Efficacy of chlorhexidine gluconate ointment (oronine H^®) for experimentally-induced comedones

Background: Oronine H^® ointment, which contains chlorhexidine gluconate as its active component, is a well known disinfectant, and has been widely used for treatment of acne in Japan. In this study, we investigated the inhibitory effect of this ointment on the formation of comedones induced by application of 50% oleic acid on the orifices of the external auditory canals of rabbits. Methods: The application sites were observed with a dermatoscope, and the area of the hair pores was measured using an Image analysis software program. Results: The chlorhexidine gluconate ointment inhibited comedone formation significantly more effectively than the liquid paraffin used as a control (P < 0.001). We also investigated the therapeutic effect of this ointment on comedones. After starting application of chlorhexidine gluconate ointment or liquid paraffin on the comedone area, the hair pore size was gradually decreased in the group treated with chlorhexidine gluconate ointment compared with the hair pore size at baseline. Conclusion: These results suggest that chlorhexidine gluconate ointment is effective for inhibiting comedone formation as well as for treating already formed comedones. Chlorhexidine gluconate ointment is a useful topical medicine for the treatment of early-stage acne and for preventing acne.