Effect of etoricoxib administration using nanotechnology for the treatment of experimental arthritis in a mouse model1: SummaryL Inflammation is a fundamental but complex process that protects the body by eliminating both the causes and consequences of injury, such as microbes, toxins and necrotic cells. Therefore, plasma proteins, circulating cells and tissue phagocytes (the body's defenders against foreign invaders) must be recruited into the extravascular space in order to rid the body of these factors (Kumar et al., 2010 ). Recent advances in nanomedical research have provided scientists with nanocarriers with many unique and tunable properties to meet the specific requirements of treating various inflammatory diseases. Etoricoxib is a nonsteroidal anti-inflammatory drug that selectively inhibits isoform 2 of the enzyme cyclooxygenase (cox-2). The drug is approved for use in more than 70 countries around the world for the treatment of rheumatoid arthritis, psoriatic arthritis and osteoarthritis. Although it is available for the treatment of many inflammatory conditions, its low bioavailability and untargeted biodistribution often limit its success in controlling disease symptoms. Neutral nanoparticles with a size smaller than the vascular pore threshold are likely to escape surface opsonization and will have a significantly low impact. uptake by the reticuloendothelial system. These particles will circulate longer in the blood and can be passively targeted to inflamed tissues. On the other hand, particles intended for uptake by macrophages should be larger and contain distinct surface charges to facilitate their interaction and internalization by macrophages (Moghimi et al., 2001). Therefore, nanoencapsulation of etori...... middle of article ......ng the general linear model procedure in SPSS (2004).5: Use/contribution of research results to solve Developmental Issues in the Kingdom of Saudi Arabia Arthritis is a prevalent chronic inflammatory disease involving damage to the joints of the body. Rheumatoid arthritis, the most common form of inflammatory arthritis, is a destructive joint disease that can affect 0.5 to 1% of the population in the industrialized world, causing significant disability and reduced quality of life (Lee and Weinblatt, 2001; The results of this research will provide a means to improve the treatment of rheumatoid arthritis by saving the time and effort required for suboptimal treatment, and as such, the research proposed here will result in an increase in the overall productivity of the population of the Kingdom of Saudi Arabia..