Liquid chromatography-mass spectrometry method for the quantification of posaconazole in human plasma: application to pharmacokinetics following single-dose administration in the fasted state and with a high-fat meal.

A liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed to determine concentrations of posaconazole in human plasma precipitated by acetonitrile including internal standard. Rapid chromatographic separation was achieved in the mobile phase composition of acetonitrile, water and formic acid (v/v/v, 55:45:0.1) with a flow rate of 0.25 ml/min. Posaconazole-d4 was used as internal standard. Detection was undertaken with cation electrospray tandem mass spectrometry on a Sciex/API3000. The method was accurate, specific and sensitive for the analysis of posaconazole in human plasma in the concentration range of 2-1000 ng/ml. The inter- and intra-batch accuracy was within +/- 10% and the lower limit of quantification was 2 ng/ml. The method facilitated a clinical pharmacokinetic study after oral administration of a single-dose of posaconazole suspension in the fasted state and with a high-fat meal in a two-period crossover design. Cmax (maximum concentration) and AUC (area under serum drug concentration) were significantly increased, and Tmax (time to maximum plasma concentration) was delayed under fed condition, which suggested that simultaneous administration of posaconazole with food may help to achieve higher plasma concentrations and result in better antifungal efficacy.

The difference in pharmacokinetics and pharmacodynamics between extended-release fluvastatin and immediate-release fluvastatin in healthy Chinese subjects.

The aim of this study was to evaluate the difference in pharmacokinetics and pharmacodynamics between extended-release (ER) fluvastatin tablet and its immediate-release (IR) capsule in Chinese healthy subjects. This was an open-label, single/multiple-dose, two-period, two-treatment, crossover, randomized trial with a minimum washout period of 7 days. Twenty healthy male adult subjects were given fluvastatin ER tablet 80 mg QD by oral administration or fluvastatin IR capsule 40 mg BID for seven days. Blood samples were collected up to 24 hours after dosing on day 1 and day 7. Serum concentrations of fluvastatin were determined by LC-MS/MS. For fluvastatin ER tablet 80 mg QD, C(max) was 61.0 ± 39.0 and 63.9 ± 29.7 ng/mL, and AUC(0-24 h) was 242 ± 156 and 253 ± 91.1 ng·h/mL on day 1 and 7, respectively. For fluvastatin IR capsule 40 mg BID, C(max) was 283 ± 271 and 382 ± 255 ng/mL, and AUC(0-24 h) was 720 ± 776 and 917 ± 994 ng·h/mL on day 1 and day 7, respectively. The relative bioavailability of fluvastatin ER tablet 80 mg QD to fluvastatin IR capsule 40 mg BID is (45.3 ± 23.9)% and (43.3 ± 24.1)% on day 1 and day 7, respectively. T(max) for fluvastatin ER tablet was 2.50 and 2.60 h and for capsule was 0.78 and 0.88 h on day 1 and day 7, respectively. In the first period, compared to baseline, cholesterol decreased 15.3% in fluvastatin ER tablet 80 mg QD and 16.9% in fluvastatin IR capsule 40 mg BID. Triglyceride decreased 3.7% in fluvastatin ER tablet 80 mg QD and 19.1% in fluvastatin IR capsule 40 mg BID. The difference has no statistical significance at P > 0.05 in reduction percent of cholesterol and triglyceride between the two groups. No adverse events were recorded. The results indicated that C(max) of fluvastatin ER tablet is reduced and T(max) is prolonged compared with IR capsule. There is no accumulation for ER formulation after multiple doses.

Determination of chiglitazar, a dual alpha/gamma peroxisome proliferator-activated receptor (PPAR) agonist, in human plasma by liquid chromatography-tandem mass spectrometry.

Chiglitazar is a dual alpha/gamma peroxisome proliferator-activated receptor (PPAR) agonist. A LC-MS/MS method for the determination of chiglitazar was developed and validated. The assay used 0.2 mL of plasma. 90% acetonitrile containing internal standard was used for protein precipitation. The mobile phase contained 70/30 (v/v) of methanol and water at a flow rate of 0.25 mL/min. Detection was by negative ion electrospray tandem mass spectrometry on a Sciex API 3000. The standard curve, which ranged from 2 to 1500 ng/mL, was fitted to a 1/x weighted quadratic regression model. The validation results demonstrated that the method was sensitive, rapid, selective and robust and provided satisfactory precision and accuracy. The method has been successfully used for the analysis of clinical samples in pharmacokinetic studies of chiglitazar.

Pharmacokinetics and safety of recombinant human parathyroid hormone (1-34) (teriparatide) after single ascending doses in Chinese healthy volunteers.

The pharmacokinetics and safety of recombinant human parathyroid hormone (1-34) [rhPTH (1-34)] after single ascending doses were evaluated in Chinese healthy volunteers. Nine healthy volunteers (five male and four female) were recruited for an open label, randomized, three multiply three crossover, single ascending dose (10, 20, and 40 microg) study. Using a validated radioimmunoassay, we determined the plasma concentrations of rhPTH (1-34). The mean peak plasma concentration (Cmax) were 123.6, 195.6, and 318.2 pg x mL(-1) respectively, and were reached from 25.6 to 36.1 min after subcutaneous administration. After Cmax was reached, the plasma drug level decreased quickly, with elimination halflife (t(1/2)) of 53.9 to 64.1 min. The mean AUC(0-infinity) (the area under the plasma concentration versus time curve from time zero to infinite) of rhPTH (1-34) were 11794.2 +/- 974.8, 21606.7 +/- 4753.9, 33877.0 +/- 8374.4 pg x min x mL(-1), respectively. The mean AUC(0-t) (the area under the plasma concentration versus time curve from time zero to the last quantifiable concentration) of rhPTH (1-34) were 9034.4 +/- 1073.9, 17883.3 +/- 4597.1, 31693.5 +/- 6574.8 pg x min x mL(-1), respectively. Dose-related linear trend were observed for AUC(o-t) and Cmax of rhPTH (1-34). t(1/2) and Tmax (time to Cmax) of rhPTH (1-34) were independent of administered dose. rhPTH (1-34) was safe and well tolerated by all volunteers.

Pharmacokinetics and urinary excretion of eprosartan in Chinese healthy volunteers of different gender.

The study aims to evaluate the pharmacokinetics and urinary excretion of eprosartan in Chinese healthy volunteers and to study the effect of gender on pharmacokinetics of eprosartan. Twenty healthy volunteers (ten men and ten women) were recruited for an open trial and received a single dose of 600 mg eprosartan. Using a validated LC/MS/MS method, plasma and urinary concentrations of eprosartan were determined. The following pharmacokinetic parameters were elucidated after administration: the area under the plasma concentration versus time curve from 0 to 32 h (AUC0-32h) 14818.75 +/- 7312.11 ng x h/mL, the area under the plasma concentration versus time curve from 0 to infinite (AUC(0-infinity)) 15081.62 +/- 7379.63 ng x h/mL, peak plasma concentration (Cmax) 3664.25 x 1653.94 ng x h/mL, time to Cmax (Tmax) 1.63 +/- 0.46 h, elimination half-life (t(1/2)) 8.03 +/- 4.04 h, apparent clearance (CL/F) 47.84 +/- 19.21 L/h, apparent volume of distribution of the central compartment (V/F) 537.21 +/- 287.91 L, renal clearance (CLr) 1.33 +/- 0.41 L/h, amount of unchanged eprosartan excreted into urine 18.44 +/- 6.43 mg and fraction of unchanged eprosartan excreted into urine 3.07 +/- 1.07%. Our results also indicated that no gender differences were observed in the pharmacokinetics of eprosartan in Chinese healthy volunteers.