Spiperone is a potent intracellular Ca ²⁺ enhancer (EC ₅₀ =9.3 μM) and stimulates intracellular Ca ²⁺ through a protein tyrosine kinase-coupled phospholipase C-dependent pathway, which results in increased secretion of Cl ^- in Calu-3 and CFBE41o ^- cell monolayers.
Spiperone significantly decreases the production of nitric oxide in lipopolysaccharide-stimulated BV-2 microglia cells, primary microglia and primary astrocyte cultures. Spiperone also significantly inhibits nitric oxide production in ATP-stimulated primary microglia cultures. Spiperone markedly decreases the production of TNF-α in BV-2 microglia cells. Spiperone attenuates the expression of inducible nitric oxide synthase and proinflammatory cytokines such as IL-1β and TNF-α at mRNA levels in BV-2 microglia cells.

Spiperone (1.5 mg/kg; intraperitoneal injection; on days 1, 3, 6, 7, and 13-21; C57Bl/6 mice) treatment reduces infiltration of the alveolar interstitium and alveolar ducts with inflammatory cells and prevents the growth of the connective tissue in the parenchyma of Bleomycin lungs.