About benzalkonium chloridea nitrogenous cationic surfactant, quaternary ammonium compound, antiseptic,disinfectant, a vaginal contraceptive spermicidal agent.mechanism of action of benzalkonium chloridethe mechanism of bactericidal/microbicidal action is due to disruption of intermolecular interactions. this cause dissociation of cellular membrane bilayers, which compromises cellular permeability controls and induces leakage of cellular contents. other biomolecular complexes within the bacterial cell can also undergo dissociation. it also inactivates the enzyme produced by different microorganisms. it also has spermicidal action. they work by damaging and killing sperm in the vagina. therefore, the sperm are not able to travel from the vagina into the uterus and fallopian tubes, where fertilization usually takes place.