Spray-congealing processes

The three overlay plots shown in Fig. 4.11 illustrate another example of how process variations can lead to unexpected changes in material behavior. Consider the instance of a spray congealing process where a mixture of one or more waxes with a melting point below that of the... 

Fig. 4.11. Unexpected formation of a metastable phase of acetaminophen as a result of exposure to the molten wax formulation during spray-congeal processing. Note The three curves have been manually offset on the F-axis from the normal zero milliwatt baselines in order to display the relative X-axis (temperature) differences between the three samples.

Hydrogenated Vegetable Oils These primarily consist of the family of stearines. Hydrogenated castor oil (Cutina HR ) has been used as a wax matrix material both in melt-granulation and spray-congealing processes.f ... 

Rodriguez, L. Passerini, N. Cavallari, C. Cini, M. Sancin, P. Fini, A. Description and preliminary evaluation of a new ultrasonic atomizer for spray-congealing processes. Int. J. Pharm. 1999, 183, 133-143. 

Maschke A, Becker C, Eyrich D, Kiermaier J, Blunk T, Gdpferich A (2007) Deyelopment of a spray congealing process for the preparation of insulin-loaded lipid microparticles and characterization thereof. European Journal of Pharmaceutics and Biopharmaceutics 65(2) 175-187. 

Spray Congealing Spray dried enzyme powder can be incorporated into a molten fat or wax. This mixture is atomized through a rotary nozzle into a cooled chamber essentially equivalent to a spray drier tower. The atomized droplets cool, solidify into particles, and harden as they fall, resulting in round particles. A simplified box diagram of spray congealing process is shown in Figure 6.11. 

FIGURE 6.11 Manufacture of enzyme granules with spray congealing process. 

Killeen, M.J. The process of spray drying and spray congealing. Pharm. Engineering 1993,13 (4), 56-64. 

The melt processes require at least a meltable material in the manufacture of the solid dosage form. This article intends to address the influence of meltable materials on the processes of melt pelletization, melt granulation, and tumbling melt granulation. Approaches to meet the processing attributes of the meltable materials for these melt agglomeration processes, via spray congealing, are discussed. 

Additionally, carnauba wax has been experimentally investigated for use in producing microparticles in a novel hot air coating (HAC) process developed as an alternative to conventional spray-congealing techniques. 

Shell materials can be solvent-based, water-based, molten, reactive, or molecnlar. Variations of atomization, spray coating, and coextrusion are available to deposit shell or matrix materials from solvent, water, or as a molten material. For example, spray drying is snitable for encapsnlating with solvent-based or water-based matrix materials, while spray congealing nses molten fats or waxes. Fewer shell material selections are available with the emulsion-based processes. For example, complex coacervation is most often associated with the use of gelatin as the shell, and the generation of polyurea or polymelamine formaldehyde shells is associated with in situ polymerization. Further limited examples include the use of cyclodextrins for molecular complexation or phospholipids for the formation of liposomes. 

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