Peptidylarginine deiminase-4: Medico-formulative strategy towards management of rheumatoid arthritis.

Peptidylarginine deiminase-4 (PAD4) is a calcium-dependent enzyme that catalyzes the conversion of arginine into citrulline of macromolecules in the body. It governs several processes including apoptosis, innate immunity (Netosis), and pluripotency. Dysregulated PAD4 plays a vital role in the occurrence and development of Rheumatoid arthritis (RA). Therefore, PAD4 is considered a promising target for diagnosing and treating RA. Over the last few years research has been carried out on PAD4 inhibitors. When administered it circulates to the entire body and inhibits PAD4 causing immunosuppression which may lead to infection. A growing number of studies have demonstrated infiltration and differentiation of monocytes and macrophages into the inflamed synovium, inducing overexpression of PAD4 levels in the inflamed joints. To overcome the above-mentioned critical issues, the targeted drug delivery systems inhibit PAD4 at the inflamed site. This review provides an update on the PAD4 inhibitors and emerging advanced drug delivery systems for the treatment of RA. Finally, we concluded that active targeting of PAD4 inhibitors to inflamed joints via hybrid nanocarriers provided an improved therapeutic efficacy, minimized extra synovial toxicity, and prevent the occurrence of inflammation in RA.