Simultaneous Quantification of Diazepam and Dexamethasone in Plasma by High-Performance Liquid Chromatography with Tandem Mass Spectrometry and Its Application to a Pharmacokinetic Comparison between Normoxic and Hypoxic Rats

Abstract

In order to investigate the pharmacokinetics of a combination of diazepam and dexamethasone under hypoxic conditions, a novel, sensitive and specific liquid chromatography with tandem mass spectrometry (LC-MS/MS) method for the simultaneous determination of diazepam and dexamethasone in rat plasma was developed and validated. The chromatographic separation of analytes was successfully achieved on an XTerra® MS C18 column using a gradient elution of methanol and water containing 0.1% formic acid at a flow rate of 0.5 mL/min. This method demonstrated good linearity and no endogenous material interferences. The linear ranges were 1.0–100 ng/mL for diazepam and 2.0–200 ng/mL for dexamethasone. The intra- and inter-day precision for the two compounds in plasma were lower than 10.0%, and the accuracy was between −7.9% and 11.5%. Our method was then successfully applied in a pharmacokinetic comparison between normoxic and hypoxic rats. The results indicated that there were significant differences in the main pharmacokinetics parameters of diazepam and dexamethasone between normoxic and hypoxic rats. The results provide the important and valuable information for discovering and developing novel anti-hypoxia drug combinations, as well as a better understanding of the safety and efficacy of these drugs.

Effect of hypoxia on the pharmacokinetics and metabolism of zaleplon as a probe of CYP3A1/2 activity

“…Our studies indicated that hypoxia could markedly change the pharmacokinetic characteristics of some drugs. [9][10][11][12] The present results also showed that there were an increase of AUC and C max of ZAL in hypoxic rats via Fig. 7 Effect of hypoxia on CYP3A1 and CYP3A2 expression in rat liver.…”

“…In recent years, there are many reports about the inuence of acute and chronic hypoxia on the cytochrome P450 enzymes and transmembrane transporters, resulting in alteration of in vivo disposition and pharmacokinetic characteristics for some drugs, which further affect the pharmacological activities, toxicities and clinical effects. [9][10][11][12] In the altitude area of 3780 meters with acute and chronic hypoxic environment, the main pharmacokinetic parameter of sulfamethoxazole, including t 1/2 , MRT and AUC, in the healthy volunteers were signicantly enhanced, but the clearance markedly decreased. 20 However, at the 4360 m altitude plateau with heavy hypoxia, the clearance of acetazolamide in the volunteer was found to increase, and the values of the MRT and V d were signicantly lower than those in the low altitude plain.…”

“…6,7 Several studies indicate that hypoxia markedly alter the pharmacokinetic characteristics of some drugs. [8][9][10][11][12] About 30-40% of the cytochrome P-450 isoforms belongs to the CYP3A subfamily in liver and 70% of that in intestine. More than 60% of the drugs in clinical practice are metabolized by the CYP3A enzyme; therefore, it is very important to evaluate the activity and expression of CYP3A protein.…”

Comparison of Pharmacokinetics and Tissue Distribution Kinetics of Roxithromycin and Expression of CYP 3A1 between Pregnant Mice and Foetuses

“…Comparing the main pharmacokinetic parameters of roxithromycin between plasma and amniotic fluid, the AUC and elimination half‐life in amniotic fluid were increased 1.8 and 4.3 times, respectively, suggesting that this drug had high exposure and slow elimination in amniotic fluid. The concentration versus time profile of roxithromycin in amniotic fluid showed two drug concentration peaks, suggesting that plasma delivery accounted for the first peak and roxithromycin from the placenta produced the second peak . Simple diffusion across the cell membrane is the major transport mechanism for lipid‐soluble drugs and depends on the concentration gradient.…”

A high-throughput bioanalytical assay to support pharmacokinetic interaction study of oxycodone and diazepam in Sprague Dawley rats

“…Similarly, several LC-MS methods have been published for the quantication of diazepam in human plasma or whole blood, [30][31][32] human oral uids 33 and in rat plasma. 34 The reported methods have limitations in a high-throughput setting, for lower sample volumes and shorter run times. Also, these methods cannot be applied to simultaneous analysis of oxycodone and diazepam in rat plasma.…”