The Pharmacokinetics of Fucoidan after Topical Application to Rats

Fucoidan, a fucose-rich polysaccharide from brown algae, has been used for transdermalformulations targeting inflammatory skin conditions, for the treatment of thrombosis, vascularpermeability diseases, subcutaneous wounds, and burns. However, the pharmacokinetics offucoidan after topical application has not been described. In this study, an ointment (OF)containing 15% fucoidan was topically applied to rats at the doses of 50-150 mg/g. The anti-Xaactivity was selected as the biomarker, and the amidolytic assay method was validated and appliedfor pharmacokinetic studies of fucoidan. Fucoidan in OF penetrated the skin and distributed intothe skin, striated muscle, and plasma with AUC0-48 = 0.94 μg·h/g, 2.22 μg·h/g, and 1.92 μg·h/mL,respectively. The longest half-life for fucoidan was observed in plasma, then in striated muscle andskin. It was found that the pharmacokinetics of fucoidan after topical OF application was linear, inthe range of 50-150 mg/kg. No accumulation of fucoidan in plasma was observed after repeatedtopical applications of 100 mg/kg during five days. Our results support the rationality of topicalapplication of formulations with fucoidan.