The main purpose of this study was to evaluate the pharmacokinetics of levosulpiride in humans after single and multiple intramuscular injections. Six males and six females received single dose of either 25 mg or 50 mg levosulpiride, or multiple doses of 25 mg every 12 h for 5 consecutive days. In the single 25 mg study, the mean peak plasma concentration (Cmax) was 441 ng/mL, the mean area under the concentration–time curve from 0 to 36 h (AUC0–36) was 1724 ng h/mL, and the mean elimination half-life (t1/2) was 7.0 h. In the single 50 mg study, the mean Cmax was 823 ng/mL, the mean AUC0–36 was 3748 ng·h/mL, and the mean t1/2 was 6.8 h. After multiple doses of 25 mg levosulpiride, the average plasma concentration (Cav) was 136 ng/mL, the fluctuation index (DF) was 3.60, and the accumulation ratio (R) was 1.2. Levosulpiride injections appeared to be well tolerated by the subjects, and can be used for successive administration.
G004 is a novel sulfonylurea hypoglycemic drug which aimed at reducing macro- and micro-vascular complications as well as controlling glucose excursion in type 2 diabetes mellitus. The pharmacokinetics of G004 in rats was sex- and dose-dependent over the dose range of 1-10 mg kg(-1). The mean AUC values in the female rats were fivefold higher than those in males. Drug blood and tissue levels in female rats were higher than the most counterparts of males. Compared with male rats, G004 was eliminated slowly from female rats in the bile, urine and feces. Consistent with the in vivo observations, marked sex-related difference of the metabolizing activity between the male and female liver microsomes (RLM) was observed. The intrinsic clearance (V max/K m) of G004 was 3.1-fold larger in the RLM from male than female rats. Seventeen oxidative metabolites were identified in rat liver microsomes. The amount of three metabolites of G004 showed relatively sex-related difference in RLM incubations. CYP2C11 was demonstrated mainly contributing to the sex-related differences in the pharmacokinetics and disposition of G004 in rats.
A steep gradient elution mode was applied to reduce the risk of matrix effect (ME) for the determination of G004, a novel sulfonylurea hypoglycemic drug, in a tissue distribution study by LC-MS/MS. The mass spectra of the total-ion-current chromatograms combined with the post-column infusion traces enabled the 'unseen' interfering species to be directly detected, and ensured that the chromatography conditions and sample preparation method were adequate to overcome the ME. According to this, a steep gradient elution mode was designed to overcome the intense ME from different tissues. The analysis was performed by monitoring the transitions m/z 558.1 → 419.0 for G004 and m/z 489.3 → 364.1 for glimepiride used as the internal standard. Calibration curves recovered over a range from 0.1 to 10000 ng/mL for seven different tissues. Sex-related difference was found in the tissue distribution. The drug levels in the tissues of female rats were about two to three times higher than those in male counterparts. The highest level was observed in liver, then in kidney, heart, pancreas, lung and spleen, but no G004 was detected in brain. G004 was slowly eliminated from female rats compared with male rats. There was no long-term accumulation of G004 in male or female rat tissues.
A simple, sensitive and reproducible liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-MS-MS) method was developed and validated for the first time for simultaneous quantification of lercanidipine and valsartan in human plasma. The analytes were extracted by simple protein precipitation with acetonitrile and separated on a Hanbon Hedera ODS-2 C (150 mm× 2.1 mm, 5 μm) column. The mobile phase was composed of a mixture (53:47, v/v) of acetonitrile and 10 mmol/L ammonium acetate containing 0.5% formic acid. The analytes were ionized by positive electrospray ion and detected in the multi-reaction monitoring mode with m/z 612.1 → 280.2 for lercanidipine, m/z 436.0 → 235.1 for valsartan and m/z 285.1 → 193.1 for diazepam, the internal standard. The calibration curves obtained were linear over the concentration range of 0.01504-10.07 ng/mL for lercanidipine and 5.025-6,030 ng/mL for valsartan. The results of the intra- and inter-day precision studies were within the acceptance range. The recoveries of the analytes were in the range of 98-103%. This method was successfully applied to the pharmacokinetic study of a novel fixed-dose combination of lercanidipine and valsartan formulation after an oral administration to healthy Chinese subjects.
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