Dimemorfan phosphate is a sigma 1 receptor agonist, used as a potent antitussive. In Vitro: Dimemorfan (5-20 μM) inhibits both fMLP- and PMA-induced ROS production in a concentration-dependent manner and is relatively more potent in inhibiting fMLP-induced ROS production with an IC₅₀ value of 7.0 μM. Dimemorfan (10-50 μM) does not display significant activity in scavenging free radicals by xanthine/xanthine oxidase system. Dimemorfan significantly suppressed Mac-1 upregulation both in PMA- and fMLP-activated groups. Dimemorfan (10-20 μM) significantly suppresses LPS-induced ROS and NO production, and suppresses LPS-induced iNOS protein expression, and both the percentage of the positively stained population and the MCF intensities of MCP-1 and TNF-α in BV2 cytosol. Dimemorfan (20 μM) significantly blocks the degradation of cytosolic Iκ-Bα and nuclear translocation of NF-κB p65, as well as the transcriptional activity of NF-κB^[2]. In Vivo: Dimemorfan (6.25 or 12.5 mg/kg, s.c.) significantly attenuates the BAY k-8644-induced convulsive behaviors, in a dose-related manner (6.25 mg/kg dimemorfan+BAY k-8644 or 12.5 mg/kg dimemorfan+BAY k-8644 versus Saline+BAY k-8644, P<0.05 and P<0.01, respectively). Dimemorfan significantly attenuates BAY k-8644-induced increases in the c-fos and c-jun protein expression in a dose-dependent manner. Dimemorfan does not significantly affect locomotor activity or produce significant circling behavior in any locomotor pattern in mice^[1]. Dimemorfan (1 and 5 mg/kg, i.p.) surpresses the incarease of the plasma levels of TNF-α in mice. The infiltration of neutrophils into lung and liver as well as the production of oxidative stress (EB staining) in these tissues induced by LPS is markedly inhibited by the treatment with dimemorfan^[2].