size, shape, and size distribution.
• Derived properties: density, porosity, packing arrangement, and flow behavior.

2.2 Pharmaceutical Importance of Micromeritics

Manipulating particle characteristics can profoundly influence:

• Dissolution rate and bioavailability: Smaller particles (micronized drugs) dissolve
faster, enhancing absorption.

• Suspendability: Fine particles (0.5–10 µm) remain uniformly dispersed in
suspensions.

• Dose uniformity: Consistent particle size ensures even drug distribution in powder
blends and solid dosage forms.

• Inhalation therapy: Only particles within 1–5 µm can penetrate deep into the
respiratory tract.

• Patient comfort: Fine powders (50–100 µm) reduce grittiness in dermal and
ophthalmic products.

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