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.
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.
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