Quantification of field-incurred residues of cyantraniliprole and IN-J9Z38 in cabbage/soil using QuEChERS/HPLC-PDA and dietary risk assessment.

Cyantraniliprole is an anthranilic diamide insecticide used for the effective management of diamondback moth in cabbage. Dietary risk assessment of pesticides in food is a major concern now. This study developed a QuEChERS/HPLC-PDA-based highly efficient and reliable method, registering 89.80-100.11% recoveries of cyantraniliprole and its metabolite IN-J9Z38 from cabbage and soil with a relative standard deviation of 0.43-5.77%. Field experiment was conducted to study the residue dissipation of cyantraniliprole in cabbage and soil. Two foliar treatments of 10.26% formulation (Benevia) at 60 (T1 ) and 120 (T2 ) gram active ingredient/hectare were applied. The dissipation half-lives of cyantraniliprole in cabbage and soil were determined to be 3.5-4.2 and 3.8-5.3 days at T1 and 3.9-4.8 and 4.1-4.7 days at T2 , respectively. The maximum concentrations of IN-J9Z38 at T1 and T2 were 0.819 and 1.061 mg/kg, respectively, on the fifth day. A risk quotient value of <1 indicates no dietary risk to the consumers. The residues in the harvested cabbage were below the tolerance level of 2.0 mg/kg established by the regulatory body in India.

Assessment of safety and tolerability of remogliflozin etabonate (GSK189075) when administered with total daily dose of 2000 mg of metformin.

BACKGROUND: Patients with type 2 diabetes mellitus (T2DM) are characterized by an elevated glycemic index and are at a higher risk for complications such as cardiovascular disease, nephropathy, retinopathy and peripheral neuropathy. Normalization of glycemic index can be achieved by dosing combinations of metformin with other anti-diabetic drugs. The present study (Clintrials number NCT00519480) was conducted to evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics of remogliflozinetabonate, an SGLT2 inhibitor, withdoses (500 mg and 750 mg BID) greater than the commercial dose (100 mg BID)in combination with metformin with minimum daily dose of 2000 mg given in two divided doses. METHODS: This was a randomized, double-blinded, repeat dose study in 50 subjects with T2DM. The study was conducted in three phases; run-in, randomization, and treatment. All subjects were on a stable metformin dosing regimen. Cohort 1 subjects were randomly allocated to receive either remogliflozin etabonate 500 mg BID or placebo BID (2:1) in addition to metformin. Cohort 2 subjects were administered with either remogliflozin etabonate 750 mg BID or placebo BID (2:1) in addition to metformin for 13 days. All the subjects were assessed for safety (adverse events, lactic acid levels, vital signs, electrocardiogram [ECG]), pharmacokinetic evaluation, and pharmacodynamics (Oral Glucose Tolerance Testing) parameters. RESULTS: Co-administration of remogliflozin etabonate and metformin was well tolerated in all subjects during the observation period. There were no severe or serious adverse events (SAEs) and no increase in lactic acid concentration was reported during the study. The statistical results showed that concomitant administration of remogliflozin etabonate, either 500 mg or 750 mg BID, with metformin had no effect on the pharmacokinetics of metformin. The accumulation ratios, Day 13 vs. Day 1, for AUC values of remogliflozin etabonate and its metabolites were all very close to 1, indicating no accumulation in plasma concentrations of remogliflozin etabonate and its metabolites. Mean glucose values from baseline and glucose and insulin values following oral glucose tolerance test (OGTT) were decreased in all treatment groups. CONCLUSION: Co-administration of doses of remogliflozin etabonate (500 mg BID or 750 mg BID) greater than the commercial dose (100 mg BID) with metformin (2000 mg BID) was shown to be safe and effective during the observation period. TRIAL REGISTRATION: ClinicalTrials.gov , NCT00519480 . Registered:22 August 2007.

Lorlatinib Exposure-Response Analyses for Safety and Efficacy in a Phase I/II Trial to Support Benefit-Risk Assessment in Non-Small Cell Lung Cancer.

Lorlatinib is a small molecule inhibitor of anaplastic lymphoma kinase (ALK) and c-ROS oncogene 1 (ROS1) tyrosine kinases and is approved for the treatment of patients with ALK-positive advanced non-small cell lung cancer (NSCLC). In the phase I/II study (NCT01970865), potential exposure-response (E-R) relationships between lorlatinib and selected safety and efficacy end points were evaluated in patients with NSCLC. E-R relationships were assessed for safety end points with incidence > 10% in all treated patients (n = 328). In total, 4 safety end points were assessed: hypercholesterolemia grade ≥ 3, hypertriglyceridemia grade ≥ 3, weight gain grade ≥ 2, and treatment-emergent adverse events (TEAEs) grade ≥ 3. Using logistic regression, significant relationships were identified between lorlatinib plasma exposure and risk of hypercholesterolemia grade ≥ 3 (odds ratio (OR) 5.256) and risk of TEAE grade ≥ 3 (OR 3.214). The covariates baseline cholesterol and time on study prior to the event (TE) were associated with the probability of hypercholesterolemia grade ≥ 3. Baseline cholesterol and TE were found to have a statistically significant correlation with TEAE grade ≥ 3. Exposure-efficacy relationships were assessed for objective response rate (ORR; n = 197) and intracranial objective response rate (IC-ORR; n = 132). Lorlatinib plasma exposure was not identified as a statistically significant factor related to either efficacy end point. The only significant E-R relationships identified for efficacy were between baseline alkaline phosphatase and baseline amylase with IC-ORR (ORs 0.363 and 1.015, respectively). These findings support the lorlatinib indicated dose and dose modification guidelines regarding the management of lorlatinib-related AEs.

Comparative assessment of the effects of bumped kinase inhibitors on early zebrafish embryo development and pregnancy in mice.

Bumped kinase inhibitors (BKIs) are effective against a variety of apicomplexan parasites. Fifteen BKIs with promising in vitro efficacy against Neospora caninum tachyzoites, low cytotoxicity in mammalian cells, and no toxic effects in non-pregnant BALB/c mice were assessed in pregnant mice. Drugs were emulsified in corn oil and were applied by gavage for 5 days. Five BKIs did not affect pregnancy, five BKIs exhibited ~15-35% neonatal mortality and five compounds caused strong effects (infertility, abortion, stillbirth and pup mortality). Additionally, the impact of these compounds on zebrafish (Danio rerio) embryo development was assessed by exposing freshly fertilised eggs to 0.2-50 µM of BKIs and microscopic monitoring of embryo development in a blinded manner for 4 days. We propose an algorithm that includes quantification of malformations and embryo deaths, and established a scoring system that allows the calculation of an impact score (Si) indicating at which concentrations BKIs visibly affect zebrafish embryo development. Comparison of the two models showed that for nine compounds no clear correlation between Si and pregnancy outcome was observed. However, the three BKIs affecting zebrafish embryos only at high concentrations (≥40 µM) did not impair mouse pregnancy at all, and the three compounds that inhibited zebrafish embryo development already at 0.2 µM showed detrimental effects in the pregnancy model. Thus, the zebrafish embryo development test has limited predictive value to foresee pregnancy outcome in BKI-treated mice. We conclude that maternal health-related factors such as cardiovascular, pharmacokinetic and/or bioavailability properties also contribute to BKI-pregnancy effects.

Critical Assessment of Pharmacokinetic Drug-Drug Interaction Potential of Tofacitinib, Baricitinib and Upadacitinib, the Three Approved Janus Kinase Inhibitors for Rheumatoid Arthritis Treatment.

The introduction of novel, small-molecule Janus kinase inhibitors namely tofacitinib, baricitinib and upadacitinib has provided an alternative treatment option for patients with rheumatoid arthritis outside of traditional drugs and expensive biologics. This review aimed to critically assess the drug-drug interaction potential of tofacitinib, baricitinib and upadacitinib and provide a balanced perspective for choosing the most appropriate Janus kinase inhibitor based on the needs of patients with rheumatoid arthritis including co-medications and renal/hepatic impairment status. Based on the critical assessment, all three approved Janus kinase inhibitors generally provide a favourable opportunity for co-prescription with a plethora of drugs. While cytochrome P450 3A4-related inhibition or induction altered the exposures (area under the curve) of tofacitinib and upadacitinib, it did not impact the exposure of baricitinib. Transporter drug-drug interaction studies revealed that the disposition of baricitinib was altered with certain transporter inhibitors as compared with either tofacitinib or upadacitinib. Adjustment of tofacitinib or baricitinib dosages but not that of upadacitinib is required with the progression of renal impairment from a mild to a severe condition. While the dosage of tofacitinib needs to be adjusted for patients with moderate hepatic impairment status, it is not the case for either baricitinib or upadacitinib. Assessment of the drug-drug interaction potential suggests that tofacitinib, baricitinib and upadacitinib generally show a favourable disposition with no perpetrator activity; however, as victim drugs, they show subtle pharmacokinetic differences that may be considered during polypharmacy. Moreover, careful choice of the three drugs could be made in patients with rheumatoid arthritis with varying degrees of renal/hepatic impairments.

Clinical implications of assessment of apixaban levels in elderly atrial fibrillation patients: J-ELD AF registry sub-cohort analysis.

PURPOSE: To investigate the distribution of plasma apixaban levels and their relationships with clinical outcomes in elderly patients with atrial fibrillation (AF). METHOD: The J-ELD AF Registry is a multicenter prospective observational study of Japanese non-valvular AF patients aged ≥75 years taking an on-label dose of apixaban (3015 patients from 110 institutions). Among them, plasma apixaban levels at trough were estimated by anti-Xa assay (Api-AXA) in 943 patients. Patients with standard (5 mg bid; n = 431) and reduced (2.5 mg bid; n = 512) dose were further divided into two groups with low and high Api-AXA levels (boundary: median value). RESULTS: The incidence rates (per 100 person-years) of events in the low- and high-Api-AXA groups were as follows: 1.48 and 1.99 (log-rank test, P = 0.695) for stroke or systemic embolism, 0.98 and 1.49 (P = 0.652) for bleeding requiring hospitalization, and 0.49 and 0.99 (P = 0.565) for total deaths in patients with standard dose, versus 0.84 and 1.68 (P = 0.414), 0.42 and 4.64 (P = 0.004), and 2.52 and 6.65 (P = 0.035) in patients with a reduced dose, respectively. In multivariate Cox regression analysis among patients with a reduced dose, a high Api-AXA level was independently associated with bleeding requiring hospitalization (HR 12.12, 95% CI: 1.56-94.22) and nonsignificantly with total deaths. CONCLUSIONS: A high trough apixaban level in patients indicated for standard dose was not associated with adverse events, while a high apixaban level in patients indicated for a reduced dose was associated with bleeding requiring hospitalization.

Assessment of low plasma concentrations of apixaban in the periprocedural setting.

INTRODUCTION: Estimation of residual apixaban plasma concentrations may be requested in the management of emergencies. This study aims at assessing the performance of specific anti-Xa assays calibrated with apixaban on real-life samples with low apixaban plasma concentrations (<30 ng/mL) and on-treatment ranges, with and without interference of low-molecular-weight heparin (LMWH). METHODS: The performance of the STA® -Liquid Anti-Xa assay (STA® LAX) and the low and normal procedures of the Biophen® Direct Factor Xa Inhibitors (DiXaI) assay was tested on 134 blood samples, collected from patients on apixaban, wherefrom 74 patients received LMWH after apixaban cessation. The results were compared with the liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) measurements. RESULTS: The Biophen® DiXaI, Biophen® DiXaI LOW, and STA® LAX showed very good correlation with LC-MS/MS measurements in patients without LMWH administration (Spearman r .95, .99, and .98, respectively). Their limits of quantitation were defined at 48, 24, and 12 ng/mL, respectively. The Bland-Altman test measured mean bias (SD) at 5.6 (13.1), -2.5 (5.0), and -0.8 (6.1) ng/ml, respectively. The Spearman r of the Biophen® DiXaI decreased to 0.64 in presence of low apixaban concentrations. The Spearman r of the Biophen® DiXaI LOW and STA® LAX decreased to 0.39 and 0.26, respectively, in presence of LMWH. CONCLUSIONS: The accuracy of the low methodologies (Biophen® DiXaI LOW and STA® LAX) is slightly improved for low apixaban plasma concentrations, compared with the normal procedure of Biophen® DiXaI. The interference of LMWH on the low methodologies is measurable, however, less important than the previously reported interference of LMWH on rivaroxaban calibrated specific anti-Xa assays.

In vitro assessment of P-gp and BCRP transporter-mediated drug-drug interactions of riociguat with direct oral anticoagulants.

As an alternative to vitamin K antagonists (VKAs), direct oral anticoagulants (DOACs) are increasingly prescribed in combination with riociguat in the treatment of chronic thromboembolic pulmonary hypertension (CTEPH). Pharmacokinetics of riociguat and DOACs are influenced by efflux transporters, such as P-glycoprotein (P-gp) and Breast Cancer Resistance Protein (BCRP). This work aimed to assess P-gp and BCRP-mediated drug-drug interactions of riociguat with DOACs using in vitro models. Bidirectional permeabilities of apixaban and rivaroxaban were investigated across MDCK-MDR1 and MDCK-BCRP models, in the absence and in the presence of increasing concentrations of riociguat (0.5-100 µm). Calculated efflux ratios were subsequently used to determine riociguat inhibition percentages and half maximal inhibitory concentration (IC50). P-gp-mediated efflux of apixaban and rivaroxaban was inhibited by 8% and 21%, respectively, in the presence of 100 µm riociguat. BCRP-mediated transport of apixaban and rivaroxaban was inhibited by 36% and 77%, respectively. IC50s of riociguat on MDCK-MDR1 and MDCK-BCRP models were higher than 100 µm for apixaban and higher than 100 µm and 46.5 µm for rivaroxaban, respectively. This work showed an in vitro inhibition of BCRP-mediated DOACs transport by riociguat. In vivo studies may be required to determine the clinical relevance of these transporter-mediated interactions.

Assessment of the effect of erdafitinib on cardiac safety: analysis of ECGs and exposure-QTc in patients with advanced or refractory solid tumors.

PURPOSE: To characterize the effect of erdafitinib on electrocardiogram (ECG) parameters and the relationship between erdafitinib plasma concentrations and QTc interval changes in patients with advanced or refractory solid tumors. METHODS: Triplicate ECGs and continuous 12-lead Holter data were collected in the dose escalation part (Part 1) of the first-in-human study, with doses ranging from 0.5 to 12 mg. Triplicate ECG monitoring continued in Parts 2-4 where 2 dose regimens selected from Part 1 were expanded in prespecified tumor types. Analyses of ECG data included central tendency analyses, identification of categorical outliers and morphological assessment. A concentration-QTc analysis was conducted using a linear mixed-effect model based on extracted time matching Holter data. RESULTS: Central tendency, categorical outlier, and ECG morphologic analyses from 187 patients revealed no clinically significant effect of erdafitinib on heart rate, atrioventricular conduction or cardiac depolarization (PR and QRS), and no effect on cardiac repolarization (QTc). Concentration-QTc analysis from 62 patients indicated that the slopes of relationship between total and free erdafitinib plasma concentrations and QTcI (mean exponent of 0.395) were estimated as - 0.00269 ms/(ng/mL) and - 1.138 ms/(ng/mL), respectively. The predicted change in QTcI at the observed geometric mean of total and free concentration at the highest therapeutic erdafitinib dose (9 mg daily) was < 10 ms at the upper bound of the two-sided 90% confidence interval. CONCLUSIONS: ECG data and the concentration-QTc relationships demonstrate that erdafitinib does not prolong QTc interval and has no effects on cardiac repolarization or other ECG parameters. Clinical trial registration numbers NCT01703481, EudraCT: 2012-000697-34.

In vivo assessment of neuroinflammation in progressive multiple sclerosis: a proof of concept study with [18F]DPA714 PET.

BACKGROUND: Over the past decades, positron emission tomography (PET) imaging has become an increasingly useful research modality in the field of multiple sclerosis (MS) research, as PET can visualise molecular processes, such as neuroinflammation, in vivo. The second generation PET radioligand [18F]DPA714 binds with high affinity to the 18-kDa translocator-protein (TSPO), which is mainly expressed on activated microglia. The aim of this proof of concept study was to evaluate this in vivo marker of neuroinflammation in primary and secondary progressive MS. METHODS: All subjects were genotyped for the rs6971 polymorphism within the TSPO gene, and low-affinity binders were excluded from participation in this study. Eight patients with progressive MS and seven age and genetic binding status matched healthy controls underwent a 60 min dynamic PET scan using [18F]DPA714, including both continuous on-line and manual arterial blood sampling to obtain metabolite-corrected arterial plasma input functions. RESULTS: The optimal model for quantification of [18F]DPA714 kinetics was a reversible two-tissue compartment model with additional blood volume parameter. For genetic high-affinity binders, a clear increase in binding potential was observed in patients with MS compared with age-matched controls. For both high and medium affinity binders, a further increase in binding potential was observed in T2 white matter lesions compared with non-lesional white matter. Volume of distribution, however, did not differentiate patients from healthy controls, as the large non-displaceable compartment of [18F]DPA714 masks its relatively small specific signal. CONCLUSION: The TSPO radioligand [18F]DPA714 can reliably identify increased focal and diffuse neuroinflammation in progressive MS when using plasma input-derived binding potential, but observed differences were predominantly visible in high-affinity binders.

Laboratory Assessment of the Anticoagulant Activity of Apixaban in Patients With Nonvalvular Atrial Fibrillation.

Our aim is to determine the most appropriate laboratory tests, besides anti-factor Xa (anti-FXa) chromogenic assays, to estimate the degree of anticoagulation with apixaban and compare it with that of rivaroxaban in real-world patients. Twenty patients with nonvalvular atrial fibrillation treated with apixaban 5 mg twice daily and 20 patients on rivaroxaban 20 mg once daily were studied. Conventional coagulation tests, thrombin generation assay (TGA), and thromboelastometry (nonactivated TEM [NATEM] assay) were performed in the 40 patients and 20 controls. The anti-FXa chromogenic assays were used to measure apixaban and rivaroxaban plasma levels. The NATEM measurements showed no significant difference between the 2 groups of patients. Concerning TGA, endogenous thrombin potential (ETP) was significantly decreased in patients on rivaroxaban as compared to those treated with apixaban (P < .003). A statistically significant, strong inverse correlation between apixaban plasma concentrations and ETP (P < .001) was observed. Apixaban significantly reduces ETP compared to controls, but to a lesser extent than rivaroxaban. Thrombin generation assay might provide additional information on apixaban exposure, which is required in order to individualize treatment especially for patients with a high bleeding risk. Our findings have to be further investigated in studies with larger sample sizes, in the entire range of apixaban exposure, with other direct oral anticoagulants, and in relation to clinical outcomes.

In Vitro Assessment of Pharmacokinetic Drug-Drug Interactions of Direct Oral Anticoagulants: Type 5-Phosphodiesterase Inhibitors Are Inhibitors of Rivaroxaban and Apixaban Efflux by P-Glycoprotein.

Because of their lower bleeding risk and simplicity of use, direct oral anticoagulants (DOACs) could represent an interesting alternative to conventional anticoagulant treatment with vitamin K antagonists for patients with pulmonary arterial hypertension (PAH). P-glycoprotein (P-gp) plays a key role in DOAC pharmacokinetics. Type 5-phosphodiesterase inhibitors (PDE5is), a drug class commonly used in the treatment of PAH, have been shown to strongly inhibit P-gp. This work aimed to assess potential P-gp-mediated drug-drug interactions between PDE5is and DOACs using in vitro methods. A cellular model of drug transport assay, using P-gp-overexpressing Madin-Darby canine kidney cells (transfected with the human P-gp gene), was used to determine the bidirectional permeabilities of two DOACs (rivaroxaban and apixaban) in the absence and presence of increasing concentrations (0.5-100 µM) of three PDE5is (sildenafil, tadalafil, and vardenafil). Permeabilities and efflux ratios were calculated from DOAC concentrations, were measured with liquid chromatography coupled with mass spectrometry, and were subsequently used to determine the PDE5i percentage of inhibition and half maximal inhibitory concentration (IC50 ). Rivaroxaban efflux was inhibited by 99%, 66%, and 100% with 100 µM sildenafil, tadalafil, and vardenafil, respectively. Similarly, apixaban efflux was inhibited by 97%, 74%, and 100%, respectively. The IC50 values of the three PDE5is were 8, 28, and 5 µM for rivaroxaban and 23, 15, and 3 µM for apixaban, respectively. This study showed strong in vitro inhibition of DOAC efflux by PDE5is. In vivo studies are required to determine the clinical relevance of these interactions.

Assessment of Safety, Tolerability, Pharmacokinetics, and Pharmacological Effect of Orally Administered CORT125134: An Adaptive, Double-Blind, Randomized, Placebo-Controlled Phase 1 Clinical Study.

CORT125134 is an orally active, high-affinity, selective antagonist of the glucocorticoid receptor that is being developed for indications that may benefit from the modulation of cortisol activity. This first-in-human study was conducted to evaluate the dose-related safety, tolerability, pharmacokinetics and pharmacological effects of CORT125134 and its active metabolite CORT125201. Eighty-one healthy male or female subjects received a single dose of 5 to 500 mg CORT125134 or matching placebo across 9 cohorts; 1 cohort received 150 mg CORT125134 after a high-fat breakfast; and 46 subjects received 50 to 500 mg CORT125134 or matching placebo once daily for up to 14 days across 4 cohorts. CORT125134 was well tolerated at doses up to 250 mg per day for 14 days. CORT125134 was absorbed rapidly and eliminated with a mean half-life ranging from 11 to 19 hours. Steady state was achieved by day 7. Exposure increased in a greater than proportional manner, particularly at lower doses. Exposure to CORT125201 at steady state was less than 5% that of parent CORT125134. Evidence for the desired pharmacological effect (glucocorticoid receptor antagonism) was demonstrated by the ability of CORT125134 to prevent several effects of the glucocorticoid receptor agonist prednisone.

The effectiveness of a fixed-dose combination pour-on formulation of 1.25% fipronil and 2.5% fluazuron against economically important ectoparasites and associated pharmacokinetics in cattle.

The present work consisted of eight studies to evaluate the ectoparasiticidal spectrum and determine the pharmacokinetic parameters of a pour-on combination of fipronil 1.25mg/kg+fluazuron 2.5mg/kg for cattle against Rhipicephalus microplus, Haematobia irritans and the larvae of Dermatobia hominis and Cochliomyia hominivorax. The analysis fipronil and fluazuron were performed by liquid chromatography using a mass detector for the detection and quantification of analytes (LC-MS/MS). Additionally, in two of these studies, the animals were artificially infested with R. microplus ticks (stall tests), and the efficacy of this formulation was compared with that of two other standalone pour-on formulations of fipronil 1.0mg/kg and fluazuron 2.5mg/kg. In the two stall studies, 28 calves were artificially infested with 5000 R. microplus (different strains), and daily collections of all of the engorged female ticks that detached from each calf were performed until 60 and 100days post-treatment (dpt). For the R. microplus field trials, 20 bovines were selected by counting the semi-engorged females, and the therapeutic and residual efficacy was evaluated by taking tick counts at 3, 7, 14, 21, 28, 35, 42, 49 and 56dpt. Forty bovines that were naturally infested with Dermatobia hominis larvae were selected, and the numbers of larvae were counted by visual and tactile inspection on 3, 7, 14, 28, 35, 42 and 49dpt. To address the efficacy on C. hominivorax larvae, two circular skin incisions (one on each side of the body) measuring approximately 4cm in diameter each were made in 12 crossbred calves, and the natural exposure of the lesions to C. hominivorax infestations was then allowed. The incisions from the 12 animals were carefully examined daily from 1 to 10dpt. Based on the PK results obtained for this pour-on combination containing fipronil 1.25mg/kg+fluazuron 2.5mg/kg, the maximum concentrations (Cmax) and the half-lives (T1/2) of these two active ingredients were detected on days 2, 5/6 and 19 (±2)/24, 4 (±3.5) days for fipronil and fluazuron, respectively. Furthermore, the combination showed higher therapeutic and residual efficacy against R. microplus (P≤0.05) when compared with commercial standalone formulations that were administered separately. A high efficacy for this new combination was also found against C. hominivorax and D. hominis larvae (efficacy≥99%). This study's results show that the combination of these two active ingredients, as opposed to their separate use, could represent a tool for extending the life cycle of these two molecules against cattle ectoparasites, especially R. microplus. Further studies would be desirable to further confirm this.

Assessment of absorption potential of poorly water-soluble drugs by using the dissolution/permeation system.

This study aims to assess the absorption potential of oral absorption of poorly water-soluble drugs by using the dissolution/permeation system (D/P system). The D/P system can be used to perform analysis of drug permeation under dissolution process and can predict the fraction of absorbed dose in humans. When celecoxib at 1/100 of a clinical dose was applied to the D/P system, percentage of dose dissolved and permeated significantly decreased with an increase in the applied amount, resulting in the oral absorption being predicted to be 22-55%. Whereas similar dissolution and permeation profiles of montelukast sodium were observed, estimated absorption (69-85%) was slightly affected. Zafirlukast absorption (33-36%) was not significantly affected by the dose, although zafirlukast did not show complete dissolution. The relationship between clinical dose and predicted oral absorption of drugs corresponded well to clinical observations. The limiting step of the oral absorption of celecoxib and montelukast sodium was solubility, while that of zafirlukast was dissolution rate. However, due to high permeability of montelukast, oral absorption was not affected by dose. Therefore, the D/P system is a useful tool to assess the absorption potential of poorly water-soluble drugs for oral use.

Assessment of the drug interaction risk for remogliflozin etabonate, a sodium-dependent glucose cotransporter-2 inhibitor: evidence from in vitro, human mass balance, and ketoconazole interaction studies.

Remogliflozin etabonate is the ester prodrug of remogliflozin, a selective sodium-dependent glucose cotransporter-2 inhibitor. This work investigated the absorption, metabolism, and excretion of [(14)C]remogliflozin etabonate in humans, as well as the influence of P-glycoprotein (Pgp) and cytochrome P450 (P450) enzymes on the disposition of remogliflozin etabonate and its metabolites to understand the risks for drug interactions. After a single oral 402 ± 1.0 mg (106 ± 0.3 µCi) dose, [(14)C]remogliflozin etabonate is rapidly absorbed and extensively metabolized. The area under the concentration-time curve from 0 to infinity [AUC((0-∞))] of plasma radioactivity was approximately 14-fold higher than the sum of the AUC((0-∞)) of remogliflozin etabonate, remogliflozin, and 5-methyl-4-({4-[(1-methylethyl)oxy]phenyl}methyl)-1H-pyrazol-3-yl-ß-d-glucopyranoside (GSK279782), a pharmacologically active N-dealkylated metabolite. Elimination half-lives of total radioactivity, remogliflozin etabonate, and remogliflozin were 6.57, 0.39, and 1.57 h, respectively. Products of remogliflozin etabonate metabolism are eliminated primarily via renal excretion, with 92.8% of the dose recovered in the urine. Three glucuronide metabolites made up the majority of the radioactivity in plasma and represent 67.1% of the dose in urine, with 5-methyl-1-(1-methylethyl)-4-({4-[(1-methylethyl)oxy]phenyl}methyl)-1H-pyrazol-3-yl-ß-d-glucopyranosiduronic acid (GSK1997711) representing 47.8% of the dose. In vitro studies demonstrated that remogliflozin etabonate and remogliflozin are Pgp substrates, and that CYP3A4 can form GSK279782 directly from remogliflozin. A ketoconazole clinical drug interaction study, along with the human mass balance findings, confirmed that CYP3A4 contributes less than 50% to remogliflozin metabolism, demonstrating that other enzyme pathways (e.g., P450s, UDP-glucuronosyltransferases, and glucosidases) make significant contributions to the drug's clearance. Overall, these studies support a low clinical drug interaction risk for remogliflozin etabonate due to the availability of multiple biotransformation pathways.

Assessment of the pharmacokinetic interaction between eltrombopag and lopinavir-ritonavir in healthy adult subjects.

Eltrombopag is an orally bioavailable thrombopoietin receptor agonist that is approved for the treatment of chronic idiopathic thrombocytopenic purpura. It is being developed for other medical disorders that are associated with thrombocytopenia. Patients with human immunodeficiency virus (HIV) may suffer from thrombocytopenia as a result of their HIV disease or coinfection with hepatitis C virus (HCV). HIV medications, particularly ritonavir (RTV)-boosted HIV protease inhibitors, are involved in many drug interactions. This study evaluated the potential drug-drug interaction between eltrombopag and lopinavir (LPV)/RTV. Forty healthy adult subjects enrolled in this open-label, three-period, single-sequence crossover study received a single 100-mg dose of eltrombopag (period 1), LPV/RTV at 400/100 mg twice daily (BID) for 14 days (period 2), and LPV/RTV at 400/100 mg BID (2 doses) with a single 100-mg dose of eltrombopag administered with the morning LPV/RTV dose (period 3). There was a 3-day washout between periods 1 and 2 and no washout between periods 2 and 3. Serial pharmacokinetic samples were collected during 72 h in periods 1 and 3 and during 12 h in period 2. The coadministration of 400/100 mg LPV/RTV BID with a single dose of 100 mg eltrombopag decreased the plasma eltrombopag area under the plasma concentration-time curve from time zero extrapolated to infinity (AUC(0-∞)) by 17%, on average, with no change in plasma LPV/RTV exposure. Adverse events (AEs) reported in period 2 were consistent with known LPV/RTV AEs, such as diarrhea, abdominal pain, nausea, vomiting, rash, and fatigue. No subjects withdrew due to AEs, and no serious AEs were reported. These study results suggest that platelet counts should be monitored and the eltrombopag dose adjusted accordingly if LPV/RTV therapy is initiated or discontinued.

A randomised assessment of the pharmacokinetic, pharmacodynamic and safety interaction between apixaban and enoxaparin in healthy subjects.

Following major orthopaedic surgery, guidelines usually recommend continued thromboprophylaxis after hospitalisation. The availability of an effective oral anticoagulant with an acceptable safety profile that does not require routine clinical monitoring may lead clinicians to switch patients from subcutaneous to an oral therapy either during hospitalisation or at discharge. The purpose of this study was to assess the effect of enoxaparin on the pharmacokinetics, pharmacodynamics and safety of apixaban, an oral, direct inhibitor of coagulation factor Xa. In this four-period, crossover study, 20 healthy subjects were randomised to receive single doses of apixaban 5 mg orally; enoxaparin 40 mg subcutaneously; apixaban 5 mg and enoxaparin 40 mg concomitantly; and apixaban 5 mg followed 6 hours (h) after by enoxaparin 40 mg. Pharmacokinetics of apixaban were not affected by enoxaparin. Average peak pharmacodynamic effect, measured by anti-Xa activity, was 1.36 U/ml after administration of apixaban and was 0.42 U/ml after enoxaparin. Following co-administration of apixaban and enoxaparin, peak anti-Xa activity was 42% higher than for apixaban alone. Following administration of enoxaparin 6 h after apixaban, peak anti-Xa activity was 15% higher than for apixaban alone. In conclusion, enoxaparin had no effect on the pharmacokinetics of apixaban. The increase in anti-Xa activity after co-administration was modest and appeared to be additive. Peak anti-Xa activity increases are mitigated by separating administration of subcutaneous anticoagulation and apixaban when switching between therapies; the potential for pharmacodynamic interaction may be further mitigated by transitioning at the next scheduled dose (12 h).

Comparative impact on prostanoid biosynthesis of celecoxib and the novel nonsteroidal anti-inflammatory drug CG100649.

Nonsteroidal anti-inflammatory drugs (NSAIDs) elevate cardiovascular risk by disrupting cyclooxygenase-2 (COX-2)-dependent biosynthesis of prostacyclin (PGI(2)). CG100649 is a novel NSAID proposed to inhibit both COX-2 and carbonic anhydrase (CA)-I/-II. We compared its impact on prostanoid biosynthesis with that of celecoxib, an NSAID purposefully designed to selectively inhibit COX-2. In a controlled, double-blind randomized trial, single oral doses of 2 or 8 mg CG100649, 200 mg celecoxib, or placebo were well tolerated by healthy volunteers (n = 23). Both CG100649 and celecoxib had the effect of depressing urinary excretion of 2,3-dinor-6-keto-PGF(1α) (PGI-M); the effect of CG100649 was dose-dependent and more sustained (up to 240 h after the dose) than that of celecoxib. Neither CG100649 nor celecoxib significantly inhibited COX-1-dependent prostanoid formation. CA inhibition was not detected after administration of CG100649, despite its partitioning asymmetrically into erythrocytes. CG100649 and celecoxib are both relatively selective inhibitors of COX-2, but they differ in duration of action. Whether they have similar impact on cardiovascular events remains to be determined.