Incorporation in Lipid Microparticles of Acid Red 87, a Colorant Used in Tattoo Inks: Effect on Photodegradation Under Simulated Sunlight and Laser Radiation

Abstract

Tattoo colorants decompose under solar radiation and when exposed to laser light for their removal, leading to the accumulation in the dermis of toxic products. Aim of this study was to develop lipid microparticles (LMs) loaded with the colorant, Acid Red 87 (C.I. 45380) used in tattoo inks, and to investigate the effect of this system on the photostability of the colorant under simulated sunlight or laser irradiation. LMs loaded with C.I. 45380 were prepared by melt emulsification using tristearin and phosphatidylcholine as excipients. They were characterized by optical microscopy, laser diffraction, X‐ray diffraction and release studies. Free C.I. 45380 and the colorant‐loaded LMs were irradiated with a solar simulator or a Q‐switched laser. Irradiation with a solar simulator demonstrated that photodecomposition of C.I. 45380 was markedly reduced by incorporation of the dye in the LMs, from 20.5 ± 4.6% to 1.3 ± 1.8%. Conversely, the laser‐induced degradation of the colorant (30.1 ± 6.6%) was not significantly influenced by encapsulation in the LMs (the encapsulated C.I. 45380 loss was 27.4 ± 5.5%). Incorporation of C.I. 45380 in lipid microparticles enhances the photostability under sunlight of tattoo inks containing this colorant, without affecting its laser‐induced degradation and hence laser removal efficiency.

Glyceryl Tristearate-Based Lipid Microparticles Loaded with the Tattoo Colorant, Acid Red 87: Colorant Retention Capacity in Excised Porcine Skin

“…In the previous study on the development of C.I. 45380-loaded LMs, the lipidic excipients, stearic acid, and glyceryl tristearate were shown to provide, in vitro, the optimal retention capacity for the examined colorant [12]. However, in the present investigation, glyceryl tristearate was selected as the lipid carrier since, at variance with fatty acids such as stearic acid, it does not elicit inflammatory reactions in animal skin [19, 25].…”

“…The size of the developed LMs, ranging between 25 and 170 μm, is greater than the particle dimensions in tattoo inks which has been reported to vary from <100 nm to ca. 8 μm [3, 12, 29, 30]. The larger sized LMs reported here should exhibit decreased in vivo diffusion in the extracellular matrix of the dermis and limited transfer to the regional lymph nodes [6], where the transport of smaller pigment particles is favored [31, 32].…”

“…A Model 702 NR syringe (25 μL; Hamilton, Bonaduz, Switzerland) was used for sample injections. Separations were performed according to a previously published method [12] on a 3.5-μm Zorbax SB-CN column (150 × 4.6 mm i.d. ; Agilent Technology, Waldbronn, Germany) fitted with a guard column (5 μm particles, 4 × 3 mm i.d.)…”

“…However, in the previous study on the incorporation of the colorant C.I. 45380 in LMs [12], the retention efficacy of the particle system was evaluated in a medium (PBS), which is not representative of the real conditions occurring in tattooing. Consequently, in order to gain further information on the potential application of LMs for the formulation of tattoo inks, in the present investigation, the release characteristics of the developed LMs were examined following their intradermal administration in the excised animal skin.…”

“…In a recent investigation by this group [12], the encapsulation of a tattoo colorant in lipid-based microparticles was reported for the first time and the photostabilizing effect of the particles under laser radiation and simulated sunlight exposure was demonstrated in vitro. The xanthene dye, Acid Red 87 (Color Index number, C.I.…”