“GXR” GRANUREX® Technology

Pellet Formation (Spherical Granulation) and Pellet/Powder Coating

What is GRANUREX®?

GRANUREX® is a processing insert that will fit within a FLO-COATER® fluid bed system.

What does GRANUREX® do?

By far, the GRANUREX® is the most powerful pellet/powder processor available in the market place. The applications are endless:

  1. Pellet Formation: Spherical granulation of powders into spherical granules/pellets (as low as 50 micron).
  2. Solution/Suspension Coating: Precisely applying a coating onto a core material
  3. Dry Powder Layering: Rapidly increasing size of pellet by directly applying a powder. The powder could be an API (Active Pharmaceutical Ingredient), a controlled release polymer, or an excipient.

How does GRANUREX® work?

Finely divided/Micronized API and excipient is loaded on to a conical rotor. Air atomized binder liquid is applied to the powder. Rotor energy is used to densify and spheronize the powder resulting in uniform granules.


Applying solution or suspension based active or polymer via air atomizing spray gun. The process may include application of glidant or other excipient via the precision powder feeder to enhance the rate of spray and/or the amount of solids applied per unit time. Some actives and polymers are adhesive as they dry, applying glidant via the powder feeder can improve spray rates dramatically by mitigating this adhesive nature. In some cases this can allow solid content in solution/suspension to be doubled. Conventionally, glidant may be added to the suspension before spraying. By not adding it to the suspension, gun blockage is eliminated, suspension preparation is simple and the process is streamlined.


A powder feed system can be integrated into the GRANUREX® process, which greatly increases the rate of pellet formation.  Finely divided/Micronized API and/or micronized polymer and/or micronized excipient is loaded in to a precision powder feeder. Core particles from 100 to 2000+ microns are loaded on to a conical rotor. A small amount of binder, plasticizer or liquid solvent is atomized and sprayed on to the core particles while the dry micronized powders are fed in to the cores via the precision powder feeder. Rotor energy and the precise balance of micronized powder and liquid addition results in very fast coatings of active, polymer or combinations that would take hours or days if applied conventionally from solution. Product movement on the rotor ensures very high uniformity.

Pellet Formation With Drying Capabilities

Historically, rotor-based processors were limited on drying capacity.

FREUND designed the Drying Accelerator Duct within the GRANUREX® processor.

This greatly reduces process time and increases yield.

In this picture, the spherical granulation process is complete and the product is getting dried via the Drying Accelerator Duct.

GRANUREX® Case Study: Pellet Generation (Spherical Granulation)

Granules produced by the GRANUREX® rotor processor are dense and spherical in shape. The pictures and graphs shown below demonstrate how the GRANUREX® rotor processes Ibuprofen from a 7µm poorly flowing powder to 200µm granules with excellent flow characteristics.

Starting Material: Unprocessed Ibuprofen

After 30 minutes of processing within a GRANUREX® processor, Ibuprofen pellets were generated and shown below. Ending product characteristics: 250 micron spherical pellets, 0.59 g/cc density, with very good flow properties.

Using GRANUREX®, 250 micron (d50) Ibuprofen pellets were formed within 30 minutes.

Case Study: Pellet Formation (Powder Coating)

Using a powder feed system, pellets can be dramatically increased in size in a short period of time. The powder applied can be the API, allowing for very heavy loading of active drug onto an existing pellet.

In the picture below, the goal was to form pellets with an 80% drug loading with 97% yeild. The API material dispensed through the powder feed system was micronized Flurbiprofen. Within a 2 hour period inside the GRANUREX®, the 80% goal was achieved representing in a 400% increase over the original starting sugar pellet. An aqueous binding solution was used.

Finished pellet with 80% loading of Flurbiprofen

Case Study: Dry Polymer Coating

With a GRANUREX® processor, polymer coatings can be applied without the use of organic solvents. Using commercially available polymers, such as Dow’s ETHOCEL HP®, a film coating can be produced onto a pellet (perhaps formed from the previous case studies). A plasticizer solution is applied at the same time the dry polymer is being introduced inside the GRANUREX® chamber.

In the case study below, acetaminophen beads were coated with ETHOCEL HP® to produce a time-released coating. No solvents were used during this process.

A pellet with ETHOCEL HP® coating applied. 1. ETHOCEL HP® coating; 2. API layer; 3. Starting Core.

Contact FREUND

Find a Sales Representative