Nao-Qing
solution has been shown to be clinically effective in the treatment of
acute ischemic stroke (AIS). The purpose of this study was to improve the pharmacokinetics and brain uptake of
Nao-Qing, administered as an oil-in-water microemulsion. Sprague-Dawley (SD) rats were given
Nao-Qing microemulsion by intranasal or intragastric routes. Samples of blood, brain, heart, liver, lung and kidney were collected at pre-determined time intervals, and the contents of
ginsenosides Rg1 and Rb1 (active ingredients of the
Nao-Qing microemulsion) were analyzed by high-performance liquid chromatography (HPLC). The results showed that contents of
ginsenosides Rg1 and Rb1 in
Nao-Qing microemulsion was 8475.13 ± 54.61 μg/ml and 6633.42 ± 527.27 μg/ml, respectively, and that the particle size, pH and viscosity of the microemulsion were 19.9 ± 5.07 nm, 6.1 and 3.056 × 10(-3 )Pas, respectively. Absorption of
ginsenoside Rg1 was higher than that of
ginsenoside Rb1, which was barely detectable after intragastric administration; furthermore, the concentration of
ginsenoside Rg1 in blood and other tissues at each time point was lower for intragastric than for
intranasal administration. Compared with intragastric
administration, intranasal administration resulted in a shorter tmax (0.08 versus 1 h), a higher Cmax (16.65 versus 11.29 μg/ml), and a higher area under the concentration-time curve (AUC) (592.91 versus 101.70 μgċh/ml) in the brain. The relative rates of uptake (Re) and the ratio of peak concentration (Ce) in the brain were 126.31% and 147.48% for
ginsenoside Rg1, respectively. These data illustrate that
intranasal administration can promote the absorption of drugs in
Nao-Qing microemulsion and achieve fast effect.