beta-Lapachone has drawn increasing attention as an anti-inflammatory and anti-cancer drug. However, its oral bioavailability has not been yet assessed, which might be useful to develop efficient dosage forms possibly required for non-clinical and clinical studies and future market. The aim of the present study was thus to investigate pharmacokinetic properties of beta-lapachone as well as its first-pass metabolism in the liver, and small and large intestines after oral administration to measure the absolute bioavailability in rats. A sensitive HPLC method was developed to evaluate levels of beta-lapachone in plasma and organ homogenates. The drug degradation profiles were examined in plasma to assess the stability of the drug and in liver and intestinal homogenates to evaluate first-pass metabolism. Pharmacokinetic profiles were obtained after oral and intravenous administration of beta-lapachone at doses of 40 mg/kg and 1.5 mg/kg, respectively. The measured oral bioavailability of beta-lapachone was 15.5%. The considerable degradation of beta-lapachone was seen in the organ homogenates but the drug was quite stable in plasma. In conclusion, we suggest that the fairly low oral bioavailability of beta-lapachone may be resulted from the first-pass metabolic degradation of beta-lapachone in the liver, small and large intestinal tracts and its low aqueous solubility.
Administration, Intravenous ; Administration, Oral ; Animals ; Biological Availability* ; Chromatography, High Pressure Liquid ; Dosage Forms ; Intestines ; Liver ; Metabolism* ; Pharmacokinetics ; Plasma ; Rats* ; Solubility

Retinyl palmitate (RP)-loaded pectinate micro- and nano-particles (PMP and PNP) were designed for stabilization of RP that is widely used as an anti-wrinkle agent in anti-aging cosmeceuticals. PMP/PNP were prepared with an ionotropic gelation method, and anti-oxidative activity of the particles was measured with a DPPH assay. The stability of RP in the particles along with pectin gel and ethanolic solution was then evaluated. In vitro release and skin permeation studies were performed using Franz diffusion cells. Distribution of RP in each skin tissue (stratum corneum, epidermis, and dermis) was also determined. PMP and PNP could be prepared with mean particle size diameters of 593~843 mum (PMP) and 530 nm (i.e., 0.53 mum, PNP). Anti-oxidative activity of PNP was greater than PMP due largely to larger surface area available for PNP. The stability of RP in PMP and PNP was similar but much greater than RP in pectin bulk gels and ethanolic solution. PMP and PNP showed the abilities to constantly release RP and it could be permeated across the model artificial membrane and rat whole skin. RP was serially deposited throughout the skin layers. This study implies RP loaded PMP and PNP are expected to be advantageous for improved anti-wrinkle effects.
Animals ; Diffusion ; Epidermis ; Ethanol ; Gels ; Membranes, Artificial ; Nanoparticles ; Particle Size ; Rats ; Skin*