ABSTRACT

Granulation is the process of agglomeration of a powder mixture, which results in the enlargement of the particles. This is often necessary for manufacturing of solid dosage forms such as tablets. Thematerials, which are compressed into tablets, must possess adequate flowability, density, and compressibility. This is because the requisite amount of powder mixture required to compress each tablet is filled into the die cavity by volume and not by weight. This requirement of adequate flowability, density, and compressibility is particularly important during a high-speed tablet production where the dwell time is often short. For example, active pharmaceutical ingredients such as ibuprofen and acetaminophen, which have inadequate flow and compression properties, and a relative high dose, are often granulated prior to compression into tablets. Thus, the overall purpose of granulation is to improve the flowability and compressibility of the powder mixture. Besides improving the flowability and compressibility, the granulation process can also

Densify the powder mixture and reduce dust Narrow the particle size distribution of the powder mixture Ensure uniform distribution of the drug in the powder mixture Improve the dissolution characteristics of the finished tablets. The three commonly used granulation methods include wet granulation, dry

granulation, and hot-melt granulation. These methods are categorized based on the type of binder and the process employed during granulation. The equipment that is used during the granulation processes is classified into the following three major categories, based on the shearing strength it generates on the powder bed:

1. Low-shear granulators-twin shell (Peterson Kelly, PK) with an agitator bar, dough mixer or planetary mixer, ribbon blenders, and fluid bed granulator without the rotogranulator

2. Medium-shear granulators-fluid bed granulators with a rotogranulator attachment

3. High-shear granulators.