Human Pharmacokinetic Studies Research Articles

First promising non-stimulant (guanfacine) transdermal patch for long-acting treatment of ADHD by solid dispersion technique

Guanfacine (GFC) extended-release tablet (Intuniv®) is an effective non-stimulant medication prescribed for attention deficit hyperactivity disorder (ADHD), presenting limitations regarding patient compliance and safety risks. The study aimed to design a novel long-acting transdermal delivery system of GFC to address these issues. Polyvinylpyrrolidone (PVP)-GFC solid dispersions were constructed by the co-evaporation method to improve drug-loading capacity to approximately 10 % (w/w). A PVP-GFC ratio of 3:1 was determined to prevent drug crystallization and promote rapid dissolution. The mechanisms underlying solid dispersion formation were revealed by XRD, DSC, molecular docking, FTIR, and Raman imaging. Hydrogen-bond interactions between PVP and GFC played a crucial role. The prescription and preparation process were optimized using single-factor and Box-Behnken design experiments. The optimized patch exhibited excellent crystallization resistance and adhesion for at least six months. Additionally, superior rheology, mechanical strength, in vitro drug release, and percutaneous permeation characteristics were observed. In human pharmacokinetic studies, the therapeutic efficacy, skin safety, and adhesion of transdermal patches were initially demonstrated for the three-day treatment of ADHD. Therefore, the innovative work expands the comprehension of solid dispersion techniques and facilitates the industrialization and commercialization of the first non-stimulant transdermal patches, providing a promising alternative for ADHD therapy.

Simultaneous quantification of baloxavir marboxil and its active metabolite in human plasma using UHPLC-MS/MS: Application to a human pharmacokinetic study with different anticoagulants

Baloxavir marboxil (BXM) is a cap-dependent nucleic acid endonuclease inhibitor, which exerts its antiviral effects after being metabolized to its active form baloxavir acid (BXA). Ethylenediamine tetra-acetic acid (EDTA) and heparin are the two most used anticoagulants in clinical blood sample collection to estimate drug levels in plasma. However, compared to heparin plasma, there is a lack of clinical pharmacokinetic data of BXA using EDTA anticoagulant tubes for blood collection. In the present study, an efficient, rapid, and sensitive ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) method was developed and validated for simultaneous quantification of BXM and its active metabolite BXA in human plasma with its isotopic baloxavir-d5 (BXA-d5) as internal standard (IS). Plasma samples (50 μL) were undergone using acetonitrile containing 0.1 % formic acid a precipitant. Chromatographic separation was achieved by a Waters XBridge®C8 (2.1 mm × 50 mm, 2.5 µm) column. The gradient mobile phase was 0.1 % formic acid in water (A, pH 2.8) and 0.1 % formic acid in acetonitrile (B) and delivered at a flow rate of 0.6 mL/min for 4.5 min. BXM and BXA were monitored using a positive electrospray triple quadrupole mass spectrometer (TRIPLE QUAD™ 6500+) via multiple reaction monitoring mode. The mass-to-charge ratios (m/z) were 572.2→247.0, 484.2→247.0 and 489.2→252.0 for BXM, BXA, and BXA-d5 (IS). Calibration curves exhibited excellent linearity in the range of 0.1–10 ng/mL for BXM (r2 > 0.996), and 0.3–300 ng/mL for BXA (r2 > 0.998). Within-run and between-run precisions in coefficients of variations were less than 11.62 % for BXM and less than 7.47 % for BXA, and accuracies in relative error were determined to be within −7.78 % to 5.70 % for BXM and −6.67 % to 8.56 % for BXA. Extraction recovery efficiency was 92.76 % for BXM, 95.32 % for BXA, and 99.26 % for BXA-d5, respectively. The matrix effect of BXM and BXA was in line with the requirements, where the relative deviation of the accuracy was less than 6.67 % and the precision was less than 6.69 %. The validated efficient and simple UHPLC-MS/MS method was successfully used in the pharmacokinetic study of BXM and BXA in healthy human volunteers with K2EDTA and heparin tubes for blood collection. EDTA might compete with BXA for chelating metal ions and thereby decrease the plasma ratio in whole blood, leading to approximately 50 % lower measurement of pharmacokinetic parameters as compared with those obtained from heparin plasma anticoagulant tubes.

389 Combination Therapy With Paclitaxel, Carboplatin, and Low-Intensity Ultrasound for Recurrent Glioblastoma: Rationale for Ongoing Phase II Clinical Trial

INTRODUCTION: We recently participated in Phase 1/2 clinical trials where patients with recurrent glioblastoma received surgery for resection of the tumor followed by implantation of an ultrasound device (SonoCloud-9, Carthera, Lyon, France) into a window in the skull for subsequent repeated blood-brain barrier (BBB) opening and concomitant delivery of chemotherapy. Intraoperative experiments demonstrated a 4-6-fold increase in the brain concentration of paclitaxel (NCT04528680) and carboplatin (NCT03744026) after BBB disruption. METHODS: We analyzed the cytotoxicity of paclitaxel and carboplatin in vitro against five human cell lines and six patient-derived xenografts (PDX) as monotherapy and in combination at concentrations derived from our human intraoperative pharmacokinetic studies. Synergy was assessed using the Loewe model and survival benefit was evaluated in two xenografts where drugs were delivered with ultrasound. We also examined the effects on cell cycle progression, DNA damage, and apoptosis. RESULTS: Cell lines exhibited non-overlapping susceptibility to paclitaxel and carboplatin, with 27% being exclusively susceptible to one drug. The combination covered 81% of cell lines, demonstrating synergy in 55% of cell lines. Notably, paclitaxel, carboplatin, and ultrasound proved more effective than monotherapy in two xenograft models. Combination therapy led to distinct effects on cell cycle progression and enhanced DNA damage and apoptosis. CONCLUSIONS: Combination therapy may be more effective than monotherapy, as has been shown in other cancers, due to synergy and independent susceptibility to each drug in glioma cell lines. This strategy is currently under investigation in an ongoing phase II clinical trial to further evaluate the safety and efficacy of this approach in patients with recurrent glioblastoma (NCT04528680).

A validated LC-MS/MS method for determination of Molnupiravir and Favipiravir in human plasma; Assessment of the remarkable potential synergistic effect against SARS-CoV-2 Infection: Application to a pharmacokinetic study in healthy Egyptian volunteers

Several clinical trials were carried out to find the route for an efficient therapy against SARS-CoV-2 infection. Mono- and dual therapy of various antivirals were investigated and found to have a clinical benefit in infected patients. Some of these antivirals are Molnupiravir (MOL) and Favipiravir (FAV), both drugs were evaluated for combined antiviral activity in some recent clinical trials. In this study, an efficient, simple, and rapid LC-MS/MS method for simultaneous determination of N-hydroxycytidine (NHC), MOL active metabolite, and FAV in human plasma of healthy volunteers was developed. Plasma protein precipitation was performed using acetonitrile. Compounds’ separation was achieved using Agilent Zorbax Eclipse plus C18, 4.6 × 150 mm, 3.5 µm and an isocratic elution of a mobile phase composed of methanol − 0.2 % acetic acid (10:90, v/v) at a flow rate of 0.5 mL/min using pyrazinamide as an internal standard (IS). Drugs were quantified using API 6500 + Qtrap mass spectrometer employing a selective ion mode combining a positive and negative ESI interface. The bioanalytical method was validated in accordance with the US-FDA bioanalytical guidance. The calibration range for both NHC and FAV was 10.0–––10000.0 ng/mL computed via weighted linear regression approach (1/x2). The proposed method could be applied to support the upcoming clinical studies for therapeutic drug monitoring of patients undergoing dual combination therapy as the latter combination proved more efficacious and powerful tool for the complete treatment of SARS-CoV-2 cases. Finally, the suggested bioanalytical method was efficiently utilized in human pharmacokinetic study of NHC and FAV, after simultaneous co-administration, in healthy volunteers.

DDDR-23. COMBINATION THERAPY WITH PACLITAXEL, CARBOPLATIN, AND LOW-INTENSITY ULTRASOUND FOR RECURRENT GLIOBLASTOMA: RATIONALE FOR ONGOING PHASE II CLINICAL TRIAL

Abstract We recently participated in phase 1/2 clinical trials where patients with recurrent glioblastoma received surgery for tumor resection followed by implantation of an ultrasound device into a skull window for subsequent repeated blood-brain barrier opening and concomitant delivery of chemotherapy (Sonabend et al., Lancet Oncology). Intraoperative experiments demonstrated a 3.7 to 5.9-fold increase in the brain concentration of paclitaxel (NCT04528680) and carboplatin (NCT03744026). Building on the pharmacokinetics and safety of these trial results, and the historical use of paclitaxel and carboplatin as a combination in other cancers, we investigated the efficacy of this combination in glioblastoma models. First, we analyzed the cytotoxicity of both drugs in vitro against five human cell lines and six patient-derived xenografts as monotherapy and in combination at concentrations derived from our human intraoperative pharmacokinetic studies. Cell lines exhibited little overlap in susceptibility to the drugs, with 27% being exclusively susceptible to one of the two drugs tested. The combination covered 81% of cell lines, compared to 54% covered with monotherapy. We also assessed for synergy using the Loewe model and recorded synergy in 55% of cells. We then evaluated the benefit of this combination in vivo in two xenograft models (MES83 and GBM6) where drugs were administered with ultrasound. Combination therapy proved more effective than monotherapy with either of the drugs, led to distinct effects on cell cycle progression and enhanced DNA damage and apoptosis. We conclude that the addition of carboplatin to paclitaxel may be more effective than monotherapy with paclitaxel, which we performed in our phase 1 trial. This combination is supported by its efficacy in other cancers, and the synergy and independent susceptibility to each drug in glioma models. The safety and efficacy of this approach are currently under investigation in an ongoing phase II trial for patients with recurrent GBM (NCT04528680).

Sensitivity of Pharmacokinetics to Differences in the Particle Size Distribution for Formulations of Locally Acting Mometasone Furoate Suspension-Based Nasal Sprays.

To assess bioequivalence of locally acting suspension-based nasal sprays, the U.S. FDA currently recommends a weight-of-evidence approach. In addition to in vitro and human pharmacokinetic (PK) studies, this includes a comparative clinical endpoint study to ensure equivalent bioavailability of the active pharmaceutical ingredient (API) at the site of action. The present study aimed to assess, within an in vitro/in vivo correlation paradigm, whether PK studies and dissolution kinetics are sensitive to differences in drug particle size for a locally acting suspension-based nasal spray product. Two investigational suspension-based nasal formulations of mometasone furoate (MF-I and MF-II; delivered dose: 180 μg) differed in API particle size and were compared in a single-center, double-blind, single-dose, randomized, two-way crossover PK study in 44 healthy subjects with oral charcoal block. Morphology-directed Raman spectroscopy yielded volume median diameters of 3.17 μm for MF-I and 5.50 μm for MF-II, and dissolution studies showed that MF-II had a slower dissolution profile than MF-I. The formulation with larger API particles (MF-II) showed a 45% smaller Cmax and 45% smaller AUC0-inf compared to those of MF-I. Systemic bioavailability of MF-I (2.20%) and MF-II (1.18%) correlated well with the dissolution kinetics, with the faster dissolving formulation yielding the higher bioavailability. This agreement between pharmacokinetics and dissolution kinetics cross-validated both methods and supported their use in assessing potential differences in slowly dissolving suspension-based nasal spray products.

Sex Differences in Plasma, Adipose Tissue, and Central Accumulation of Cannabinoids, and Behavioral Effects of Oral Cannabis Consumption in Male and Female C57BL/6 Mice.

Cannabis edibles are an increasingly popular form of cannabis consumption. Oral consumption of cannabis has distinct physiological and behavioral effects compared with injection or inhalation. An animal model is needed to understand the pharmacokinetics and physiological effects of oral cannabis consumption in rodents as a model for human cannabis edible use. Adult male and female C57BL/6 mice received a single dose of commercially available cannabis oil (5 mg/kg Δ⁹-tetrahydrocannabinol [THC]) by oral gavage. At 0.5, 1, 2, 3, and 6 hours post exposure, plasma, hippocampus, and adipose tissue were collected for THC, 11-OH-THC, and THC-COOH measures. We report delayed time to peak THC and 11-OH-THC concentrations in plasma, brain, and adipose tissue, which is consistent with human pharmacokinetics studies. We also found sex differences in the cannabis tetrad: (1) female mice had a delayed hypothermic effect 6 hours post consumption, which was not present in males; (2) females had stronger catalepsy than males; (3) males were less mobile following cannabis exposure, whereas female mice showed no difference in locomotion but an anxiogenic effect at 3 hours post exposure; and (4) male mice displayed a longer-lasting antinociceptive effect of oral cannabis. Oral cannabis consumption is a translationally relevant form of administration that produces similar physiological effects as injection or vaping administration and thus should be considered as a viable approach for examining the physiological effects of cannabis moving forward. Furthermore, given the strong sex differences in metabolism of oral cannabis, these factors should be carefully considered when designing animal studies on the effects of cannabis.

Therapeutic Potential of Genistein: Preclinical Studies, Clinical Evidence, and Nanotechnology Application.

Genistein (4',5,7-trihydroxyisoflavone) is a natural plant-derived phytoestrogen that can be found, for example, in soybean seeds. Genistein is present mainly in the human diet and is a common precursor in the antimicrobial phytoalexins biosynthesis and phytoanticipins in vegetables. The interest in genistein has increased due to its pharmacological effects, including anti-cancer activity, neuroprotective effects, cardiovascular protection, anti-inflammatory effects, antioxidant activity, and prevention of obesity. The most challenging issue for improving genistein is its low oral bioavailability, which has led to many animal and human pharmacokinetic studies and numerous clinical trials. Several drug delivery systems have been developed to protect and stabilize genistein to overcome the challenge of low bioavailability. This work concerns a revision of the literature reporting nano and microformulations for genistein encapsulation, including lipid nanoparticles, liposomes, tocotrienol-rich nanoemulsions, polymeric nanoparticles, dextran complexes, chitosan complexes, and Fe3O4 nanoparticles with carboxymethylated chitosan. Regarding the enormous potential of genistein, several clinical trials and marketed formulations can be found in the market.

Validation of a method for itraconazole and major metabolite hydroxyitraconazole for LC-MS/MS analysis with application in a formulation clinical study

A high-performance liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed for the analysis of itraconazole (ITZ) and hydroxyitraconazole (ITZ-OH) as part of a human pharmacokinetic study of novel tablet formulations. We demonstrated that 100 µL of plasma sample can be used with a protein precipitation extraction by optimizing different composition of acid in organic solvent for the precipitation solvent, giving comparable recovery to more time-consuming liquid-liquid or solid phase extractions. Additionally, we have shown that by monitoring the halogen isotopic peak for ITZ as well as optimizing chromatographic conditions, we are able to avoid carryover and endogenous interferences, allowing for a lower limit of quantification for our study. We validated the method to quantify ITZ and ITZ-OH from 1 to 250 ng/mL in human plasma and applied this to a formulation research clinical study (NCT04035187). This is the first itraconazole study to demonstrate robustness of the assay by performing interference testing of over-the-counter and common co-administered medications. We are also the first publication to perform incurred sample reanalysis (ISR) at the conclusion of a 672 sample clinical study to show reproducibility of assay performance.

Interaction of Statins with Grapefruit Juice

Grapefruit juice, which discovered to interact with felodipine for the first time, is now known to interact with more that 80 drugs. Statins are among the drugs that interact with grapefruit juice. Grapefruit juice-statin interactions were first investigated in 1998 in human pharmacokinetic studies with lovastatin and simvastatin. The pharmacokinetic and pharmacodynamic basis of the interaction has been extensively investigated in studies. Flavonoids and furanocoumarins, the main components of grapefruit juice, have been reported to cause drug interactions. Furthermore, statin-grapefruit juice interactions occur mostly through inhibition of cytochrome-3A4 (CYP3A4), to a lesser extent through inhibition of P-glycoprotein (P-gp) and organic anion transporting polypeptides (OATPs). Changes in plasma drug levels as a result of interaction may increase the side-effect of statins or reduce their therapeutic efficacy. Therefore, patients using statins are generally advised to avoid grapefruit juice consumption.

A novel method to estimate the absorption rate constant for two-compartment model fitted drugs without intravenous pharmacokinetic data.

The in vivo performances of most drugs after extravascular administration are fitted well with the two-compartment pharmacokinetic (PK) model, but the estimation of absorption rate constant (ka) for these drugs becomes difficult during unavailability of intravenous PK data. Herein, we developed a novel method, called the direct method, for estimating the ka values of drugs without using intravenous PK data, by proposing a new PK parameter, namely, maximum apparent rate constant of disposition (kmax). The accuracy of the direct method in ka estimation was determined using the setting parameters (k12, k21, and k10 values at high, medium, and low levels, respectively) and clinical data. The results showed that the absolute relative error of ka estimated using the direct method was significantly lower than that obtained using both the Loo-Riegelman method and the statistical moment method for the setting parameters. Human PK studies of telmisartan, candesartan cilexetil, and tenofovir disoproxil fumarate indicated that the ka values of these drugs were accurately estimated using the direct method based on good correlations between the ka values and other PK parameters that reflected the absorption properties of drugs in vivo (Tmax, Cmax, and Cmax/AUC0-t). This novel method can be applied in situations where intravenous PK data cannot be obtained and is expected to provide valuable support for PK evaluation and in vitro-in vivo correlation establishment.

Abstract 5667: CYT-303 FLEX-NKTM engager dose response efficacy mechanisms in HCC tumor model and safety in cynomolgus monkey toxicology studies support clinical evaluation in hepato-cellular carcinoma

Abstract BACKGROUND: CYT-303 is a multifunctional bispecific NK engager (NKE) targeting NK cell activating receptor NKp46 and tumor antigen Glypican-3 (GPC3) expressed in HCC (hepatocellular carcinoma). Cytovia’s proprietary FLEX-NKTM platform utilizes a novel FLEX-linker and human IgG1 back bone to allow for simultaneous binding to targeted cancer cells and NK cells. We evaluated CYT-303 dose response pharmacology efficacy mechanisms in HCC tumor models and conducted safety assessment studies in cynomolgus monkeys to support first in human clinical studies in HCC patients. METHODS: CYT-303 dose response pharmacology mechanistic studies were conducted in NSG-hIL-15 mice bearing Hep3B tumors and flow cytometry was used to assess bold and tumor NK cells. A 4-week CYT-303 repeat dose GLP toxicology study in cynomolgus monkeys at 6, 20 and 60 mg/kg dose was conducted following weekly intravenous infusions followed by a 6-week recovery period. CYT-303 toxicokinetic and anti-drug antibody (ADA) assessments were conducted using validated immunoassays. RESULTS: CYT-303 dose response in HCC tumor models showed increased tumor growth inhibition at the lower 2-3 mg/kg doses compared to higher 5-10 mg/kg doses consistent with the dose response previously reported in NK cell redirected cytotoxicity assays against HCC tumors. The increased anti- tumor efficacy observed at the lower doses were associated increased infiltration of PBNK’s to the tumor and corresponding reductions in PBNK’s in blood suggesting CYT-303 facilitates PBNK entry and retention in HCC tumors expressing GPC3 tumor antigen. CYT-303 safety assessment in the 4-week toxicology study in cynomolgous monkeys showed no treatment related toxicities or cytokine release and the NOAEL was determined to 60 mg/kg/week the highest dose administered in the study. No treatment related clinical signs, clinical pathology (hematology and clinical chemistry) and anatomic pathology (macroscopic, microscopic and organ weights) changes were observed. CYT-303 toxicokinetic analysis showed dose dependent increases in Cmax and AUC’s and no evidence for CYT-303 accumulation. CYT-303 anti-drug antibodies in monkeys were minimal and only observed in one low dose animal (1 out of 22) which also showed reduced CYT-303 exposures. Based on these pharmacology and toxicology results a pharmacologically active dose (PAD) based approach together with pharmacokinetic modeling would be utilized to estimate first in human dosing in HCC patients. CONCLUSIONS: CYT-303 efficacious doses identified in the HCC model together with safety in cynomolgus monkeys and planned human pharmacokinetic modeling studies support clinical evaluation of CYT-303 in first in human HCC clinical trials. Citation Format: Vishal Khairnar, Christine Waters, Solgalim Diaz, David De Franco, Jean Kadouche, Daniel Teper, Wei Li, Antonio Arulanandam. CYT-303 FLEX-NKTM engager dose response efficacy mechanisms in HCC tumor model and safety in cynomolgus monkey toxicology studies support clinical evaluation in hepato-cellular carcinoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5667.

Development and validation of two bioanalysis methods for the determination of etimicin in human serum and urine by liquid chromatography-tandem mass spectrometry: Applications to a human pharmacokinetic and breakpoint study.

Etimicin is a fourth-generation aminoglycoside antibiotic. It has potent activity and low toxicity when employed for the treatment of Gram-negative and Gram-positive bacterial infections. The pharmacokinetics of etimicin in humans have not been elucidated completely. Two liquid chromatography-tandem mass spectrometry (LC-MS/MS) bioanalytical methods, without the use of any ion-pairing reagents, were developed and validated for the quantification of etimicin in human samples of serum and urine. Using a deuterated reagent as the internal standard, analytes in serum and urine samples were extracted by protein precipitation and dilution before LC-MS/MS analysis, respectively. For the two methods, chromatographic separations were undertaken under isocratic elution of water-ammonia solution-acetic acid (96:3.6:0.2, v/v/v) and methanol at 50%:50% and a flow rate of 0.35ml/min within 5min. A Waters XTerra MS C18 column (2.1 × 150mm, 3.5μm) and a column temperature of 40°C were chosen. A Sciex Qtrap 5500 mass spectrometer equipped with an electrospray ion source was used in both methods under multiple-reaction monitoring in positive-ion mode. The two methods showed good linearity, accuracy, and precision with high recovery and a minimal matrix effect in the range of 50.0-20000ng/ml for serum samples and 50.0-10000ng/ml for urine samples, respectively. Carry-over effects were not observed. Etimicin remained stable in human samples of serum or urine under the storage, preparation, and analytical conditions of the two methods. These two simple and reliable methods were applied successfully to a dose-escalation, phase I clinical trial of etimicin in Chinese healthy volunteers after intravenous administration of single and multiple doses. Based on these two methods we ascertained, for the first time, the comprehensive pharmacokinetics of etimicin in humans, which will be used for the exploration of the breakpoint research further.

In vitro-based prediction of human plasma concentrations of food-related compounds.

Efforts have been made to replace animal experiments in safety evaluations, including in vitro-based predictions of human internal exposures, such as predicting peak plasma concentration (Cmax) values for xenobiotics and comparing these values with in vitro-based toxicity endpoints. Herein, the authors predicted the Cmax values of food-related compounds in humans based on existing and novel in vitro techniques. In this study, 20 food-related compounds, which have been previously reported in human pharmacokinetic or toxicokinetic studies, were evaluated. Human induced pluripotent stem cell-derived small intestinal epithelial cells (hiPSC-SIEC) and Caco-2 cells, HepaRG cells, equilibrium dialysis of human plasma, and LLC-PK1 cell monolayer were used to assess intestinal absorption and availability, hepatic metabolism, unbound plasma fraction, and secretion and reabsorption in renal tubular cells, respectively. After conversion of these parameters into human kinetic parameters, the plasma concentration profiles of these compounds were predicted using in silico methods, and the obtained Cmax values were found to be between 0.017 and 183 times the reported Cmax values. When the in silico-predicted parameters were modified with in vitro data, the predicted Cmax values came within 0.1-10 times the reported values because the metabolic activities of hiPSC-SIECs, such as uridine 5’-diphospho-glucuronosyl transferase, are more similar to those of human primary enterocytes. Thus, combining in vitro test results with the plasma concentration simulations resulted in more accurate and transparent predictions of Cmax values of food-related compounds than those obtained using in silico-derived predictions alone. This method facilitates accurate safety evaluation without the need for animal experiments.

A Validated UHPLC-MS/MS Method for Determination of Nalbuphine in Human Plasma and Application for Pharmacokinetic Study of Patients Undergoing General Anesthesia.

Nalbuphine was a semisynthetic opioid analgesic widely used in the treatment of both acute and chronic pain. We developed and validated a rapid, simple and sensitive method by ultra-performance liquid chromatography-tandem mass spectrometry (MS/MS) for the simultaneous quantitation of nalbuphine in human plasma, and we reported the pharmacokinetic features of patients during general anesthesia for abdominal surgery. Sample separation was achieved on a Kinetex Phenyl-Hexyl column (50 × 2.1mm, 1.7μm) after simple protein precipitation with acetonitrile. The mobile phase was composed of acetonitrile and 3mM of ammonium acetate aqueous solution with 0.1% formic acid. Gradient elution was used in 4.5min with a flow rate of 0.5mL/min at 40°C. MS detection using AB Sciex QTRAP 5500 mass spectrometer was characterized by electrospray ionization for positive ions in multiple reaction monitoring mode. Quantitative ion pairs were m/z 358.4→340.1 for nalbuphine and m/z 340.0→268.3 for nalmefene, which were used as the internal standard (IS). The calibration curves showed good linearity (r2>0.99) over concentration range of 0.1-500ng/mL. The intra-and inter-batch precisions were within 10.67%, and accuracy ranged from 94.07 to 105.34%. The IS-normalized matrix factors were 1.02-1.03 with RSD% (≤5.82%). The recoveries ranged from 101.09 to 106.30%. In conclusion, a rapid, simple, sensitive and economical analytical method was developed and validated to detect the concentration in plasma samples obtained from patients receiving nalbuphine intravenous injection and was successfully applicated to human pharmacokinetic studies of nalbuphine.

LC-MS/MS-based metabolite quantitation of the antiviral prodrug baloxavir marboxil, a new therapy for acute uncomplicated influenza, in human plasma: Application to a human pharmacokinetic study

Baloxavir marboxil (BXM) is a novel orally administrated prodrug for the treatment of acute uncomplicated influenza. In the present study, a bioanalytical LC-MS/MS method was developed and validated for the quantification of baloxavir acid (BXA), the active form of baloxavir marboxil in plasma of healthy volunteers using dolutegravir as an internal standard (IS) following plasma protein precipitation with acetonitrile. BXA and the internal standard were chromatographically separated using Waters Xterra® MS C8 column (5 µm, 4.6 × 50 mm) and a mobile phase comprised of 10.0 mM ammonium formate pH 3.5 and acetonitrile (80:20, v/v) delivered at a flow rate of 0.6 mL/min. The transitions of m/z 484.00 → 247.0 and 420.30 → 277.1 for BXA and IS, respectively in multiple reaction monitoring (MRM) mode in a positive ESI interface were used for quantitation through triple-quad mass spectrometry, API 4000. The method linearity was proven across the concentration range of 0.5–200.0 ng/mL, adjusted, and validated completely in accordance with the bioanalytical guidelines of the United States-FDA. Finally, the present method was effectively applied for the pharmacokinetic study of BXA in healthy human volunteers with accepted reproducibility and ruggedness.

A Physiologically-Based Pharmacokinetic Model of the Brain Considering Regional Lipid Variance.

Modeling and simulation of the central nervous system provides a tool for understanding and predicting the distribution of small molecules throughout the brain tissue and cerebral spinal fluid (CSF), and these efforts often rely on empirical data to make predictions of distributions to move toward a better mechanistic understanding. A physiologically based pharmacokinetic model presented here incorporates multiple means of drug distribution to assemble a model for understanding potential factors that may determine the distribution of drugs across various regions of the brain, including both intra- and extracellular regions. Two classes of parameters are presented. The first concerns regional gross anatomic variability of the brain; the second concerns estimation of unbound fractions of drugs using know membrane phospholipid heterogeneity derived from regional lipid content. The model was then tested by comparing its outcomes to data from published human pharmacokinetic studies of acetaminophen, morphine, and phenytoin. The alignment of model predictions in the plasma, CSF, and tissue concentrations with the published data from studies of those three drugs suggests that the model can be a template for identifying drug localization in the brain. Clearly, knowledge of differentiated drug distribution in the brain is a requisite step in postulating pharmacodynamic and certain disease mechanisms. SIGNIFICANCE STATEMENT: This study concerns the application of heterogenous lipid distribution in brain tissue to predict regional variations in drug distribution in the brain via a mathematical model, thus expanding upon the current understanding of mechanisms of drug distribution in the central nervous system.

FORMULATION AND CHARACTERIZATION OF ODT USING DIFFERENT CO-PROCESS CONTAINING DACLATSVIR: IN VITRO AND IN VIVO PHARMACOKINETICS STUDY ON HEALTHY VOLUNTEERS FOR HEPATITIS C TREATMENT

Objective: This study aimed to prepare and evaluate oral disintegrating tablets (ODTs) of Daclatasvir dihydrochloride (DCV) using different co-processed excipients to enhance drug dissolution and improve oral bioavailability for the treatment of hepatitis C infection. Methods: Ten Daclatasvir-ODTs formulae were prepared using co-processed excipients via direct compression. The prepared formulae were evaluated according to taste masking, weight variation, thickness, friability, hardness, drug content, and wetting time. In vitro disintegration time, in vivo disintegration time, and in vitro dissolution tests were also evaluated and taken as parameters for the selection of the best formula. The selected best formula was subjected to an in vivo study on volunteers and compared to a marketed product. Results: All DCV-ODTs had acceptable physical properties in accordance with pharmacopeial standards. DCV-ODTs prepared with Pharmaburst® (F10) recorded the shortest wetting time (14±0.08s), fastest in vitro disintegration time (46±0.16s), shortest in vivo disintegration time (27±0.16s), and attained the fastest onset of dissolution (94.3±0.03 %) at 5 min to all other excipients and has been identified as the best formula. The in vivo pharmacokinetic study showed that the Pharmaburst-based formula has a significant Cmax increase of (2.17±0.28 μg/ml) compared to (1.42±0.59) for the marketed product and a significant decrease of Tmax to 60 min instead of 110 min for the marketed product. Conclusion: The in vivo pharmacokinetic study in humans showed that the ODTs was found to be appropriate for delivery of Daclatasvir with a faster drug absorption rate when compared to the marketed products with applicable taste related to the nature of dosage form.

A Pharmacokinetic Dose-Optimization Study of Cabotegravir and Bictegravir in a Mouse Pregnancy Model.

Animal pregnancy models can be useful tools to study HIV antiretroviral safety and toxicity and to perform mechanistic studies that are not easily performed in humans. Utilization of clinically relevant dosing in these models improves the relevance of the findings. Cabotegravir and bictegravir are new integrase strand transfer inhibitors (INSTIs), recently approved for the treatment of people living with HIV. Studies of these drugs in pregnancy are very limited. The objective of this study was to perform a dose-optimization study of cabotegravir and bictegravir in a mouse pregnancy model with the goal of determining the dose that would yield plasma drug concentrations similar those observed in humans. Pregnant mice were administered increasing doses of cabotegravir or bictegravir in combination with emtricitabine and tenofovir by oral gavage from gestational day 11.5 to 15.5. Drug concentrations in the maternal plasma at 1 h and 24 h post drug administration and in the amniotic fluid at 1 h post drug administration were determined using high-performance liquid chromatography coupled with tandem mass spectrometry. A review of cabotegravir and bictegravir human pharmacokinetic studies are also reported. We hope these data will encourage studies of HIV antiretroviral safety/toxicity and mechanistic studies in animal pregnancy models.

Caffeine and Methylliberine: A Human Pharmacokinetic Interaction Study

Introduction: Methylliberine and theacrine are methylurates found in the leaves of various Coffea species and Camellia assamica var. kucha, respectively. We previously demonstrated that the methylxanthine caffeine increased theacrine’s oral bioavailability in humans. Methods: Consequently, we conducted a double-blind, placebo-controlled pharmacokinetic study in humans administered methylliberine, theacrine, and caffeine to determine methylliberine’s pharmacokinetic interaction potential with either caffeine or theacrine. Subjects received an oral dose of either methylliberine, caffeine, methylliberine plus caffeine, or methylliberine plus theacrine using a randomized, double-blind, crossover design. Blood samples were analyzed using UPLC-MS/MS. Results: Methylliberine exhibited linear pharmacokinetics that were unaffected by co-administration of either caffeine or theacrine. However, methylliberine co-administration resulted in decreased oral clearance (41.9 ± 19.5 vs. 17.1 ± 7.80 L/hr) and increased half-life (7.2 ± 5.6 versus 15 ± 5.8 hrs) of caffeine. Methylliberine had no impact on caffeine’s maximum concentration (440 ± 140 vs. 458 ± 93.5 ng/mL) or oral volume of distribution (351 ± 148 vs. 316 ± 76.4 L). Conclusions: We previously demonstrated theacrine bioavailability was enhanced by caffeine, however, caffeine pharmacokinetics were unaffected by theacrine. Herein, we found that methylliberine altered caffeine pharmacokinetics without a reciprocal interaction, which suggests caffeine may interact uniquely with different methylurates.