AIM To develop a sensitive and specific method for the determination of loratadine in human plasma by LC-MS. METHODS Loratadine
was extracted from human plasma by ethyl acetate and analyzed by LC-MS. Selected ion monitoring(SIM)was used to detect loratadine and its internal standard. RESULTS The calibration curve of loratadine was linear within the range of 0.1-20 mg·L -1,with r= 0.9994. The recovery of this method was within 96.8%-107.2%,within day and between day RSD were less than 13%.The
pharmacokinetic parameters of the reference and test
formulations were(4.60±2.43)and(4.85±2.30)mg·L -1 for c max;(19.56±10.24) and (19.28±9.43) mg·h·L -1 for AUC 0→24;(3.57±1.5) and (3.15±1.2)h for T 1/2;(1.2±0.4) and (1.3±0.5)h for t max respectively.Results from statistic analysis showed that there were no significant differences between the c max,AUC 0→24,T 1/2 and t max values of the two formulations. The relative bioavailability of tablet I with respect to tablet Ⅱ was (98.6±7.2)% from the AUC 0→24 measurement. Bioequivalance was observed between the two tablets. CONCLUSION The method is specific and sensitive,it is suitable for the pharmacokinetic research of loratadine in human plasma.The results demonstrate that the two preparations are bioequivalent.