drug nanocrystals: novel technique for delivery of ... - Ijsidonline.info

Sneha V Sawant et al., IJSID 2011, 1 (3), 1-152. Piston-gap homogenizationIt is also known as High pressure homogenization in water (Dissocubes®).Drug nanocrystals can also beproduced by high-pressure homogenization using piston gap homogenizers.Depending on the homogenizationtemperature and the dispersion media, there is a difference between the Dissocubes® technology and theNanopure® technology.Dispersion medium of the suspensions was water. A piston in a large bore cylinder createspressure up to 2000bar. The suspension is pressed through a very narrow ring gap. The gap width is typically inthe range of 3-15 micrometer at pressures between 1500-150 bar. There is a high streaming velocity in the gapaccording to the Bernouli equation. Due to the reduction in diameter from the large bore cylinder (e.g. 3 cm) to thehomogenization gap, the dynamic pressure (streaming velocity) increases and simultaneously decreases the staticpressure on the liquid. The liquid starts boiling, and gas bubbles occur which subsequently implode, when thesuspension leaves the gap and is again under normal pressure (cavitation). Gas bubble formation and implosionlead to shock waves which cause particle diminution. The patent describes cavitation as the reason for theachieved size diminution. [18] The use of water as dispersion medium is associated with some disadvantages.Hydrolysis of water-sensitive drugs can occur, as well as problems during drying steps. In cases of thermolabiledrugs or drugs possessing a low melting point, a complete water removal requires relatively expensive techniques,such as lyophilization. For these reasons, the Dissocubes® technology is particularly suitable if the resultingnanosuspension is directly used without modifications, such as drying steps.Many different drugs have beenprocessed by high pressure homogenization to produce DissoCubes. Up to now each drug investigated could beconverted into a nanosuspension. Examples include RMKP22, carbamazepin, bupravaquone aphidicolin,cyclosporine, paclitaxel, RMBB98, azodicarbonamide, and prednisolone. [19]3. Nanopure® TechnologyIn Nanopure technology (PharmaSol GmbH, Germany), poorly water-soluble drugs are transferred to drugnanocrystals via a high-pressure homogenization process. The drug powder is dispersed in a surfactant solutionand the forces in the high-pressure homogenizer are strong enough to disintegrate the coarse drug powder intodrug nanoparticle with a mean diameter, typically between 200–600 nm. The drug powder is dispersed in anonaqueous medium (e.g., PEG 600, Miglyol 812) or a water-reduced mixture (e.g., water-ethanol) and theobtained presuspension is homogenized in a piston-gap homogenizer. A suitable machine for the laboratory scaleis the Micron Lab 40 (APV Deutschland GmbH). Nonaqueous dispersion media such as PEG or oils yieldsuspensions that are suitable for the direct filling of capsules and thus an intermediate step required when usingpure aqueous nanosuspension is avoided. With nanopure technology, homogenization can be performed in anonaqueous phase or phases with reduced water content. And, in contrast to more pronounced cavitation at highertemperatures, homogenization was similar or more efficient at lower temperatures, even below the freezing pointof water. [20]International Journal of Science Innovations and Discoveries, Volume 1, Issue 3, November-Deceber 20116