Efficacy of endoscopy in assessing the local disease response in nasopharyngeal carcinoma patients after treated with intensity-modulated radiotherapy.

AIM: The optimal local disease assessment after intensity-modulated radiotherapy (IMRT) for nasopharyngeal carcinoma (NPC) patients remains unclear. Our aim was to investigate the efficacy of post-IMRT endoscopies. METHODS: The medical record of NPC patients with IMRT treatments during 2013 to 2015 was reviewed. Endoscopies and nasopharyngeal biopsies were performed at 6 weeks post-IMRT. Second biopsies were performed 4 weeks later for patients with abnormal first biopsies. Results of endoscopic assessments were correlated with histology using standard descriptive statistics. RESULTS: A total of 262 patients were reviewed. Endoscopy showed a sensitivity, specificity, positive predictive value, and negative predictive value (NPV) of 71%, 90%, 41% and 97%, respectively. Disease remission at 6 weeks was observed in 234 patients (89.3%). Sixteen patients (6.1%) had ultimate disease remission (late responders) and 12 (4.6%) had persistent local disease. CONCLUSION: Endoscopy had high specificity and NPV; therefore, invasive biopsy could be exempted in case of normal endoscopy.

The Use of Post-ablation Stimulated Thyroglobulin in Predicting Clinical Outcomes in Differentiated Thyroid Carcinoma - What Cut-off Values Should We Use?

AIMS: Recently published international guidelines recommended using the stimulated thyroglobulin (sTg) post-radioactive iodine (RAI) ablation, in conjunction with tumour stage, as a risk stratification factor. The choice of cut-off values for sTg, namely 1 and 10 ng/ml, was, however, largely based on the functional sensitivities of the assays used, with relatively few published data addressing the prognostic impact of alternative cut-off values. Our study aims to provide data on the prognostic value of sTg at different levels of sensitivities and specificities. MATERIALS AND METHODS: We conducted a retrospective review of all adult cases of differentiated thyroid carcinoma receiving RAI ablation at our centre from 2008 to 2010. All patients had sTg measured at around 6 months post-ablation. The functional sensitivity of our assay was 0.5 ng/ml. The outcome was adverse clinical event, defined as cancer-related death, persistent macroscopic disease demonstrable on imaging (including radioisotope scan) and/or receiving further treatment for persistent or recurrent disease. A receiver operating characteristic (ROC) analysis was carried out. RESULTS: We identified 140 patients treated in the review period, with 106 of them suitable for further analysis. The reasons for exclusion included the presence of anti-thyroglobulin antibodies and medullary or anaplastic histological subtypes. Most (54.7%) had intermediate-risk disease as per the American Thyroid Association classification (2009). The median follow-up duration was 6.4 years; the minimum, excluding deaths, was 5.0 years. ROC analysis showed that the optimal cut-off value of sTg for predicting adverse clinical events was >1.0 ng/ml, associated with a sensitivity of 90.9%, a specificity of 81.0%, a positive predictive value of 55.6% and a negative predictive value of 97.1%. CONCLUSION: Based on ROC analysis of sensitivities and specificities, our data showed that a post-ablation sTg value of 1 ng/ml is the optimal cut-off in prognostication of adverse clinical events.

Safety, tolerability, pharmacodynamics and pharmacokinetics of DWP14012, a novel potassium-competitive acid blocker, in healthy male subjects.

BACKGROUND: A novel potassium-competitive acid blocker, DWP14012, is in clinical development as a potential alternative to proton pump inhibitors for the treatment of acid-related diseases. AIMS: To evaluate the safety, tolerability, pharmacodynamics and pharmacokinetics of DWP14012 in humans. METHODS: A randomised, double-blind, double-dummy, placebo- and active-controlled, single- and multiple-ascending dose (SAD and MAD, respectively) study was conducted in healthy male subjects without Helicobacter pylori infection. Subjects randomly received a single oral dose of 10-320 mg DWP14012, esomeprazole (active comparator) or placebo in the SAD study (n = 72) and once daily doses of 20-160 mg DWP14012, esomeprazole or placebo for 7 days in the MAD study (n = 48; 8:2:2). Tolerability was evaluated using a microRNA-122 assay. Pharmacodynamics were evaluated through 24-hour gastric pH monitoring, and pharmacokinetics were evaluated plasma and urine DWP14012 concentrations. RESULTS: DWP14012 was generally well tolerated. The liver toxicity of DWP14012 was not higher than that of placebo after multiple oral administrations. DWP14012 showed rapid and sustained suppression of gastric acid secretion for 24 hours after dosing. Clear dose-response and exposure-response relationships were observed. Plasma concentrations of DWP14012 increased in a dose-proportional manner in the MAD study, whereas in the SAD study, DWP14012 did not significantly accumulate in the plasma. CONCLUSIONS: DWP14012 was well tolerated, and showed a rapid and long-lasting gastric acid suppression effect in healthy subjects. These results justify further investigation of DWP14012 in patients with acid-related disorders.

Risk factors for suboptimal drug concentration of posaconazole oral suspension in patients with hematologic malignancy.

Absorption of posaconazole oral suspension is influenced by several factors including diet, medications, and mucosal integrity. However, there are few prospective data about which is the most important modifiable factor in routine clinical practice. We prospectively analyzed clinical risk factors associated with low posaconazole trough concentrations in 114 patients receiving anticancer chemotherapy due to acute myeloid leukemia or myelodysplastic syndrome who received posaconazole oral suspension. In multivariate analyses, risk factors for drug level<500ng/mL included low calorie intake, mucositis≥grade 2, H2 blocker famotidine and proton-pump inhibitor. The only significant risk factor for drug level<700ng/mL was famotidine use (adjusted relative risk, 3.18; 95% confidence interval, 1.07-9.11; P=0.038). In conclusion, medication of H2 blocker famotidine should be cautious in patients with hematologic malignancy receiving posaconazole suspension.

Performance of the Minto model for the target-controlled infusion of remifentanil during cardiopulmonary bypass.

We studied the predictive performance of the Minto pharmacokinetic model during cardiopulmonary bypass in patients undergoing cardiac surgery. Patients received remifentanil target-controlled infusion using the Minto model during total intravenous anaesthesia with propofol. From 56 patients, 275 arterial blood samples were drawn before, during and after bypass to determine the plasma concentration of remifentanil, and the predicted concentrations were recorded at each time. For pooled data, the median prediction error and median absolute prediction error were 21.3% and 21.8%, respectively, and 22.1% and 22.3% during bypass. Both were 148.4% during hypothermic circulatory arrest and measured concentrations were more than three times greater than predicted (26.9 (17.0) vs. 7.1 (1.6) ng.ml-1 ). The Minto model showed considerable bias but overall acceptable precision during bypass. The target concentration of remifentanil should be reduced when using the Minto model during hypothermic circulatory arrest.

A novel K+ competitive acid blocker, YH4808, sustains inhibition of gastric acid secretion with a faster onset than esomeprazole: randomised clinical study in healthy volunteers.

BACKGROUND: YH4808, a K+ -competitive acid blocker, is under clinical development for the treatment of acid-related disorders, such as gastroesophageal reflux disease. AIMS: To determine the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of YH4808, compared to placebo and esomeprazole. METHODS: This double-blind, randomised, placebo- and active comparator (esomeprazole)-controlled study was conducted with 123 healthy male volunteers. We evaluated YH4808 (30-800 mg) properties, administered in single (N=55) and multiple (N=24) oral doses, and recorded the effects on 24-hour intragastric acidity. Results were compared to placebo (N=20) and esomeprazole 40 mg (N=24). RESULTS: Plasma YH4808 exposure increased dose-proportionally and declined in a multi-phasic manner. YH4808 ≥200 mg/d maintained intragastric acidity at pH >4 for longer times than esomeprazole during both day and night (%Time at pH >4: >70% vs 58% of a 24-hour period, respectively; and >50% vs 33% of a 9-hour night respectively). A twice-daily regimen of YH4808 more effectively controlled intragastric pH at night than a once-daily regimen. In evaluating the mean areas under the intragastric pH-time curves in 15-minute intervals for 2 hours after dosing, we found that YH4808 had a faster onset than esomeprazole. Moreover, unlike esomeprazole, YH4808 PK and PD were not significantly affected by the CYP2C19 genotype of the subjects. YH4808 was well-tolerated at all doses administered. CONCLUSION: This study showed that YH4808 produced a rapid, sustained suppression of gastric secretion with good tolerability. The results at YH4808 ≥200 mg/d provide a rationale for further clinical investigations in populations with acid-related diseases.

An Accelerator Mass Spectrometry-Enabled Microtracer Study to Evaluate the First-Pass Effect on the Absorption of YH4808.

14 C-labeled YH4808, a novel potassium-competitive acid blocker, was intravenously administered as a microtracer at 80 µg (11.8 kBq or 320 nCi) concomitantly with the nonradiolabeled oral drug at 200 mg to determine the absolute bioavailability and to assess the effect of pharmacogenomics on the oral absorption of YH4808. The absolute bioavailability was low and highly variable (mean, 10.1%; range, 2.3-19.3%), and M3 and M8, active metabolites of YH4808, were formed 22.6- and 38.5-fold higher after oral administration than intravenous administration, respectively. The product of the fraction of an oral YH4808 dose entering the gut wall and the fraction of YH4808 passing on to the portal circulation was larger in subjects carrying the variants of the CHST3, SLC15A1, and SULT1B1 genes. A combined LC+AMS is a useful tool to construct a rich and highly informative pharmacokinetic knowledge core in early clinical drug development at a reasonable cost.

Combined untargeted and targeted metabolomic profiling reveals urinary biomarkers for discriminating obese from normal-weight adolescents.

BACKGROUND: Childhood and adolescent obesity may lead to obesity and related complications in adulthood. Biomarkers of obesity can be useful for screening for obesity complications and promoting early intervention during school age. Thus, the metabolomic differences in obese children and adolescents should be investigated for identification of potential biomarkers. OBJECTIVES: We investigated urinary biomarkers to distinguish metabolomic characteristics between obesity and normal weight in adolescents. METHODS: Adolescent subjects were divided into non-obese (n = 91) and obese (n = 93) groups according to body mass index. Untargeted and targeted metabolomic profiling of urine was performed using high-performance liquid chromatography (LC)-quadrupole time-of-flight mass spectrometry (MS), LC-MS/MS and flow injection analysis-MS/MS systems, respectively. RESULTS: Multivariate statistical analysis showed clear discrimination between the untargeted metabolomes of non-obese and obese groups. Seven endogenous metabolites were distinguished in the obese group, and inflammation-related metabolite markers showed strong predictive power for group classification. From targeted metabolomics, 45 metabolites mostly related to inflammation were significantly different in the obese group. CONCLUSIONS: Significantly different metabolome signatures were identified between normal-weight and obese adolescents. Combined untargeted and targeted metabolomics demonstrated that inflammation-driven insulin resistance, ammonia toxicity and oxidative stress may represent crucial metabolomic signatures in obese adolescents.

Exploration of Biomarkers for Amoxicillin/Clavulanate-Induced Liver Injury: Multi-Omics Approaches.

To explore potential biomarkers for amoxicillin/clavulanate-induced liver injury (AC-DILI), we conducted a clinical trial in 32 healthy subjects based on multi-omics approaches. Every subject was administered amoxicillin/clavulanate for 14 days. The liver-specific microRNA-122 (miR-122) level increased prior to and correlated well with the observed alanine aminotransferase (ALT) level increase. This result indicates its potential as a sensitive early marker for AC-DILI. We also identified urinary metabolites, such as azelaic acid and 7-methylxanthine, with levels that significantly differed among the groups classified by ALT elevation level on day 8 after drug administration (P < 0.05). Lymphocyte proliferation in response to the drug was also observed. These findings demonstrate sequential changes in the process of AC-DILI, including metabolic changes, increased miR-122 level, increased liver enzyme activity, and enhanced lymphocyte proliferation after drug administration. In conclusion, this study provides potential biomarkers for AC-DILI based on currently known mechanisms using comprehensive multi-omics approaches.

Inhibition of the multidrug and toxin extrusion (MATE) transporter by pyrimethamine increases the plasma concentration of metformin but does not increase antihyperglycaemic activity in humans.

We hypothesized that the pharmacodynamic (PD) characteristics of metformin would change with inhibition of the multidrug and toxin extrusion (MATE) transporter, which mediates renal elimination of metformin. Twenty healthy male subjects received two doses (750/500 mg) of metformin, with and without 50 mg of pyrimethamine (a potent MATE inhibitor), with 1 week of washout in between each dose. The PD characteristics of metformin were assessed using oral glucose tolerance tests (OGTTs) before and after the metformin dose. Metformin concentrations in plasma and urine were determined using liquid chromatography-electrospray ionization-tandem mass spectrometry. When metformin was co-administered with pyrimethamine, its area under the concentration-time curve from 0 to 12 h was 2.58-fold greater (p < 0.05), whereas the antihyperglycaemic effects of metformin were decreased. The mean differences (90% confidence interval) in mean and maximum serum glucose concentrations and in 2-h-post-OGTT serum glucose concentration were -0.6 (-1, -0.2), -0.9 (-1.6, -0.3) and -0.5 (-1.1, 0.1) mmol/l, respectively. These findings indicate that the response to metformin is not only related to the plasma exposure of metformin but is also related to other factors, such as inhibition of uptake transporters and the gastrointestinal-based pharmacology of metformin.

Investigation of bioequivalence of a new fixed-dose combination of acarbose and metformin with the corresponding loose combination as well as the drug-drug interaction potential between both drugs in healthy adult male subjects.

WHAT IS KNOWN AND OBJECTIVE: Both metformin and acarbose are recommended monotherapy and add-on therapy in type 2 diabetes mellitus (T2DM). A fixed-dose combination (FDC) of acarbose and metformin has been developed to reduce pill burden and potentially improve compliance. The current study investigated the bioequivalence of the acarbose/metformin FDC compared with the individual agents administered simultaneously (loose combination). Secondary endpoints were the safety and tolerability of the FDC and the potential for drug-drug interactions between acarbose and metformin. METHODS: A single-centre, randomized, open-label, four-period crossover study was conducted in healthy male Korean subjects aged 18-45 years. Following one-period balanced Williams design, participants were randomized to receive four single oral treatments on different study days separated by ≥7 days' washout. Treatments were as follows: (i) acarbose/metformin 50/500 mg FDC (test); (ii) acarbose 50 mg and metformin 500 mg as loose combination (reference); (iii) acarbose 50 mg; and (iv) metformin 500 mg. Serial blood samples were taken for glucose and insulin levels for 4 h after a sucrose load on the day before and day of study drug administration. Additionally, serial blood samples were taken for analysis of metformin levels for 24 h after each drug containing metformin. The area under the curve for 4 h post-test (AUC0-4 h ) and the maximal serum concentration (Cmax ) of plasma glucose and serum insulin were primary pharmacodynamic (PD) parameters, and Cmax , AUC0-last and AUC for metformin levels were primary pharmacokinetic (PK) parameters. The bioequivalence of the FDC to the loose combination was considered established if the 90% confidence intervals (CIs) of the baseline-adjusted PD parameter ratios (test vs. reference) for plasma glucose and the PK parameter ratios for metformin fell completely within current acceptance limits (0·8-1·25). RESULTS AND DISCUSSION: Thirty-three of 40 randomized subjects completed the study; five withdrew consent and two discontinued because of adverse events (AEs). The 24-h plasma concentration-time curves of metformin and the 4-h plasma glucose-time curves after acarbose/metformin FDC (test) and acarbose + metformin loose combination (reference) were almost superimposable. The geometric least squares (LS) mean of the RatioAUC and RatioCmax for plasma glucose after the FDC vs. loose combination, and the LS mean of the ratios in metformin AUC, AUC0-last and Cmax were close to unity, and the 90% CI of all these parameters fell within the predefined equivalence range of 0·8-1·25, confirming bioequivalence. The metformin AUC was reduced by 26% and Cmax by 34% after acarbose + metformin compared with metformin alone. Eight subjects (20·0%) reported AEs, but all were mild, and most were gastrointestinal, as expected for these agents. The incidence of AEs was not higher with the combinations vs. monotherapy. WHAT IS NEW AND CONCLUSION: These data demonstrate that the acarbose/metformin FDC is bioequivalent to the loose combination of these agents. Although acarbose slightly reduced the bioavailability of metformin, the accumulated evidence of the efficacy of this combination implies that this is clinically irrelevant. The observed AE profile was consistent with the established knowledge on the safety of the two drugs.

Aspirin decreases systemic exposure to clopidogrel through modulation of P-glycoprotein but does not alter its antithrombotic activity.

Decreased oral clopidogrel absorption caused by induction of intestinal permeability glycoprotein (P-gp) expression after aspirin administration was observed in rats. This study evaluated the effect of aspirin coadministration on the pharmacokinetics/pharmacodynamics of clopidogrel in humans. A single 75-mg dose of clopidogrel was orally administered before and after 2 and 4 weeks of once-daily 100-mg aspirin administration in 18 healthy volunteers who were recruited based on CYP2C19 and PON1 genotypes. Plasma concentrations of clopidogrel and its active metabolite, H4, and relative platelet inhibition (RPI) were determined. The P-gp microRNA miR-27a increased by up to 7.67-fold (P = 0.004) and the clopidogrel area under the concentration-time curve (AUC) decreased by 14% (P > 0.05), but the AUC of H4 remained unchanged and RPI increased by up to 15% (P = 0.002) after aspirin administration. These findings indicate low-dose aspirin coadministration may decrease clopidogrel bioavailability but does not decrease its efficacy.

Evaluation of endogenous metabolic markers of hepatic CYP3A activity using metabolic profiling and midazolam clearance.

This study aimed to evaluate endogenous metabolic markers of hepatic cytochrome P450 (CYP)3A activity in healthy subjects using a metabolomics approach. Twenty-four subjects received the following medication during the following three study periods: 1 mg of i.v. midazolam alone (control phase), 1 mg of i.v. midazolam after 4 days of pretreatment with 400 mg of ketoconazole once daily (CYP3A-inhibited phase), and 2.5 mg of i.v. midazolam after 10 days of pretreatment with 600 mg of rifampicin once daily (CYP3A-induced phase). During each study period, 24 h before and after the administration of midazolam, urine samples were collected at 12-h intervals for metabolomic analyses. We derived an equation to predict midazolam clearance (CL) based on several of these markers. We demonstrated that a combination of the concentrations and ratios of several endogenous metabolites and the CYP3A5*3 genotype is a reliable predictive marker of hepatic CYP3A activity as assessed by i.v. administration of midazolam.

Pharmacokinetics and pharmacodynamics of intravenous dexmedetomidine in healthy Korean subjects.

WHAT IS KNOWN AND OBJECTIVE: Dexmedetomidine is a selective alpha2-adrenoreceptor agonist used for sedation in critically ill patients. The current study aimed to evaluate the pharmacokinetics (PKs), pharmacodynamics and tolerability of intravenous dexmedetomidine in healthy Korean subjects. METHODS: A randomized, double-blind, placebo-controlled study with three parallel dosage groups was conducted. Twenty-four subjects were randomly assigned to placebo or one of three dexmedetomidine dosing regimens, 3 µg/kg/h for 10 min followed by 0.17 µg/kg/h for 50 min (low dose), 6 µg/kg/h for 10 min followed by 0.34 µg/kg/h for 50 min (middle dose) and 3.7 µg/kg/h for 35 min followed by 0.7 µg/kg/h for 25 min (high dose). Serial blood samples for PK analysis were taken up to 12 h. PK parameters were determined using non-compartmental methods (WinNonlin(®)), and a population PK model was developed using nonmem(®). The sedative effect of dexmedetomidine was assessed by Ramsay sedation score and visual analogue scales/sedation. Adverse events, clinical laboratory tests, electrocardiograms, physical examinations and vital signs were monitored for tolerability assessment. RESULTS: Six subjects were assigned to each of the three active treatment group or placebo group. The AUC(last) of the low-, middle- and high-dose group were 1096.8 ± 119.9 (mean ± SD) ng*h/L, 2643.0 ± 353.2 ng*h/L and 5600.6 ± 411.0 ng*h/L, respectively. PK of dexmedetomidine was best described using a two-compartment model. The typical value of the population model can be calculated using the following equations: central volume of distribution (L) = 19.9 (age/27)(0.954), peripheral volume of distribution (L) = 59.4, clearance (L/h) = 33.7 (albumin level/4.3)(1.42) and inter-compartment clearance (L/h) = 67.7. Sedative effects were significantly increased by dexmedetomidine compared to placebo. The blood pressure and heart rate were decreased, but oxygen saturation was maintained stable. WHAT IS NEW AND CONCLUSION: Dexmedetomidine shows linear PK characteristics and dose-dependent sedative effects. A two-compartment population PK model was developed for healthy Korean subjects. The PK parameter estimates are similar in Koreans and Caucasians.

Pharmacodynamic comparison of two formulations of Acarbose 100-mg tablets.

WHAT IS KNOWN AND OBJECTIVE: Acarbose, an α-glycosidase inhibitor, is used to treat diabetic patients. Pharmacokinetic evaluation of acarbose is difficult because <2% is absorbed systemically. The current investigation evaluated the bioequivalence of two formulations of acarbose through pharmacodynamic comparison. METHODS: This investigation consisted of a pilot study and a main study. The pilot study had an open, single-dose, single-sequence design. Subjects received placebo and then two tablets of reference formulation (Glucobay(®) 100 mg tablet; Bayer Healthcare) on two consecutive days with sucrose. The main study was an open, randomized, two-period, two-sequence crossover study. Subjects randomly received placebo and two tablets of either test formulation (generic acarbose 100-mg tablet) or reference formulation with sucrose on two consecutive days in the first period. In the second period, placebo and alternative formulation were administered. Serial blood samples for pharmacodynamic assessment were taken after each administration. The maximum serum glucose concentration (G(max)) and the area under the serum glucose concentration-time profile (AUC(gluc)) were determined and compared. RESULTS AND DISCUSSION: Five subjects completed the pilot study. The AUC(gluc) from dosing until 1 h post-dose (AUC(gluc,1 h)) was significantly different between the placebo and acarbose. A total of 33 subjects completed the main study. The mean differences in G(max) (ΔG(max)) and AUC(gluc,1 h) (ΔAUC(gluc,1 h)) for the reference formulation compared with placebo were 22·0 ± 18·3 mg/dL and 928·2 ± 756·0 mg min/dL, respectively. The corresponding values for the test formulation were 23·3 ± 21·2 mg/dL and 923·0 ± 991·4 0 mg min/dL, respectively. The geometric mean ratios (GMRs) of the test formulation to the reference formulation for ΔG(max) and ΔAUC(gluc, 1 h) were 1·06 and 1·00, respectively, and the 90% confidence intervals (CIs) corresponding values were 0·79-1·39 and 0·64-1·36, respectively. WHAT IS NEW AND CONCLUSION: The 90% CIs of GMRs for the pharmacodynamic parameters chosen for bioequivalence evaluation of two formulations of acarbose did not meet the commonly accepted regulatory criteria for bioequivalence (0·80-1·25).

Open label, three period, single sequence, study of 5, 25, 50 mg sertraline pharmacokinetics in healthy male Korean volunteers.

BACKGROUND: Sertraline is a naphthalenamine derivative which has the effect of selective serotonin reuptake inhibition. It has been used for major depression, and obsessive compulsive disorder. This study was performed to evaluate the pharmacokinetic (PK) characteristics after the administration of low dose sertraline for the purpose of exploring an application of microdosing methods in PK studies. METHODS: An open-label, three-period, single-sequence, dose-escalation study was performed in 6 healthy Korean male volunteers. Subjects were administered a single dose of 5 mg, 25 mg and 50 mg sertraline orally in each period, with 1 week washouts between periods. Blood samples were obtained up to 96 h after drug administration. Plasma concentrations were determined using high performance liquid chromatography-tandem mass spectrometry. PK parameters of sertraline were analyzed using non-compartmental methods. RESULTS: A total of 6 subjects completed the study. After the administration of sertraline at 5 mg, 25 mg and 50 mg, the median tmax were 6.0, 6.0 and 4.0 h and the mean (SD) elimination half-lives were 31.9 (6.5), 27.2 (6.7) and 28.0 (6.6) h, respectively. The AUC and Cmax increased dose-dependently. The dose-normalized mean (SD) AUC and Cmax were different in each dosing group (p < 0.01) with 2.0 (0.8), 5.3 (1.2) and 6.0 (1.9) mg × hr/l/mg in the 5 mg, 25 mg and 50 mg groups for dose-normalized AUC, and 0.07 (0.01), 0.18 (0.05) and 0.21 (0.08) mg/l/mg in the 5 mg, 25 mg and 50 mg groups for dose-normalized Cmax, respectively, which indicates a lack of dose proportionality. CONCLUSION: A lack of dose proportional properties was shown in the 5 mg dose relative to the 25 mg and 50 mg doses of sertraline. This shows that the PK parameters for low-dose sertraline could be different from those in clinical concentrations.

Pharmacokinetics and tolerability of probucol after multiple oral administrations in healthy volunteers.

BACKGROUND: Probucol is indicated for primary hyperlipidemia and for hypercholesterolemia with hypertriglyceridemia. The objective of this study was to evaluate the tolerability and pharmacokinetics of probucol by multiple oral administration in healthy Korean male subjects. METHODS: This study was conducted by a randomized, openlabel, three-treatment, parallel-group design. A total of 30 subjects were randomly assigned to 1 of the 3 treatment groups were administered probucol orally at 250 mg once daily (QD) after breakfast (250 mg/d), at 500 mg once daily after breakfast (500 mg/d), or at 250 mg twice a day (b.i.d) after breakfast and dinner (500 mg/d) for 14 days. Serial samples of blood were collected and plasma drug concentrations were determined using liquid chromatography-tandem mass spectrometry (LC/MS/MS). For tolerability assessment, measurement of vital signs and electrocardiograms (ECG), clinical laboratory tests and physical examinations were performed. RESULTS: At Day 13, the mean of the AUC(24h) of probucol was 123,800 µg × h/l in the 250 mg QD group, 198,500 µg × h/l in the 500 mg QD group, and 244,700 µg × h/l in the 250 mg BID group. The mean accumulation index for AUC(24h) (ratio of AUC(24h) for Day 13 to that for Day 1) was 2.5 in the 250 mg QD group, 2.85 in the 500 mg QD group, and 4.21 in the 250 mg b.i.d. group. No clinically significant changes in ECG, including QTc prolongation were observed during the study period. All adverse events were mild and no clinically significant changes were observed in any other tolerability assessment, thus confirming tolerability for all regimens tested. CONCLUSIONS: This study provided data on the pharmacokinetics and tolerability of probucol by multiple oral administrations in healthy male volunteers.

Prolonged use of aspirin alters human and rat intestinal cells and thereby limits the absorption of clopidogrel.

Clopidogrel therapy to prevent atherothrombosis faces the challenge of reduced responsiveness. The absorption of clopidogrel is regulated by multidrug-resistance protein 1 (MDR1) in the intestinal epithelium. Given that aspirin induces MDR1 in cancer cells and peripheral blood cells, it may induce MDR1 in intestinal epithelial cells as well, thereby affecting the absorption of clopidogrel. In this study, aspirin treatment induced the expression of MDR1 in human epithelial colorectal (Caco-2) cells in vitro and in rat intestine in vivo, as evidenced by dose-dependent increases in gene, protein, and efflux function. Along with the upregulation of MDR1 proteins by aspirin, clopidogrel absorption was significantly decreased in the aspirin-treated Caco-2 cells and in rat intestine. Our data provide evidence that prolonged use of aspirin may reduce the intestinal absorption of clopidogrel. Further human studies would be necessary to clarify whether these data have any relevance to prevention of stroke or myocardial infarction.

Effect of multiple doses of fimasartan, an angiotensin II receptor antagonist, on the steady-state pharmacokinetics of digoxin in healthy volunteers.

UNLABELLED: Fimasartan (BR-A-657) is an angiotensin II receptor antagonist, recently approved as an antihypertensive agent. OBJECTIVE: This study aimed to investigate whether administration of fimasartan has an effect on the steady-state pharmacokinetics of digoxin. METHODS: An open-label, two-period, two-treatment, single-sequence, crossover study was conducted in 14 healthy male volunteers. On the first day of each 7-day treatment period, subjects received a loading dose of digoxin 0.5 mg, either alone or together with fimasartan 240 mg in the morning, followed by an additional dose of digoxin 0.25 mg after 6 h. On the subsequent 6 days, digoxin 0.25 mg, either alone or with fimasartan 240 mg was administered once daily. Serial blood samples for pharmacokinetics were collected up to 24 h after the last administration in each period. RESULTS: The geometric mean ratio and 90% confidence intervals (CI) for the Cmax,ss and AUCτ,ss of digoxin (with/without fimasartan) were 1.307 (1.123 - 1.520) and 1.087 (1.015 - 1.165), respectively. Study medications were well-tolerated without serious adverse events or clinically meaningful changes. CONCLUSIONS: Coadministration of fimasartan with digoxin does not result in clinically significant changes of digoxin pharmacokinetics at steady-state in healthy subjects.