Vortioxetine hydrobromide (Lu AA21004 hydrobromide) is a serotonin (5-HT) modulator and stimulator (SMS), inhibits 5-HT1A/1B/3A/7 receptor and SERT (IC50: 15/33/3.7/19/1.6 nM).

Subcutaneous injection of Lu AA21004 (2.5-10.0 mg/kg) into the medial prefrontal cortex and ventral hippocampal area of rats was found to elevate extracellular levels of 5-HT, DA, and NA. A specific dose of Lu AA21004 (5 mg/kg) targeting the rats’ ventral hippocampal region resulted in a 200% increase in extracellular 5-HT levels. Additionally, administration of Lu AA21004 (at doses of 5 and 10 mg/kg) showed a significant elevation in ACh levels to 224% and 204% respectively, 20 minutes post-injection. This compound, when administered to the ventral hippocampal area of awake rats at doses of 5 and 10 mg/kg, enhanced extracellular 5-HT levels, and a 3-day treatment of the medial prefrontal cortex with Lu-AA21004 (at 5 and 10 mg/kg) substantially raised the basal levels of 5-HT. Furthermore, Lu AA21004 (10 mg/kg) notably decreased pain perception in rats. In terms of pharmacokinetics within rats, Lu-AA21004 exhibited a liver clearance rate of 7.1 (L/h)/kg and an oral bioavailability of 16%. Lastly, Lu AA21004 dose-dependently affected the rats' Bezold-Jarisch reflex by inhibiting transient bradycardia (ED50: 0.11 mg/kg).

Lu AA21004 acts as an agonist for the h5-HT1B receptor, with an EC50 value of 460 nM and demonstrating 22% intrinsic activity in whole-cell assays. It inhibits recombinant human cytochrome P450 enzymes CYP1A2, CYP2C9, CYP2D6, and CYP3A4 with IC50 values of 40 μM, 39 μM, 9.8 μM, and 10 μM, respectively. Furthermore, Lu AA21004 binds to the r5-HT7 receptor with a Ki value of 200 nM in vitro whole-cell cAMP assays and functions as a competitive antagonist with an IC50 of 2 μM.

Assay of MEK Kinase Activity: Anti-MEK1 antibody is used to immunoprecipitate MEK1 molecules. MEK kinase activity is measured as the ability of immuno-isolated MEK1 to activate recombinant ERK1 in a coupled assay using MBP as the end point of the assay. Phosphorylated MBP is resolved on a 14% SDS-PAGE gel and vacuum-dried before exposure to X-ray film.