Application of microdialysis to study the in vivo release of pingyangmycin from in situ gels in rabbits

Microdialysis was used together with HPLC to monitor the local concentration of pingyangmycin hydrochloride (PYM) after embolizing rabbit ear‐veins with an injectable sustained release formulation, PYM‐Zein/PYM‐Zein‐sucrose acetate isobutyrate (SAIB), in situ gel. The dialysis probe was perfused at 2 µL/min. The in vivo recovery was 46.6 3.1% ( n = 4). The samples were injected directly into HPLC. PYM was detected using UV detector at 291 nm. Separation from other components in the dialysate was performed using a Discovery ® RP‐Amide C 16 column within 12 min. The response for PYM in the dialysate was linear ( r 2 > 0.996) over the range of 2.5–212 µg/mL. The limit of detection and limit of quantitation of PYM in the dialysate were 0.4 and 1.5 µg/mL, respectively. The results demonstrated that the in situ gel of PYM‐Zein‐SAIB could extend the release of PYM to 4 days. SAIB could significantly cut down the initial burst of PYM from the in situ gels ( p < 0.05). Copyright © 2006 John Wiley & Sons, Ltd.