The hydrochloride salt of fluphenazine, a phenothiazine with antipsychotic activity and potential antineoplastic activity. Fluphenazine blocks postsynaptic dopamine D2 receptors in the limbic system, cortical system and basal ganglia, resulting a reduction of schizophrenia-associated hallucinations and delusions. In addition, as a serotonin antagonist, this agent may inhibit lymphocyte and myeloma cell proliferation by blocking 5-hydroxytrptamine type 1B (5-HT type 1B) receptors for serotonin.