Pharmaceutical Granultion Understanding A Big Picture

With increase demand in pharmaceutical granules, many recent technologies are developed offering more preferred methods. Discussed below is a short overview of each development progressed in the granulation technique. For your ease, we have categorized them as dry and wet granulation.

Recent Advancements in Dry Granulation

Upon comparing with wet granulation, there has not been considerable advancement taken place in the dry granulation technique except:

Pneumatic Dry Granulation (PDG)

This is an innovative technology that encompasses roller compaction and air classification method to form extraordinary granules with excellent flowability and compressibility. Firstly, granules are produced by the application of compaction force. Secondly, the fine or smaller granules are separated from the intended granules in a fraction chamber by the application of a gas stream or pneumatic system. While intended granules are passed through a fraction chamber for tablet compression. The fine granules are transferred to a device where it recycles and recirculates to a roller compactor for re-processing.

Recent Advancements in Wet Granulation

Wet granulation is a popular technique where granules are formed by wet massing and incorporation of APIs liquid granulation with or without desirable binders. The technique has improved with high performance and more advancement to give you high significance in pharmaceutical production. Some of them are:

Reverse Wet Granulation

This technology is also known as reverse-phase wet granulation. This  is indeed a new development where dry powder formulation incorporated with liquid binder followed by a controlled breakage in order to form granules.

Here, a binder solution is prepared prior to immersion of dry powder in the granulator. Later wet granules are milled soon after achieving optimum drying. The granules formed by this method are well-defined, well handled, with have a good flowability ratio as compared to the conventional wet granulation method.

Steam Granulation

This is a well-modified version of the conventional wet granulation technique where steam is used as a substitution for the liquid binder. It involves a steam injection over the fluidized bed particles that are meant to be granulated.

A steam offers a higher diffusion rate to powder particle that favors thermal drying requiring only a small amount of energy for evaporation of liquid particles.

Moisture Activated Dry Granulation

This is also known as a ‘single pot’ or ‘one pot process’.

MADG process was explained over 20 years ago although it was not widely accepted. This is because of its unusual simple methodology with equipment uncertainty. This process does not require a drying step because the concentration of the binder is almost negligible.  Here moisture is utilized for granule formation. The moist agglomerates blends with common raw material resulting in a uniform and free-flowing particles. In this technique, only 14% of solvent content is incorporated to form agglomerates.

Thermal Adhesion Granulation

Wei- Ming Pharmaceutical was the first who developed this methodology which is analogous to moist granulation. In contrast to MADG, this process utilizes moisture and organic solvents with the help of fine spray. The mixture is subjected to heat ranging from 90 to 105◦C for water while 70 to 90◦C for organic solvents in a closed system. It is followed by a tumble rotation for 3 to 20 minutes to achieve powder agglomerates. The formed granules are sieved through 24 mesh.

Melt Granulation

This is also known as ‘Thermo-Plastic Granulation’ where granules are formed by the incorporation of molten binder or solid binder.  The technique is ideal for water-sensitive substances and a perfect alternative to other wet granulation techniques.

Freeze Granulation

W. Rhodes and S. Prochazka in the mid 70^thclaimed about free granulation technology for the first time. So, according to our analysis, freeze-drying (spray freeze drying and spray freezing) was first established in the 1980s by the Swedish Ceramic Institute. The following techniques help to create homogenous, free-flowing granules with binders. In the 1990s, this method was successfully employed for commercial projects. Primarily, this technique involved spray droplets or atomization of powder into liquid nitrogen where they are transformed into frozen granules. The freeze-drying of these droplets forms free-flowing granules with excellent homogeneity.

Foam Granulation

This technique is involved a continuous addition of liquid binder as foam rather than spraying or direct pouring over the powder bed. After achieving homogenous granules, they are dried in a fluidized bed dryer till obtaining the desired moisture content.