Determination of phloroglucinol by HPLC-MS/MS and its application to a bioequivalence study in healthy volunteers.

OBJECTIVE: The aim of this study was to compare the pharmacokinetic characteristics of phloroglucinol between an orally disintegrating tablet and an orally lyophilized tablet of phloroglucinol in healthy volunteers under fasting condition. PATIENTS AND METHODS: A rapid and simple method based on high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method has been developed and validated for the determination of phloroglucinol in human plasma. The plasma sample was prepared by liquid-liquid extraction, and paracetamol was chosen as the internal standard. Phloroglucinol and IS were separated on a C18 column with a mobile phase consisted of methanol/water (80:20 v/v) with 0.02% formic acid. HPLC-MS/MS analyses were performed on a triple- quadruple tandem mass spectrometer by monitoring protonated parent→daughter ion pairs at m/z 125.0→56.9 for phloroglucinol, and m/z 150.2→107.0 for paracetamol (IS). The method was the high sensitivity with a lower limit of quantification (LLOQ) of 1.976 ng/mL. RESULTS: Drug and IS were detected by HPLC/MS/MS with negative electrospray ionization (ESI). Accuracy and precision for the assay were determined by calculating the intra- and inter-batch variation of quality control (QC) samples at three concentration levels. The relative standard deviation (RSD) was less than 15.0%. The detection and quantitation of drug and IS within 4.5 min make this method suitable for high-throughput analyses. In this study, the Cmax of phloroglucinol were calculated to 515.6 ± 134.4 ng/mL and 536.0 ± 144.8 ng/mL for the test drug and the reference drug, respectively. The AUC0-t values were 459.5 ± 81.03 ng·mL-1·h and 491.8 ± 95.17 ng·mL-1·h for the test drug and the reference drug; 24 subjects completed the study, respectively. The geometric mean ratio (GMR) and the 90% confidence intervals (CIs) of Cmax and AUC0-t of phloroglucinol were 97.1 (90.2-103.9) and 93.8 (88.7-99.2), respectively. CONCLUSIONS: The method was employed for the first time during pharmacokinetic studies of phloroglucinol in human plasma following a single dose of phloroglucinol 160 mg tablets. There was no significant difference in pharmacokinetic profiles between the two treatments.

Effect of Food on the Single-dose Pharmacokinetics and Tolerability of Subutinib and its Active Metabolite in Chinese Healthy Volunteers.

The aim of this study is to investigate a food effect on the single-dose pharmacokinetics and tolerability of subutinib maleate capsules in healthy Chinese volunteers. The author evaluated the effect of being under a fasting or fed state at the time of drug intake on the single-dose of subutinib maleate capsules in a randomized, balanced, single-dose, 2-treatment (fasting and fed), 2-period design with a 3-week washout period. The end points were the maximum plasma drug concentration (Cmax) and areas under the plasma-concentration curve (AUC) for 336 h exposure (AUC0-336) and total exposure (AUC0-∞). All volunteers completed the whole study without side effects being observed. For subutinib, Cmax were 6.13 and 5.04 ng·mL(-1), and AUC0-336 were 278.4 and 304.5 h·ng·mL(-1) in the fasting and the fed state, respectively. For active metabolite, Cmax were 0.90 and 0.61 ng·mL(-1), and AUC0-336 were 65.5 and 56.4 h·ng·mL(-1) in the fasting and the fed state, respectively. The authors showed that food intake was associated with a slight increase in AUC values but decrease in Cmax of subutinib, and it was associated with a decrease both in AUC and Cmax of active metabolite.

Pharmacokinetics of metronidazole, tetracycline and bismuth in healthy volunteers after oral administration of compound tablets containing a combination of metronidazole, tetracycline hydrochloride and bismuth oxide.

BACKGROUND: To eradicate Helicobacter pylori in human pylorus and to heal duodenal ulcers, recently, a new formulation of combination tablets containing metronidazole 125 mg, tetracycline hydrochloride 125 mg and bismuth oxide 40 mg has been developed. OBJECTIVE: To investigate the pharmacokinetics of metronidazole, tetracycline and bismuth in healthy Chinese volunteers after oral administration of the test formulation. METHODS: A one-sequence, 3-period study was conducted in 12 Chinese healthy volunteers (6 male, 6 female). Volunteers each received single low dose (1 tablet) under fed condition in period 1, single high dose (3 tablets) under fasted condition in period 2, and single high dose (3 tablets) and multiple doses (3 tablets at once, 4 times daily for 7 consecutive days) under fed condition in period 3. Blood samples were collected and determined over 48 h in every period. RESULTS AND CONCLUSION: After single high dose administration under fed condition, the C max of metronidazole, tetracycline and bismuth were 6.833 ± 0.742 µg/mL, 0.8513 ± 0.1253 µg/mL and 3.32 ± 1.89 ng/mL, respectively. The C max and AUC 0-48 of metronidazole increased in proportion to the doses within the tested dose range, but tetracycline and bismuth did not. Food caused 10% and 80% decrease of the C max for metronidazole and bismuth, respectively, but did not affect tetracycline. No gender effect was found on the pharmacokinetics of the 3 ingredients. In the steady state, the C av of metronidazole, tetracycline and bismuth were 20.75 ± 3.52 µg/mL, 1.900 ± 0.243 µg/mL and 5.61 ± 1.34 ng/mL, respectively.

Neuroprotective effects of hydroxysafflor yellow A against excitotoxic neuronal death partially through down-regulation of NR2B-containing NMDA receptors.

Hydroxysafflor yellow A (HSYA) is a component of the flower Carthamus tinctorius L. that elicits neuroprotective effects in vivo and in vitro. The purpose of this study was to investigate pharmacological properties of HSYA on neurotoxicity of glutamate in primary cultured rat cortical neurons along with its possible mechanism of action. After challenge with N-methyl-d-aspartate (NMDA, 100 microM) for 30 min, loss of cell viability and excessive apoptotic cell death were observed in cultured cortical neurons. However, the excitotoxic neuronal death was attenuated markedly by HSYA treatment. Western blot analysis revealed that HSYA decreased expression of Bax and rescued the balance of pro-and anti-apoptotic proteins. In addition, HSYA significantly reversed up-regulation of NR2B-containing NMDA receptors by exposure to NMDA, while it did not affect the expression of NR2A-containing NMDA receptors. These finding suggest that HSYA protects cortical neurons, at least partially, from inhibiting the expression NR2B-containing NMDA receptors and by regulating Bcl-2 family.

Pharmacokinetic profile of talipexole in healthy volunteers is not altered when it is co-administered with Madopar (co-beneldopa).

OBJECTIVES: To investigate the pharmacokinetics of talipexole hydrochloride tablets and the potential influence of Madopar (benserazide and levodopa combination; co-beneldopa) tablets on talipexole's pharmacokinetics when the two tablets are co-administered orally to healthy Chinese volunteers. METHODS: A sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to measure talipexole concentration in human plasma in an open-label, randomized, two-way crossover, single-dose study, with 1-week washout period. Healthy Chinese volunteers were randomized to receive talipexole tablets either alone or together with Madopar tablets by oral administration after an overnight fast. Serial blood samples were collected for a period of 36 h after the administration. Pharmacokinetic parameters C(max), t(max), t(1/2z), mean residence time (MRT), AUC(0-tau), AUC(0-infinity), CL(z)/F and V(z)/F were determined under the non-compartmental model. Pharmacokinetic values of talipexole administered alone to the subjects were compared with those administered simultaneously with Madopar to determine whether or not the differences were statistically significant. RESULTS: The subjects experienced mild gastrointestinal irritation when talipexole was administered alone as well as together with Madopar. For talipexole hydrochloride, there were no significant differences in the pharmacokinetic values between the two administrations. No pharmacokinetic differences based on gender were observed either. CONCLUSION: A single oral dose of Madopar co-administered with talipexole does not significantly change talipexole's pharmacokinetics in human.

Direct evidence for histamine H3 receptor-mediated inhibition of norepinephrine release from sympathetic terminals of guinea pig myocardium.

AIM: To study the histamine H3 receptors mediated inhibition of norepinephrine (NE) release from cardiac sympathetic terminals of guinea pig isolated atria. METHODS: Release of NE induced by electric field stimulation (50 mA, 5 ms) in the bath solution was measured by HPLC-ECD. RESULTS: The release of NE caused by field stimulation was attenuated by (R)-alpha-methyl-histamine (alpha-MeHA, 0.1 nmol.L-1(-10) mumol.L-1) in a concentration-dependent manner. Thioperamide concentration-dependently antagonized the inhibition of alpha-MeHA. Blockade of H1, H2, alpha 2, beta 2-receptors failed to prevent the inhibitory effect of alpha-MeHA. Thioperamide (1 nmol.L-1(-10) mumol.L-1), when used alone, concentration-dependently facilitated the release of NE evoked by field stimulation. CONCLUSION: The presynaptic histamine H3-receptors inhibited the NE release from cardiac sympathetic terminals.

High-performance liquid chromatographic determination of free ferulic acid in serum of rabbits with blood stasis.

A Simple, rapid and sensitive reversed phase high performance liquid chromatographic (RP-HPLC) method for the analysis of free ferulic acid in serum of rabbits with blood stasis has been developed. Coumarin was used as internal standard. 0.2 ml of serum containing ferulic acid was deproteinized with acetonitrile which contained the internal standard (coumarin). The supernatant was evaporated to dryness. The residue was dissolved in 60 microliters of acetonitrile. A Du Pont Zorbox C18 column was used. A mixture of acetonitrile and 0.10 mol.L-1 phosphoric acid (3:7, v/v, pH 2.5) was used as the mobile phase, and UV detection was performed at 320 nm. The detection limit (signal-to-noise ratio = 3) and the mean recovery from serum were 1 ng and 97.0 +/- 1.8%, respectively. The method was linear within the range of 20-800 ng.ml-1 (r = 0.9986). The relative standard deviation were all less than 7%. The method was applied to pharmacokinetic studies in healthy rabbits and rabbits with blood stasis. Through this experiment we have found significant difference in the pharmacokinetic parameters between healthy rabbits and rabbits with blood stasis. The results obtained are coincident with syndrome and pharmacokinetics.

[Pharmacokinetic characteristics of tetramethylpyrazine and study on hemorheology in rat model of spleen deficiency syndrome].

UNLABELLED: In this experiment, the essence of Spleen Deficiency Syndrome (SDS) was explored with the rat model of SDS using tetramethylpyrazine (TMP). 120 Wistar rats were divided into two groups, 60 each for control and test group, they were treated with normal saline and reserpine respectively. The hemorheological parameters were also studied in 6 each of both groups. The pharmacokinetic properties were investigated in the remaining control group and test group. RESULTS: (1) Two-compartment open model of the control group was turned into that of one-compartment in test group; (2) The SDS model significantly affected the absorption and distribution of TMP in rats. AUC was much higher and serum concentration of TMP increased significantly than that of control. Hemorheological parameters (viscosity of whole blood, fibrinogen, etc.) increased significantly (P < 0.05-0.01), it demonstrated that the SDS model was in a state of Blood Stasis. It might be one of the pharmacokinetic mechanisms of TMP in the SDS model of rats.