Previcox (firocoxib) is a “preferential COX-2 inhibitor” nonsteroidal anti-inflammatory drug (NSAID) that is used to treat inflammation, mild to moderate pain, and fever in dogs and horses.
NSAID's are called “nonsteroidal” because they are not related to the steroid drugs (synthetic drugs that closely resemble cortisol, a hormone that is naturally produced by the adrenal glands). Steroids work by suppressing the immune system, whereas NSAID's work mainly by preventing the formation of prostaglandins, hormone-like substances which trigger pain and inflammation. Prostaglandins are produced within the body's cells by the enzyme cyclooxygenase (Cox).
The conventional, first generation NSAID's work by inhibiting both COX-1 and COX-2 enzymes. By blocking COX-2 they are effective in relieving pain and inflammation, but by inhibiting COX-1 they often produce unacceptable gastrointestinal side effects including diarrhea, bloating, heartburn, upset stomach (dyspepsia) and ulcers. In contrast, the COX-2 meds have been shown to provide comparable pain relief and to cause significantly fewer adverse gastrointestinal (GI) events than the conventional, nonselective NSAID's.