Plasma Pharmacokinetic Profiles Research Articles

Safety, Tolerability, and Pharmacokinetic Profile of the Novel Translocator Protein 18 kDa Antagonist ONO-2952 in Healthy Volunteers

PurposeTo investigate safety, tolerability, and pharmacokinetic properties of single and multiple doses of novel translocator protein 18 kDa antagonist ONO-2952 in healthy subjects. MethodsDouble-blind, placebo-controlled single (SAD) and multiple (MAD) dose escalation studies were conducted. Healthy men and women aged 18 to 55 years inclusive and without history of psychiatric disorders were eligible. Forty-eight volunteers received single doses of ONO-2952 (3, 10, 30, 100, 200, or 400 mg) or placebo under fasted conditions (SAD study), and 36 received ONO-2952 (30, 60, or 100 mg/d) or placebo for 21 consecutive days under fed conditions (MAD study). ONO-2952 10 and 200 mg were administered under fasted and fed conditions in the SAD study to investigate the effect of food on the absorption of ONO-2952. Safety assessments included adverse events, vital signs, 12-lead ECGs, and clinical laboratory evaluations. Plasma and urine pharmacokinetic profiles of ONO-2952 were determined. FindingsAcross both studies, mean age ranged from 29.8 to 39.8 years, most participants were white, and the proportion of female volunteers was 52%. No treatment or dose-related trends in adverse events were observed. The most frequent adverse events were headache and presyncope (n = 2 each [SAD study]) and constipation and headache (n = 3 each [MAD study]). All headache and constipation episodes were possibly related to the study drug. Plasma ONO-2952 concentrations peaked 2.5 to 3.5 hours (SAD study) and 3.0 to 4.0 hours (MAD study) postdose. ONO-2952 systemic exposure increased less than dose proportionally under fasted conditions. Fed conditions significantly increased exposure compared with fasted conditions: geometric mean ratios of Cmax (90% CIs) were 229% (176–299 [10 mg]) and 778% (623–971 [200 mg]), and AUClast were 159% (131–192 [10 mg]) and 382% (288–506 [200 mg]). In the MAD study, the systemic exposure of ONO-2952 increased in a slightly greater than dose-proportional manner. Geometric mean accumulation ratios (95% CI) of AUC24 were 2.50 (2.09–2.98 [30 mg]), 2.23 (1.85–2.68 [60 mg]), and 2.73 (2.10–3.55 [100 mg]); and Cmax were 1.65 (1.43–1.90 [30 mg]), 1.56 (1.31–1.85 [60 mg]), and 1.85 (1.38–2.49 [100 mg]). ImplicationsONO-2952 was safe and well tolerated in these early clinical studies investigating safety, tolerability, and pharmacokinetic properties of single and multiple doses. ONO-2952 systemic exposure increased in a less than dose-proportional manner under fasted conditions and in a slightly greater than dose-proportional manner under fed conditions. These results support the progression of ONO-2952 to further studies in humans.SAD study: ClinicalTials.gov identifier: NCT01364441. MAD study: ClinicalTrials.gov identifier: NCT01489345.

Metabolism and plasma pharmacokinetics of isoorientin, a natural active ingredient, in Sprague-Dawley male rats after oral and intravenous administration

1. Several pharmacological effects have been revealed on isoorientin, suggesting its potential medicinal prospects. The metabolic and plasma pharmacokinetic profiles of isoorientin were investigated in rats.2. For intra-gastric gavage, parent drug and three metabolites were detected in urine and feces by HPLC–MS/MS, but only one metabolite was found in plasma and identified as isoorientin 3′- or 4′-O-sulfate (M1) according to MS and UV absorbance spectra.3. After a single i.v. administration of isoorientin (5, 10, or 15 mg/kg B.W.) in rats, linear pharmacokinetic property was observed with favorable terminal half-lives (1.67 ± 1.32–2.07 ± 0.50 h). After a single p.o. administration of isoorientin (150 mg/kg B.W.) in rats, plasma isoorientin concentration was low, but the concentration of M1 was comparatively high. Low systemic exposure of oral isoorientin in rats could result from its low aqueous solubility and extensive first-pass metabolism, and plasma concentration of M1 can be used as a biomarker of isoorientin intake. Isoorientin showed low oral bioavailability (8.98 ± 1.07%), and had about 6% or 45% dose recovery in urine or feces, respectively, 72 h after intra-gastric gavage.4. These studies are the first to describe the pharmacokinetics of isoorientin via i.v. or p.o. dosing, providing important information for understanding its process in vivo.

Differential cytochrome P450 2D metabolism alters tafenoquine pharmacokinetics.

Cytochrome P450 (CYP) 2D metabolism is required for the liver-stage antimalarial efficacy of the 8-aminoquinoline molecule tafenoquine in mice. This could be problematic for Plasmodium vivax radical cure, as the human CYP 2D ortholog (2D6) is highly polymorphic. Diminished CYP 2D6 enzyme activity, as in the poor-metabolizer phenotype, could compromise radical curative efficacy in humans. Despite the importance of CYP 2D metabolism for tafenoquine liver-stage efficacy, the exact role that CYP 2D metabolism plays in the metabolism and pharmacokinetics of tafenoquine and other 8-aminoquinoline molecules has not been extensively studied. In this study, a series of tafenoquine pharmacokinetic experiments were conducted in mice with different CYP 2D metabolism statuses, including wild-type (WT) (reflecting extensive metabolizers for CYP 2D6 substrates) and CYPmouse 2D knockout (KO) (reflecting poor metabolizers for CYP 2D6 substrates) mice. Plasma and liver pharmacokinetic profiles from a single 20-mg/kg of body weight dose of tafenoquine differed between the strains; however, the differences were less striking than previous results obtained for primaquine in the same model. Additionally, the presence of a 5,6-ortho-quinone tafenoquine metabolite was examined in both mouse strains. The 5,6-ortho-quinone species of tafenoquine was observed, and concentrations of the metabolite were highest in the WT extensive-metabolizer phenotype. Altogether, this study indicates that CYP 2D metabolism in mice affects tafenoquine pharmacokinetics and could have implications for human tafenoquine pharmacokinetics in polymorphic CYP 2D6 human populations.

Pharmacokinetics of aconitine-type alkaloids after oral administration of Fuzi (Aconiti Lateralis Radix Praeparata) in rats with chronic heart failure by microdialysis and ultra-high performance liquid chromatography–tandem mass spectrometry

Ethnopharmacological relevanceFuzi [the lateral root of Aconitum carmichaeli Debx (Ranunculaceae)] is a well-known traditional medicinal herb used to treat chronic heart failure (CHF). Aconitine-type alkaloids are major alkaloids that are responsible for the pharmacological activity and toxicity of this herb.To investigate therapeutic effects and pharmacokinetic profiles of aconitine-type alkaloids in CHF rats. Materials and methodsThe plasma pharmacokinetic profiles of aconitine, mesaconitine, and hypaconitine were investigated after once treatment of Fuzi extract (containing aconitine 0.086mg/g, mesaconitine 0.84mg/g, and hypaconitine 1.97mg/g) using a rapid and sensitive combinative method of ultra-high performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) and microdialysis (MD). The cardiac function and antioxidant enzyme activities were also evaluated. ResultsRecoveries of MD sampling ranged from 35.06% to 45.74% with RSD below 6.05%. Fuzi extract improved the myocardial function and antioxidant enzymatic activities of rats with CHF. Aconitine, mesaconitine, and hypaconitine exhibited slower absorption into the bloodstream, and yielded 11-fold less values of area under concentration–time curve (AUC) in the CHF rats than those in normal rats. The plasma AUC showed that the maximum blood concentration (Cmax) was 5.561ng/mL for aconitine, 17.30ng/mL for mesaconitine, and 17.78ng/mL for hypaconitine in normal rats, while these were 0.6059ng/mL, 2.430, and 0.7461ng/mL in CHF rats, respectively. ConclusionAconitine-type alkaloids associated with Fuzi׳s efficacy have lower intake and slower elimination in the CHF rats, indicating a non-interdependent relationship between its efficacy and toxicity. It may contribute to the depth understanding of the toxicological and pharmacological profiles of Fuzi and further benefit the herbal drug development with safety and efficacy for CHF treatment.

Differential CYP 2D6 metabolism alters primaquine pharmacokinetics.

Primaquine (PQ) metabolism by the cytochrome P450 (CYP) 2D family of enzymes is required for antimalarial activity in both humans (2D6) and mice (2D). Human CYP 2D6 is highly polymorphic, and decreased CYP 2D6 enzyme activity has been linked to decreased PQ antimalarial activity. Despite the importance of CYP 2D metabolism in PQ efficacy, the exact role that these enzymes play in PQ metabolism and pharmacokinetics has not been extensively studied in vivo. In this study, a series of PQ pharmacokinetic experiments were conducted in mice with differential CYP 2D metabolism characteristics, including wild-type (WT), CYP 2D knockout (KO), and humanized CYP 2D6 (KO/knock-in [KO/KI]) mice. Plasma and liver pharmacokinetic profiles from a single PQ dose (20 mg/kg of body weight) differed significantly among the strains for PQ and carboxy-PQ. Additionally, due to the suspected role of phenolic metabolites in PQ efficacy, these were probed using reference standards. Levels of phenolic metabolites were highest in mice capable of metabolizing CYP 2D6 substrates (WT and KO/KI 2D6 mice). PQ phenolic metabolites were present in different quantities in the two strains, illustrating species-specific differences in PQ metabolism between the human and mouse enzymes. Taking the data together, this report furthers understanding of PQ pharmacokinetics in the context of differential CYP 2D metabolism and has important implications for PQ administration in humans with different levels of CYP 2D6 enzyme activity.

Enantioselective Pharmacokinetics of Primaquine in Healthy Human Volunteers

Primaquine (PQ), a racemic drug, is the only treatment available for radical cure of relapsing Plasmodium vivax malaria and blocking transmission of P. falciparum malaria. Recent studies have shown differential pharmacologic and toxicologic profiles of individual PQ enantiomers in rodent, dog, and primate animal models. This study was conducted in six healthy adult human volunteers to determine the plasma pharmacokinetic profile of enantiomers of PQ and carboxyprimaquine (cPQ), the major plasma metabolite. The individuals were orally administered PQ diphosphate, equivalent to 45-mg base, 30 minutes after a normal breakfast. Blood samples were collected at different time intervals, and plasma samples were analyzed for enantiomers of PQ and cPQ. Plasma PQ concentrations were low and variable for both parent enantiomers and peaked around 2-4 hours. Peak (-)-(R)-PQ concentrations ranged from 121 ng/ml to 221 ng/ml, and peak (+)-(S)-PQ concentrations ranged from 168 ng/ml to 299 ng/ml. The cPQ concentrations were much higher and were surprisingly consistent from subject to subject. Essentially all the cPQ detected in plasma was (-)-cPQ. The peak concentrations of (-)-cPQ were observed at 8 hours (range: 1104-1756 ng/ml); however, very high concentrations were sustained through 24 hours. (+)-cPQ was two orders of magnitude lower than (-)-cPQ, and in a few subjects it was detected but only under the limit of quantification. In vitro studies with primary human hepatocytes also suggested more rapid metabolism of (-)-PQ compared with (+)-PQ. The results suggest more rapid metabolism of (-)-PQ to (-) cPQ compared with (+)-PQ. Alternatively, (+)-PQ or (+)-cPQ could be rapidly converted to another metabolite(s) or distributed to tissues. This is the first clinical report on enantioselective pharmacokinetic profiles of PQ and cPQ and supports further clinical evaluation of individual PQ enantiomers.

Evaluating plasma pharmacokinetics of intravenous iron formulations: judging books by their covers?

Intravenous (IV) iron formulations provide a clinical treatment option for patients when iron supplementation is required but oral administration is unsuitable because of intolerance or lack of efficacy. IV iron use is increasing worldwide, especially in the chronic kidney disease (CKD) population [1]. Pharmacokinetic (PK) analysis of IV iron formulations is challenging unless the compound can be directly measured or it is manufactured with a radiolabelled form of iron (e.g. Fe) to distinguish the IV iron formulation from endogenous serum iron [2]. It is also not well appreciated by clinicians that IV iron formulations exhibit zero-order or capacity-limited metabolism by the reticuloendothelial system [3]. This results in longer residence time in plasma with higher administered doses, especially with larger molecular weight formulations [3]. Commercially available IV iron formulations consist of an iron oxyhydroxide core surrounded by carbohydrate shells of various sizes and polysaccharide branch characteristics in colloidal suspensions [4]. The size of commercially available IV iron–carbohydrate complexes range from 5 to 100 nm and thus meet the definition for nanoparticles, enhancing the complexity of PK studies of these agents [4]. In this issue of Clinical Pharmacokinetics, MuellerPlock et al. [5] evaluate plasma ferumoxytol data from healthy subjects and CKD patients, using a population PK approach seeking to bridge the PK profiles between populations with iron deficiency anaemia. This is arguably one of the larger PK analyses of IV iron plasma data to date, and ferumoxytol offers the distinct advantage of being able to be directly measured by nuclear magnetic resonance. The authors show that, as previously published, ferumoxytol plasma concentration–time profiles were best fitted with a two-compartment model with nonlinear elimination, consistent with the known capacity-limited metabolism by the reticuloendothelial system [3]. A limitation of Mueller-Plock et al.’s analysis, as well as the collective published data on IV iron plasma PK, is that these data likely represent an oversimplification of the PK profile of IV iron–carbohydrate complexes. Ferumoxytol is a superparamagnetic iron oxide nanoparticle (SPION), which was originally developed for use in magnetic resonance imaging (MRI). Biodistribution data for SPIONs demonstrate that different carbohydrate shell structures determine the relative uptake by endothelial and lymphatic cells, as well as by the reticuloendothelial system [6]. Thus, analysis of only short-term plasma PK provides limited information on the ultimate disposition and fate of these agents. Ultimately, the complexity of IV iron–carbohydrate nanoparticle formulations has important implications with regard to both efficacy and safety in treatment of iron deficiency anaemia. These agents have not been well studied with regard to comparative biodistribution, metabolic fate, and potential extracellular and intracellular deposition profiles, and further evaluation of these agents is urgently needed. Analysing short-term plasma data to infer IV iron–carbohydrate PK profiles has been typically acceptable for IV iron registry trials; however, on the basis of the SPION data in the MRI literature, these agents exhibit complicated PK and pharmacodynamic (PD) profiles, which can differ vastly between agents because of carbohydrate shell heterogeneity [6]. Thus, although shortterm plasma PK profiles among groups of healthy and This comment refers to the article available at doi:10.1007/s40262-014-0203-9.

Empirical and semi-mechanistic modelling of double-peaked pharmacokinetic profile phenomenon due to gastric emptying.

Models have been developed to explain double-peaked plasma concentration-time profiles using mechanisms such as variable absorption and enterohepatic recirculation. Interruption of gastric emptying has also been shown to produce double-peaks, and this work proposes models for analysis of such data. In the presence of levodopa, gastric emptying is interrupted at times associated with double-peaks in pharmacokinetic profiles. Data from a simultaneous scintigraphy and paracetamol absorption study with levodopa was obtained, and models with compartments for stomach, intestine, central and peripheral tissue were developed to describe levodopa and paracetamol pharmacokinetics, including the double-peak phenomenon. The empirical model uses two gastric emptying parameter rates which are applied over separate time periods to describe the varying gastric emptying rate. The semi-mechanistic model uses a feedback mechanism acting via an effect compartment to link the plasma concentration of levodopa to the rate of gastric emptying, allowing levodopa pharmacokinetics to vary the rate of gastric emptying and give rise to a multiple-peaked plasma pharmacokinetic profile. The models were applied to plasma levodopa and paracetamol pharmacokinetic data with and without simultaneous analysis of scintigraphy data, in both cases giving a good fit and in the absence of scintigraphy data adequately predicting the stomach profile. For the semi-mechanistic model, the first-order constant governing gastric emptying was shown to switch between fast and slow values at a critical levodopa effect compartment concentration. New models have thus been proposed for analysis of plasma concentration profiles that exhibit double-peak phenomenon and applied successfully to levodopa data.

A novel GC-MS method for determination of chrysophanol in rat plasma and tissues: Application to the pharmacokinetics, tissue distribution and plasma protein binding studies.

The purpose of this study was to explore the plasma protein binding (PPB), pharmacokinetics profiles and tissue distribution of chrysophanol in rats. Biological samples were extracted by ethyl ether, separated and determined by a novel, sensitive and specific GC-MS method under selected ion monitoring (SIM) mode for the first time. This method was validated for the quantification of chrysophanol, in the range of 0.005-1.50μgmL-1 in rat plasma and 0.04-12μgmL-1 in tissue homogenates, respectively. The limit of detection (LOD) was 0.4ngmL-1 or 5.0ngg-1, which obtained excellent sensitivity for the pharmacokinetics analysis in rats. The intra- and inter-day assay of precisions in plasma and tissues were less than 10% and the intra- and inter-day accuracies were 82.1-92.9%. The method recoveries of all samples were more than 90%, except for liver samples (>80%), which indicated that chrysophanol may be partly metabolized in liver homogenates. The PPB rates in rat plasma, human plasma and bovine serum albumin were 83±2, 88±3 and 58±3%, respectively. The main pharmacokinetic parameters were the time of peak concentration (Tmax)=(0.665±0.034) h, the peak concentration (Cmax)=(929.8±102.7)ngmL-1, the area under the curve (AUC)=(1197.6±258.5)nghmL-1 and the clearance (CL)=(0.013±0.0028)mLmg-1h-1. The tissue distribution of chrysophanol in rats after the oral administration showed a decreasing tendency in different tissues (heart>kidney>spleen>liver>lung>cerebrum).

Safety, tolerability, pharmacokinetics, and pharmacodynamics of single-dose antiinterleukin- 18 mAb GSK1070806 in healthy and obese subjects.

To investigate the safety, tolerability, pharmacokinetics, and pharmacodynamics of GSK1070806, a novel IgG1 mAb that neutralizes human interleukin (IL)-18. In this first-timein-human (FTIH) study, cohorts of healthy and obese subjects were randomly allocated to receive single doses of GSK1070806 (0.008 - 10 mg/kg) or placebo. Blood was sampled ≤ 274 days post-dosing, and safety monitored. GSK1070806 was generally well tolerated. The most common AEs were nasopharyngitis and headache, arising as frequently in the placebo as in the active drug groups; most AEs were mild to moderate and unrelated to dose level. There were no allergic, delayed-type hypersensitivity, or infusion-related reactions and the incidence of immunogenicity was low. GSK1070806 plasma pharmacokinetic profiles were comparable in healthy and obese subjects; there was no major deviation from dose proportionality for AUC(∞) and C(max) although a trend for dose-dependent increase in t(1/2) was observed. Serum drug-bound IL-18 levels increased post-dosing and were sustained for a long time-period following GSK1070806 administration. Ex-vivo whole blood assay demonstrated prolonged pharmacological activity of GSK1070806 as determined by its primary immunological mechanism of action, inhibition of IL-18-induced IFN-γ production. GSK1070806 warrants clinical investigation in patients.

Abstract 4578: A novel polymer-anticancer drug micelle formulation showing enhanced efficacy over Abraxane

Abstract Advances in the development of novel nanocarriers and their applications in the area of drug delivery have inspired and created new opportunities for anticancer formulation development. About 10 anticancer nanomedicines in various dosage forms of liposomes and polymeric micelles have been approved since 1995, with albumin-bound paclitaxel (Abraxane) being a milestone in the treatment of a variety of aggressive cancers. These nanomedicines outperform the low molecular weight anticancer chemotherapeutic agents by their favorable pharmacokinetics and tissue distribution, resulting in improved efficacy and concomitantly decreased systematic side effect. We have developed a novel linear water soluble polymeric nano-carrier, poly-(L-γ-glutamylglutamine) (PGGA) by addition of a hydrophilic glutamic acid layer onto a poly-(L-glutamic acid) backbone. PGGA is proved to be versatile as nanocarrier for making both polymer drug conjugates as well as polymeric micelle formulations. By incorporating an appropriate hydrophobic moiety to PGGA backbone, a novel series of PGGA-based polymer hydrotrope is created and utilized in producing stable paclitaxel-encapsulated polymeric micelles (PMs). A lead candidate, designated as NittoX, has been identified from a matrix of such PMs varying in encapsulated paclitaxel and conjugated hydrophobic moiety contents. For NittoX bioperformance, an outstanding anticancer efficacy is observed in NCI-H460 lung cancer xenograft. Dose response is evident and NittoX is able to completely suppress tumor growth at the dosage of 80 mg/kg. More importantly, NittoX is statistically significantly more efficacious than Abraxane at the same dose levels. Dosages are well tolerated by animals in terms of body weight loss and survival. In addition to NCI-H460, NittoX is also found efficacious in a variety of tumor models, including pancreatic cancer. The improved performance is even more evident when administrated with multiple-dose regimens. The improved efficacy is presumably attributed to its superior plasma and tumor pharmacokinetic profile. NittoX not only enhances circulation stability over Abraxane, but also demonstrates preferential tumor PK profile with three-fold elevation of Cmax and AUC(0-168h) as compared to Abraxane. Meanwhile, the results from pharmacodynamic analysis of tubulin polymerization alteration and consequent tumor cell proliferation inhibition are in accordance with in vivo tumor efficacy data. Strong correlation between tumor PK and PD is observed. These preclinical data undoubtedly suggest that NittoX has potential to become a more potent taxane nanomedicine superior to Abraxane. Citation Format: Wenbin Ying, Jihua Liu, Kwok Yin Tsang, Li Wang, Haiqing Yin, Hao Bai, Yuwei Wang, Liping Wang, Yoshiro Niitsu. A novel polymer-anticancer drug micelle formulation showing enhanced efficacy over Abraxane. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4578. doi:10.1158/1538-7445.AM2014-4578

Abstract CT221: The effect of food on the oral bioavailability of the novel PARP 1/2 inhibitor BMN 673 in healthy male subjects

Abstract Introduction: BMN 673 is a novel, potent (IC50 < 1.0 nM in vitro) inhibitor of Poly(ADP-ribose) polymerase (PARP) 1 and PARP 2 in clinical development for the treatment of genetically defined cancers. Methods: The effect of food on the oral bioavailability of BMN 673 was evaluated in 18 healthy male subjects who received a single 0.5 mg dose of BMN 673 following an overnight fast (fasted condition) and a single 0.5 mg dose of BMN 673 following a high-fat, high-calorie meal (fed condition) in a randomized two-sequence, two-period crossover design. Serial blood samples were collected to determine plasma pharmacokinetic (PK) profiles out to 21 days postdose during each treatment period. Urine samples to determine BMN 673 urine concentrations were collected out to 48 hours postdose during each treatment period. The relative bioavailability under fed and fasted conditions was determined using a linear mixed effects model fitted to the log-transformed PK parameters Cmax, AUC0-t, and AUC0-∞. A nonparametric Koch test was used to evaluate the effect of food on Tmax. Results: Food delayed the absorption of orally-administered BMN 673, as indicated by a prolonged Tmax and reduced Cmax under fed compared to fasted conditions, but did not affect the overall extent of absorption, as indicated by similar AUC0-t and AUC0-∞ values under fed and fasted conditions. Comparing fed (test) to fasted (reference) conditions, the treatment difference median (90% CI) in Tmax was 2.63 hours (2.13 to 3.13 hours), the geometric least squares mean (GLSM) ratio (90% CI) in Cmax was 54% (48% to 60%), and the GLSM ratios (90% CI) in AUC0-t and AUC0-∞ were 98% (92% to 103%) and 98% (92% to 103%), respectively. Mean values of the amount of BMN 673 excreted in the urine were similar under fed and fasted conditions. There were no clinically significant findings in vital signs, clinical laboratory evaluations, ECGs, or physical examinations during the study. The incidence and types of adverse events (AEs) were similar following administration of BMN 673 in the fed and fasted conditions. Importantly, there were no SAEs and no withdrawals due to AEs. Conclusions: A high-fat, high-calorie meal delayed the absorption of orally-administered BMN 673, but did not affect the overall extent of absorption. Single 0.5 mg doses of BMN 673 were safe and well tolerated in healthy male subjects in the fed and fasted conditions. Based on these results, BMN 673 can be administered with or without food. Citation Format: Joshua Henshaw, Huiyu Zhou, Don Musson, Charles O'Neill, Randall Stoltz, Andrew Dorr. The effect of food on the oral bioavailability of the novel PARP 1/2 inhibitor BMN 673 in healthy male subjects. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr CT221. doi:10.1158/1538-7445.AM2014-CT221

Abstract 4293: Whole-body bio-distribution of anti-5T4-mcMMAF (anti-5T4-ADC) using fluorescence molecular tomography (FMT) imaging in a non-small cell lung cancer mice model

Abstract Introduction: Currently bio-distribution of biologic drugs is evaluated by PET imaging, autoradioraphy using radio-labeled molecules or ex vivo methods. Advances in optical probes and non-invasive imaging technologies have given us an opportunity to conduct such studies without the use of radio-labeled materials or by traditional pharmacokinetic (PK) studies. 5T4 (also known as TPBG or oncofetal antigen) is a transmembrane glycoprotein expressed highly on tumor-initiating cells. Anti-5T4-mcMMAF used in these studies is an anti-5T4-antibody drug conjugate (ADC) that reacts to human, cyno and marmoset orthologs of 5T4. Previously, we showed the efficacy of anti-5T4-ADC in pre-clinical models (Sapra et al.,). In this study we show the utility of Fluorescence Molecular Tomography (FMT) imaging in bio-distribution studies with this ADC using a H1975 non-small cell lung cancer (NSCLC) xenograft model. Methods: For the H1975 xenograft model, five million cells in 50% matrigel were injected into the subcutaneous flanks of the female nu/nu mice, and a biodistribution study was initiated when the tumors reached ∼500 mm3. The anti-5T4-ADC and a control ADC (non-binding) were conjugated with near-IR fluorophore VivoTag680XL. The labeling efficiency and quality was determined by Nanodrop-8000 spectrophotometer and binding assays. FMT imaging was performed longitudinally at 5min, 6hr, 24hr, 48hr, 96hr and 240hrs post injection of labeled ADCs. Ex vivo imaging of organs was performed at intermittent time points after perfusing with PBS. Data was analyzed using TrueQuant software. Plasma and tissues were collected at various time points and analyzed by GyrolabTM workstation and LCMS methods. Results: VivoTag680XL conjugation was efficient and achieved degree of labeling between 2-3. Three-dimensional quantitative analysis of FMT data showed significant specific targeting of anti-5T4-ADC to the tumors (ex vivo and in vivo comparison), relative to the control non-binding ADC. The peak accumulation in tumor was observed at 48hrs post injection and the concentration decreased in later time points. Liver was the major organ for the non-specific accumulation of these antibodies/ADCs, followed by kidneys and lung. Both 5T4-ADC and Control-ADC showed similar accumulation at 48hrs and 96hrs in liver, whereas it decreased significantly at 240hrs. The FMT imaging data was comparative and correlated with the traditional plasma PK profile data. Conclusion: These results show that anti-5T4-ADC targets the tumor better than non-binding ADC. This study also shows the utility of FMT in bio-distribution studies of biologics. Since the fluorophore can be conjugated to any protein/peptide, this novel approach can become a platform technology in conducting biodistribution studies of all biologic drugs. Citation Format: Anand Giddabasappa, Rand Norberg, Mauricio Leal, David Paterson, Kush Lalwani, Ted Levkoff, Stella Rapa, Puja Sapra, Michael Ritche, Joann Wentland, Brian Rago, Jeetendra Eswaraka. Whole-body bio-distribution of anti-5T4-mcMMAF (anti-5T4-ADC) using fluorescence molecular tomography (FMT) imaging in a non-small cell lung cancer mice model. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4293. doi:10.1158/1538-7445.AM2014-4293

Discovery of highly potent DPP-4 inhibitors by hybrid compound design based on linagliptin and alogliptin

Highly potent DPP-4 inhibitors have been identified by hybrid compound design based on linagliptin and alogliptin. The most promising compound 2h (IC50 = 0.31 nM) exhibited 8.5-fold and 2.5-fold more potent activity than that of alogliptin (IC50 = 2.63 nM) and linagliptin (IC50 = 0.77 nM), respectively. Compound 2h had a good inhibition selectivity for DPP-4 over DPP-8/9 and thus was selected for further biological evaluation, including oral glucose tolerance, plasma DPP-4 inhibitory activity, pharmacokinetic profile, acute toxicity and hERG inhibition. The assay results showed that 2h displayed significant in vivo glucose-lowering effect and low risk of toxicity. Further studies are expected to confirm 2h as a potential drug candidate for the treatment of type 2 diabetes.

Pharmacokinetic comparisons of five ephedrine alkaloids following oral administration of four different Mahuang–Guizhi herb-pair aqueous extracts ratios in rats

Ethnopharmacological relevanceHerba Ephedra (Mahuang in Chinese), is derived from dried Ephedra sinica Stapf stems and has been widely used to treat the common cold, coughs, asthma, and edema for thousands of years. The Mahuang–Guizhi herb-pair is a famous formula composed of Mahuang and Ramulus Cinnamomi (Guizhi in Chinese, the dried twig of Cinnamomum cassia Presl.), used to improve pharmacological effects and reduce toxicity. In order to investigate the influence of Mahuang–Guizhi herb-pair ratios on bioavailability, the plasma pharmacokinetics profiles of five ephedrine alkaloids were compared following oral administration of four different ratios to rats. Materials and methodsSprague-Dawley rats were randomly assigned to four groups and orally administered Mahuang–Guizhi (ratios 3:0; 3:1; 3:2; 3:4, w/w). Assays for five ephedrine alkaloids (ephedrine, pseudoephedrine, methylephedrine, norephedrine, and norpseudoephedrine) were developed and validated using ultra-high-performance liquid chromatography tandem mass spectrometry coupled with liquid-liquid extraction. ResultsKey pharmacokinetic parameters of the five ephedrine alkaloids (maximal plasma concentration, mean residence time, and half-life) were significantly different (p<0.05) after oral administration of Mahuang–Guizhi herb-pair ratios, as compared to those of Mahuang. ConclusionEphedrine alkaloid pharmacokinetic differences in rat plasma could help explain previous findings of pharmacological and toxicity differences between Mahuang and Mahuang–Guizhi herb-pair preparations. These results could facilitate future studies to increase the efficacy and decrease the toxicity of Mahuang and Guizhi.

Systemic pharmacokinetics and cerebrospinal fluid uptake of intravenous ceftriaxone in patients with amyotrophic lateral sclerosis.

The cephalosporin antibiotic ceftriaxone was evaluated as a potential therapeutic agent for the treatment of amyotrophic lateral sclerosis (ALS). The pharmacokinetics (PK) of ceftriaxone in plasma and cerebrospinal fluid (CSF) were investigated in 66 participants in a previously reported clinical trial. Their mean age was 51 years, and 65% were male. Participants were randomly assigned to 1 of 3 treatment groups receiving intravenous infusions (mean duration: 25 minutes) every 12 hours of either: placebo and placebo; 2 g ceftriaxone and placebo; or 2 g ceftriaxone twice. Mean steady-state plasma PK variables were: volume of distribution, 14 L (0.17 L/kg); elimination half-life, 8-9 h; total clearance, 17-21 mL/min (0.22-0.25 mL/min/kg). Values were not different between dosage groups. CSF PK analysis, determined through sparse CSF sampling, indicated apparent entry and elimination half-life values of 1.0 and 34 hours, respectively. With both dosage regimens, CSF concentrations were maintained above the target threshold of 1.0 µM (0.55 µg/mL) as determined from in vitro models. The plasma and CSF PK profiles of ceftriaxone were used as a basis for planning the Phase 3 clinical trial of ceftriaxone in ALS.

Changes in pharmacokinetic profiles of acetaminophen and its glucuronide after pretreatment with combinations of N-acetylcysteine and either glycyrrhizin, silibinin or spironolactone in rat

1. The present study was to investigate the effects of giving N-acetylcysteine (NAC) alone and in combination with either glycyrrhizin (GL), silibinin (SIB) or spironolactone (SL) on the plasma pharmacokinetic (PK) profiles, hepatic exposure, biliary excretion and urinary excretion of acetaminophen (APAP) and its major metabolite, acetaminophen glucuronide (AG).2. Groups of rats (n = 5) were pretreated with oral doses of either NAC, NAC + GL, NAC + SIB or NAC + SL on five occasions every 12 h. At 1 h, after the last dose, they received APAP (200 mg/kg) by intraperitoneal injection. Blood, bile, liver and urine samples were collected at various times after APAP injection and analyzed for APAP and AG by HPLC. NAC alone and NAC + SIB did not significantly change the PK profiles of APAP and AG. In contrast, NAC + GL decreased the biliary excretion of APAP and AG leading to accumulation of APAP in the liver and systemic circulation whereas NAC + SL [multidrug resistance associated 2 (Mrp2) inducer] increased the biliary excretion of AG and decreased the hepatic exposure to APAP and AG.3. Our results suggest that Mrp2 inhibitor GL should be discouraged with NAC to treat APAP hepatotoxicity. Such PK drug–drug interactions should be considered in the treatment of APAP-induced liver injury.

Pharmacokinetics and skin concentrations of lincomycin after intravenous and oral administration to cats

The aim of the present study was to describe the plasma pharmacokinetic profile and skin concentrations of lincomycin after intravenous administration of a 15% solution and oral administration of 300 mg tablets at a dosing rate of 15 mg/kg to cats. Susceptibility of staphylococci (n = 31) and streptococci (n = 23) strains isolated from clinical cases was also determined. Lincomycin plasma and skin concentrations were determined by microbiological assay using Kocuria rhizophila ATCC 9341 as test microorganism. Susceptibility was established by the antimicrobial disc diffusion test. Individual lincomycin plasma concentration–time curves were analysed by a non-compartmental approach. After intravenous administration, volume of distribution, body clearance and elimination half-life were 0.97 L/kg ± 0.15 L/kg, 0.17 L/kg ± 0.06 L/h.kg and 4.20 h ± 1.12 h, respectively. After oral administration, peak plasma concentration, time of maximum plasma concentration and bioavailability were 22.52 µg/mL ± 10.97 µg/mL, 0.80 h ± 0.11 h and 81.78% ± 24.05%, respectively. Two hours after lincomycin administration, skin concentrations were 17.26 µg/mL ± 1.32 µg/mL (intravenous) and 16.58 µg/mL ± 0.90 µg/mL (oral). The corresponding skin: plasma ratios were 2.08 ± 0.47 (intravenous) and 1.84 ± 0.97 (oral). The majority of staphylococci and streptococci tested in this study were susceptible to lincosamides (87.09% and 69.56%, respectively). In conclusion, lincomycin administered orally at the assayed dose showed a good pharmacokinetic profile, with a long elimination half-life and effective skin concentration. Therefore, it could be a good first option for treating skin infections in cats.

The effectiveness of borneol on pharmacokinetics changes of four ginsenosides in Shexiang Baoxin Pill in vivo

Shexiang Baoxin Pill (SBP) is a traditional Chinese medicine, widely used for cardiovascular diseases in the clinic. Ginsenosides are important effective components in SBP, but their pharmacokinetic characteristics are still not known. In this paper, we studied the pharmacokinetics of ginsenoside Rb1, Rc, Re and Rg1 in SBP and investigated the effect of borneol on the pharmacokinetic characteristic of ginsenosides based on an Agilent G6410A triple quadrupole LC/MS system. Results showed that the pharmacokinetic parameters of ginsenoside Rb1, Rc, Re and Rg1 in rat plasma after oral administration of SBP are significantly different with oral administration of SBP without Borneolum Syntheticum. Plasma pharmacokinetic profiles after oral administration of ginsenoside Rb1, Rc, Re, Rg1 and co-administration with borneol at three different ratios (10:1, 1:1 and 1:10 ginsenoside vs borneol, w/w) were also determined. It was demonstrated that borneol can elevate the plasma concentration of ginsenosides after co-admininstration.

Usefulness of oral loading of oxcarbazepine suspension in selected patients with epilepsy

Oral loading of oxcarbazepine tablet is effective and well tolerated to adequately achieve the therapeutic levels of its active metabolite, 10,11-dihydro-10-hydroxy-carbazepine (monohydroxy derivative, MHD) in epilepsy patients. The present study was performed to investigate the safety, tolerability, and pharmacokinetic profiles of oral loading of oxcarbazepine suspension in epilepsy patients with a high risk of recurrent seizures. Oxcarbazepine suspension was administered orally at a single loading dose of 30 mg/kg to 38 adult patients with recurrent seizures, who required rapid seizure control or temporarily discontinued antiepileptic drugs for diagnostic or pre-surgical evaluation. Plasma concentrations of oxcarbazepine and MHD were determined, and adverse events were assessed at 2, 4, 6, 8, 10, 12, 14, 16, and 24 hours after oral loading of oxcarbazepine suspension. 30 patients experienced ≥ 1 adverse event during the first 24 hours after oral loading of oxcarbazepine (e.g., dizziness, transient diplopia, nausea or vomiting), most of which occurred within 4 hours after loading, suggesting no temporal association with MHD plasma levels. 35 (92.1%) patients were still compliant with a maintenance dose of oxcarbazepine after discharge from hospital. 34 (89.4%) patients reached the lower therapeutic level of MHD (12 mg/l) at 4 hours after oral loading of oxcarbazepine suspension, which lasted up to 24 hours in most patients. No patient reached the supratherapeutic levels of MHD (> 35 mg/l) during the study. The mean plasma concentration-time curves and pharmacokinetic profiles of oral loading of oxcarbazepine suspension were similar to those of oral loading of oxcarbazepine tablet. Oral loading of oxcarbazepine suspension followed by maintenance dosing is well tolerated and effective in steadily achieving the therapeutic level of MHD in selected patients with epilepsy.