Question

Which of the following method is not suitable for preparation of microparticles?

• A. \( \text{Spray drying} \)
• B. \( \text{Freeze drying} \)
• C. \( \text{Interfacial polymerization} \)
• D. \( \text{Solvent evaporation} \)

Hint:

Think of spray drying, solvent evaporation, and interfacial polymerization as methods involving controlled particle formation from solutions or emulsions. Freeze drying is more about removing water to stabilize a product.

Answer 1

The Correct Option is B

Spray drying and solvent evaporation are well-established methods for the preparation of microparticles, where a drug is dissolved or dispersed in a polymer solution, which is then processed to form small particles. Interfacial polymerization is also used to form microcapsules or microparticles by polymerization at the interface of two immiscible liquids. Freeze drying (lyophilization), on the other hand, is primarily a dehydration process used to stabilize biological materials or pharmaceuticals that are unstable in aqueous solutions. While freeze drying can result in a porous solid matrix, it is not typically used as a primary method for the controlled formation of microparticles with defined size and morphology in the same way as spray drying, solvent evaporation, or interfacial polymerization. The main goal of freeze drying is to remove solvent while maintaining the structure and activity of the solute, often resulting in a cake or powder that may need further processing into particles.