Abstract: The characterization of microdialysis probe was performed in vitro and in vivo. No net flux method and retrodialysis method were used to find the recovery in vitro and in vivo respectively. On the basis of the probe characterization, transdermal delivery of ondansetron HCI (ON) solution in propylene glycol (PG) with a widely used enhancer oleic acid (OA) was carried out in rats. Dialysate samples collected from the probe were analyzed by HPLC. There was no significant difference between the in vitro recovery (35.46±4.2%) and the in vivo recovery (32.53±1.8%) (P>0.1). The ON concentration in both dialysate and dermis reached a plateau at 1.5 h by coapplication of 5% OA in solution of ON in PG, while at about 3.5 h by co-application of 2% OA. And the plateau ON concentration in case of 5% OA was about two fold of that of 2% OA. Oleic acid at concentrations of 2% and 5% (w/v) increased the delivery rates from 0.001 to 0.030 and 0.058 μg·h^-1 respectively. OA proved to be an effective enhancer for transdermal delivery of ON in rats.

Key words: Microdialysis, Microdialysis, Ondansetron HCI, Ondansetron HCI, Transdermal delivery, Transdermal delivery, Enhancer, Enhancer