Topical isonicotinic acid hydrazide (isoniazid) as a new skin depigmenting compound

Topical isonicotinic acid hydrazide (isoniazid) as a new skin depigmenting compound

 Ahmadi S.¹, Pourahmadi M.¹, Aslani F.S.², Kasraee B.³

1 Jahrom University of Medical Sciences, Jahrom, Iran

2  Department of Pathology, Shiraz University of Medical Sciences, Shiraz, Iran

3 Scientis Pharma SA, Geneva, Switzerland

• Isonicotinic acid hydrazide (isoniazid) is the most commonly used antituberculosis medication. This molecule is a substrate for the enzyme peroxidase present within the tuberculosis bacillus and its metabolization by this enzyme is responsible for its bactericidal effect. In melanocytes, the enzyme peroxidase is involved in several steps of melanin synthesis and we have previously suggested that peroxidase substrates might act as skin depigmenting molecules.
• We report herein that isoniazid acts as a potent skin depigmenting molecule when used topically in black guinea pig model. Six uniformely black guinea pigs were treated with a cream containing 10% isoniazid on one of their ears and with the vehicle alone on their contralateral ears daily for two consecutive weeks. Visible depigmentation occured in isoniazid treated sites already after one week of application while the vehicle treated areas remained unchanged. Dermacatch^® colorimetric examinations confirmed the significant depigmenting effect of isoniazid compared to control. Histologic (H&E and Fontana-Masson) and immunohistologic (Mela-A and HMB-45) examinations as well as spectrophotometric melanin quantification in the splitted epidermis unequivocally confirmed the significant depigmenting action of topical isoniazid.

• Isoniazid can serve as a novel lead compound for the discovery of new skin depigmenting molecules in the future. Peroxidase substrates may be considered as a new family of skin depigmenting agents.

September 2012 – 17th Meeting of the European Society for Pigment Cell Research (ESPCR)  – Geneva, Switzerland