Determination Of Pseudoephedrine In Human Plasma By HPLC-MS And Study Of Its Pharmacokinetics

Objectives: To establish a sensitive and specific method for determination of Pseudoephedrine in human plasma by HPLC-MS and study its pharmacokinetics. Methods: Pseudoephedrine was extracted from plasma with 0.8 mL methanol, with the addition of glipizide. HPLC analysis was carried out through XTerra (?) MS C₁₈ column( 3.5μm×100mm×2.1mm ).The mobile phase consisted of Methanol-5mmol·L^-1 NH₄AC( 90:10, V/V) at a flow rate of 0.2 mL·min^-1. The column temperature was 25℃. Analysis in the mass spectrometer was performed in the selected-ion monitoring(SIM) model. The m/z of ions selected for quantification were 148.4(PSE) and m/z 468.1 (internal standard, glipizide). 10 healthy volunteers received tested tablets for a single oral dose of Pseudoephedrine 120,240mg and multidose. Drug concentrations in plasma were determined.Results: 1. The standard curve was linear in the range of 5.01ng·mL^-1 - 1002.00 ng·mL^-1(f =0.00332×C+0.00088, r=0.9997, n=5). The lowest limit of detection was 1.00ng·ml^-1.The relative standard derivation of inter-day and intra-day was smaller than 7.10% ( n=5) and 5.20%(n=3).The absolute recoveries of Pseudoephedrine were 89.60%-95.10%, The relative recoveries of Pseudoephedrine were 102.20%-105.80%.2. Pharmacokinetic parameters of PSE after single oral doses(120, 240mg) were as follows: t_1/2:(5.51±0.66),(5.18±0.68)h, T_max: (4.80±0.92),(4.70±0.82)h, C_max: (226.66±21.10),(455.08±100.16) ng·mL^-1,CL: (41.90±18.60),(46.57±15.00)L·h^-1,V_d: (209.30±116.00),(218.40±103.50)L, AUC_(0-tn): (2929.90±474.90),(5466.80±1372.60) ng·h·mL^-1, MRT_(0-tn): ( 10.24±0.72),( 9.65±0.84)h. The results showed that, T_max was similar to those sustained tablets reported domestic and abroad after single oral doses(120,240mg PSE), but was slower than conventional tablets which shows that the slow-release effect of PSE in tested tablets was obvious and its correlation of cumulative dissolution in vitro and in vivo had statistical significance. In addition t_1/2 was similar to those sustained tablets reported domestic and abroad after single oral doses(120,240mg PSE), and the course of PSE in healthy volunteers had no obvious gender difference. After single oral doses (120,240mg PSE), AUC_(0-tn) was (2929.90±474.90)ng·h·mL^-1 and (5466.80±1372.60) ng·h·mL^-1, which explained that the absorption degree of PSE in healthy volunteers had dose-dependent manner.3. The main pharmacokinetic parameters of multidose(120mg, bid ) were as follows: t_1/2=(6.06±0.67)h, T_max=(3.90±0.99)h, C_max=(272.03±52.56) ng·mL^-1, CL: (58.70±16.80)L·h^-1, V_d=(255.30±71.20)L, AUC_(0-tn)= (3419.70±750.80)ng·h·mL^-1, MRT_(0-tn)=(9.45±0.61)h. After multidose(120mg, bid ) 3 days, the plasma concentration of PSE arrived steady state, the main pharmacokinetic parameters of steady state were as follows: C_(ss.max): (272.03±52.56)ng·mL^-1, C_(ss.min): (104.99±37.15)ng·mL^-1, C_av: (198.55±38.95)ng·mL^-1, DF: (0.86±0.20),AUC_ss: (2382.61±467.44)ng·h·mL^-1,Conclusions: The method was specific, sensitive and simple, and suitable for determination of Pseudoephedrine in human plasma and pharmacokinetics researches. The results were accurate, a non-compartment pharmacokinetic model was adapted to Pseudoephedrine plasma concentration-time data analysis, the main pharmacokinetic parameters were similar to those reported domestic and abroad. So it could provide information in clinic and new drugs' applying.