A high-throughput LC-MS/MS assay for quantification of artesunate and its metabolite dihydroartemisinin in human plasma and saliva

A simple sensitive UFLC-MS/MS method for the simultaneous quantification of artesunate, dihydroartemisinin and quercetin in rat plasma and its application to pharmacokinetic studies

An ultrafast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) method was developed for the simultaneous estimation of artesunate (ART), dihydroartemisinin (DHA, an active metabolite of ART) and quercetin (QRT) in rat plasma. The separation was achieved using a Zorbax C18 column (3 μm, 50 mm × 4.6 mm) as a stationary phase with a mobile phase of 0.1% formic acid (10% by volume) and methanol (90% by volume) at a flow rate of 0.4 mL min-1 and an injection volume of 10 μL. Artemisinin (ATM) was used as the internal standard (IS). Mass detection was performed by electrospray ionization (ESI)-tandem mass spectrometry via multiple reaction monitoring (MRM) in positive mode except for QRT, where negative ionization was used. The extraction recoveries of ART, DHA, and QRT from plasma were found to be 91.05-99.62%, 95.12-98.56% and 89.35-98.90%, respectively. The developed method was validated and successfully applied to the quantitative analysis of ART, DHA and QRT in plasma samples after the oral administration of ART and ART-QRT pure drugs to rats at the dose of 5 mg kg-1 each. The results reveal that the developed method can be further used for the quantification of the proposed combination drugs in nanoformulations.

Quantitative determination of artemisinin in rat hemolyzed plasma by an HPLC-HRMS method

Iron present in hemolyzed plasma could cause the degradation of artemisinin by reductively cleaving the peroxide bridge of artemisinin during sample preparation, which is a significant technical challenge for artemisinin determination. In this paper, this issue was resolved by using sodium nitrite as methemoglobin-forming agent to oxidize hemoglobin to methemoglobin in the presence of acetic acid and prevent the degradation of artemisinin in hemolyzed plasma during the sample preparation procedure. Then, a high-performance liquid chromatography tandem high-resolution mass spectrometry method was developed and validated for the determination of artemisinin in normal and hemolyzed plasma. The linear range was validated over the concentration range of 5-500 ng ml^-1 . The matrix effect and stability were also evaluated. This robust and sensitive assay was successfully applied to a pharmacokinetic study in rats after an oral administration of Artemisia annua L. extract.

Population pharmacokinetics of artesunate and dihydroartemisinin during long-term oral administration of artesunate to patients with metastatic breast cancer

PURPOSE

The purpose of this study were firstly to characterize the population pharmacokinetics of artesunate (ARS) and its active metabolite dihydroartemisinin (DHA) in patients with metastatic breast cancer during long-term (>3 weeks) daily oral ARS administration and secondly to study the relationship between salivary and plasma concentrations of DHA.

METHODS

Drug concentration-time data from 23 patients, receiving oral ARS (100, 150, or 200 mg OD), was analyzed using nonlinear mixed effects modeling. A combined drug-metabolite population pharmacokinetic model was developed to describe the plasma pharmacokinetics of ARS and DHA in plasma. Saliva drug concentrations were incorporated as being directly proportional to plasma concentrations.

RESULTS

A first-order absorption model for ARS linked to a combined two-compartment disposition model for ARS and one-compartment disposition model for DHA provided the best fit to the data. No covariates were identified that could explain between-subject variability. A time-dependent increase in apparent elimination clearance of DHA was observed. Salivary DHA concentrations were proportionally correlated with total DHA plasma concentrations, with an estimated slope factor of 0.116.

CONCLUSIONS

Population pharmacokinetics of ARS and DHA in patients with breast cancer was well described by a combined drug-metabolite model without any covariates and with an increase in apparent elimination clearance of DHA over time. The estimated DHA saliva/plasma ratio was in good agreement with the reported DHA unbound fraction in human plasma. Saliva ARS concentrations correlated poorly with plasma concentrations. This suggests the use of saliva sampling for therapeutic drug monitoring of DHA. However, further studies are warranted to investigate the robustness of this approach.