ABSTRACT
AIM:To establish an LC-MS method for determining the concentrations of loratadine (LOR) in human plasma and to evaluate its pharmacokinetic characteristics. METHODS: A ZORBAX Eclipse XDB-C8 (5 μm, 150 mm×4.6 mm) column was used, atmospheric pressure electronic spray ionization (AP-ESI) and ion mass spectrum (m/z) of 388.2 (M+H)+ were selected to quantify LOR, and 275.1 (M+H)+ for ropivacaine (internal standard, IS). RESULTS: The linear range of LOR standard curve was 0.5-50 ng·ml-1, and the determination limit was 0.5 ng·ml-1. The pharmacokinetic parameters of LOR after a single dose of 20 mg tablet (T1), capsule (T2) and reference (R) were as follows, the half life (t1/2) 13.52±1.35, 13.14±0.98 and 14.00±1.25 h, the time to peak concentration (Tmax) 1.24±0.06, 1.18±0.12 and 1.17±0.12 h, the peak concentration (Cmax) 21.72±7.70, 21.49±8.34 and 20.50±8.65 ng·ml-1, the area under time-concentration curve (AUC0-48 and AUC0-∞) 137.24±47.84 and 146.61±51.03 ng·ml-1·h, 139.65±45.69 and 148.04±48.10 ng·ml-1·h, 134.19±49.03 and 143.70±52.08 ng·ml-1·h, the relative bioavailability of LOR tablet and capsule were (105.49±8.08)% and (102.90±10.02)%, respectively. CONCLUSION: The LC-MS method for determining the concentration of LOR in human plasma is sensitive and accurate and can be used for LOR bioavailability and pharmacokinetic studies. LOR tests and reference are bioequivalent.