Screening and quantification of undeclared PGF_2α analogs in eyelash-enhancing cosmetic serums using LC-MS/MS

In recent years, cosmetics deemed equivalent to pharmaceutical products containing prostaglandin F_2α (PGF_2α) analogs have been distributed overseas in the form of eyelash serums that can be purchased via the internet. The purpose of this study was to investigate the presence or absence of PGF_2α analogs in eyelash serums procured in Japan via the internet to elucidate the actual composition. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) measurement system was developed for the determination of 14 PGF_2α analogs in cosmetic serums. In total, 64 eyelash serum samples were purchased from 34 websites. After pretreatment, eyelash serum samples were screened for PGF_2α analogs using the LC-MS/MS system. Products containing PGF_2α analogs were subjected to quantification of these compounds. Of the 64 products, four were found to contain bimatoprost, among which, three did not indicate their contents on their package labels. In contrast, no samples were found to contain latanoprost, travoprost, or tafluprost, which are prescribed for glaucoma treatment. Additionally, eight products contained other PGF_2α analogs, which have not been used as pharmaceuticals. The ease of access to cosmetic serums containing PGF_2α analogs via online purchases presents a risk of serious side effects, particularly when consumers are not informed of their contents on the packages. This issue requires serious consideration to avoid the incorporation of pharmaceutical substances into cosmetic products.