O-Demethyl apremilast is an active metabolite of the phosphodiesterase 4 (PDE4) inhibitor apremilast .¹It inhibits the activity of PDE4 isolated from U937 cells and LPS-induced TNF-α production in isolated human peripheral blood mononuclear cells (PBMCs; IC₅₀s = 8.3 and 5.6 µM, respectively). O-Demethyl apremilast is also an oxidative degradation product of apremilast.^2,3

1.Hoffmann, M., Kumar, G., Schafer, P., et al.Disposition, metabolism and mass balance of [14C]apremilast following oral administrationXenobiotica41(12)1063-1075(2011) 2.Lu, Y., Shen, X., Hang, T., et al.Identification and characterization of process-related substances and degradation products in apremilast: Process optimization and degradation pathway elucidationJ. Pharm. Biomed. Anal.14170-78(2017) 3.Bhole, R.P., Naksakhare, S.R., and Bonde, C.G.A stability indicating HPTLC method for apremilast and identification of degradation products using MS/MSJ. Pharm. Sci. & Res.11(5)1861-1869(2019)