Determination of rutin deca(H-) sulfate sodium in rat plasma using ion-pairing liquid chromatography after ion-pairing solid-phase extraction.

Rutin deca(H-) sulfate sodium (RDS) is one of the most important drug candidates, which possesses very good activity as inhibitor of the complement system of warm-blooded animals and human immunodeficiency virus (HIV). In order to understand RDS metabolism and disposition, an ion-pairing coupled with solid-phase extraction technique (IP-SPE) was developed to extract RDS from rat plasma sample. Tetrabutyl ammonium bromide (TBAB) buffer (0.2 M, pH 8.0) was used as the ion-pairing extraction reagent and LC-18 was used as SPE sorbent. In addition, an ion-pairing HPLC method was established for the specific determination of RDS. A reversed phase C8 column was used for the separation of RDS and nitrendipine (internal standard). The mobile phase was composed of 10 mM phosphate buffer solution containing 25 mM TBAB-acetonitrile (52:48, v/v, pH 7.5). The calibration curve was linear from 0.3 to 30 nmol/mL. The analytical recovery from rat plasma was found to be 97.9+/-4.1% (n = 15). LOD and LOQ for RDS in plasma were calculated to be 0.12 nmol/mL and 0.30+/-0.024 nmol/mL (R.S.D. = 8.2%, n = 5), respectively. The intra- and inter-day precision was less than 9.2%. The assay was applied to a preliminary pharmacokinetic study in three male rats after those received a single intravenous bolus via caudal vein of 12 micromol/kg RDS.