In vitro activity: Capsazepine converts the NKA into Na-ATPase. CPZ inhibits K+-dependent activity but allows Na-ATPase associated with Na+ transport. CPZ has no effect on Na-ATPase measured in the absence of K+. CPZ also inhibits para-nitrophenyl phosphatase activity, albeit with a lower affinity. CPZ strongly reduces the steady-state EP level and the Na+ affinity for phosphorylation decreased 3-fold after CPZ treatment. In summary, CPZ blocks an Na+/K+ cycle in the NKA but leaves an Na+ cycle intact, reducing the transport stoichiometry of the pump. Capsazepine(CPZ) at a concentration of 94.2 μg/ml (IC50 concentration of capsazepine) exhibits a statistically significant inhibition of osteoclast growth and proliferation

Kinase Assay: Capsazepine is an antagonist of TRPM8 with an IC50 of 562 nM. A major problem in clinical trials of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) as cancer therapy is the development of resistance to TRAIL. Therefore, agents that can overcome TRAIL resistance have great therapeutic potential. Capsazepine, as a TRPV1 antagonist, has ability to sensitize human colon cancer cells to TRAIL-induced apoptosis. Capsazepine potentiated the effect of TRAIL, as shown by its effect on intracellular esterase activity; activation of caspase-8,-9, and -3; and colony-formation assay. Capsazepine induced death receptors (DRs) DR5 and DR4, but not decoy receptors, at the transcriptional level and in a non-cell-type-specific manner.

Cell Assay:The cells are plated and treated with different concentrations of the test compounds and allowed to proliferate for 72 h. After 72 h of proliferation the cells are fixed in 10% formalin saline (50 μl/well) for 30 min. Then the cells are stained with crystal violet (0.05% w/v) for 30 min. The wells are then washed thoroughly with distilled water to remove any unbound dye and destained with Sorenson's buffer (0.1 M sodium citrate in 50% ethanol, pH 4.2). The absorbance of the extracted stain is measured at 540 nm.