Individualized medication of venetoclax based on therapeutic drug monitoring in Chinese acute myeloid leukemia patients using an HPLC method.

OBJECTIVE: The aim of this study was to establish a simple and sensitive high-performance liquid chromatography method for therapeutic drug monitoring of venetoclax (VEN) and optimize regimens. METHODS: The analysis required the extraction of a 50 µl plasma sample and the precipitation of proteins using acetonitrile extraction. The chromatographic method employed a mobile phase of acetonitrile: 0.5% KH 2 PO 4 (pH 3.5) (60/40, v/v) on a Diamond C 18 (4.6 mm × 250 mm, 5 µm) column at a flow rate of 1.0 ml/min. The quantitative method was validated based on standards described in 'Bioanalytical Method Validation: Guidance for Industry' published by the US Food and Drug Administration (FDA). RESULTS: The calibration curve was linear ( R2  = 0.9998) over the range of 75-4800 ng/ml, with limits of quantification of 25 ng/ml. The coefficients of intraday and interday validation, specificity, recovery, and stability all met the criteria of FDA guidance. The method was successfully applied to analyze VEN concentrations in 30 cases of acute myeloid leukemia patients. The peak concentration ( Cmax ) was 1881.19 ±â€…756.61 ng/ml, while the trough concentration ( Cmin ) was 1212.69 ±â€…767.92 ng/ml in acute myeloid leukemia patients. CONCLUSION: Our study establishes a simple, precise, and sensitive high-performance liquid chromatography method for monitoring VEN and confirms its applicability for therapeutic drug monitoring of VEN in hematological cancers.

LC-MS/MS method for quick detection of vonoprazan fumarate in human plasma: Development, validation and its application to a bioequivalence study.

A liquid chromatography-tandem mass spectrometry method with vonoprazan fumarate-d4 as a stable isotope-labeled internal standard was developed and validated aiming at quantification of vonoprazan fumarate in human plasma for a bioequivalence study. Chromatographic separation was achieved by acetonitrile one-step protein precipitation using a gradient elution of 0.1% formic acid aqueous solution and acetonitrile with a run time of 3.65 min. Detection was carried out on a tandem mass spectrometer in multiple reaction monitoring mode via a positive electrospray ionization interface. The multiple reaction monitoring mode of precursor-product ion transitions for vonoprazan fumarate and vonoprazan fumarate-d4 were m/z 346.0 → 315.1 and 350.0 → 316.0, respectively. The linear range was 0.150-60.000 ng/ml. This method was fully validated with acceptable results in terms of selectivity, carryover, lower limit of quantification, calibration curve, accuracy, precision, dilution effect, matrix effect, stability, recovery and incurred sample reanalysis. A successful application of this method was realized in the bioequivalence study of vonoprazan fumarate tablet (20 mg) among healthy Chinese volunteers.

Pharmacokinetic evaluation of oral deracoxib in geese (Anser anser domesticus).

The integration of pain management in veterinary practice, driven by heightened animal welfare concerns, extends to avian species where subtle and nonspecific behavioral signs pose challenges. Given that safety concerns with classical NSAIDs highlight the need for more targeted alternatives in birds, this study explores the pharmacokinetic (PK) properties of Deracoxib (DX), a COX-2 selective NSAID approved for use in dogs, following a single oral administration in geese. Six healthy female geese received 4 mg/kg DX. Blood was drawn from the left wing vein to heparinized tubes at 0, 0.25, 0.5, 0.75, 1, 1.5, 2, 4, 6, 8, 10, and 24 h. Plasma DX concentrations were measured using HPLC coupled to an UV detector, and the data were pharmacokinetically analyzed using PKanalix™ software in a non-compartmental approach. The results indicated a terminal half-life of 6.3 h and a Tmax of 1 h, with no observed adverse effects. While refraining from claiming absolute safety based on a single dose, it is worth highlighting that further safety studies for DX in geese are warranted, suggesting a possibility for intermittent use. In addition, drawing conclusions on efficacy and suitability awaits further research, particularly in understanding COX-2 selectivity and protein binding characteristics specific to geese.

A Rapid and Sensitive Liquid Chromatography-Tandem Mass Spectrometry Bioanalytical Method for the Quantification of Encorafenib and Binimetinib as a First-Line Treatment for Advanced (Unresectable or Metastatic) Melanoma-Application to a Pharmacokinetic Study.

The combination regimen targeting BRAF and MEK inhibition, for instance, encorafenib (Braftovi™, ENF) plus binimetinib (Mektovi®, BNB), are now recommended as first-line treatment in patients with unresectable or metastatic melanoma with a BRAF V600-activating mutation. Patients treated with combination therapy of ENF and BNB demonstrated a delay in resistance development, increases in antitumor activity, and attenuation of toxicities compared with the activity of either agent alone. However, the pharmacokinetic profile of the FDA-approved ENF and BNB is still unclear. In this study, a rapid and sensitive LC-MS/MS bioanalytical method for simultaneous quantification of ENF and BNB in rat plasma was developed and validated. Chromatography was performed on an Agilent Eclipse plus C18 column (50 mm × 2.1 mm, 1.8 µm), with an isocratic mobile phase composed of 0.1% formic acid in water/acetonitrile (67:33, v/v, pH 3.2) at a flow rate of 0.35 mL/min. A positive multiple reaction monitoring (MRM) mode was chosen for detection and the process of analysis was run for 2 min. Plasma samples were pre-treated using protein precipitation with acetonitrile containing spebrutinib as the internal standard (IS). Method validation was assessed as per the FDA guidelines for the determination of ENF and BNB over concentration ranges of 0.5-3000 ng/mL (r2 ≥ 0.997) for each drug (plasma). The lower limits of detection (LLOD) for both drugs were 0.2 ng/mL. The mean relative standard deviation (RSD) of the results for accuracy and precision was ≤ 7.52%, and the overall recoveries of ENF and BNB from rat plasma were in the range of 92.88-102.28%. The newly developed approach is the first LC-MS/MS bioanalytical method that can perform simultaneous quantification of ENF and BNB in rat plasma and its application to a pharmacokinetic study. The mean result for Cmax for BNB and ENF was found to be 3.43 ± 0.46 and 16.42 ± 1.47 µg/mL achieved at 1.0 h for both drugs, respectively. The AUC0-∞ for BNB and ENF was found to be 18.16 ± 1.31 and 36.52 ± 3.92 µg/mL.h, respectively. On the other hand, the elimination half-life (t1/2kel) parameters for BNB and ENF in the rat plasma were found to be 3.39 ± 0.43 h and 2.48 ± 0.24 h, and these results are consistent with previously reported values.

Relatively mild symptoms after chronic overdose with a double-dose encorafenib: a case report.

Encorafenib (Braftovi) is indicated for the treatment of adult patients with unresectable or metastatic melanoma with a BRAF V600 mutation, in combination with binimetinib (Mektovi). According to the product label of encorafenib, there are no specific treatment recommendations in case of an overdose. We report on a 63-year-old man who ingested a double dose (900 mg) of encorafenib for 16 days. He developed overall minor chronic overdose symptoms such as nausea and vomiting grade 1 and muscle pain. Based on the most occurring adverse events of encorafenib, liver values, kidney function parameters and QTc interval were measured. Kidney function parameters were normal, whereas liver values were slightly increased (grade 1) and QTc slightly prolonged. The plasma concentration 3 h after the last dose was 2110 ng/mL. We describe the course of a case with a chronic overdose during 16 days of the double dose of encorafenib as well as the followed approach, which could be taken into account when observing an encorafenib overdose. Providing information in times of Covid-19 is challenging, but remains necessary for good clinical care.

Development of a High-Throughput Quantification Method for Pazopanib Using Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry and Its Clinical Application in Patients With Soft Tissue Tumors.

BACKGROUND: Pazopanib is widely used to treat renal cell carcinomas and soft tissue tumors in Japan. Pazopanib has significant therapeutic efficacy but it is associated with frequent severe adverse effects. Therapeutic drug monitoring (TDM) may help to prevent adverse effects. A more convenient and rapid pazopanib assay is desirable for the application of TDM in clinical settings. In this study, the authors developed a high-throughput method for quantifying pazopanib in human plasma using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). METHODS: After a simple solid-phase extraction step using a 96-well plate, pazopanib was analyzed by UHPLC-MS/MS in the positive electrospray ionization mode. RESULTS: The novel method fulfilled the requirements of the US Food and Drug Administration and the European Medicines Agency guidelines for assay validation, and the lower limit of quantification was 0.5 mcg/mL. The calibration curves were linear over the concentration range of 0.5-100 mcg/mL. The average recovery rate was 102.0% ± 3.9% (mean ± SD). The precision was below 5.0%, and the accuracy was within 12.0% for all quality control levels. Matrix effect varied between 90.9% and 97.1%. This assay was successfully applied to TDM of pazopanib trough concentrations in 3 patients treated with the drug for soft tissue tumors. CONCLUSIONS: The authors succeeded in developing a novel high-throughput UHPLC-MS/MS method for quantifying pazopanib in human plasma. This method can be applied to TDM of patients receiving pazopanib in clinical settings.

Species differences in the CYP3A-catalyzed metabolism of TPN729, a novel PDE5 inhibitor.

TPN729 is a novel phosphodiesterase 5 (PDE5) inhibitor used to treat erectile dysfunction in men. Our previous study shows that the plasma exposure of metabolite M3 (N-dealkylation of TPN729) in humans is much higher than that of TPN729. In this study, we compared its metabolism and pharmacokinetics in different species and explored the contribution of its main metabolite M3 to pharmacological effect. We conducted a combinatory approach of ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry-based metabolite identification, and examined pharmacokinetic profiles in monkeys, dogs, and rats following TPN729 administration. A remarkable species difference was observed in the relative abundance of major metabolite M3: i.e., the plasma exposure of M3 was 7.6-fold higher than that of TPN729 in humans, and 3.5-, 1.2-, 1.1-fold in monkeys, dogs, and rats, respectively. We incubated liver S9 and liver microsomes with TPN729 and CYP3A inhibitors, and demonstrated that CYP3A was responsible for TPN729 metabolism and M3 formation in humans. The inhibitory activity of M3 on PDE5 was 0.78-fold that of TPN729 (The IC50 values of TPN729 and M3 for PDE5A were 6.17 ± 0.48 and 7.94 ± 0.07 nM, respectively.). The plasma protein binding rates of TPN729 and M3 in humans were 92.7% and 98.7%, respectively. It was astonishing that the catalyzing capability of CYP3A4 in M3 formation exhibited seven-fold disparity between different species. M3 was an active metabolite, and its pharmacological contribution was equal to that of TPN729 in humans. These findings provide new insights into the limitation and selection of animal model for predicting the clinical pharmacokinetics of drug candidates metabolized by CYP3A4.

Clinical Importance of Plasma Drug Concentration of Oral Molecular Targeted Drugs for Renal Cell Carcinoma.

PURPOSE: Therapeutic drug monitoring (TDM) is widely used in clinical practice to maximize drug efficacy and minimize toxicities. Currently, it is also practiced in the use of oral molecular targeted drugs. The objective of this study was to assess the clinical importance of measuring the systemic concentration of oral molecular targeted drugs used to treat renal cell carcinoma (RCC). METHODS: The systemic concentrations of the oral molecular targeted drugs sorafenib, sunitinib, axitinib, pazopanib, and everolimus used for RCC were useful for therapeutic interventions, and clinical outcomes were evaluated retrospectively. RESULTS: The interventional use of systemic drug concentration was confirmed in 26 of 87, and their categories are presented. The systemic concentration of sunitinib was useful in dose reduction and/or discontinuation (n = 10), dose escalation (n = 3), and adherence monitoring (n = 2). Nine of the 10 patients whose dose was reduced showed reduced adverse event. Two patients who were intervened in adherence monitor showed improved adherence. For axitinib, dose reduction and/or discontinuation (n = 1) and dose escalation (n = 6) were confirmed. For pazopanib, dose reduction and/or discontinuation (n = 1) and drug interaction detection (n = 1) were confirmed, both of them were confirmed to have reduced adverse events. For everolimus, dose reduction and/or discontinuation (n = 1) and drug interaction detection (n = 1) were confirmed, a patient with reduced dose recovered from adverse events. Interventions for sorafenib were not identified. CONCLUSIONS: This study demonstrated that systemic concentrations of oral molecular targeted drugs for RCC were considered to be clinically useful for dose adjustment, monitoring of treatment adherence, and the detection of drug interactions. Moreover, this information could be successfully used to guide individualized therapy to maximize the antitumor effects of these drugs.

Pharmacokinetics of S-epacadostat, an indoleamine 2,3-dioxygenase 1 inhibitor, in dog plasma and identification of its metabolites in vivo and in vitro.

S-epacadostat (S-EPA) is an efficient and selective small-molecule inhibitor of indoleamine 2,3-dioxygenase 1. It is an EPA analog with a sulfur atom instead of a nitrogen atom at the furazan C3 position. This study documents the pharmacokinetics of S-EPA in dogs and its metabolic pathway. After an oral administration of 15 mg/kg of S-EPA in dogs, the time to peak concentration was 0.80 h, the mean elimination half-life was 7.3 h, and the absolute bioavailability was 55.8%. Furthermore, we identified S-EPA metabolites in dog plasma and dog liver microsomes by UPLC-Q Exactive Orbitrap HRMS. In dog plasma, we found five metabolites, which came from glucuronidation (M1 and M2), deoxygenation (the amidine M4), glucuronidation of M4 (M3), and desulfonamidation and oxidation of M4 (the carboxylic acid M5). In dog liver microsomes, we identified three major metabolites, namely, the glucuronide conjugate (M6), a mono-oxidation product (M7), and a desulfonamidation and oxidation product (M8). Gut microbiota may cause the differences between in vivo and in vitro oxidation metabolisms. Contrary to EPA, S-EPA did not undergo dealkylation, suggesting that substituting the nitrogen with sulfur affects the metabolism of the adjacent alkyl side chain.

Drug-drug interactions of newly approved small molecule inhibitors for acute myeloid leukemia.

Several small molecule inhibitors (SMIs) have been recently approved for AML patients. These targeted therapies could be more tolerable than classical antineoplastics, but potential drug-drug interactions (DDI) are relatively frequent. Underestimation or lack of appropriate awareness and management of DDIs with SMIs can jeopardize therapeutic success in AML patients, which often require multiple concomitant medications in the context of prior comorbidities or for the prevention and treatment of infectious and other complications. In this systematic review, we analyze DDIs of glasdegib, venetoclax, midostaurin, quizartinib, gilteritinib, enasidenib, and ivosidenib. CYP3A4 is the main enzyme responsible for SMIs metabolism, and strong CYP3A4 inhibitors, such azoles, could increase drug exposure and toxicity; therefore dose adjustments (venetoclax, quizartinib, and ivosidenib) or alternative therapies or close monitoring (glasdegib, midostaurin, and gilteritinib) are recommended. Besides, coadministration of strong CYP3A4 inducers with SMIs should be avoided due to potential decrease of efficacy. Regarding tolerability, QTc prolongation is frequently observed for most of approved SMIs, and drugs with a potential to prolong the QTc interval and CYP3A4 inhibitors should be avoided and replaced by alternative treatments. In this study, we critically assess the DDIs of SMIs, and we summarize best management options for these new drugs and concomitant medications.

Effects of Concomitant Administration of Vonoprazan Fumarate on the Tacrolimus Blood Concentration in Kidney Transplant Recipients.

Vonoprazan fumarate (vonoprazan) is a new kind of acid suppressant with potent acid inhibitory effects. Therefore, it has been administered to kidney transplant recipients for treatment or prophylaxis of steroid ulcers, refractory peptic ulcers, and gastroesophageal reflux disease. Because tacrolimus, which is a well-established immunosuppressant for kidney transplantation, and vonoprazan share the CYP3A4 system for metabolism, drug interactions are anticipated upon simultaneous administration. We retrospectively analyzed 52 kidney transplant recipients who were converted from rabeprazole, which has a small effect on the tacrolimus trough blood concentration (C0), to vonoprazan between August 2016 and July 2019. We compared the tacrolimus C0/tacrolimus dose (C0/D) before and after conversion and serum liver enzymes, serum total bilirubin, and the estimated glomerular filtration rate (eGFR). As a result, mean tacrolimus C0/D before and after conversion was 1.98 ± 1.02 and 2.19 ± 1.15 (ng/mL)/(mg/d), respectively, (p < 0.001). Additionally, mean aspartate transaminase (AST) before and after conversion was 18.6 ± 4.2 and 19.6 ± 5.2 IU/L, respectively, (p = 0.037). Mean alanine transaminase (ALT) before and after conversion was 15.8 ± 5.5 and 17.6 ± 7.1 IU/L, respectively, (p = 0.007). Mean eGFR before and after conversion was 50.6 ± 14.4 and 51.4 ± 14.7 mL/min/1.73 m2, respectively (p = 0.021). Mean AST, ALT, and eGFR were slightly but significantly elevated within normal ranges after conversion. In conclusion, our study suggests that the mean tacrolimus C0/D was elevated significantly by converting from rabeprazole to vonoprazan, but it had little clinical significance. Vonoprazan can be administered safely to kidney transplant recipients receiving tacrolimus.

Possibility for Dose Optimization of Pazopanib from Its Plasma Concentration in Japanese Patients with Cancer.

The currently approved dose of pazopanib (800 mg) is being re-examined owing to its adverse effects. The aim of this study was to evaluate the relationships among starting or maintenance doses of pazopanib, estimated pazopanib Cmin, and other clinical factors, including albumin and α-1 acid glycoprotein levels, in soft-tissue sarcoma and renal cell carcinoma. We also determined whether therapeutic drug monitoring of pazopanib concentrations may be used to improve its therapeutic efficacy and prevent adverse effects. Forty patients who received pazopanib for renal cancer or soft-tissue sarcoma at the Hokkaido Cancer Center were evaluated prospectively. Cmin for pazopanib was calculated based on the measured values from the plasma samples. The efficacy and time to treatment failure were then assessed. The pazopanib maintenance doses were 200 (n = 4), 400 (n = 34), 600 (n = 4), and 800 mg (n = 1). Most patients (65%) who received a 400 mg dose had an effective pazopanib concentration (≧20 µg/mL), whereas 35% of patients who received the 400 mg dose had ineffective concentrations (<20 µg/mL). Logistic regression analysis revealed that only the albumin level was significantly associated with effective pazopanib concentrations (odds ratio: 1.37, p = 0.0234). In conclusion, a dose of 400 mg had been effective and well tolerated in more than half of patients in this study. However, therapeutic drug monitoring is necessary during pazopanib therapy.

Estimating Efflux Transporter-Mediated Disposition of Molecules beyond the Rule of Five (bRo5) Using Transporter Gene Knockout Rats.

Transporter gene knockout models are a practical and widely used tool for pharmacokinetic studies in drug discovery. P-glycoprotein (P-gp) and breast cancer resistance protein (Bcrp) are major efflux transporters that control absorption and bioavailability, and are important when determining oral drug disposition. To the best of our knowledge, beyond the rule of five (bRo5) molecules launched on the market to date tend to be substrates for efflux transporters. The purpose of this study is to evaluate in vivo the impact of efflux transporters on the oral absorption process and systemic clearance using rats which lack P-gp and/or Bcrp expression. We administered five bRo5 substrates (asunaprevir, cyclosporine, danoprevir, ledipasvir, and simeprevir) intravenously or orally to wild-type and Mdr1a, Bcrp, and Mdr1a/Bcrp knockout rats, calculated the clearance, oral bioavailability, and absorption rate profile of each substrate, and compared the results. Systemic clearance of the substrates in knockout rats changed within approximately ±40% compared to wild-types, suggesting the efflux transporters do not have a significant influence on clearance in rats. On the other hand, the oral absorption of substrates in the knockout rats, especially those lacking Mdr1a, increased greatly-between 2- and 5-fold more than in wild-types. This suggests that rat efflux transporters, especially P-gp, greatly reduce the oral exposure of these substrates. Moreover, results on the absorption rate-time profile suggest that efflux transporters are constantly active during the absorption period in rats. Transporter knockout rats are a useful in vivo tool for estimating the transporter-mediated disposition of bRo5 molecules in drug discovery.

Simultaneous quantification of ambrisentan, macitentan and sitaxentan in human plasma using UPLC-MS/MS.

Endothelin receptor antagonists (ERAs) such as, ambrisentan, macitentan and sitaxentan are primarily used for the treatment of pulmonary arterial hypertension. Considering the rise in endothelin in pre-eclampsia, ERAs may also be useful in its treatment. To evaluate the pharmacokinetics of ERAs, a rapid ultra-performance liquid chromatography tandem mass spectrometry method was developed and validated to determine the concentration of ambrisentan, macitentan and sitaxentan in human plasma. Plasma samples were treated with methanol to induce protein precipitation. A chromatographic separation was performed on a C18 column using a gradient of methanol-water containing 0.1% formic acid and 0.013% ammonium acetate and a flow rate of 0.5 ml/min. Multiple reaction monitoring was used for quantification. This method was validated in a linear range of 20.28-2028 µg/l for ambrisentan, 4.052-405.2 µg/l for macitentan and 205.4-10 270 µg/l for sitaxentan. The method was successfully validated according to US Food and Drug Administration guidelines to determine the concentrations of macitentan, ambrisentan and sitaxentan in human plasma. This method is now being used for study samples and clinical patient samples.

Improved Prediction of in Vivo Supersaturation and Precipitation of Poorly Soluble Weakly Basic Drugs Using a Biorelevant Bicarbonate Buffer in a Gastrointestinal Transfer Model.

The characterization of intestinal dissolution of poorly soluble drugs represents a key task during the development of both new drug candidates and drug products. The bicarbonate buffer is considered as the most biorelevant buffer for simulating intestinal conditions. However, because of its complex nature, being the volatility of CO2, it has only been rarely used in the past. The aim of this study was to investigate the effect of a biorelevant bicarbonate buffer on intestinal supersaturation and precipitation of poorly soluble drugs using a gastrointestinal (GI) transfer model. Therefore, the results of ketoconazole, pazopanib, and lapatinib transfer model experiments using FaSSIFbicarbonate were compared with the results obtained using standard FaSSIFphosphate. Additionally, the effect of hydroxypropyl methylcellulose acetate succinate (HPMCAS) as a precipitation inhibitor was investigated in both buffer systems and compared to rat pharmacokinetic (PK) studies with and without coadministration of HPMCAS as a precipitation inhibitor. While HPMCAS was found to be an effective precipitation inhibitor for all drugs in FaSSIFphosphate, the effect in FaSSIFbicarbonate was much less pronounced. The PK studies revealed that HPMCAS did not increase the exposure of any of the model compounds significantly, indicating that the transfer model employing bicarbonate-buffered FaSSIF has a better predictive power compared to the model using phosphate-buffered FaSSIF. Hence, the application of a bicarbonate buffer in a transfer model set-up represents a promising approach to increase the predictive power of this in vitrotool and to contribute to the development of drug substances and drug products in a more biorelevant way.

Pharmacokinetics of S-EPA, and its inhibition on indoleamine 2,3-dioxgenase: a case of sulfur-substitution affecting distributions in blood cells.

1. S-EPA is a sulfur-substitution analog of epacadostat (EPA), an effective small molecule indoleamine 2,3-dioxgenase1 (IDO) inhibitor. By in vitro and in vivo experiments, pharmacokinetic differences of two closely related analogs, S-EPA and EPA was investigated in this study. 2. Liver microsomes clearance experiments showed S-EPA had comparable metabolic stability with EPA in rat and human liver microsomes. The whole blood distribution experiments showed the distribution ratio of S-EPA in blood cells to plasma in mice, rats, dogs and monkey was 1.2, 4.8, 2.2 and 40.6, respectively. While the distribution ratio of EPA ranged from 0.94 to 1.30 in mice, rats, dogs and was 3.1 in monkeys. 3. The pharmacokinetic study in rats showed the exposure (AUClast) of S-EPA in plasma and blood cells was 1.7-fold and 3.9-fold higher than that of EPA, respectively. Moreover, the exposure ratio of S-EPA in blood cells to plasma was 3.7, while the ratio of EPA was 1.6. 4. In CT26 tumor bearing mice, the IDO inhibition of S-EPA and EPA on plasma or tumor kynurenine was generally consistent. And the inhibition ratio could reach at more than 50% at 3 h after single dose, at least lasting up to 8 h.

A novel, rapid and sensitive UPLC-MS/MS method for the determination of macitentan in patients with pulmonary arterial hypertension.

Macitentan is an endothelin receptor antagonist commonly used in the treatment of pulmonary arterial hypertension (PAH). A novel, rapid, simple and sensitive UPLC-MS/MS method was developed and validated for pharmacokinetic study and the determination of macitentan in PAH patients. Macitentan and bosentan, which are used as internal standards, were detected using atmospheric pressure chemical ionization in positive ion and multiple reaction monitoring mode by monitoring the mass transitions m/z 589.1 → 203.3 and 552.6 → 311.5, respectively. Chromatographic separation was performed on a reverse-phase C18 column (5 µm, 4.6 × 150 mm) with an isocratic mobile phase, which consisted of water containing 0.2% acetic acid-acetonitrile (90:10, v/v) at a flow rate of 1 mL/min. Retention times were 1.97 and 1.72 min for macitentan and IS, respectively. The calibration curve with high correlation coefficient (0.9996) was linear in the range 1-500 ng/mL. The lower limit of quantitation and average recovery values were determined as 1 ng/mL and 89.8%, respectively. This method is the first UPLC-MS/MS method developed and validated for the determination of macitentan from human plasma. The developed analytical method was fully validated for linearity, selectivity, specificity, accuracy, precision, sensitivity, stability, matrix effect and recovery according to US Food and Drug Administration guidelines. The developed method was applied successfully for pharmacokinetic study and the determination of macitentan in PAH patients.

Simplified LC-MS/MS method for quantification of IG-105, a novel tubulin ligand, and its application to the pharmacokinetic study in rats at the anticancer effective dose.

IG-105, N-(2, 6-dimethoxypyridine-3-yl)-9-methylcarbazole-3-sulfonamide, a novel carbazole sulfonamide, shows a potent anticancer activity in a variety of human tumor cells in vitro and in vivo. In the present study, a rapid and convenient liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed and applied to the pharmacokinetic study of IG-105 in rats. Chromatographic separation was accomplished on a C18 column using an isocratic mobile phase of acetonitrile-water-acetic acid (56:44:0.2, v/v/v). The ion transitions of IG-105 and combretastatin A4 (internal standard) in selected reaction monitoring mode were m/z 398→154 and m/z 317→286, respectively. The assay exhibited good linearity over the range of 2-512 ng/mL. Intra- and inter-day precisions were within 8.2 %, and the accuracies ranged from -6.0 to 3.7 %. The extraction recoveries were higher than 90 %, and the matrix effects were negligible. All quality control samples were stable at different storage conditions. The validated LC-MS/MS method was successfully applied to a preclinical pharmacokinetic study of IG-105 in rats after a single oral dose of 100, 250, or 1000 mg/kg which showed tumor growth inhibition activity. The absorption of IG-105 was proved to be rapid but saturated to a certain extent into the blood circulation, from where it was distributed and eliminated gradually.

Effects of Renal Impairment and Hemodialysis on the Pharmacokinetics and Safety of the Glecaprevir and Pibrentasvir Combination in Hepatitis C Virus-Negative Subjects.

Hepatitis C virus (HCV) infection is an independent risk factor for developing chronic renal impairment and end-stage renal disease. Limited treatment options are available for HCV genotype 2, 3, 5, and 6 infections in patients with an estimated glomerular filtration rate (eGFR) of <30 ml/min. Glecaprevir and pibrentasvir are active against all six major HCV genotypes, are primarily excreted in the bile, and have minimal renal elimination. Therefore, combined treatment with these direct-acting antivirals may be useful for patients with HCV infection and chronic kidney disease. A phase 1, multicenter, open-label study evaluated the effects of renal impairment on the pharmacokinetics and safety of glecaprevir-pibrentasvir. In substudy 1, 38 subjects with stage 2 to 5 chronic kidney disease who were not on dialysis or who had normal renal function received single doses of the combination of 300 mg glecaprevir and 120 mg pibrentasvir. In substudy 2, 8 subjects requiring hemodialysis received single doses of the combination of 300 mg glecaprevir and 120 mg pibrentasvir under dialysis and nondialysis conditions. Regression analyses demonstrated increased glecaprevir and pibrentasvir plasma exposures, as determined by the area under the curve, with decreasing renal function, up to 56% and 46%, respectively, in subjects with an eGFR of <15 ml/min/1.73 m2 In dialysis-dependent subjects, glecaprevir and pibrentasvir exposures were similar (≤18% difference) when study drugs were administered before hemodialysis or on a nondialysis day. Adverse events were mostly mild, with the most common being self-limited fatigue (3 subjects). The study findings support the clinical evaluation of glecaprevir-pibrentasvir without dose adjustment in HCV-infected subjects with renal impairment. (This study has been registered at ClinicalTrials.gov under registration number NCT02442258.).

Plasma trough concentrations of antiretrovirals in HIV-infected persons treated with direct-acting antiviral agents for hepatitis C in the real world.

BACKGROUND: Possible drug-drug interactions (DDIs) between antiretrovirals (ARVs) and direct-acting antiviral agents (DAAs) are of some concern. OBJECTIVES: To investigate ARV plasma trough concentrations (Ctrough) before and during DAAs in patients treated in the real world. METHODS: Single-centre, prospective, observational study including HIV/HCV coinfected persons undergoing DAA treatment. Self-reported adherence was assessed and ARVs Ctrough measured by HPLC-UV. Blood samples were collected before and after 2 months of DAA treatment. RESULTS: One-hundred and thirty-seven patients were included: 21.2% treated with ombitasvir/paritaprevir/ritonavir ± dasabuvir (2D/3D) and 78.8% with sofosbuvir-based regimens. Suboptimal Ctrough before and during DAA was found, respectively, in 3 (10.3%) and 3 (10.3%) cases treated with 2D/3D, and 16 (14.8%) and 11 (10.2%) with sofosbuvir-based regimens, even if self-reported ARV adherence was always ≥93%. In 2D/3D-treated patients, median darunavir Ctrough during DAAs was significantly lower than observed before DAAs [1125 ng/mL (IQR, 810-1616) versus 1903 ng/mL (IQR 1387-3983), respectively] (n = 5; P = 0.009), with a 40.9% decrease. In the same group, no differences in atazanavir or raltegravir concentrations were found. In patients treated with sofosbuvir-based regimens, Ctrough of all ARVs were similar before and during DAAs. CONCLUSIONS: In the real world of HIV/HCV coinfected patients, ARV plasma concentrations during DAAs were generally not different from those found before anti-HCV treatment. Although assessed in a small number of patients, darunavir concentrations during 2D/3D showed a significant reduction when compared with those found before DAAs. ARV plasma concentrations measurement during anti-HCV treatment may give useful information for managing HIV/HCV coinfected persons receiving treatment for both infections.