Pharmacokinetic of Pseudoephedrine in Rat Serum with Luminol-Pepsin Chemiluminescence System by Flow Injection Analysis

Abstract

Pepsin (Pep) accelerated the electron transferring rate of excited 3-aminophathlate and enhanced luminol-dissolved oxygen chemiluminescence (CL) intensity, and the flow injection (FI) luminol-Pep CL system was first developed. It was found that the CL intensity of luminol-Pep reaction could be remarkably inhibited by pseudoephedrine (PE); the decrement of CL intensity was linear to the logarithm of PE concentration in the range of 0.1∼100.0 nmol L⁻¹ with a detection limit of 0.03 nmol mL⁻¹ (3σ). At a flow rate of 2.0 mL min⁻¹, the complete process including washing and sampling was performed within 40 s, offering a sample throughput of 90 h⁻¹. This proposed method was successfully applied to determining PE in rat serum for 18 h after intragastric administration with the elimination ratio of 42.34 % and recoveries from 90.3 to 110.6 %. The pharmacokinetic results showed that PE could be rapidly absorbed into serum with peak concentration (C _max) of 1.45 ± 0.18 g L⁻¹ at the time (T _max) of 1.49 ± 0.02 h; the absorption half-life (0.35 ± 0.04 h), elimination half-life (1.86 ± 0.24 h), the area under curve (109.81 ± 6.03 mg L⁻¹ h⁻¹), mean residence time (3.82 ± 0.27 h), and elimination rate constant (2.26 ± 0.23 L g⁻¹ h⁻¹) in rats vivo were derived, respectively. The possible CL mechanism of luminol-Pep-PE reaction was discussed by FI-CL, fluorescence, and molecular docking (MD) methods.