Validated UPLC-MS/MS method for determination of moclobemide in human brain cell supernatant and its application to bidirectional transport study.

A simple and sensitive analytical method based on ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) has been developed for determination of moclobemide in human brain cell monolayer as an in vitro model of blood-brain barrier. Brucine was employed as the internal standard. Moclobemide and internal standard were extracted from cell supernatant by ethyl acetate after alkalinizing with sodium hydroxide. The UPLC separation was performed on an Acquity UPLC(TM) BEH C18 column (50 × 2.1 mm, 1.7 µm, Waters, USA) with a mobile phase consisting of methanol-water (29.5:70.5, v/v); the water in the mobile phase contained 0.05% ammonium acetate and 0.1% formic acid. Detection of the analytes was achieved using positive ion electrospray via multiple reaction monitoring mode. The mass transitions were m/z 269.16 → 182.01 for moclobemide and m/z 395.24 → 324.15 for brucine. The extraction recovery was 83.0-83.4% and the lower limit of quantitation (LLOQ) was 1.0 ng/mL for moclobemide. The method was validated from LLOQ to 1980 ng/mL with a coefficient of determination greater than 0.999. Intra- and inter-day accuracies of the method at three concentrations ranged from 89.1 to 100.9% for moclobemide with precision of 1.1-9.6%. This validated method was successfully applied to bidirectional transport study of moclobemide blood-brain barrier permeability.

Quantitative analysis of trazodone in human plasma by using HPLC-fluorescence detector coupled with strong cation exchange chromatographic column: application to a pharmacokinetic study in Chinese healthy volunteers.

A simple, selective, and sensitive high performance liquid chromatography (HPLC) procedure has been developed for determination of trazodone in human plasma. Prazosin was employed as the internal standard (IS). Sample preparation involved liquid-liquid extraction by methyl tert-butyl ether after alkalinization with ammonia. The HPLC separation was performed on a CAPCELL PAK SCX column (250mm×4.6mm, 5.0µm, Shiseido, Japan) with a mobile phase of acetonitrile/80mmol/L ammonium phosphate (pH adjusted to 6.0) (60:40, v/v) at a flow rate of 1.2mL/min. The peaks were detected by using fluorescence detector (excitation wavelength 320nm and emission wavelength 440nm). The extraction recovery was 72.6-88.3% and the method was over the concentration range of 5.0-2486ng/mL with a lower limit of quantitation (LLOQ) of 5.0ng/mL using 300µL of plasma. The intra- and inter-day accuracy of the method at three concentrations ranged from 96.7% to 104.2% for trazodone with precision of 2.9-3.7%. This validated method was successfully applied to a pharmacokinetic study enrolling 12 Chinese volunteers administered a single oral trazodone hydrochloride extended-release tablet of 75mg.

Progress on mechanism of Tripterygium wilfordii-induced liver injury and detoxification mechanism of licorice / 中国中药杂志

Tripterygium wilfordii has exihibited multiple pharmacological activities, such as anti-inflammatory, immune modulation, anti-tumor and anti-fertility. T. wilfordii have been used for the therapy of inflammation and autoimmune diseases including rheumatoid arthritis, immune complex nephritis and systemic lupus erythematosus clinically. However, it is well known that T. wilfordii has small margin between the therapeutic and toxic doses and could cause serious injury on digestive, reproductive and urogenital systems. Among all the organs, liver is one of the most remarkable targets of T. wilfordii-induced toxicities, and the damage is more serious than others. It is generally accepted that T. wilfordii-induced liver injury is a result of the combined effects of toxic elements of T. wilfordii. It is reported in several studies that the mechanism of T. wilfordii-induced liver injury may be related to lipid peroxidation, cell apoptosis and immune damage, and so on. Licorice is one of the most commonly used Chinese herbal medicine, with effects of heat- clearing and detoxicating, anti-inflammatory and hepatoprotective, reconciling various drugs, and so on. Licorice often accompany T. wilfordii in clinical application which can significantly reduce the liver injury induced by T. wilfordii. The attenuated effect is exact, but the mechanism is still a lack of in-depth study. This paper reviews the studies on T. wilfordii-induced liver injury and the related mechanism as well as licorice and other traditional Chinese medicine accompany T. wilfordii to reduce the injury in recent years, so as to provide reference for related research in the future.

Pharmacokinetic study on baicalin of Qingkailing injection in rats / 中国中药杂志

<p><b>OBJECTIVE</b>Studying the metabolic pharmacokinetic of baicalin of Qingkailing injection in rat, to search for effector substance of Qingkailing injection in vivo.</p><p><b>METHOD</b>Qingkailing sterile injection powder was given by caudal vein, then blood, liver and lung were collected in various time, the concentration of baicalin from samples were determined by HPLC-MS. Pharmacokinetic evaluation was carried out using the 3P87.</p><p><b>RESULT</b>After Qingkailing injection, Baicalin was consistent with two-compartment model in rat. 45 min, the concentration of baicalin in hepatic tissue reached maximum, followeded by decrease sharply, 120 min began to rise slowly, present double hump phenomenon. In lung, baicalin concentration was far more than in liver, was eliminated more slowly, but they have the same t(max).</p><p><b>CONCLUSION</b>After Qingkailing injection, baicalin distributed quickly to liver and lung, baicalin is one of effector substance of qingkailing injection in vivo. Baicalin might have hepatoenteral circulation.</p>

RP-HPLC study of resveratrol derivative (BTM-0512) in rat plasma and tissue distribution / 药学学报

This paper described a rapid and sensitive HPLC method to analyze (E)-3,5,4'-trimethoxystilbene (BTM-0512) in rat plasma and tissues. The analysis used a BDS Hypersil C18 analytical column (250 mm x 4.6 mm ID, 5 microm) and acetonitrile/water as the mobile phase. The UV detection wavelength was 319 nm. Proteins were precipitated with acetonitrile and diethylstilbestrol as internal standard. The method was validated according to State Food and Drug Administration of China and ICH of Technical Requirements for Registration of Pharmaceuticals for Human Use Guidelines. The limit of detection (S/N: 3/1) for BTM-0512 was 0.005 microg x mL(-1) for plasma. The method performances were shown to be selective for BTM-0512 and the linearity of the assay method was up to 10.0 microg x mL(-1) and 40.0 microg x g(-1) for plasma and tissues, respectively. At 0.1, 1 and 5 microg x mL(-1) (n=5), intraday and interday precision values (% RSD) were in the range of 2.6% - 5.1% and 2.4% - 4.8%, respectively. Mean accuracy and absolute recoveries of BTM-0512 ranged from 95.3% - 100.1% and 95.9% - 100.9% for plasma and tissues, respectively. This method can be quite useful for BTM-0512 pharmacokinetic and tissue distribution studies, for purpose which multiple plasma and tissue samples can be analyzed quickly with high reproducibility.

Mechanism of mono-hydroxylation of daidzein in human liver microsomes / 药学学报

<p><b>AIM</b>To identify the cytochrome P450 (CYP) isoform (s) involved in daidzein mono-hydroxylated metabolites using human liver microsomes.</p><p><b>METHODS</b>Kinetic analysis of the rates of formation of mono-hydroxylated metabolites of daidzein, including 7,8,4'-trihydroxyisoflavone (7,8,4'-THI), 7,3',4'-trihydroxyisoflavone (7,3',4'-THI) and 6,7,4'-trihydroxyisoflavone (6,7,4'-THI), was performed using human liver microsomes (HLM) and recombinant enzymes at substrate concentrations ranging from 0.5 to 400 micromol x L(-1). Nine selective inhibitors or substrate probes specific for different CYP isoforms were applied for screening the isoform(s) responsible for mono-hydroxylated metabolism of daidzein.</p><p><b>RESULTS</b>Michaelis-Menten kinetic parameters were best fitted to one-component enzyme kinetic model. The mean Km (micromol x L(-1) ) and V(max) (micromol x g(-1) x min(-1)) values were 27 +/- 10 and 4. 8 +/- 2.1, 54 +/- 22 and 2.3 +/- 1.0, 51 +/- 29 and 2.2 +/- 0.8, for the formation rates of 7,8,4'-THI, 7,3',4'-THI, and 6,7,4'-THI, respectively. Furafylline, the CYP1A2 specific inhibitor, estrogen, and monoclonal antibody raised against human CYP1A2 (MAB-1A2) apparently inhibited the formation of mono-hydroxylated metabolites, The IC50 of Fur for the formation of 7,3',4'-THI, 6,7,4'-THI and 7,8,4'-THI was 1.0, 0.9 and 0. 8 mol x L(-1), respectively. The IC50 of estrogen for the formation of 7,3',4'-THI, 6,7,4'-THI and 7,8,4'-THI were 51, 60 and 64 mol x L(-1) respectively. The IC50 of MAB-1A2 for the formation of the mono-hydroxylated products was 1 mol x L(-1), but neither other selective inhibitor nor substrate probes, including coumarin (CYP2D6), sulphaphenzole ( CYP2C9/10), omeprazole ( CYP2C19), quinidine (CYP2D6), diethyldithiocarbamate (CYP2E1), troleandomycin (CYP3A4) and keteconazole (CYP3A4), did so with human liver microsomes.</p><p><b>CONCLUSION</b>The in vitro studies indicated that daidzein mono-hydroxylated products were principally metabolized by CYP1A2 in human.</p>

Determination of octreotide in human plasma by HPLC-MS with solid-phase extraction and study on the relative bioavailability of domestic and imported octreotide injections / 药学学报

<p><b>AIM</b>To establish an HPLC-MS method for determination of octreotide in plasma and study the relative bioavailability of domestic and imported octreotide injections.</p><p><b>METHODS</b>Octreotide in plasma samples were extracted with a Waters solid-phase extraction mini column. HPLC-MS was carried out using a Waters Xetrra C18 column and a mobile phase consisting of CH3 OH-1% HAc (80 : 20), the flow rate was 0.2 mL x min(-1), and the internal standard was 6, 7, 4'-OH-isoflavone, the SIR ions for quantification were m/z 1 014.4 for octreotide and m/z 317.6 for internal standard. A single dose of 200 microg of domestic or imported preparations was intramuscularly given to 18 healthy volunteers in a randomized crossover study. Octreotide concentration in plasma was determined by LC-MS method. The pharmacokinetics and bioavailability were studied.</p><p><b>RESULTS</b>The regressive curve was linear (r = 0.9997) within the range of 0.5 - 40 microg x L(-1) for octreotide. The pharmacokinetics parameters of domestic and imported injection were reply to one compartment model. The mean C(max) were (19 +/- 10) microg x L(-1) and (19 +/- 11) microg x L(-1), T(max) were (0.50 +/- 0.15) h and (0.52 +/- 0.20) h, T1/2 were (1.5 +/- 0.8) h and (1.5 +/- 0.8) h, AUC(0-7 h) were (50 +/- 25) h x microg x L(-1) and (50 +/- 25) h x microg x L(-1), respectively. The relative bioavailability of domestic to imported injection was 101% +/- 10%.</p><p><b>CONCLUSION</b>The method is accurat and sensible for assay of plasma octreotide concentration. The results of statistics showed the two preparations were bioequivalent.</p>