INVESTIGATION OF IN-VIVO PENETRATION AND DISTRIBUTION OF NANOMETRIC TiO2 IN TROPICAL ALBINISTIC SKIN BY SEQUENTIAL ADHESIVE TAPE STRIPPING

摘要

The non-invasive adhesive tape stripping technique was used to evaluate dermato-pharmacokinetics of nanometric titanium dioxide in tropical albinistic skin. Ten sequential strippings were conducted on exposure sites on the forehead, inner and upper forearms of three oculocutaneous albinism individuals 26+/- 4 years old, 15 minutes post dosing of 6.75mg/cm2 of a 5% titanium dioxide cream specifically designed to retard actinic damage in albinistic persons. The strips were subsequently acid treated and analyzed for titanium content by ICP-AES. All the applied titanium was recovered from the surface and upper layers of the stratum corneum of all participants from all body sites. The average recovery of titanium was 98.50± 0.66%.No titanium was detected in strips 9 and 10 from all sites. On the inner forearm, on average 67.92± 0.95% titanium was localized on the surface (strip1and the cotton swab), 29.41± 0.60%was recovered in the upper stratum corneum strips 2-5. The small remainder was recovered from the lower strippings. On the upper forearms the average recoveries were 61.86± 0.72% Ti (surface), 34.29± 0.61% (upper stratum corneum). On the forehead the recoveries were 54.94± 0.34% (surface) and 40.55± 1.79 % (upper stratum corneum). Our results confirm that nanometric titanium ions in treatments will not pose systemic exposure risks through skin penetration when used in tropical oculocutaneous albinism treatments. The results also confirm that albinistic individuals exhibit regional differences in skin profiles due to actinic exposure that influence dermato-pharmacokinetics.