Muscle atrophy is the loss of skeletal muscle mass. It can be caused by immobility, aging, malnutrition, medications, or a wide range of injuries or diseases that impact the musculoskeletal or nervous system. Muscle atrophy leads to muscle weakness and causes disability. Disuse causes rapid muscle atrophy and often occurs during injury or illness that requires immobilization of a limb or bed rest. Depending on the duration of disuse and the health of the individual, this may be fully reversed with activity. Malnutrition first causes fat loss but may progress to muscle atrophy in prolonged starvation and can be reversed with nutritional therapy. In contrast, cachexia is a wasting syndrome caused by an underlying disease such as cancer that causes dramatic muscle atrophy and cannot be completely reversed with nutritional therapy. Sarcopenia is age-related muscle atrophy and can be slowed by exercise. Finally, diseases of the muscles such as muscular dystrophy or myopathies can cause atrophy, as well as damage to the nervous system such as in spinal cord injury or stroke. Thus, muscle atrophy is usually a finding (sign or symptom) in a disease rather than being a disease by itself. However, some syndromes of muscular atrophy are classified as disease spectrums or disease entities rather than as clinical syndromes alone, such as the various spinal muscular atrophies. Muscle atrophy results from an imbalance between protein synthesis and protein degradation, although the mechanisms are incompletely understood and are variable depending on the cause.
Several dozen analogs of celecoxib were generated with small alterations in their chemical structures. Some of these analogs retained COX-2 inhibitory activity, whereas many others did not. However, when the ability of all these compounds to kill tumor cells in cell culture was investigated, the antitumor potency did not at all depend on whether or not the respective compound could inhibit COX-2, showing the inhibition of COX-2 was not required for the anticancer effects. One of these compounds, 2,5-dimethyl-celecoxib, which entirely lacks the ability to inhibit COX-2, actually displayed stronger anticancer activity than celecoxib. References
Further reading
Dean L (2016). "Celecoxib Therapy and CYP2C9 Genotype". In Pratt VM, McLeod HL, Rubinstein WS,  et al. (eds.). Medical Genetics Summaries. National Center for Biotechnology Information (NCBI). PMID 28520369. Bookshelf ID: NBK379478. Zhang J, Ding EL, Song Y (October 2006). "Adverse effects of cyclooxygenase 2 inhibitors on renal and arrhythmia events: meta-analysis of randomized trials". JAMA. 296 (13): 1619–32. doi:10.1001/jama.296.13.jrv60015. PMID 16968832. External links
"Celecoxib". Drug Information Portal. U.S. National Library of Medicine. "COX-2 Selective (includes Bextra, Celebrex, and Vioxx) and Non-Selective Non-Steroidal Anti-Inflammatory Drugs (NSAIDs)". U.S. Food and Drug Administration (FDA). 15 July 2005. "FDA Approves Labeling Supplement for Celebrex (celecoxib)". U.S. Food and Drug Administration (FDA). 28 June 2018.