Relevance of plasma lenvatinib concentrations and endogenous urinary cytochrome P450 3A activity biomarkers in clinical practice.

Lenvatinib (LEN), a multitarget tyrosine kinase inhibitor used in various cancer treatments, is mainly metabolized by cytochrome P450 3A (CYP3A) enzymes. The importance of therapeutic drug monitoring (TDM) in patients administered LEN has been proposed. Although some biomarkers of endogenous CYP3A activity have been reported, their utility in dosage adjustments has not been well evaluated. This study investigated the correlation between plasma LEN concentrations and endogenous urinary CYP3A biomarkers in clinical practice. Concentrations of plasma LEN (N = 225) and CYP3A biomarkers (cortisol, 6ß-hydroxycortisol, deoxycholic acid, and 1ß-hydroxydeoxycholic acid) in urine (N = 214) from 20 patients (hepatocellular carcinoma, N = 6; thyroid cancer, N = 3; endometrial cancer, N = 8; and renal cell carcinoma, N = 3) collected for consultation for up to 1 year were evaluated using liquid chromatography-tandem mass spectrometry. Moreover, plasma trough LEN concentrations were predicted using a three-compartment model with linear elimination for outpatients administered LEN before sample collection. Moderate correlations were observed between the quantified actual concentrations and the predicted trough concentrations of LEN, whereas there was no correlation with endogenous urinary CYP3A biomarkers. The utility of endogenous urinary CYP3A biomarkers could not be determined. However, TDM for outpatients administered orally available medicines may be predicted using a nonlinear mixed effect model (NONMEM). This study investigated the utility of endogenous urinary CYP3A biomarkers for personalized medicine and NONMEM for predicting plasma trough drug concentrations. These findings will provide important information for further clinical investigation and detailed TDM.

Pharmacokinetics of piperaquine and its association with intermittent malaria preventive therapy outcomes during pregnancy.

BACKGROUND: Dihydroartemisinin-piperaquine (DHP) recently showed superior effectiveness over sulfadoxine-pyrimethamine for malaria intermittent preventive treatment in pregnancy (IPTp). We investigated day 7 piperaquine pharmacokinetics and its therapeutic efficacy in preventing malaria during pregnancy. METHODS: Malaria-free (mRDT) pregnant women (n = 400) who received monthly IPTp-DHP were enrolled and followed till delivery. Day 7 Plasma piperaquine concentrations were determined after each IPTp dose using UPLC/MS/MS. IPTp outcomes (symptomatic malaria and parasitemia during pregnancy, placental malaria, and maternal malaria at delivery) were monitored. Linear mixed model and Cox regression were used to assess predictors of day 7 piperaquine concentration and treatment outcome, respectively. RESULTS: The incidences of symptomatic malaria and parasitemia during pregnancy per 100 person-year at risk were 2 and 33, respectively. The prevalence of histopathologically confirmed placental malaria and maternal malaria at delivery were 3% and 9.8%, respectively. Repeated monthly IPTp-DHP resulted in significantly increased day 7 plasma piperaquine concentration (p < 0.001). Following the 1st, 2nd, and 3rd monthly IPTp-DHP doses, the proportions of women with day 7 piperaquine concentration below the therapeutic threshold (< 30 ng/mL) were 6.1%, 4.1% and 3.6%, respectively. Factors such as maternal age, body weight and trimester were not significant predictors of day 7 piperaquine concentration. However, having a low day 7 piperaquine plasma concentration (< 30 ng/mL) was significantly associated with a higher risk of parasitemia during pregnancy (p = 0.004). CONCLUSION: Lower day 7 piperaquine plasma concentration is a risk factor for parasitemia during pregnancy. Single plasma sampling at day 7 can be used to monitor piperaquine effectiveness during IPTp-DHP. TRIAL REGISTRATION: Registered 09/12/2016, PACTR201612001901313.

Determination of valsartan and pitavastatin using synchronous spectrofluorimetry and augmented least squares chemometric models: A comparative study with greenness and blueness assessment.

Hypertension and hyperlipidemia are two common conditions that require effective management to reduce the risk of cardiovascular diseases. Among the medications commonly used for the treatment of these conditions, valsartan and pitavastatin have shown significant efficacy in lowering blood pressure and cholesterol levels, respectively. In this study, synchronous spectrofluorimetry coupled to chemometric analysis tools, specifically concentration residual augmented classical least squares (CRACLS) and spectral residual augmented classical least squares (SRACLS), was employed for the determination of valsartan and pitavastatin simultaneously. The developed models exhibited excellent predictive performance with relative root mean square error of prediction (RRMSEP) of 2.253 and 2.1381 for valsartan and pitavastatin, respectively. Hence, these models were successfully applied to the analysis of synthetic samples and commercial formulations as well as plasma samples with high accuracy and precision. Besides, the greenness and blueness profiles of the determined samples were also evaluated to assess their environmental impact and analytical practicability. The results demonstrated excellent greenness and blueness scores with AGREE score of 0.7 and BAGI score of 75 posing the proposed method as reliable and sensitive approach for the determination of valsartan and pitavastatin with potential applications in pharmaceutical quality control, bioanalytical studies, and therapeutic drug monitoring.

A developed and validated centrifugal ultrafiltration coupled with high performance liquid chromatography-tandem mass spectrometry method for rapid quantification of unbound lenvatinib in human plasma.

In clinical practice, the determination of unbound drug concentration is very important for dose adjustment and toxicity prediction because only the unbound fraction can achieve a pharmacological effect. A fast, sensitive and accurate analytical method of centrifugal ultrafiltration coupled with high performance liquid chromatography-tandem mass spectrometry method was developed and applied to allow the quantification of unbound lenvatinib concentration. The application of linear regression analysis was used to examine the effects of centrifugal force, centrifugal time, and protein content on ultrafiltrate volume (Vu). The results indicated that the centrifugal force and centrifugal time have an influence on Vu that is significantly positive (P < 0.05). This developed method with good linearity (r2 = 0.9996), good accuracy (bias % ≤ 2.24 %), good precision (CV % ≤ 7.10 %), and good recovery (95.46 %-106.46 %) was suitable for routine clinical practice and studies. Particularly, the ultrafiltration membrane had no non-specific binding to lenvatinib. The unbound fractions can be separated in just 15 min. This method was applied to quantify clinical samples and to determine the plasma protein binding and unbound fraction of lenvatinib. This study provides a more effective and promising method for determination of unbound lenvatinib. It could be beneficial to measure the unbound concentration of lenvatinib in personalized medicine and therapeutic drug monitoring in routine clinical practice.

Comparison of lumefantrine, mefloquine, and piperaquine concentrations between capillary plasma and venous plasma samples in pregnant women with uncomplicated falciparum and vivax malaria.

Capillary samples offer practical benefits compared with venous samples for the measurement of drug concentrations, but the relationship between the two measures varies between different drugs. We measured the concentrations of lumefantrine, mefloquine, piperaquine in 270 pairs of venous plasma and concurrent capillary plasma samples collected from 270 pregnant women with uncomplicated falciparum or vivax malaria. The median and range of venous plasma concentrations included in this study were 447.5 ng/mL (8.81-3,370) for lumefantrine (day 7, n = 76, median total dose received 96.0 mg/kg), 17.9 ng/mL (1.72-181) for desbutyl-lumefantrine, 1,885 ng/mL (762-4,830) for mefloquine (days 3-21, n = 90, median total dose 24.9 mg/kg), 641 ng/mL (79.9-1,950) for carboxy-mefloquine, and 51.8 ng/mL (3.57-851) for piperaquine (days 3-21, n = 89, median total dose 52.2 mg/kg). Although venous and capillary plasma concentrations showed a high correlation (Pearson's correlation coefficient: 0.90-0.99) for all antimalarials and their primary metabolites, they were not directly interchangeable. Using the concurrent capillary plasma concentrations and other variables, the proportions of venous plasma samples predicted within a ±10% precision range was 34% (26/76) for lumefantrine, 36% (32/89) for desbutyl-lumefantrine, 74% (67/90) for mefloquine, 82% (74/90) for carboxy-mefloquine, and 24% (21/89) for piperaquine. Venous plasma concentrations of mefloquine, but not lumefantrine and piperaquine, could be predicted by capillary plasma samples with an acceptable level of agreement. Capillary plasma samples can be utilized for pharmacokinetic and clinical studies, but caution surrounding cut-off values is required at the individual level.CLINICAL TRIALSThis study is registered with ClinicalTrials.gov as NCT01054248.

Population pharmacokinetic-pharmacodynamic modeling of serum biomarkers as predictors of tumor dynamics following lenvatinib treatment in patients with radioiodine-refractory differentiated thyroid cancer (RR-DTC).

Lenvatinib is a receptor tyrosine kinase (RTK) inhibitor targeting vascular endothelial growth factor (VEGF) receptors 1-3, fibroblast growth factor (FGF) receptors 1-4, platelet-derived growth factor receptor-α (PDGFRα), KIT, and RET that have been implicated in pathogenic angiogenesis, tumor growth, and cancer. The primary objective of this work was to evaluate, by establishing quantitative relationships, whether lenvatinib exposure and longitudinal serum biomarker data (VEGF, Ang-2, Tie-2, and FGF-23) are predictors for change in longitudinal tumor size which was assessed based on data from 558 patients with radioiodine-refractory differentiated thyroid cancer (RR-DTC) receiving either lenvatinib or placebo treatment. Lenvatinib PK was best described by a 3-compartment model with simultaneous first- and zero-order absorption and linear elimination from the central compartment with significant covariates (body weight, albumin <30 g/dL, ALP>ULN, RR-DTC, RCC, HCC subjects, and concomitant CYP3A inhibitors). Except for body weight, none of the covariates have any clinically meaningful effect on exposure to lenvatinib. Longitudinal biomarker measurements over time were reasonably well defined by a PK/PD model with common EC50, Emax, and a slope for disease progression for all biomarkers. Longitudinal tumor measurements over time were reasonably well defined by a tumor growth inhibition Emax model, which in addition to lenvatinib exposure, included model-predicted relative changes from baseline over time for Tie-2 and Ang-2 as having significant association with tumor response. The developed PK/PD models pave the way for dose optimization and potential prediction of clinical response.

Simultaneous determination of febuxostat and montelukast in human plasma using fabric phase sorptive extraction and high performance liquid chromatography-fluorimetric detection.

In the present work, a new sensitive and selective high-performance liquid chromatography-fluorimetric detection (HPLC-FLD) method was developed and validated to quantify febuxostat (FBX) and montelukast (MON) in human plasma. The developed procedure was successfully applied to a study aimed at evaluating the pharmacokinetic profiles of febuxostat and montelukast in human plasma. A sol-gel poly (caprolactone)-block-poly(dimethylsiloxane)-block-poly(caprolactone) (sol-gel PCAP-PDMS-PCAP) extraction sorbent coated fabric phase sorptive extraction membrane was used in the extraction process. The entire chromatographic analysis was performed with isocratic elution of the composition of the mobile phase (acetonitrile:water, 60:40, v:v, 0.032% glacial acetic acid) on the C18 column. The flow rate is varied during the analysis, particularly from 0.5 mL min-1 at the start and linearly increased to 1.5 mL min-1 in 7 min. The detection and quantification of the analytes was carried out by means of a fluorimetric detector at 320 nm and 350 nm as absorption wavelengths and at 380 and 400 nm as emission wavelengths for FBX and MON, respectively. The calibration curves demonstrated linearity in the range 0.3-10 ng mL-1 and 5-100 ng mL-1 for FBX and MON, respectively, while the LOD and LOQ values were 0.1 and 0.3 ng mL-1 for FBX and 1.5 and 5 ng mL-1 for MON. Intraday and interday RSD% values were found lower than 5.79%. As reported, the method was applied to real plasma samples obtained from a volunteer who was co-administered both the drugs. Pharmacokinetic data reveal that the concentration of both the drugs reaches the plateau approximately at the same time, but exhibits an elimination phase at different rates. This study demonstrated the usefulness of the new method and its applicability in therapeutic drug monitoring (TDM).

Interspecies comparison of plasma metabolism and sample stabilization for quantitative bioanalyses: Application to (R)-CE3F4 in preclinical development, including metabolite identification by high-resolution mass spectrometry.

The CE3F4 is an inhibitor of the type 1 exchange protein directly activated by cAMP (EPAC1), which is involved in numerous signaling pathways. The inhibition of EPAC1 shows promising results in vitro and in vivo in different cardiac pathological situations like hypertrophic signaling, contributing to heart failure, or arrhythmia. An HPLC-UV method with a simple and fast sample treatment allowed the quantification of (R)-CE3F4. Sample treatment consisted of simple protein precipitation with 50 µL of ethanol and 150 µL of acetonitrile for a 50 µL biological sample. Two wavelengths were used according to the origin of plasma (220 or 250 nm for human samples and 250 nm for murine samples). Accuracy profile was evaluated for both wavelengths, and the method was in agreement with the criteria given by the EMA in the guideline for bioanalytical method validation for human and mouse plasma samples. The run time was 12 min allowing the detection of the (R)-CE3F4 and a metabolite. This study further permitted understanding the behavior of CE3F4 in plasma by highlighting an important difference between humans and rodents on plasma metabolism and may impact future in vivo studies related to this molecule and translation of results between animal models and humans. Using paraoxon as a metabolism inhibitor was crucial for the stabilization of (R)-CE3F4 in murine samples. HPLC-UV and HPLC-MS/MS studies were conducted to confirm metabolite structure and consequently, the main metabolic pathway in murine plasma.

A rapid, simple and sensitive LC-MS/MS method for lenvatinib quantification in human plasma for therapeutic drug monitoring.

Lenvatinib (LENVA) is an oral antineoplastic drug used for the treatment of hepatocellular carcinoma and thyroid carcinoma. LENVA therapeutic drug monitoring (TDM) should be mandatory for a precision medicine to optimize the drug dosage. To this end, the development of a sensitive and robust quantification method to be applied in the clinical setting is essential. The aim of this work was to develop and validate a sensitive, rapid, and cost-effective LC-MS/MS method for the quantification of LENVA in human plasma. On this premise, sample preparation was based on a protein precipitation and the chromatographic separation was achieved on a Synergi Fusion RP C18 column in 4 min. The method was completely and successfully validated according to European Medicines Agency (EMA) and Food and Drug Administration (FDA) guidelines, with good linearity in the range of 0.50-2000 ng/mL (R≥0.9968). Coefficient of variation (CV) for intra- and inter-day precision was ≤11.3% and accuracy ranged from 96.3 to 109.0%, internal standard normalized matrix effect CV% was ≤2.8% and recovery was ≥95.6%. Successful results were obtained for sensitivity (signal to noise (S/N) ratio >21) and selectivity, dilution integrity (CV% ≤ 4.0% and accuracy 99.9-102%), and analyte stability under various handling and storage conditions both in matrix and solvents. This method was applied to quantify LENVA in patient's plasma samples and covered the concentration range achievable in patients. In conclusion, a sensitive and robust quantification method was developed and validated to be applied in the clinical setting.

A novel method for the quantification of anlotinib in human plasma using two-dimensional liquid chromatography.

A simple, efficient, and stable detection method of two-dimensional liquid chromatography (2D-LC) was established and validated to determine anlotinib in the human plasma. The 2D-LC system comprises a first-dimensional column (LC1), an intermediate transfer column, and a second-dimensional column (LC2). With simple protein precipitation treatment, the samples were processed directly for detection. The analysis cycle time was completed within 9.50 min. For the anlotinib concentrations, the calibration curve was linear over the 5.00-320.00 ng/mL range. The intra-day and inter-day precision ranges were 0.77-6.22% and 1.92-4.26%, respectively, for anlotinib concentrations. The recoveries were in the range of 97.85-102.50%. A total of 135 plasma samples from 94 patients were analyzed by our method. The plasma concentrations of patients were in the range of 5.17-106.38 ng/mL, in which the female had a higher plasma concentration (6.44-106.38 ng/mL). The simultaneous application of dexamethasone can increase the anlotinib concentration in the plasma. In our clinical application, we found that the factors that affect the plasma concentration include the time and dose of the medication, gender, and drug interactions. The method appears to be sensitive, precise, selective, and suitable for determining the concentration of anlotinib in the plasma sample.

Efficacy and safety of bosutinib versus imatinib for newly diagnosed chronic myeloid leukemia in the Asian subpopulation of the phase 3 BFORE trial.

Bosutinib is approved in the United States, Europe, Japan, and other countries for treatment of newly diagnosed chronic phase (CP) chronic myeloid leukemia (CML), and CML resistant/intolerant to prior therapy. In the phase 3 BFORE trial (Clinicaltrials.gov, NCT02130557), patients were randomized 1:1 to first-line bosutinib or imatinib 400 mg once daily. We examined efficacy, safety, and patient-reported outcomes of bosutinib vs imatinib and pharmacokinetics of bosutinib in the Asian (n = 33 vs 34) and non-Asian (n = 235 vs 234) subpopulations of BFORE followed for at least 24 months. At the data cutoff date, 72.7 vs 66.7% of Asian and 70.6 vs 66.4% of non-Asian patients remained on treatment. The major molecular response rate at 24 months favored bosutinib vs imatinib among Asian (63.6 vs 38.2%) and non-Asian (60.9 vs 52.6%) patients, as did the complete cytogenetic response rate by 24 months (86.7 vs 76.7%, 81.5 vs 76.3%). Treatment-emergent adverse events in both subpopulations were consistent with the primary BFORE results. Trough bosutinib concentration levels tended to be higher in Asian patients. Health-related quality of life was maintained after 12 months of bosutinib in both subpopulations. These results support bosutinib as a first-line treatment option in Asian patients with CP CML.

High-throughput liquid chromatography/electrospray ionization-tandem mass spectrometry method using in-source collision-induced dissociation for simultaneous quantification of imatinib, dasatinib, bosutinib, nilotinib, and ibrutinib in human plasma.

Recent studies have shown that therapeutic drug monitoring of tyrosine kinase inhibitors (TKIs) could improve treatment efficacy and safety. A simple analytical method using high-performance LC/electrospray ionization-tandem mass spectrometry has been developed and validated for simultaneous quantification of BCR-ABL and Bruton's TKIs used for chronic leukemia (imatinib, dasatinib, bosutinib, nilotinib, and ibrutinib) in human plasma. Although these structures and physical properties are similar, owing to their different linear ranges, simultaneously determining the plasma levels of these five TKIs by applying optimal MS parameters remains difficult. A quantitative range exceeding 60,000-fold was required, and the linear dynamic ranges of imatinib, bosutinib, and nilotinib were limited because of the presence of a saturated detection signal. In this study, we applied the in-source collision-induced dissociation technique to control the ion amounts in mass spectrometry. This new method allowed rapid determination within 5 min with simple pretreatment. The method was validated according to the US Food and Drug Administration guidelines. Moreover, all samples of patients with chronic leukemia were successfully measured and their values were within the linear range of measurement. Therefore, our high-throughput analytical system is useful to measure the plasma concentrations of imatinib, dasatinib, bosutinib, nilotinib, and ibrutinib in clinical practice.

Biotransformation patterns of dictamnine in vitro/in vivo and its relative molecular mechanism of dictamnine-induced acute liver injury in mice.

Dictamnine (DIC), a typical furan-quinoline alkaloid, has a wide range of pharmacological and toxicological effects, such as anti-bacterial, antifungal, anti-cancer, and hepatoxicity. But the molecular mechanism of DIC-induced hepatoxicity in mice remains unclear. This study aimed to clarify the biotransformation patterns of DIC in vitro/in vivo and the relative molecular mechanism of DIC-induced hepatoxicity in mice. All metabolites of DIC were identified by comparing the blank and drug-containing urine, feces, plasma, and liver samples. The structure of epoxide intermediate derived from DIC was confirmed by trapping assay. Oxidative stress injury and inflammation have been confirmed to be involved in the toxicological process of DIC-induced hepatoxicity in mice by detecting the relative biochemical indexes. The results will help to develop a deeper understanding about the biotransformation patterns of DIC, structure of the epoxide intermediate, and the molecular mechanism of DIC-induced hepatoxicity in mice.

Pharmacokinetics and Bioequivalence Evaluation of Two Montelukast Sodium Chewable Tablets in Healthy Chinese Volunteers Under Fasted and Fed Conditions.

PURPOSE: The aim of this study was to assess and compare the pharmacokinetic (PK) properties and bioequivalence of montelukast sodium chewable tablets prepared by two different manufacturers in healthy Chinese volunteers to obtain adequate PK evidence for the registration approval of the test formulation. PATIENTS AND METHODS: A randomized-sequence, single-dose, open-label, 2-period crossover study was conducted in fasted and fed healthy Chinese volunteers (Chinese Clinical Trials Registry identifier: CTR20182362). Eighteen subjects each were selected for a fasted study and a fed study. Eligible participants were randomly assigned in a 1:1 ratio to receive a single dose of the reference formulation or the test formulation, followed by a 5-day washout period and the administration of the alternate formulation. Plasma samples were collected over a 24-hour period following tablet administration and analyzed for montelukast contents by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The PK parameters, such as maximum serum concentration (Cmax), area under the curve (AUC) from t = 0 to the last quantifiable concentration (AUC0-t), AUC from t = 0 to infinity (AUC0-∞), half-life (t1/2), time to Cmax (Tmax), and terminal elimination rate constant (λz), were evaluated. The safety assessment included changes in vital signs (blood pressure, pulse, and temperature) or laboratory tests (hematology, blood biochemistry, hepatic function, and urinalysis) and the incidence of adverse events (AEs). RESULTS: The geometric mean ratios (GMRs) between the two formulations for the primary pharmacokinetic parameters (Cmax, AUC0-24, and AUC 0-∞) and the corresponding 90% confidence intervals (Cis) were all within the range of 80.00-125.00% for both the fasting and fed states. The safety profiles for both treatments were comparable. CONCLUSION: The PK analysis revealed that the test and reference formulations of montelukast sodium chewable tablets were bioequivalent and well-tolerated by healthy Chinese subjects.

Effects of SLC22A2 808G>T polymorphism and bosutinib concentrations on serum creatinine in patients with chronic myeloid leukemia receiving bosutinib therapy.

The purpose of this study was to investigate the effects of SLC22A2 808G>T polymorphism and trough concentrations (C0) of bosutinib on serum creatinine in 28 patients taking bosutinib. At 1, 3, 6, 12, 24, and 36 months after administration, analysis of bosutinib C0 and creatinine was performed at the same time of day. Significant correlations were observed between bosutinib C0 and the change rate of serum creatinine or the estimated glomerular filtration rate (eGFR; r = 0.328, P < 0.001 and r = - 0.315, P < 0.001, respectively). These correlations were particularly high in patients having the SLC22A2 808G/G genotype (r = 0.345 and r = - 0.329, respectively); however, in patients having the 808T allele, there were no significant differences. In multivariate analyses, the SLC22A2 808G/G genotype, patient age, bosutinib C0 and second-line or later bosutinib were independent factors influencing the change rate of creatinine. Bosutinib elevated serum creatinine through organic cation transporter 2 (OCT2). We observed a 20% increase in serum creatinine with a median bosutinib C0 of 63.4-73.2 ng/mL. Periodic measurement of serum creatinine after bosutinib therapy is necessary to avoid progression to severe renal dysfunction from simple elevation of creatinine mediated by OCT2 following bosutinib treatment.

The Impact of Hemodialysis and Liver Cirrhosis on the Plasma Concentrations of Tyrosine Kinase Inhibitors in a Patient with Chronic Myeloid Leukemia.

We recently treated a chronic myeloid leukemia (CML) patient with liver and renal dysfunction, who was undergoing hemodialysis (HD). He was treated with 50 mg dasatinib (DAS) once daily just before HD. The maximum plasma concentration of DAS was 227 ng/mL on a non-HD day and 46.9 ng/mL on a HD day. He was subsequently treated with 200 mg bosutinib (BOS) once daily. The plasma concentration of BOS changed from 74.5 ng/mL before HD to 58.8 ng/mL after HD. Our results indicate that close monitoring of the plasma tyrosine kinase inhibitor concentrations should be considered in CML patients with organ impairment.

Influences of ABC transporter and CYP3A4/5 genetic polymorphisms on the pharmacokinetics of lenvatinib in Chinese healthy subjects.

PURPOSE: To investigate whether the CYP3A4/5 and ABC transporter genetic polymorphisms could affect the pharmacokinetics of lenvatinib in Chinese healthy subjects. METHODS: Thirty-two healthy Chinese volunteers were enrolled and took oral administration of 8 mg lenvatinib. Plasma concentration of lenvatinib was determined by UPLC-MS/MS, the CYP3A4*1G, CYP3A5*3, ABCB1 (3435 C>T, 1236 C>T, 2677 G>T/A), ABCG2 (421 C>A, 34 G>A), and ABCC2-24 C>T genotypes were determined by SnapShot Technique. RESULTS: In ABCB1 3435T carriers (n = 19), AUC0-120h (815.7 (701.9-923.9) ng·h/mL) and AUC0-∞ (843.3 (722.2-977.7) ng·h/mL) were significantly higher than ABCB1 3435CC homozygous subjects (n = 13, 575.3 (513.7-756.9) ng·h/mL and 590.0 (540.5-782.0) ng·h/mL, respectively); on the contrary, the clearance (CL/F) of ABCB1 3435T carriers was significantly lower (9.5 (8.2-11.1) L/h vs. 13.6 (10.4-14.8) L/h). And the Cmax in CYP3A4*1G/*1G allele carrier subjects was higher than *1 carrier (73.4 ng/mL vs. 53.5 (46.1-60.6) ng/mL), but did not reach the level of significantly statistical difference. Genetic polymorphisms of ABCC2, ABCG2, and CYP3A5 could not influence pharmacokinetic parameters of lenvatinib. CONCLUSIONS: This work presented an evidence that the ABCB1 3435 C>T polymorphism could significantly affect the exposure and clearance of lenvatinib. These findings may explain the reasons for the huge inter-individual differences in lenvatinib, and should contribute to clinical individualized treatment.

High-Performance Liquid Chromatography for Therapeutic Drug Monitoring of Serum Lenvatinib.

BACKGROUND: Therapeutic drug monitoring (TDM) and dose adjustment of lenvatinib may be beneficial in the treatment of radioiodine-refractory thyroid cancer, by maximizing antitumor effects and minimizing adverse drug reactions. The aim of this study was, therefore, to develop and validate a high-performance liquid chromatography method using an ultraviolet detection system for routine serum lenvatinib detection in patients with thyroid cancer. METHODS: Serum specimens, spiked with an internal standard, were treated by a solid-phase extraction through an octadecylsilyl silica cartridge. Lenvatinib and internal standard were concomitantly separated from serum using a conventional octadecylsilyl silica column through isocratic elution, using a mobile phase consisting of 0.02 mol/L sodium phosphate (pH 6.7) and acetonitrile (50/50, vol/vol) at a flow rate of 1.0 mL/min. The detection wavelength was set at 244 nm. Serum samples from 5 patients were used for clinical validation of the method. RESULTS: The calibration curve for lenvatinib was linear (Pearson correlation coefficient, r = 0.9998) over the concentration range of 6.25-400 ng/mL, with a lower limit of quantification of 6.25 ng/mL. Extraction recoveries for lenvatinib were 97% or more, with coefficients of variation less than 2.2%. The coefficients of variation for intraday and interday assays were less than 4.7% and 6.0%, respectively. CONCLUSIONS: This sensitive high-performance liquid chromatography method can be used for lenvatinib therapeutic drug monitoring when liquid chromatography-tandem mass spectrometry facilities are unavailable.

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: Ccap = 1.04×Cven+4.20 (R2 = 0.832) without transformation of data, and lnCcap = 1.01×lnCven+0.0125, (R2 = 0.945) with natural logarithm transformation. The mean ratio (±SD) of Ccap/Cven 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.

LC-MS/MS assay for the quantification of foretinib in rat plasma and its application to preclinical pharmacokinetic study.

A simple and sensitive ultra-high-performance liquid chromatography tandem mass spectrometric method was developed and validated for the determination of foretinib in rat plasma. The analyte and internal standard were extracted from the bio-samples with acetonitrile and then separated on an Acquity UPLC BEH C18 column (50 × 2.1 mm, 1.7 µm) using 0.1% formic acid aqueous and acetonitrile as mobile phase, at a flow rate of 0.4 ml/min. The mass detection was performed in positive selected reaction monitoring mode with precursor-to-product transitions at m/z 317.1 > 128.1 for foretinib and m/z 502.2 > 323.1 for internal standard. The assay was demonstrated to be linear in the concentration range of 0.5-1000 ng/ml, with correlation coefficient >0.999. The mean extraction recovery of foretinib from rat plasma was within the range of 84.55-88.09%, while the matrix effect was in the range of 88.56-99.21%. The intra- and inter-day precisions were <12.95% and the accuracy ranged from -7.55 to 8.57%. Foretinib was stable in rat plasma under the tested storage conditions. The validated assay was successfully applied to the pharmacokinetic study of foretinib in the rats. The results revealed that foretinib showed moderate elimination half-life, low clearance and dose-independent pharmacokinetic profiles inrats.