Explain wet granulation and dry granulation and when each is used.

• A. Dry granulation uses a binder liquid to form cohesive granules.
• B. Wet granulation uses a binder liquid to form cohesive granules.
• C. Dry granulation compacts powders to form granules.
• D. Wet granulation is never used for moisture-sensitive drugs.

Answer: (B)

Wet granulation is defined by using a liquid binder to cause powder particles to adhere and form cohesive granules. This liquid bonding step creates granules with improved flow, compressibility, and uniform distribution of the active ingredient. After granulation, the granules are dried to the desired moisture level and then sized and blended for tablet or capsule formation. This method is typically chosen when the powder blend has poor flow or poor compressibility and when a uniform content is needed, provided the formulation can tolerate moisture and the subsequent drying step.

Dry granulation, in contrast, avoids any liquid binder. It forms granules by compacting the powder blend under high pressure (through slugging or roller compaction), followed by milling to the target granule size. This approach is used for drugs or excipients that are sensitive to moisture or heat, or when adding liquids could cause degradation or solvent-related issues. It’s also useful when avoiding a drying step is desirable.

So, the defining idea is that wet granulation uses a binder liquid to cohesion the particles, which is why that option is the best description.