Sensitive and rapid liquid chromatography/tandem mass spectrometric assay for the quantification of piperaquine in human plasma

A high-throughput LC-MS/MS assay for piperaquine from dried blood spots: Improving malaria treatment in resource-limited settings

Background

Malaria is a parasitic disease that affects many of the poorest economies, resulting in approximately 241 million clinical episodes and 627,000 deaths annually. Piperaquine, when administered with dihydroartemisinin, is an effective drug against the disease. Drug concentration measurements taken on day 7 after treatment initiation have been shown to be a good predictor of therapeutic success with piperaquine. A simple capillary blood collection technique, where blood is dried onto filter paper, is especially suitable for drug studies in remote areas or resource-limited settings or when taking samples from children, toddlers, and infants.

Methods

Three 3.2 mm discs were punched out from a dried blood spot (DBS) and then extracted in a 96-well plate using solid phase extraction on a fully automated liquid handling system. The analysis was performed using LC-MS/MS with a calibration range of 3 - 1000 ng/mL.

Results

The recovery rate was approximately 54-72 %, and the relative standard deviation was below 9 % for low, middle and high quality control levels. The LC-MS/MS quantification limit of 3 ng/mL is sensitive enough to detect piperaquine for up to 4-8 weeks after drug administration, which is crucial when evaluating recrudescence and drug resistance development. While different hematocrit levels can affect DBS drug measurements, the effect was minimal for piperaquine.

Conclusion

A sensitive LC-MS/MS method, in combination with fully automated extraction in a 96-well plate format, was developed and validated for the quantification of piperaquine in DBS. The assay was implemented in a bioanalytical laboratory for processing large-scale clinical trial samples.

Determination of piperaquine concentration in human plasma and the correlation of capillary versus venous plasma concentrations

Background

A considerable challenge in quantification of the antimalarial piperaquine in plasma is carryover of analyte signal between assays. Current intensive pharmacokinetic studies often rely on the merging of venous and capillary sampling. Drug levels in capillary plasma may be different from those in venous plasma, Thus, correlation between capillary and venous drug levels needs to be established.

Methods

Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was used to develop the method. Piperaquine was measured in 205 pairs of capillary and venous plasma samples collected simultaneously at ≥24hr post dose in children, pregnant women and non-pregnant women receiving dihydroartemisinin-piperaquine as malaria chemoprevention. Standard three-dose regimen over three days applied to all participants with three 40mg dihydroartemisinin/320mg PQ tablets per dose for adults and weight-based dose for children. Correlation analysis was performed using the program Stata® SE12.1. Linear regression models were built using concentrations or logarithm transformed concentrations and the final models were selected based on maximal coefficient of determination (R²) and visual check.

Results

An LC-MS/MS method was developed and validated, utilizing methanol as a protein precipitation agent, a Gemini C₁₈ column (50x2.0mm, 5μm) eluted with basic mobile phase solvents (ammonium hydroxide as the additive), and ESI⁺ as the ion source. This method had a calibration range of 10–1000 ng/mL and carryover was negligible. Correlation analysis revealed a linear relationship: C_cap = 1.04×C_ven+4.20 (R² = 0.832) without transformation of data, and lnC_cap = 1.01×lnC_ven+0.0125, (R² = 0.945) with natural logarithm transformation. The mean ratio (±SD) of C_cap/C_ven was 1.13±0.42, and median (IQR) was 1.08 (0.917, 1.33).

Conclusions

Capillary and venous plasma PQ measures are nearly identical overall, but not readily exchangeable due to large variation. Further correlation study accounting for disposition phases may be necessary.

Development of a lateral flow dipstick for simultaneous and semi-quantitative analysis of dihydroartemisinin and piperaquine in an artemisinin combination therapy

Dihydroartemisinin (DHA) and piperaquine (PPQ) are two drugs used in an artemisinin-based combination therapy (ACT). The circulation of counterfeit antimalarial drugs demands the development of simple, point-of-care (POC) tests for monitoring drug quality. Here we aimed to design an antibody-based lateral flow dipstick assay for simultaneous quality control of DHA and PPQ. To obtain a monoclonal antibody (mAb) for PPQ, one structural unit of the symmetric PPQ molecule was used to derive a carboxylic acid for linkage to a carrier protein as immunogen. Screening of hybridoma cells identified an mAb 4D112B2 that reacted with the PPQ-based immunogen. A highly-sensitive icELISA was designed based on this mAb, which showed 50% inhibition concentration of PPQ at 1.66 ng/mL and a working range of 0.35 - 7.40 ng/mL. The mAb showed 10.2, 15.9 and 30.4% cross reactivity to hydroxychloroquine sulfate, chloroquine and amodiaquine, respectively. No cross reactivity was observed to lumefantrine, mefloquine artemisinin and its derivatives. Using our previous DHA dipstick design, a lateral flow dipstick for simultaneous analysis of PPQ and DHA was developed. The indicator ranges for PPQ and DHA were 2 - 5 μg/mL and 250 - 500 ng/mL, respectively. The dipstick was used to semi-quantitatively analyze PPQ and DHA content in commercial ACT drugs, which produced agreeable results to those determined by high-performance liquid chromatography. This combination dipstick makes it a potential POC device for quality control of the two active ingredients in a commonly used ACT.

Simultaneous determination of piperaquine and its N-oxidated metabolite in rat plasma using LC-MS/MS

A sensitive and efficient liquid chromatography tandem mass spectrometry method was developed and validated for the simultaneous determination of piperaquine (PQ) and its N-oxidated metabolite (PQ-M) in plasma. A simple protein precipitation procedure was used for sample preparation. Adequate chromatographic retention was achieved on a C₁₈ column under gradient elution with acetonitrile and 2 mm aqueous ammonium acetate containing 0.15% formic acid and 0.05% trifluoroacetic acid. A triple-quadrupole mass spectrometer equipped with an electrospray source was set up in the positive ion mode and multiple reaction monitoring mode. The method was linear in the range of 2.0-400.0 ng/mL for PQ and 1.0-50.0 ng/mL for PQ-M with suitable accuracy, precision and extraction recovery. The lower limits of detection (LLOD) were established at 0.4 and 0.2 ng/mL for PQ and PQ-M, respectively, using 40 μL of plasma sample. The matrix effect was negligible under the current conditions. No effect was found for co-administrated artemisinin drugs or hemolysis on the quantification of PQ and PQ-M. Stability testing showed that two analytes remained stable under all relevant analytical conditions. The validated method was successfully applied to a pharmacokinetic study performed in rats after a single oral administration of PQ (60 mg/kg).

Research progress in electroanalytical techniques for determination of antimalarial drugs in pharmaceutical and biological samples

The review focusses on the role of electroanalytical methods for determination of antimalarial drugs in biological matrices and pharmaceutical formulations with a critical analysis of published voltammetric and potentiometric methods.

Determination of the antimalarial drug piperaquine in small volume pediatric plasma samples by LC-MS/MS

AIM

Determination of piperaquine (PQ) in pediatric plasma requires a method with a small sample volume.

RESULTS

We report a sensitive LC-MS/MS method for quantitation of PQ with only 25 µl human plasma. Using a deuterated internal standard (PQ-d6), an analytical PFP column, APCI(+) as the ion source and MRM (535/288 for PQ and 541/294 for the IS) for detection, the method has a linear calibration range of 1.5-250 ng/ml with a runtime of 3.0 min per sample. The method was applied to plasma samples from children.

CONCLUSION

The developed LC-MS/MS method is suitable for pediatric studies with small volume plasma samples collected via capillary tubes. One limitation was the performance of PFP columns varied among different brands.

In vitro metabolism of piperaquine is primarily mediated by CYP3A4

Piperaquine (PQ) is part of a first-line treatment regimen for Plasmodium falciparum malaria recommended by the World Health Organization (WHO). We aimed to determine the major metabolic pathway(s) of PQ in vitro. A reliable, validated tandem mass spectrometry method was developed. Concentrations of PQ were measured after incubation with both human liver microsomes (HLMs) and expressed cytochrome P450 enzymes (P450s). In pooled HLMs, incubations with an initial PQ concentration of 0.3 µM resulted in a 34.8 ± 4.9% loss of substrate over 60 min, corresponding to a turnover rate of 0.009 min(-1) (r(2) = 0.9223). Miconazole, at nonspecific P450 inhibitory concentrations, resulted in almost complete inhibition of PQ metabolism. The greatest inhibition was demonstrated with selective CYP3A4 (100%) and CYP2C8 (66%) inhibitors. Using a mixture of recombinant P450 enzymes, turnover for PQ metabolism was estimated as 0.0099 min(-1); recombinant CYP3A4 had a higher metabolic rate (0.017 min(-1)) than recombinant CYP2C8 (p < .0001). Inhibition of CYP3A4-mediated PQ loss was greatest using the selective inhibitor ketoconazole (9.1 ± 3.5% loss with ketoconazole vs 60.7 ± 5.9% with no inhibitor, p < .0001). In summary, the extent of inhibition of in vitro metabolism with ketoconazole (83%) denotes that PQ appears to be primarily catalyzed by CYP3A4. Further studies to support these findings through the identification and characterization of PQ metabolites are planned.

Quantification of the antimalarial piperaquine in plasma

Malaria is one of the most common parasitic diseases in the world, with up to three million deaths a year. Piperaquine is an antimalarial drug that was extensively used in China during the 1980s and has recently received renewed interest as a partner drug in artemisinin-based combination therapy. Despite extensive use, the first bioanalytical method was published in 2003. In total there are eight previously published methods for quantification of piperaquine in different biological matrices using HPLC with UV or tandem mass spectrometric detection. Five of these allow for quantification of piperaquine in plasma and are discussed in this paper.