New classes of lipids such as lipoxins, resolvins, protectins and maresin are found to promote the resolution of inflammation. The resolving actions of these endogenous lipids are mediated by membrane receptors such as lipoxin A4 receptor/formyl peptide receptor 2 (ALX/FPR2) and cysteinyl leukotriene receptor 1 (CysLT1). Further, there exists G protein-coupled receptor 32 (GPR32), chemokine receptor-like (CMLKLR), LTB4 receptor 1 (BLT1) and unidentified high-affinity surface binding receptors in human polymorphonuclear leukocytes (PMN).

In particular, RX-10001 (resolvin E1) and RX-10004 (synthetic analog of resolvin, phase II) are being studied clinically in many inflammatory diseases including dry eye, retinal disease, asthma, inflammatory bowel diseases, rheumatic arthritis and cardiovascular diseases by Resolvyx Pharmaceuticals. These novel lipid classes of inflammation resolving mediators might offers new opportunities for candidates of drugs modulating chronic inflammatory diseases. Here, the progress of resolvins as new drug candidates is introduced and research on the resolution phase of inflammation is emphasized.