AUC Ratio Research Articles

Assessing Ganglion Cell Layer Topography in Human Albinism Using Optical Coherence Tomography.

PurposeTo test whether ganglion cell layer (GCL) and inner plexiform layer (IPL) topography is altered in albinism.MethodsOptical coherence tomography scans were analyzed in 30 participants with albinism and 25 control participants. Horizontal and vertical line scans were acquired at the fovea, then strip registered and averaged. The Duke Optical Coherence Tomography Retinal Analysis Program was used to automatically segment the combined GCL and IPL and total retinal thickness, followed by program-assisted manual segmentation of the boundary between the GCL and IPL. Layer thickness and area under the curve (AUC) were calculated within 2.5 mm of the fovea. Nasal-temporal and superior-inferior asymmetry were calculated as an AUC ratio in each quadrant.ResultsGCL and IPL topography varied between participants. The summed AUC in all quadrants was similar between groups for both the GCL (P = 0.84) and IPL (P = 0.08). Both groups showed nasal-temporal asymmetry in the GCL, but only participants with albinism had nasal-temporal asymmetry in the IPL. Nasal-temporal asymmetry was greater in albinism for both the GCL (P < 0.0001) and the IPL (P = 0.0006). The GCL usually comprised a greater percentage of the combined GCL and IPL in controls than in albinism.ConclusionsThe GCL and IPL have greater structural variability than previously reported. GCL and IPL topography are significantly altered in albinism, which suggests differences in the spatial distribution of retinal ganglion cells. This finding provides insight into foveal development and structure-function relationships in foveal hypoplasia.

Total, renal and hepatic clearances of doxorubicin and formation clearance of doxorubicinol in patients with breast cancer: Estimation of doxorubicin hepatic extraction ratio

Doxorubicin (DOX) is a cytotoxic drug which has remained as an essential component of chemotherapy regiment for breast cancer. The cardiotoxicity of DOX is related to the accumulation of its main metabolite doxorubicinol (DOXOL) in the cardiac tissue. Although the pharmacokinetics of DOX shows high interindividual variability, there are no significant covariates to improve dose adjustment. The present study reports the pharmacokinetics of both DOX and DOXOL in a homogeneous population of young female patients with breast cancer (n = 12) making use of a standardized drug association, evaluated in the very first chemotherapy cycle, using plasma and urine data that allowed the calculation of the renal clearance of DOX, the formation clearance of DOXOL and the hepatic clearance of DOX. The extensive data availability also made it possible to estimate the hepatic extraction ratio of DOX for the investigated population, as well as to determine DOXOL unbound fraction in plasma for the first time in humans. DOX and DOXOL simultaneous analysis in plasma, plasma ultrafiltrate, and urine were performed by liquid chromatography coupled to mass spectrometry (LC–MS/MS). The pharmacokinetics profile of both DOX and DOXOL showed high variability (geometric coefficient of variation of area under the plasma concentration versus time curve extrapolated to infinity was approximately 215 %). The geometrics means were 0.26 for DOXOL/DOX AUC ratio, 15 % and 17 % for unbound fractions of DOX and DOXOL, respectively, 30.70 L⋅h−1 for total clearance, 0.66 L⋅h−1 for renal clearance, 29.97 L⋅h−1 for hepatic clearance and 0.39 L⋅h−1 for the formation clearance of the metabolite DOXOL. The 95 % confidence interval of the estimated hepatic extraction ratio of DOX ranged from 0.14 to 0.79, which characterizes DOX as a drug of low, intermediate or high hepatic extraction ratio.

In Vitro-to-In Vivo Extrapolation of Transporter Inhibition Data for Drugs Approved by the US Food and Drug Administration in 2018.

A systematic analysis of the inhibition transporter data available in New Drug Applications of drugs approved by the US Food and Drug Administration (FDA) in 2018 (N = 42) was performed. In vitro‐to‐in vivo predictions using basic models were available for the nine transporters currently recommended for evaluation. Overall, 29 parents and 16 metabolites showed in vitro inhibition of at least one transporter, with the largest number of drugs found to be inhibitors of P‐gp followed by BCRP. The most represented therapeutic areas were oncology drugs and anti‐infective agents, each comprising 31%. Among drugs with prediction values greater than the FDA recommended cutoffs and further evaluated in vivo, 56% showed positive clinical interactions (area under the concentration‐time curve ratio (AUCRs) ≥ 1.25). Although all the observed or simulated inhibitions were weak (AUCRs < 2), seven of the nine interactions (involving five drugs) resulted in labeling recommendations. Interestingly, more than half of the drugs with predictions greater than the cutoffs had no further evaluations, highlighting that current basic models represent a useful, simple first step to evaluate the clinical relevance of in vitro findings, but that multiple other factors are considered when deciding the need for clinical studies. Four drugs had prediction values less than the cutoffs but had clinical evaluations or physiologically‐based pharmacokinetic simulations available. Consistent with the predictions, all of them were confirmed not to inhibit these transporters in vivo (AUCRs of 0.94–1.09). Overall, based on the clinical evaluations available, drugs approved in 2018 were found to have a relatively limited impact on drug transporters, with all victim AUCRs < 2.

Local Irradiation Modulates the Pharmacokinetics of Metabolites in 5-Fluorouracil-Radiotherapy-Pharmacokinetics Phenomenon.

BackgroundThe effects of radiotherapy (RT) on the pharmacokinetics (PK) of 5-FU and 5-fluoro-5,6-dihydro-uracil (5-FDHU) were investigated by animal experiments.MethodsWhole-pelvis RT with 0.5 and 2 Gy was delivered to Sprague–Dawley rats. 5-FU at 100 mg/kg was intravenously infused 24 h after radiation. The pharmacokinetics of 5-FU and 5-FDHU in the plasma and bile system were calculated.ResultsThe areas under the concentration versus time curve (AUC) of 5-FU in the plasma were reduced by local irradiation by 23.7% at 0.5 Gy (P < 0.001) and 35.3% at 2 Gy (P < 0.001). The AUCs of 5-FDHU were also reduced by 21.4% at 0.5 Gy (P < 0.001) and 51.5% at 2 Gy (P < 0.001). Irradiation significantly increased the clearance values (CLs) of 5-FU by 30.6% at 0.5 Gy and 50.1% at 2 Gy, respectively. The CLs of 5-FDHU were increased by 27.2% at 0.5 Gy and 106% at 2 Gy. The AUCs of 5-FU in the bile were increased by 36.7% at 0.5 Gy (P < 0.001) and 68.6% at 2 Gy (P = 0.005). The AUCs of 5-FDHU in the bile were increased by 40.3% at 0.5 Gy (P < 0.001) and 248.1% at 2 Gy (P < 0.001). The CLs of 5-FU in the bile were increased by 31.8% at 0.5 Gy and 11.2% at 2 Gy. However, the CLs of 5-FDHU in the bile were decreased by 29.1% at 0.5 Gy and 71.0% at 2 Gy.ConclusionBoth conventional and low-dose irradiation can affect the pharmacokinetics of 5-FU and its metabolite, 5-FDHU. RT plus 5-FU could cause more adverse events than 5-FU alone by increasing the AUC ratio of 5-FU/5-FDHU. Irradiation decreases the AUC of 5-FU in the plasma, which may cause poor clinical outcomes.

Predicting Clinical Effects of CYP3A4 Modulators on Abemaciclib and Active Metabolites Exposure Using Physiologically Based Pharmacokinetic Modeling.

Abemaciclib, a selective inhibitor of cyclin‐dependent kinases 4 and 6, is metabolized mainly by cytochrome P450 (CYP)3A4. Clinical studies were performed to assess the impact of strong inhibitor (clarithromycin) and inducer (rifampin) on the exposure of abemaciclib and active metabolites. A physiologically based pharmacokinetic (PBPK) model incorporating the metabolites was developed to predict the effect of other strong and moderate CYP3A4 inhibitors and inducers. Clarithromycin increased the area under the plasma concentration‐time curve (AUC) of abemaciclib and potency‐adjusted unbound active species 3.4‐fold and 2.5‐fold, respectively. Rifampin decreased corresponding exposures 95% and 77%, respectively. These changes influenced the fraction metabolized via CYP3A4 in the model. An absolute bioavailability study informed the hepatic and gastric availability. In vitro data and a human radiolabel study determined the fraction and rate of formation of the active metabolites as well as absorption‐related parameters. The predicted AUC ratios of potency‐adjusted unbound active species with rifampin and clarithromycin were within 0.7‐ and 1.25‐fold of those observed. The PBPK model predicted 3.78‐ and 7.15‐fold increases in the AUC of the potency‐adjusted unbound active species with strong CYP3A4 inhibitors itraconazole and ketoconazole, respectively; and 1.62‐ and 2.37‐fold increases with the concomitant use of moderate CYP3A4 inhibitors verapamil and diltiazem, respectively. The model predicted modafinil, bosentan, and efavirenz would decrease the AUC of the potency‐adjusted unbound active species by 29%, 42%, and 52%, respectively. The current PBPK model, which considers changes in unbound potency‐adjusted active species, can be used to inform dosing recommendations when abemaciclib is coadministered with CYP3A4 perpetrators.

A Relative Bioavailability Study of Two Misoprostol Formulations Following a Single Oral or Sublingual Administration.

IntroductionMisoprostol (Cytotec) was primarily made for treating gastric ulcers. However today it is mostly used for abortion, treating postpartum hemorrhage, and for induction of labor. The tablet contains 200 µg of misoprostol, yet the dosages used for induction of labor are much smaller (25–50 µg), leading to uncertainty of dosage in daily use.AimTo evaluate and compare the relative bioavailability of two misoprostol products (Angusta 25 µg and Cytotec 200 µg tablets) administered orally or sublingually given in a daily clinical setting to women admitted for induction of labor at term.MethodsWomen carrying a live, singleton fetus in a cephalic position and with a gestational age between 259 and 296 days were included. Blood samples were collected at 0, 5, 10, 20, 30, 40, 50, 75, 100, 120, 180, and 240 minutes. A serum analytical assay was performed and pharmacokinetic parameters were calculated. Patients were assigned to one of three groups.ResultsA total of 72 patients were included. No significant differences demographic characteristics were found. The ratios for AUC, AUC (0−t), and Cmax were similar in all three groups, but CI-values were outside the required 80–125%. Sublingual administration yielded a 20–30% higher bioavailability and a 50% higher Cmax than compared to the oral route.ConclusionThe relative bioavailability between Angusta and Cytotec could not be confirmed as being equal at the 25 µg or 50 µg level because the 90% CI-values when comparing the ratios for AUC, AUC(0−t), and Cmax were wider than accepted. The reason for this could be the real-life, non-standardized circumstances in which the study was conducted. Sublingual administration seems to have higher bioavailability than oral administration. More studies are needed to ascertain an optimal dosage regime balancing both safety and efficacy for mother and child.Clinical Trial Registrationwww.ClinicalTrials.gov, identifier NCT02516631.

Physiologically based pharmacokinetic modelling of oxycodone drug-drug interactions.

Oxycodone is an opioid analgesic with several pharmacologically active metabolites and relatively narrow therapeutic index. Cytochrome P450 (CYP) 3A4 and CYP2D6 play major roles in the metabolism of oxycodone and its metabolites. Thus, inhibition and induction of these enzymes may result in substantial changes in the exposure of both oxycodone and its metabolites. In this study, a physiologically based pharmacokinetic (PBPK) model was built using GastroPlus™ software for oxycodone, two primary metabolites (noroxycodone, oxymorphone) and one secondary metabolite (noroxymorphone). The model was built based on literature and in house in vitro and in silico data. The model was refined and verified against literature clinical data after oxycodone administration in the absence of drug-drug interactions (DDI). The model was further challenged with simulations of oxycodone DDI with CYP3A4 inhibitors ketoconazole and itraconazole, CYP3A4 inducer rifampicin and CYP2D6 inhibitor quinidine. The magnitude of DDI (AUC ratio) was predicted within 1.5-fold error for oxycodone, within 1.8-fold and 1.3-4.5-fold error for the primary metabolites noroxycodone and oxymorphone, respectively, and within 1.4-4.5-fold error for the secondary metabolite noroxymorphone, when compared to the mean observed AUC ratios. This work demonstrated the capability of PBPK model to simulate DDI of the administered compounds and the formed metabolites of both DDI victim and perpetrator. However, the predictions for the formed metabolites tend to be associated with higher uncertainty than the predictions for the administered compound. The oxycodone model provides a tool for forecasting oxycodone DDI with other CYP3A4 and CYP2D6 DDI perpetrators that may be co-administered with oxycodone.

Effect of high-dose rifampicin on efavirenz pharmacokinetics: drug-drug interaction randomized trial.

High-dose rifampicin is considered to shorten anti-TB treatment duration but its effect on antiretroviral metabolism is unknown. To assess the effect of doubling the rifampicin dose (to 20 mg/kg/day, R20) on efavirenz pharmacokinetics (PK) in HIV/TB coinfected patients. Open-label Phase 2 drug-drug interaction randomized trial. Pulmonary TB, ART-naive adults were randomized to R20 and either efavirenz 600 mg (EFV600) or 800 mg (EFV800), or rifampicin 10 mg/kg/day (R10) and EFV600 with a 1:1:1 ratio. Patients were first started on TB treatment and 2-4 weeks later started on ART. They were switched to R10 and EFV600 after 8 weeks. Full PK sampling was done 4 weeks (on rifampicin) and 24 weeks (off rifampicin) after ART initiation. Transaminases, plasma HIV-1 RNA and sputum cultures were monitored. The efavirenz geometric mean ratio (GMR) of AUC at 4 and 24 weeks after ART initiation within the same patient was calculated in each arm and its 90% CI was compared with a preset range (0.70-1.43). Of 98 enrolled patients (32 in the R20EFV600 arm, 33 in the R20EFV800 arm and 33 in the R10EFV600 arm), 87 had full PK sampling. For the R20EFV600, R20EFV800 and R10EFV600 arms, GMRs of efavirenz AUC were 0.87 (90% CI: 0.75-1.00), 1.12 (90% CI: 0.96-1.30) and 0.96 (90% CI: 0.84-1.10). Twelve weeks after ART initiation, 78.6%, 77.4% and 72.4% of patients had HIV-1 RNA below 100 copies/mL and 85.7%, 86.7% and 80.0% had Week 8 culture conversion, respectively. Two patients per arm experienced a severe increase in transaminases. Doubling the rifampicin dose had a small effect on efavirenz concentrations and was well tolerated.

Image-Derived Input Functions for Quantification of A1 Adenosine Receptors Availability in Mice Brains Using PET and [18F]CPFPX.

PurposeIn vivo imaging for the A1 adenosine receptors (A1ARs) with positron emission tomography (PET) using 8-cyclopentyl-3-(3-[18F]fluoropropyl)-1-propylxan- thine ([18F]CPFPX) has become an important tool for studying physiological processes quantitatively in mice. However, the measurement of arterial input functions (AIFs) on mice is a method with restricted applicability because of the small total blood volume and the related difficulties in withdrawing blood. Therefore, the aim of this study was to extract an appropriate [18F]CPFPX image-derived input function (IDIF) from dynamic PET images of mice.ProceduresIn this study, five mice were scanned with [18F]CPFPX for 60 min. Arterial blood samples (n = 7 per animal) were collected from the femoral artery and corrected for metabolites. To generate IDIFs, three different approaches were selected: (A) volume of interest (VOI) placed over the heart (cube, 10 mm); (B) VOI set over abdominal vena cava/aorta region with a cuboid (5 × 5 × 15 mm); and (C) with 1 × 1 × 1 mm voxels on five consecutive slices. A calculated scaling factor (α) was used to correct for partial volume effect; the method of obtaining the total metabolite correction of [18F]CPFPX for IDIFs was developed. Three IDIFs were validated by comparison with AIF. Validation included the following: visual performance; computing area under the curve (AUC) ratios (IDIF/AIF) of whole-blood curves and parent curves; and the mean distribution volume (VT) ratios (IDIF/AIF) of A1ARs calculated by Logan plot and two-tissue compartment model.ResultsCompared with the AIF, the IDIF with VOI over heart showed the best performance among the three IDIFs after scaling by 1.77 (α) in terms of visual analysis, AUC ratios (IDIF/AIF; whole-blood AUC ratio, 1.03 ± 0.06; parent curve AUC ratio, 1.01 ± 0.10) and VT ratios (IDIF/AIF; Logan VT ratio, 1.00 ± 0.17; two-tissue compartment model VT ratio, 1.00 ± 0.13) evaluation. The A1ARs distribution of average parametric images was in good accordance to autoradiography of the mouse brain.ConclusionThe proposed study provides evidence that IDIF with VOI over heart can replace AIF effectively for quantification of A1ARs using PET and [18F]CPFPX in mice brains.

The Effect of Image Resolution on Deep Learning in Radiography.

To examine variations of convolutional neural network (CNN) performance for multiple chest radiograph diagnoses and image resolutions. This retrospective study examined CNN performance using the publicly available National Institutes of Health chest radiograph dataset comprising 112 120 chest radiographic images from 30 805 patients. The network architectures examined included ResNet34 and DenseNet121. Image resolutions ranging from 32 × 32 to 600 × 600 pixels were investigated. Network training paradigms used 80% of samples for training and 20% for validation. CNN performance was evaluated based on area under the receiver operating characteristic curve (AUC) and label accuracy. Binary output networks were trained separately for each label or diagnosis under consideration. Maximum AUCs were achieved at image resolutions between 256 × 256 and 448 × 448 pixels for binary decision networks targeting emphysema, cardiomegaly, hernias, edema, effusions, atelectasis, masses, and nodules. When comparing performance between networks that utilize lower resolution (64 × 64 pixels) versus higher (320 × 320 pixels) resolution inputs, emphysema, cardiomegaly, hernia, and pulmonary nodule detection had the highest fractional improvements in AUC at higher image resolutions. Specifically, pulmonary nodule detection had an AUC performance ratio of 80.7% ± 1.5 (standard deviation) (0.689 of 0.854) whereas thoracic mass detection had an AUC ratio of 86.7% ± 1.2 (0.767 of 0.886) for these image resolutions. Increasing image resolution for CNN training often has a trade-off with the maximum possible batch size, yet optimal selection of image resolution has the potential for further increasing neural network performance for various radiology-based machine learning tasks. Furthermore, identifying diagnosis-specific tasks that require relatively higher image resolution can potentially provide insight into the relative difficulty of identifying different radiology findings. Supplemental material is available for this article. © RSNA, 2020See also the commentary by Lakhani in this issue.

A Physiologically Based Pharmacokinetic Model of Voriconazole Integrating Time-Dependent Inhibition of CYP3A4, Genetic Polymorphisms of CYP2C19 and Predictions of Drug-Drug Interactions.

Voriconazole, a first-line antifungal drug, exhibits nonlinear pharmacokinetics (PK), together with large interindividual variability but a narrow therapeutic range, and markedly inhibits cytochrome P450 (CYP) 3A4 in vivo. This causes difficulties in selecting appropriate dosing regimens of voriconazole and coadministered CYP3A4 substrates. This study aimed to investigate the metabolism of voriconazole in detail to better understand dose- and time-dependent alterations in the PK of the drug, to provide the model basis for safe and effective use according to CYP2C19 genotype, and to assess the potential of voriconazole to cause drug-drug interactions (DDIs) with CYP3A4 substrates in more detail. In vitro assays were carried out to explore time-dependent inhibition (TDI) of CYP3A4 by voriconazole. These results were combined with 93 published concentration-time datasets of voriconazole from clinical trials in healthy volunteers to develop a whole-body physiologically based PK (PBPK) model in PK-Sim®. The model was evaluated quantitatively with the predicted/observed ratio of the area under the plasma concentration-time curve (AUC), maximum concentration (Cmax), and trough concentrations for multiple dosings (Ctrough), the geometric mean fold error, as well as visually with the comparison of predicted with observed concentration-time datasets over the full range of recommended intravenous and oral dosing regimens. The result of the half maximal inhibitory concentration (IC50) shift assay indicated that voriconazole causes TDI of CYP3A4. The PBPK model evaluation demonstrated a good performance of the model, with 71% of predicted/observed aggregate AUC ratios and all aggregate Cmax ratios from 28 evaluation datasets being within a 0.5- to 2-fold range. For those studies reporting CYP2C19 genotype, 89% of aggregate AUC ratios and all aggregate Cmax ratios were inside a 0.5- to 2-fold range of 44 test datasets. The results of model-based simulations showed that the standard oral maintenance dose of voriconazole 200mg twice daily would be sufficient for CYP2C19 intermediate metabolizers (IMs; *1/*2, *1/*3, *2/*17, and *2/*2/*17) to reach the tentative therapeutic range of > 1-2mg/L to < 5-6mg/L for Ctrough, while 400mg twice daily might be more suitable for rapid metabolizers (RMs; *1/*17, *17/*17) and normal metabolizers (NMs; *1/*1). When the model was integrated with independently developed CYP3A4 substrate models (midazolam and alfentanil), the observed AUC change of substrates by voriconazole was inside the 90% confidence interval of the predicted AUC change, indicating that CYP3A4 inhibition was appropriately incorporated into the voriconazole model. Both the in vitro assay and model-based simulations support TDI of CYP3A4 by voriconazole as a pivotal characteristic of this drug's PK. The PBPK model developed here could support individual dose adjustment of voriconazole according to genetic polymorphisms of CYP2C19, and DDI risk management. The applicability of modeling results for patients remains to be confirmed in future studies.

Quantitative Prediction of Interactions Mediated by Transporters and Cytochromes: Application to Organic Anion Transporting Polypeptides, Breast Cancer Resistance Protein and Cytochrome 2C8.

The in vivo mechanistic static model (IMSM) is an effective method to predict the magnitude of drug-drug interactions (DDIs) mediated by cytochromes. The aim of this study was to extend the IMSM paradigm to DDIs mediated by organic anion transporting polypeptide (OATP)1Bs, breast cancer resistance protein (BCRP) and cytochrome 2C8. First, a generic model for this kind of interaction was established, and a literature search was then conducted to retrieve the area under the concentration-time curve (AUC) ratio of a large set of DDIs involving OATP1B1, OATP1B3, BCRP and cytochromes 2C8 or 3A4. The model was fitted to the data to estimate the characteristic parameters (contribution ratios [CRs] and inhibition or induction potencies [IXs]) by nonlinear regression, and the model was qualified by external validation on a different dataset. Lastly, the model was used to identify the risks of overexposure by DDIs of this type. A total of 27 substrates, 26 inhibitors, 3 inducers and 3 genetic variants were considered in the regression analysis. The number of observations (AUC ratios, denoted as Robs) was 101. Forty-six CRs and 47 IXs were estimated. The proportions of predictions within 0.67- to 1.5-fold and 0.5- to twofold Robs were 90% and 99%, respectively, for the internal validation, and 78% and 96%, respectively, for the external validation. The median fold-error was 1.03 (the ideal value is 1). The interquartile range of fold-error was 0.31, and the relative standard error of parameter estimates was, at most, 17%. The IMSM approach was successfully extended to DDIs mediated by OATP1Bs, BCRP and cytochromes 2C8 or 3A4. The method revealed good predictive performances by internal and external validation.

Characterizing Breast Lesions Using Quantitative Parametric 3D Subharmonic Imaging: A Multicenter Study

Breast cancer is the leading type of cancer among women. Visualization and characterization of breast lesions based on vascularity kinetics was evaluated using three-dimensional (3D) contrast-enhanced ultrasound imaging in a clinical study. Breast lesions (n = 219) were imaged using power Doppler imaging (PDI), 3D contrast-enhanced harmonic imaging (HI), and 3D contrast-enhanced subharmonic imaging (SHI) with a modified Logiq 9 ultrasound scanner using a 4D10L transducer. Quantitative metrics of vascularity derived from 3D parametric volumes (based on contrast perfusion; PER and area under the curve; AUC) were generated by off-line processing of contrast wash-in and wash-out. Diagnostic accuracy of these quantitative vascular parameters was assessed with biopsy results as the reference standard. Vascularity was observed with PDI in 93 lesions (69 benign and 24 malignant), 3D HI in 8 lesions (5 benign and 3 malignant), and 3D SHI in 83 lesions (58 benign and 25 malignant). Diagnostic accuracy for vascular heterogeneity, PER, and AUC ranged from 0.52 to 0.75, while the best logistical regression model (vascular heterogeneity ratio, central PER, and central AUC) reached 0.90. 3D SHI successfully detects contrast agent flow in breast lesions and characterization of these lesions based on quantitative measures of vascular heterogeneity and 3D parametric volumes is promising.

Relationship between the effects of food on the pharmacokinetics of oral antineoplastic drugs and their physicochemical properties

BackgroundFood is known to affect drug absorption by delaying gastric emptying time, altering gastrointestinal pH, stimulating bile flow, increasing splanchnic blood flow, or physically interacting with drugs. Although food is known to affect the pharmacokinetics of oral antineoplastic drugs, the relationship between the effects of food and the physicochemical properties of drugs remains unclear.MethodsIn this study, we surveyed the literature on three kinds of pharmacokinetic changes, AUC ratio, Cmax ratio and Tmax ratio, in the fasted and fed state for 72 oral antineoplastic drugs that were listed on the drug price standard in May 2018 in Japan. We further predicted the physicochemical properties from the 2D chemical structure of the antineoplastic drugs using in silico predictions.ResultsAs a result of analyzing the relationship between the effects of food and physicochemical properties, we found that compounds that show increased absorption in the fed state had higher logP and lower solubility in fasted-state simulated intestinal fluid (FaSSIF). However, compounds with delayed absorption had higher solubility in FaSSIF. Furthermore, as a result of decision tree analysis, it was classified as AUC increase with logP ≥4.34. We found that an AUC increase in the fed state did not occur with compounds with low lipid solubilities (logP < 1.59). From these results, it is predicted that 7 compounds out of the 24 compounds for which the effects of food are unknown are at risk for increased absorption in the fed state and that no increase in absorption would occur in 13 compounds.ConclusionIn this study, we found that drugs that will show increased absorption in the fed state and drugs for which absorption is not dependent on food can generally be predicted by logP. These results suggest that logP can be a useful parameter for predicting the effects of food on drug absorption.

Pharmacokinetics of methylphenidate and ritalinic acid in plasma correlations with exhaled breath and oral fluid in healthy volunteers

PurposeThe primary aim of this study was to explore the potential of alternative sampling matrices for methylphenidate by assessing the correlations between dl-threo-methylphenidate and dl-threo-ritalinic acid concentrations in exhaled breath and oral fluid with those in plasma, in repeated samples collected after a single oral dose of methylphenidate. The secondary aim was to study the enantioselective pharmacokinetics of methylphenidate in plasma, with a focus on interindividual variability in the metabolism of methylphenidate to ritalinic acid.MethodsTwelve healthy volunteers received a single oral dose of dl-threo-methylphenidate (Ritalin® capsules, 20 mg). Venous blood samples were collected for 24 h, and plasma analyzed for threo-enantiomers of methylphenidate and ritalinic acid with LC-MS/MS. Repeated sampling of exhaled breath, using a particle filter device, and of non-stimulated oral fluid, using a felt pad device, was also performed. Exhaled breath and oral fluid were analyzed with a non-enantioselective LC-MS/MS method for dl-threo-methylphenidate and dl-threo-ritalinic acid.ResultsIn all subjects, d-threo-methylphenidate was detectable in plasma for at least 15 h after the dose with a biphasic profile. l-threo-Methylphenidate was measurable in only five subjects and in most cases in low concentrations. However, one female subject displayed a biphasic concentration-time profile for l-threo-methylphenidate. This subject also had the highest d-threo-methylphenidate AUC (191 ng*h/mL versus 32–119 ng*h/mL in the other subjects). d-threo-Ritalinic acid concentrations were on average 25-fold higher (range 6–126) than the corresponding d-threo-methylphenidate concentrations. Single-time point plasma concentration ratios between d-threo-ritalinic acid and d-threo-methylphenidate 1.5–12 h after dose correlated highly (r = 0.88–0.98) with the d-threo-ritalinic acid AUC/d-threo-methylphenidate AUC ratio. In eleven subjects, dl-threo-methylphenidate in oral fluid mirrored the biphasic profile of methylphenidate (sum of d- and l-threo-enantiomers) in plasma, but the concentrations in oral fluid were on average 1.8 times higher than in plasma. dl-threo-Methylphenidate was detected in exhaled breath in all subjects, but there was no consistent concentration-time pattern.ConclusionsIn some subjects, the pharmacologically less active l-threo-enantiomer may contribute to the total plasma methylphenidate concentrations. Monitoring methylphenidate concentrations without enantiomeric determination carries the risk of missing such subjects, which might affect how the plasma concentrations of methylphenidate are interpreted and used for clinical decision making. The use of exhaled breath and oral fluid to assess medication adherence to MPH in patients with ADHD warrants further studies.

Impact of lactation on pharmacokinetics of meloxicam in goats.

Use of drug in lactating animal should be carefully considered due to its possibility of changes in pharmacokinetics as well as drug penetration in milk. The aim of this study was to assess the effect of lactation on pharmacokinetics of meloxicam after IV and IM administrations in goats. A crossover design (2×2) was used for each lactating and nonlactating group of goats with a 3-week washout period. Meloxicam (0.5mg/kg) was administered into the jugular vein and upper gluteal muscle by IV and IM routes, respectively. The plasma and milk drug concentrations were determined by high-performance liquid chromatography with diode array detector, and the pharmacokinetic analysis was carried out by noncompartmental analysis. The pharmacokinetic parameters of meloxicam in lactating and nonlactating goats were not significantly different. The IM bioavailability of meloxicam was relatively lower in lactating (75.3±18.6%) than nonlactating goats (103.8±34.7%); however, the difference was not statistically significant. Moreover, AUC ratio between milk and plasma, which represent drug milk penetration, for both IV and IM administrations was less than 1 (about 0.3). In conclusion, pharmacokinetic parameters of meloxicam are not significantly altered by lactation for either the IV or IM routes of administration and this drug does not require a different dosage regimen for lactating animals.

Cross-Sectional Comparative Study of PK-Guided Switch between Standard Half-Life and Extended Half-Life Factor VIII Products

Background The high inter-individual variability in pharmacokinetics (PK) of factor VIII (FVIII) justifies the use of PK-guided prophylaxis, especially in switching between different products. A proposed definition of extended half-life (EHL) FVIII requires improvements of at least 1.3 times in half-life (t1/2) and 1.25 times the area under the curve (AUC) compared to standard half-life (SHL) products (Mahlangu et al. Haemophilia. 2018;24(3):348-358). The objective of this multicenter study was to analyze the results of a PK-guided switch from SHL to EHL in patients with hemophilia A (HA). Methods Multicenter comparative, cross-sectional, prospective study in HA severe/moderate patients in prophylaxis analyzing PK differences after switch from SHL to EHL (efmoroctocog alfa [rFVIII-Fc] and rurioctocog alfa pegol [PEG-rFVIII]). WAPPS-Hemo® was used to analyze PK parameters with 2-3 samples: t1/2; AUC, peak level (PL); trough level at 24, 48 and 72 h (TL24, TL48, TL72); and time to reach FVIII levels of 1, 2, 5% (T1%, T2%, T5%). We have also compared the ratio of t1/2 and AUC, the number of weekly doses and the dose/kg/week before and after the switch. Wilcoxon and Kruskal-Wallis tests (SPSS®) were used to compare the PK parameters. Results are expressed with the median and interquartile range (IQR) or range, and mean and standard deviation (SD). Results Eighty-one patients from 8 Spanish hospitals were analyzed (61 rFVIII-Fc; 20 PEG-rFVIII), 78 had severe HA and 3 moderate HA. Mean age was 30 years (range=3-64) and no differences in weight were observed between both periods [70 (range=12-116) vs 70 (13.7-116) kg; p=0,141]. Dose/kg/week and weekly infusion frequency were reduced after the switch to EHL, and significant improvements were observed in all PK parameters after the change from SHL to EHL (Table 1). These results were similar in adult and pediatric patients switching to rFVIII-Fc. The median ratios of t1/2 and AUC were 1.3 (IQR:1.2-1.6) and 1.5 (IQR:1.3-2.3) in the entire cohort. These results were reproduced in the subset of patients with ≥12 years treated with rFVIII-Fc and PEG-rFVIII (ratio t1/2: 1.4 [IQR:1.3-1.6]; ratio AUC: 1.6 [IQR:1.3-2.3]), and were slightly in the cohort of 15 patients &lt;12 years treated with rFVIII-Fc (ratio t1/2: 1.3 [IQR:0.9-1.3]; ratio AUC: 1.3 [IQR:1.1-1.9]), the only EHL approved in Europe for children. After the switch to EHL, weekly dose frequency (median 23.3%, IQR:0-33.3%) and dose/kg/week (median 16%, IQR:5.3-30%) were reduced. In a small subset of 17 patients the dose/kg/week increased a median of 31.4%, and this subset was younger than the patients with dose/kg/week reduction or no changes (median age 18 [IQR:8-22] vs. 33 [IQR:16.5-42.5]). No differences were observed in any of the PK parameters and median ratios of t1/2 and AUC in patients aged ≥12 years treated with rFVIII-Fc vs. PEG-rFVIII (46 rFVIII-Fc; 20 PEG-rFVIII; Table 2). Conclusions EHL FVIII have shown significant PK improvements in clinical real practice, allowing to reduce weekly infusion number and dose/kg/week, especially in adult patients. Outside the clinical trial setting, we have observed an increase in t1/2 and AUC ratios accordingly to EHL definition. Comparisons regarding clinical outcomes (bleeding rate after switch) will be performed after a follow-up of 1 year with EHL for the full cohort. WAPPS-Hemo PK-guided switch easily facilitates individualization of prophylaxis with a potential reduction in the cost of treatment and patient perceived outcomes. Disclosures Megias: Baxalta US INC.: Research Funding; Grifols: Research Funding. Bonanad Boix:Baxalta US INC.: Research Funding. Berrueco:NovoNordisk: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; SOBI: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Bayer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; CSL-Bering: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Mingot-Castellano:Sobi: Consultancy; Bayer: Consultancy; Amgen: Consultancy; Roche: Consultancy; Novartis: Consultancy; Novonordisk: Consultancy; Takeda: Consultancy; CSL Behring: Consultancy. Cid:Shire, a Takeda company: Honoraria; Novo Nordisk: Honoraria. Sanz:AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Boehringer-Ingelheim: Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Helsinn Healthcare: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen - Cilag: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Onconova: Membership on an entity's Board of Directors or advisory committees, Research Funding; Hoffman - La Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

Pharmacokinetic Exposure Equivalence and Preliminary Efficacy and Safety from a Randomized Cross over Phase 3 Study (ASCERTAIN study) of an Oral Hypomethylating Agent ASTX727 (cedazuridine/decitabine) Compared to IV Decitabine

Pharmacokinetic Exposure Equivalence and Preliminary Efficacy and Safety from a Randomized Cross over Phase 3 Study (ASCERTAIN study) of an Oral Hypomethylating Agent ASTX727 (cedazuridine/decitabine) Compared to IV Decitabine

Treosulfan Metabolite (S, S-EBDM) Pharmacokinetics Influences Regimen Related Toxicity in Patients with Beta Thalassaemia Major Undergoing HSCT

A toxicity reduced conditioning regimen containing Treosulfan (Treo), Fludarabine (Flu), Thiotepa in patients with class III high risk thalassemia major (TM) has significantly improved transplant outcomes compared to the historical Busulfan/cyclophosphamide based myeloablative regimen (Mathews et al, 2013). However, complications related to mixed chimerism, rejection and regimen related toxicity remain. Analysis of Treo pharmacokinetics (PK) in TM showed significant inter individual variation but no association with HSCT outcome (Mohanan et al, 2018). This may be attributed to the fact that only the pro-drug Treo was measured and not its active metabolites. Treo, administered as a prodrug, is converted non-enzymatically to its active metabolite monoepoxide 2S, 3S-1,2-epoxybutane-3,4-diol-4-methanesulfonate (S, S-EBDM) and (2S,3S)- 1,2:3,4-diepoxybutane (S, S-DEB) that causes cytotoxicity. We have now assessed the PK of both Treo and S, S-EBDM and the factors which may influence the inter-individual variation in PK, and their impact on HSCT outcome in patients with TM. Fifty-six patients with TM undergoing HSCT between January 2016 and June 2019 with Flu/Treo based conditioning regimen (Flu 40mg/m2/day x 4 days as a 1hr infusion and Treo as 14g/m2/day x 3 days infused at 5g/hr) were included in this analysis. Selected functional polymorphisms in NAD(P)H Quinone Dehydrogenase-1 (NQO1) and Glutathione S-transferase (GST) genes that showed association with Treo PK based on our previous report (Pai et al, Abstract. Proceedings of BMT Tandem Meetings 2018) were screened. Plasma Treo and S, S-EBDM were measured using an LC-MS/MS method. Treo and S, S-EBDM PK were estimated using nonlinear mixed effects modeling via Monolix 5.0.1. The covariates tested were age, sex, body weight, BSA, serum ferritin, NQO1 3'UTR (rs10517) and GSTA1*B polymorphisms. The influence of Treo &amp; S, S-EBDM PK and polymorphisms on graft rejection, regimen related toxicities (RRT), chimerism status, overall and event-free survival were estimated using logistic regression analysis. A two-compartment model best described the PK of Treo and S, S-EBDM. Two and 11-fold inter-individual variation was observed in Treo and S, S-EBDM PK respectively. Among the covariates tested, Treo Cl decreased with age (p=0.03) while, S, S-EBDM apparent Cl increased in patients with NQO1 3'UTR variant (p=0.02) and decreased in patients with GSTA1*B variant genotype (p=0.02). Neither Treo AUC nor clearance showed association with HSCT outcome. However, high S, S-EBDM AUC (213. Vs 130 mg*hr/mL, p=0.016) and low S, S-EBDM apparent Cl (68 Vs 122 L/hr/m2, p=0.013) were significantly associated with increased incidence of sinusoidal obstruction syndrome (SOS). Also, on quartile analysis, patients with S, S-EBDM AUC &gt;210 mg*hr/mL and Treo/S, S-EBDM AUC ratio &gt;18 mg*hr/mL showed increased incidence of SOS (p=0.006 &amp; p=0.026 respectively). Multivariate analysis adjusting for known clinical risk factors also showed in addition to age, only high S, S-EBDM AUC to be significantly associated with increased incidence of SOS (p=0.013). No association between rejection or mixed chimerism and Treo/S, S-EBDM PK was observed, probably due to very low incidence of graft rejection in this cohort (4/56; 7%). Our study suggests that active metabolite S, S-EBDM influences SOS following HSCT in TM patients. It is well acknowledged that Treo to S, S-EBDM conversion is a non-enzymatic nucleophilic substitution reaction and there is a difference in the disposition of Treo and S, S-EBDM in different organs including the liver (Romanski et al, 2017). Treo metabolites exert their cytotoxic activity by both DNA-DNA and DNA-protein crosslinks in these organs. The role of Treo metabolites in exhausting essential cellular proteins like GSH and NQO1 as well as the effect of GST/NQO1 variants in influencing Treo metabolism in liver which may then impact the incidence and severity of SOS need further evaluation. Disclosures No relevant conflicts of interest to declare.

731. Pharmacokinetics of Gepotidacin (GSK2140944) in Subjects with Hepatic Impairment

BackgroundGepotidacin (GEP), a first in class novel triazaacenaphthylene bacterial topoisomerase inhibitor, inhibits bacterial replication and has in vitro and in vivo efficacy activity against key pathogens, including drug-resistant strains, associated with a range of infections. In a previous absorption, distribution, metabolism, and excretion study for GEP, the mean recovery of radioactivity in urine and feces accounted for approximately 31.2% and 52.5%, respectively, of [14C]-GEP administered as a single oral dose. GEP was eliminated mainly as parent in urine, accounting for approximately 20% of the administered dose. Elimination via metabolism accounted for a total of 13% to 19% of the dose. Average total intravenous clearance of approximately 43 L/hour and renal clearance (CLr) of approximately 16 L/hour provides a hepatic clearance of 27 L/hour, suggesting that hepatic clearance is a major route of elimination of GEP.MethodsParticipants with normal and varying degrees of hepatic impairment (HI) received a single oral dose of GEP 1,500 mg. PK collections of blood, urine and saliva were performed.ResultsRelative to normal hepatic function, GEP Cmax and AUC(0-∞) in plasma were increased by 1.2-fold in subjects with moderate, and between 1.7-fold to 1.9-fold in severe HI. The fraction of dose excreted in urine increased with an increase in hepatic impairment. GEP urine concentrations remained high over a 12-hour period. Saliva concentrations displayed a linear relationship with plasma (both total and unbound) concentrations (R2 = 0.76). The geometric mean ratio of saliva AUC to unbound plasma AUC values ranged from 0.746 to 0.839 across all groups. Administration of 1,500 mg oral GEP was generally tolerated.ConclusionAn increase in the dosing interval or dose reduction may be required in patients with severe hepatic impairment. Disclosures All authors: No reported disclosures.