Prospective Cohort Study: Hexyl-2,5-Diaminobenzoate Is a Hypoallergenic Alternative for Patients With Allergic Contact Dermatitis to Para-Phenylenediamine.

BACKGROUND

Hair dyes, such as p-phenylenediamine (PPD), are a frequent cause of potentially severe allergic contact dermatitis. Our group previously described the synthesis, safety profile, and hair dye properties of novel hair dye alternatives: hexyl-2,5-diaminobenzoate (PPD6) and hexyl 2-amino-5-((4-aminophenyl)amino)benzoate (PPD7).

OBJECTIVE

Our objective was to test the allergenicity of PPD6 and PPD7 with patch tests in individuals with proven contact allergy to PPD.

METHODS

This prospective cohort study at the University of Minnesota conducted patch testing to PPD6 and PPD7 on 8 subjects. Both in vitro and in chemico tests with PPD6 and PPD7 (DPRA and skin penetration) were done on patients with current or previously relevant positive patch test reactions to PPD or PTD. PPD6 and 7 derivatives were supplied in powder form and diluted to 1% and 2% for testing, with reading and photodocumentation on days 2 and 4.

RESULTS

None of the subjects (0/8) reacted to PPD6, while most (5/8) of the subjects reacted to PPD7 and/or to the commercially available PTD (2/8) and ME-PPD (5/8).

LIMITATIONS: Further studies with larger cohorts are needed using the PPD6 as hair dye in PPD-allergic individuals.

CONCLUSION

PPD6 may be a hypoallergenic alternative for permanent dark hair dye in patients with contact allergy to PPD.