Evaluation of Neutralizing Efficacy and Possible Microbial Cell Toxicity of a Universal Neutralizer Proposed by the CTPA

The purpose of this research was to study the neutralization efficacy of a universalneutralizer proposed by the ctpa on a range of antimicrobial agents and its potentialtoxicity for microorganisms that are used for antimicrobial preservation testing. severaltypes of antimicrobial agents including a mixture of methylisothiazolinone and its5-chloro derivative, dimethylol dimethyl hydantoin, quaternium-l s'p, bronopol, benzalkoniumchloride, phenoxyethanol, methyl and propyl paraben, chlorhexidine, imidazolidinyl urea,triclosan and thiomersal built-in pharmaceutical, cosmetic or health care products, as well as6 types of these antimicrobials, i.e. a combination of methyl paraben (0.18% w/v) and propylparaben (0.02%), imidazolidinyl urea (0.3%), chlorhexidine (0.01%), benzalkonium chloride(0.02%), bronopol (0.1%) and thiomersal (0.02%) in their pure and soluble form weretested. validation of microbial recovery was carried out according to the us pharmacopeia 27guidelines. the universal neutralizer could inactivate all the studied antimicrobial agents againstdifferent strains tested except staphylococcus aureus. with regards to this microorganism,only seven preservative chemicals consisting of parabens, dimethylol dimethyl hydantoin,quaternium-l s'p, bronopol', benzalkonium chloride, phenonipf and imidazolidinyl ureawere effectively inactivated. in addition, a pure solution of 0.02% thiomersal retained itsantimicrobial properties against all studied microorganisms. the neutralizer solution showedno toxicity on any of the test organisms. in conclusion, ctpa proposed neutralizing solutionis not an inclusive neutralizer. moreover, each organism to be used in the test must be includedin the validation study.