Micronization particle size reduction

Fluid Energy Milling Particle size reduction by high-speed particle-to-particle impact and/or attrition (also known as micronizing)... 

The shape of the micronized particles was irregular and, according to SEM pictures, it was assumed that the particles were porous. With particle-size reduction and, therefore, increased specific surface area (external and internal) the dissolution rate increased to some extent, but the anticipated effective surface area was probably reduced by the drug s hydrophobicity and agglomeration of the particles during and after micronization. 

Particle size reduction of a material suspended in a liquid medium can be affected by a Microi uidizeP processor (MicroLuidics Corp., Newton, MA, http //www.microLuidicscorp.com/ processors.html). A schematic of a MicroLuidizer processor is presented in Figure 17.6. In a Micro-Luidizer processor, a liquid stream is bifurcated and the two streams are directed upon each other under pressures as high as 40,000 psi. Particles suspended in the liquid are reduced in size by forces of shear and cavitation. Suspensions can be prepared with the MicroLuidizer processor with mean particle sizes in the micron to submicron range. 

Particle size reduction involves input of energy that gets disseminated during micronization process, along with formation of smaller particles having new surfaces. With an enormous increase in surface area, the newly formed particles need to be stabilized-fo prevent subsequent agglomeration induced by interparticulate interactions and maintain their existence as individual nanoentities. 

The process by which a solid is reduced to particle sizes of less than about 100 pm by using any type of particle-size reduction equipment. Examples micronized talc, micronized pigment. 

Particle size and particle size distribution studies are important for drugs that have low water solubility. Particle size reduction by milling to a micronized form increased the absorption of low aqueous solubility drugs such as griseofulvin, nitrofurantoin, and many steroids. Smaller particle size results in an increase in the total surface area of the particles, enhances water penetration into the particles, and increases the dissolution rates. With poorly soluble drugs, a disintegrant may be added to the formulation to ensure rapid disintegration of the tablet and release of the particles. 

Huang, Y.-L., Sheu, F., Lee, M.-H., and Chau, C.-F. (2008). Effects of particle size reduction of insoluble fibres by micron technology on various caecal and faecal indices. ]. Sci. Food Agric. 88,435-441. 

Thus, to reduce the risk of dissolution rate-limited bioavailability, and if there is sufficient compound, grinding in a mortar and pestle should be done to reduce the particle size of the compound. If larger quantities are available, then ball milling or micronization can be used to reduce the particle size. The main methods of particle size reduction have been reviewed by Spencer and Dalder (1997), who devised the mill selection matrix shown in Table 6.1. 

The pre-emulsion was stable enough to remain intact during transfer to the Gaulin Sub-micron Disperser and Homogenizer. The emulsion was recycled until the desired particle size reduction was achieved. The Gaulin Homogenizer was operated at 3500 pounds per square inch of shear force. 

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