Liquid chromatographic-mass spectrometric method for the determination of alpha-,beta-arteether in rat serum

Arteether nanoemulsion for enhanced efficacy against Plasmodium yoelii nigeriensis malaria: an approach by enhanced bioavailability

The present work is focused on the preparation of nanoemulsions (NEs) loaded with arteether (ART) for its enhanced efficacy against malaria parasites. ART-NEs have been prepared using high pressure homogenization (HPH) technique with the aim of improving its solubility and thus its bioavailability. ART-NEs were optimized in terms of pressure and number of cycles. Globule size and size distributions were chosen as quality parameters. The maximum drug loading was achieved up to 93 ± 7.4% with globule size 156 ± 10.2 nm and zeta potential of -23.3 ± 3.4 mV. The developed ART-NEs were found to be stable in terms of globule size and size distribution at different pH. The in vitro release profile of the ART-NEs showed 62% drug release within 12h. The percentage cell viability of blank NEs were within acceptable limits. A sensitive assay method for the determination of ART in rat plasma by liquid chromatography-mass spectrometry (LC-MS) was employed after oral administration of ART-NEs. The pharmacokinetic study showed significantly enhanced bioavailability of ART in ART-NE-V. The area under curve (AUC) of ART-NE-V was AUC0-t 1988.411 ± 119.66 h ng/ml which was significantly higher (p<0.05) than ART in ground nut oil (GNO) AUC0-t 671.852 ± 187.05 h ng/ml. The Cmax of ART-NE-V (1506 ± 161.22 ng/ml) was also significantly higher (p<0.05) than ART in GNO (175.2 ± 16.54 ng/ml) and ART given intramuscularly (IM) (278.05 ± 38.59 ng/ml). The ART-NE-V was having significantly high antimalarial efficacy and survival rate of mice giving 80% cure rate at 12.5 mg/kg for 5 days in comparison to 30% cure rate of ART in GNO at the same daily dose and it was also comparable to the 100% cure rate at 12.5 mg/kg for 5 days for ART given intramuscularly. In conclusion ART-NE can be a promising oral delivery system for ART.

Pharmacokinetics study of arteether loaded solid lipid nanoparticles: an improved oral bioavailability in rats

Arteether (ART), an artemisinin derivative, is a life saving drug for multiple drug resistant malaria. It has a deliverance effect in Falciparum malaria and cerebral malaria. We have prepared solid lipid nanoparticles (SLN) by high pressure homogenization (HPH) technique. ART-loaded SLN (ART-SLN) has been produced reproducibly with homogeneous particle size. ART-SLN was characterized for their size measured by Zetasizer Nano-ZS, Malvern, UK and by high resolution transmission electron microscopy (HR-TEM) and which was found to be 100 ± 11.2 nm. The maximum percentage entrapment efficiency (%EE) determined with the high-performance liquid chromatography (HPLC) has been found to be 69 ± 4.2% in ART-SLN-3. The release pattern from ART-SLN revealed that the release of ART is slow but time-dependent manner, which is desirable as it will help to protect the acid degradation of ART in stomach. The percentage cytotoxicity of blank SLN has been found within the acceptable range. The pharmacokinetics results indicated that ART-SLN-3 absorption has been significantly enhanced in comparison to ART in aqueous suspension and ART in ground nut oil (GNO) in rats. The % relative bioavailability (RB%) of ART-SLN to the ART in GNO and ART in aqueous suspension in rats was 169.99% and 7461%, respectively which was found to be significantly high in both the cases. From the results, it can be concluded that ART-SLN offers a new approach to improve the oral bioavailability of ART.

Self-nanoemulsifying drug delivery systems (SNEDDS) for oral delivery of arteether: pharmacokinetics, toxicity and antimalarial activity in mice

The nontoxic SNEDDS of arteether, improved arteether bioavailability and anti-malarial efficacy.

Stability-indicating HPLC method for arteether and application to nanoparticles of arteether

A simple, precise, isocratic, reverse-phase high-performance liquid chromatography method was developed for the rapid determination of arteether using an Agilent RP C18, 4.6 × 150 mm, 5 μm XDB column. The runtime was 9 min. The effect of flow rate, injection volume and mobile phase composition on resolution was investigated. The analytical procedures of the method were validated with respect to precision, accuracy and linearity according to the International Conference on Harmonization guidelines. The limit of detection and the limit of quantitation were 3.3 and 10.0 μg/mL, respectively. Linearity range was from 10.00 to 500 μg/mL. Further, the proposed method was found to be reproducible and convenient for stability-indicating analysis of arteether as a bulk drug and from nanoparticulate formulation.

Mass spectrometry in India

This review emphasizes the mass spectrometry research being performed at academic and established research institutions in India. It consists of three main parts covering the work done in organic, atomic and biological mass spectrometry. The review reveals that the use of mass spectrometry techniques started in the middle of the 20th century and was applied to research in the fields of organic, nuclear, geographical and atomic chemistry. Later, with the advent of soft and atmospheric ionization techniques it has been applied to pharmaceutical and biological research. In due course, several research centers with advanced mass spectrometry facilities have been established for specific areas of research such as gas-phase ion chemistry, ion-molecule reactions, proscribed chemicals, pesticide residues, pharmacokinetics, protein/peptide chemistry, nuclear chemistry, geochronological studies, archeology, petroleum industry, proteomics, lipidomics and metabolomics. Day-by-day the mass spectrometry centers/facilities in India have attracted young students for their doctoral research and other advanced research applications.

A liquid chromatographic-tandem mass spectrometric method for determination of artemether and its metabolite dihydroartemisinin in human plasma

BACKGROUND

Artemether-lumefantrine is the most widely recommended artemisinin-based combination treatment for falciparum malaria. Quantification of artemether and its metabolite dihydroartemisinin in biological matrices has traditionally been difficult, with sensitivity being an issue.

RESULTS

A high-throughput bioanalytical method for the analysis of artemether and its metabolite dihydroartemisinin in human plasma using solid-phase extraction in the 96-well plate format and liquid chromatography coupled to positive ion mode tandem mass spectroscopy has been developed and validated according to US FDA guidelines. The method uses 50 µl plasma and covers the calibration range 1.43-500 ng/ml with a limit of detection at 0.36 ng/ml.

CONCLUSIONS

The developed liquid chromatography-tandem mass spectrometry assay is more sensitive than all previous methods despite using a lower plasma volume (50 µl) and is highly suitable for clinical studies where plasma volumes are limited, such as pediatric trials.

Development and validation of a liquid chromatography and ion spray tandem mass spectrometry method for the quantification of artesunate, artemether and their major metabolites dihydroartemisinin and dihydroartemisinin-glucuronide in sheep plasma

Recently, promising fasciocidal activities of artesunate and artemether were described in rats and sheep. Therefore, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to quantify artesunate, artemether and their metabolites dihydroartemisinin and dihydroartemisinin-glucuronide in sheep plasma. Protein precipitation with methanol was used for sample workup. Reversed-phase high-performance liquid chromatography (HPLC) was performed using an Atlantis C18 analytical column with a mobile phase gradient system of ammonium formate and acetonitrile. The analytes were detected by MS/MS using selected reaction monitoring (SRM) with electrospray ionisation in the positive mode (transition m/z 267.4 → 163.0). The analytical range for dihydroartemisinin, dihydroartemisinin-glucuronide and artesunate was 10-1000 ng/ml and for artemether 90-3000 ng/ml with a lower limit of quantification of 10 and 90 ng/ml, respectively. Inter- and intra-day accuracy and precision deviations were < 10%. Consistent relative recoveries (60-80%) were observed over the investigated calibration range for all analytes. All analytes were stable in the autosampler for at least 30 h (6 °C) and after three freeze and thaw cycles. The validation results demonstrated that the LC-MS/MS method is precise, accurate and selective and can be used for the determination of the artemisinins in sheep plasma. The method was applied successfully to determine the pharmacokinetic parameters of artesunate and its metabolites in plasma of intramuscularly treated sheep.

Affordable and sensitive determination of artemisinin in Artemisia annua L. by gas chromatography with electron-capture detection

Artemisinin demand has increased sharply since the World Health Organization recommended its use as part of the artemisinin combination therapies in 2001. The area for the crop cultivation has expanded in Africa and Asia and simpler and affordable methods for artemisinin analysis are needed for crop quality control. This work presented a novel chromatographic method of artemisinin analysis using gas chromatography with electron-capture detection. The sample extraction and preparation involved a single-solvent one-step extraction, with samples being analyzed in the extraction solvent directly after extraction. This method was accurate and reproducible with over 97% recoveries. The limit of detection was less than 3 microg/mL and the limit of quantification was less than 9 microg/mL, allowing samples as low as 100mg dry weight to be analyzed for artemisinin. The method can be applied to quality control of commercial plant extracts and to artemisinin-derived pharmaceuticals.

Quantitation of artemisinin and its biosynthetic precursors in Artemisia annua L. by high performance liquid chromatography–electrospray quadrupole time-of-flight tandem mass spectrometry

This study reports the development and validation of a rapid, sensitive and selective assay for the quantitation of artemisinin, arteannuin B, artemisitene and artemisinic acid in Artemisia annua L. by reversed phase high performance liquid chromatography (HPLC) electrospray (ESI) quadrupole time of flight (Q-TOF) tandem mass spectrometry (MS/MS). A recovery of >97% for all analytes was achieved by immersing one gram of fresh plant material in chloroform for 1 min. This result supports the hypothesis that artemisinin and some of its structural analogs present in the leaves A. annua L. are localized entirely in the subcuticular space of the glands on the surface of the leaves. We validated the use of this chloroform extract, without additional sample preparation steps, for quantitative Q-TOF MS/MS. No ion suppression (matrix effect) resulting from interference with other compounds was detected. For every concentration within the range of the standard curve (0.1 to 3.00 microg/ml), accuracy was between 85% and 115%. Within- and between-day variations for the analysis of A. annua L. samples were <20%.

A sensitive and selective liquid chromatographic/electrospray ionization tandem mass spectrometric assay for the simultaneous quantification of alpha-,beta-arteether and its metabolite dihydroartemisinin in plasma, useful for pharmacokinetic studies

A sensitive, selective, specific and rapid liquid chromatographic/electrospray ionization tandem mass spectrometric assay method was developed and validated for the simultaneous quantitation of alpha-,beta-arteether (alpha-,beta-AE) and its metabolite alpha-dihydroartemisinin (DHA) in monkey plasma using the propyl ether analogue of beta-arteether (PE) as an internal standard. The method involves a simple two-step liquid-liquid extraction with hexane. The analytes were chromatographed on a C(18) reversed-phase chromatographic column by isocratic elution with methanol-ammonium acetate buffer (pH 4) (92 : 8, v/v) and analysed by mass spectrometry in the multiple reaction monitoring mode. The chromatographic run time was 7 min and the weighted (1/x(2)) calibration curves were linear over the range 0.78-200 ng ml(-1). The method was validated in terms of accuracy, precision, absolute recovery, freeze-thaw stability, bench-top stability and re-injection reproducibility. The limit of detection and lower limit of quantification in monkey plasma were 0.39 and 0.78 ng ml(-1) respectively for all the analytes. The intra- and inter-batch precision and accuracy were found to be well within acceptable limits (<15%). All three analytes were stable even after three freeze-thaw cycles (deviation < 15%). The average absolute recoveries of alpha-,beta-AE, DHA and PE, used as an internal standard, from spiked plasma samples were 85.85 +/- 6.56, 70.10 +/- 7.06, 54.37 +/- 3.39 and 93.90 +/- 6.9%, respectively. The assay method described here could be applied to study the pharmacokinetics of alpha-,beta-AE and DHA in rhesus monkeys.

An HPLC-MS method for simultaneous estimation of?,?-arteether and its metabolite dihydroartemisinin, in rat plasma for application to pharmacokinetic study

This manuscript reports, the development and validation of a sensitive and selective assay method for simultaneous determination of alpha,beta-arteether and its metabolite dihydroartemisinin (DHA) in rat plasma by liquid chromatography-mass spectrometry. Chromatographic separations were achieved by gradient elution of the analytes with an initial composition of methanol-potassium acetate buffer (pH 4; 73:27, v/v) to 100% methanol in 3 min and maintained for 5 min on a Spheri-10, RP(18) (100 x 4.6 mm i.d.) column following an RP(18) (30 x 4.6 mm i.d.) guard column. The total effluent from the column was split so that one-tenth was injected into the electrospray LC/MS interface. ESI-MS analysis was performed using a Micromass Quattro II Triple Quadrupole Mass Spectrometer equipped with an electrospray source. The MS analysis was carried out at cone voltage of 22 V with a scan range of 200-500 Da. The analytes were quantified from the [M+ K](+) ion chromatograms of alpha,beta-arteether at m/z 352, DHA at m/z 323, artemisinin at m/z 321 and propyl ether analogue of arteether at m/z 365. Liquid-liquid extractions with a combination of n-hexane and hexane-ethyl acetate (8:2) were used to isolate alpha,beta-arteether and DHA from rat plasma. The method was validated and gave good accuracy and precision for the studied domain. Linearity in serum was observed over the range 4.375-70 ng/mL for alpha-arteether and 10-160 ng/mL for beta-arteether and DHA. Percentage bias (accuracy) and within- and between-assay precision were well within the acceptable range. This method was applied to study the pharmacokinetics following oral administration of alpha,beta-arteether (30 mg/kg) in rats.