Sensitization of rabbits with chlorhexidine-protein complexes

Final Report on the Safety Assessment of Chlorhexidine/Chlorhexidine Diacetate/Chlorhexidine Dihydrochloride/Chlorhexidine Digluconate

Chlorhexidine and its Diacetate and Digluconate salts are used in cosmetics as preservatives. Chlorhexidine Digluconate was slightly toxic in oral and inhalation studies. At cosmetic use concentrations, Chlorhexidine Digluconate was not irritating to the eyes or skin. Positive sensitization reactions were cited in provocative patch testing at 1.0% concentration in patients with eczema, but not in predictive patch testing of 0.05% in normal subjects. In bacterial assays, Chlorhexidine tested both positive and negative for mutagenesis. In two mammalian systems, Chlorhexidine Digluconate was not genotoxic. p-Chloroaniline is a degradation product of Chlorhexidine salts. A study of the degradation of Chlorhexidine revealed minor amounts of p-chloroaniline after 36 weeks storage. Chlorhexidine Digluconate was not carcinogenic in a 2-year drinking water study. On the basis of the data presented in this report, it is concluded that Chlorhexidine and its salts are safe for use in cosmetic products at concentrations up to 0.14% calculated as Chlorhexidine free base; 0.19% as Chlorhexidine Diacetate; 0.20% as Chlorhexidine Digluconate; and 0.16% as Chlorhexidine Dihydrochloride.

Factors influencing the immunogenicity of the haptenic drug chlorhexidine in mice--Part I. Molecular requirements for the induction of IgE and IgG anti-hapten antibodies

The immunogenicity of a novel hapten, the anti-microbial agent, chlorhexidine (1,1'-hexamethylene bis [5-(p-chlorophenyl)biguanide]) was assessed in mice, using alum as adjuvant. The i.p. injection of electrostatically-linked chlorhexidine + keyhole limpet haemocyanin (KLH) mixtures induced low level primary IgG anti-chlorhexidine antibody synthesis. In contrast, covalently-linked chlorhexidine-KLH complexes induced both IgE and IgG anti-chlorhexidine antibody synthesis. Covalent binding was facilitated by the N-chlorination of secondary amide groups on the biguanide moeities of the chlorhexidine molecule. The immunogenicity of such complexes was related to the degree of conjugation of chlorhexidine to KLH; which, in turn, was related to the molarity of chlorine used to effect N-chlorination. Immune responses to covalently-linked complexes could be enhanced by carrier priming. The induction of low levels of IgG anti-hapten antibodies by electrostatically-linked complexes may reflect T cell-independent specific B cell activation, either by chlorhexidine itself or by a "pseudo-plurivalent" chlorhexidine + KLH antigen.