Size Enlargement of Pharmaceutical Powders by Wet Agglomeration and Drying Techniques t

Today, tablets are still the most desired form of dosage due to the convenient administration, the chemical and physical stability of the drug in a solid state, and the high production rate of a tabletting machine based on the compaction of powders or granules. Because direct compression vehicles are still in the minority, pharmaceutical powders have to be processed in order to obtain a tailored particle size distribution exhibiting a good flowability, compressibility, compactibility, wettability, lack of dust, etc. Thus, the size enlargement by wet agglomeration and drying of pharmaceutical powders is an important unit operation in a batch-wise production of granules. For an optimal quality assurance, the starting materials (drug substance, excipients) and the process technologies applied need to be characterized and defined in an appropriate way. Special attention has to be paid to scale-up processes and to monitoring the amount of granulating liquid added to the powder system. Although a batch-wise production is the method of choice from the point of view of a quality assurance department, as a batch can be accepted or rejected, the trend towards lean and just-in-time production focuses the attention on the feasability of continous processes such as a wet agglomeration and drying technique. Besides the subsequent production of tablets, spherical pharmaceutical granules called pellets with a mean particle size in the range of 0.4 mm to 1.4 mm are usually filled into hard gelatine capsules. The controlled production of pellets with an appropriate mean size and narrow size distribution is highly desired. Due to environmental protection and safety, the use of distilled or demineralized water as a granulation liquid for the wet agglomeration process is the first choice. However, the design of innovative novel dosage forms, i.e. the modification of powders, may make the use of an appropriate organic solvent may be a prerequisite. Thus, the production of novel dosage forms, of specially tailored properties of granules, may need a special process technology with a solvent recovery system, i.e. a correlation can be established between novel product properties and the use of novel process technologies, such as the vacuumfluidized bed granulation and drying method.