Wet Granulation in Tablet Manufacturing

Wet granulation is a widely used process in tablet manufacturing that involves the agglomeration of powder particles
to form granules. This process is essential for improving the flow properties, compressibility, and uniformity of
the drug formulation, ultimately leading to the production of high-quality tablets. Here’s a step-by-step explanation
of the wet granulation process in tablet manufacturing:

Step 1: Weighing and Blending

The first step in wet granulation is to accurately weigh and blend the active pharmaceutical ingredient (API) with
various excipients, such as binders, diluents, and disintegrants. The blending process ensures a homogeneous mixture
of all components, which is crucial for achieving uniform drug content in the final tablet.

Step 2: Granulation Liquid Preparation

A granulation liquid, often consisting of water or a solvent, is prepared separately. This liquid serves as a
binder to promote adhesion between the powder particles and facilitate the formation of granules. The choice of
granulation liquid depends on the compatibility with the API and excipients used in the formulation.

Step 3: Wet Massing

The granulation liquid is then added to the powder blend, and the mixture is thoroughly mixed to form a wet mass.
The granulation process causes the powder particles to adhere to each other, forming small granules. The wet mass
should have the appropriate moisture content for optimal granule formation and subsequent drying.

Step 4: Wet Screening

After wet massing, the granules are passed through a wet screen to break down any large aggregates and achieve a
more uniform granule size. The wet screening step is crucial for controlling the size distribution of the granules
and ensuring content uniformity in the final tablet.

Step 5: Drying

The wet granules are then dried to remove the moisture from the formulation. Drying is typically done using
equipment such as fluid-bed dryers or tray dryers. Proper drying is essential to prevent issues such as
microbiological growth, maintain stability, and improve the flow properties of the granules.

Step 6: Dry Screening and Lubrication

Once the granules are thoroughly dried, they undergo a dry screening process to eliminate any oversized or
undersized particles. After dry screening, lubricants are added to the granules to reduce friction during
tablet compression. Magnesium stearate is a commonly used lubricant in tablet manufacturing.

Step 7: Tablet Compression

The final step in the wet granulation process is tablet compression. The lubricated granules are loaded into a
tablet press, which applies high pressure to form the granules into compact tablets. The compressed tablets are
then subjected to quality control tests to ensure they meet the required specifications for strength, weight,
and dissolution.

Advantages of Wet Granulation:

• Improved flow and compressibility of the formulation.
• Enhanced content uniformity in the tablets.
• Reduced dust generation during manufacturing.
• Higher chemical stability of the final product.
• Ability to use a wide range of excipients for formulation.

Disadvantages of Wet Granulation:

• Time-consuming process compared to direct compression.
• Requires additional equipment for drying and granulation.
• Potential for drug degradation due to exposure to moisture.
• Increased risk of cross-contamination in multi-product facilities.
• Higher costs associated with energy and equipment maintenance.

Conclusion:

Wet granulation is a fundamental process in tablet manufacturing, enabling the production of high-quality tablets
with improved properties and content uniformity. While it does have some disadvantages, wet granulation remains a
popular choice for formulating pharmaceutical tablets, especially for drugs with poor flow properties or those
requiring specific release profiles.