Effects of age and gender on the cytochrome P450 2D6 activity in a Korean population

WHAT IS KNOWN AND OBJECTIVE

Age and gender have been reported to play a crucial role in modulating the disposition of pharmacological agents, and to influence the activities of cytochrome P450 (CYP) 2D6, a drug-metabolizing enzyme involved in the disposition of clinically used drugs. In the present study, the effects of age and gender on the CYP2D6 activity were evaluated using dextromethorphan as a probe drug in humans.

METHODS

Healthy young (20 < age < 30 years, n = 60) and old age (age >60 years, n = 60) subjects were enrolled and were given 15 mg dextromethorphan orally. Blood samples were collected before and 3 h after medication. Dextromethorphan and its metabolite dextrorphan were measured using HPLC-fluorescence, and dextromethorphan metabolic ratio (MR, log [dextromethorphan/dextrorphan]) was used to evaluate the CYP2D6 activity.

RESULTS AND DISCUSSION

Mean (±SD) dextromethorphan MR was -2.42 ± 0.46 for the young male group, -2.28 ± 0.56 for the young female group, -2.46 ± 0.55 for the older male group and -2.34 ± 0.65 for the old female group. Based on our findings, the effects of age and gender on CYP2D6 activity were not statistically significant.

WHAT IS NEW AND CONCLUSION

The results of the present study indicate that age and gender play a minor role in the modulation of CYP2D6 activity in the Korean population.

Evaluation of global laboratory methods and establishing on-therapy ranges for monitoring apixaban and rivaroxaban: Experience at a single institution

BACKGROUND

Apixaban and rivaroxaban are approved for the prevention and treatment of deep vein thrombosis (DVT), pulmonary embolism (PE), and embolic stroke in atrial fibrillation (AF) patients. The aim of this study was to find appropriate methods of monitoring the anticoagulant effects of are direct oral anticoagulants (DOACs) and establish on-therapy ranges using conventional tests.

METHODS

A total of 184 samples were collected from 91 patients receiving DOACs. Concentrations of apixaban and rivaroxaban in plasma were accessed by an anti-factor Xa chromogenic assay. PT, APTT, antithrombin, D-dimer, dRVVT screen/confirm, FDP, and fibrinogen levels were measured. On-therapy ranges were calculated by substituting previously reported trough plasma concentrations of DOACs.

RESULTS

Anti-factor Xa chromogenic assay-based DOACs levels were 26.0-279.5 (115.9 ± 56.5) ng/mL for apixaban at 2.5 mg BID, 19.9-565.1 (205.3 ± 162.4) ng/mL for apixaban at 5 mg BID, 2.3-395.3 (205.3 ± 162.4) ng/mL for rivaroxaban at 15 mg OD, 3.6-494.8 (119.6 ± 95.1) ng/mL for rivaroxaban at 20 mg OD, and 9.6-431.4 (140.8 ± 113.6) ng/mL for rivaroxaban at 15 mg BID. PT (%), antithrombin, and dRVVT confirm tests showed good correlation with plasma apixaban levels. Plasma rivaroxaban concentrations were correlated well with PT (sec), PT (%),and dRVVT confirm results. On-therapy ranges established for dRVVT confirm test by linear regression were as follows: 1.32-1.52 for apixaban 2.5 mg BID, 1.12-1.75 for apixaban 5 mg BID, 1.11-1.78 for rivaroxaban 15 mg OD, 1.09-1.64 for rivaroxaban 20 mg OD, and 1.22-1.81 for rivaroxaban 20 mg BID.

CONCLUSIONS

Apixaban concentrations were well correlated with PT (%), antithrombin, and dRVVT confirm test. Rivaroxaban concentrations showed good correlation with PT (sec), PT (%), and dRVVT confirm test.

How useful is bone marrow study as an initial investigative tool without lymph node biopsy in malignant lymphoma?: Eleven years of experience at a single institution

BACKGROUND

Bone marrow (BM) study plays an important role as initial investigation specimen of lymphoma as well as staging lymphoma. This study aimed to investigate the utility of BM studies for classification of lymphoma and evaluate features of BM involvement by lymphoma over a period of 11 years.

METHODS

A total of 1162 cases of BM studies for lymphoma evaluation were reviewed for the incidence of lymphoma subtypes, the percentage of marrow involvement, the pattern of involvement and discordance with histopathologic diagnoses of lymph nodes and other tissues.

RESULTS

A total of 255 of 1162 cases underwent BM study without pathologic information, and 108 cases show lymphoma involvement. Lymph node biopsy underwent in 66 cases, and 10 cases show discordant result between BM and lymph node biopsy. Seven discordant cases were due to insufficient further studies. Lymphoma was diagnosed only by BM study in 38 cases. Abnormal lymphocytes were found in BM aspiration in 34 cases. Also, abnormal clonal lymphocytes were detected by flow cytometry in 26 cases. Four cases showed disease-related chromosomal abnormalities. FISH analysis detected abnormal findings in two cases, however, discordant with other additional studies.

CONCLUSIONS

Discrepancies between the BM study and lymph node biopsy were due to insufficient further study and discordance of immunohistochemical stain result. BM study can be utilized as initial diagnosis of lymphoma by the combination of morphological feature, involvement pattern, and additional tests such as flow cytometry, chromosomal analysis, and FISH analysis. Thus, BM study with further analysis is an essential choice when lymph node biopsies are unavailable.

Detection and genomic analysis of genital group B streptococcus in pregnant Korean women

AIM

Group B streptococcus (GBS) is a leading cause of life-threatening bacterial infections among newborns, and neonates born to heavily colonized women may be subject to vertical transmission. We sought to determine an appropriate detection method for genital GBS in pregnant women by comparing culture-based methods and real-time polymerase chain reaction (PCR). In addition, we performed molecular serotyping and multilocus sequence typing (MLST) on isolates.

METHODS

A total of 150 pregnant women were enrolled and underwent vaginal-rectal swabbing at 16-40 weeks of gestation. GBS was identified by conventional culture and real-time PCR with or without enrichment. Molecular serotyping and MLST were performed on isolates.

RESULTS

Overall genital GBS positive rate among the 150 study subjects was 17.3%. Direct culture identified 18 (12.0%) positive specimens, enrichment culture 22 (14.6%), direct PCR 24 (16.0%) and enrichment PCR 25 (16.6%). The sensitivity and specificity by direct and enrichment PCR were as follows: for direct PCR, 90.9% and 96.9%, respectively; and for enrichment PCR, 95.5% and 96.9%, respectively. Resistance rates to clindamycin and erythromycin were 33.3% and 19.1%, respectively. Serotype III-1 was the most common (26.3%), followed by serotype Ib (21.1%), III-3 (15.8%), V (15.8%), II (10.5%), IV (5.3%) and VI (5.3%). Most common sequence types (ST) were ST-1, ST-19 and ST-862 (15.8%), followed by ST-2 and ST-654 (10.5%).

CONCLUSION

Direct real-time PCR using vaginal-rectal specimen could be used for detecting GBS in emergent conditions. Molecular serotypes III, Ib and V were most common. MLST analysis frequently presented ST-1, ST-19 and ST-862.

Laboratory diagnosis of Clostridium difficile infection: Comparison of Techlab C. diff Quik Chek Complete, Xpert C. difficile, and multistep algorithmic approach

BACKGROUND

Clostridium difficile is a major pathogen responsible for nosocomial infectious diarrhea. We explored optimal laboratory strategies for diagnosis of C. difficile infection (CDI) in our clinical settings, a 1400-bed tertiary care hospital.

METHODS

Using 191 fresh stool samples from adult patients, we evaluated the performance of Xpert C. difficile (Xpert CD), C. diff Quik Chek Complete (which simultaneously detects glutamate dehydrogenase [GDH] and C. difficile toxins [CDT]), toxigenic culture, and a two-step algorithm composed of GDH/CDT as a screening test and Xpert CD as a confirmatory test.

RESULTS

Clostridium difficile was detected in 35 samples (18.3%), and all isolates were toxigenic strains. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value of each assay for detecting CDI were as follows: Quik Chek Complete CDT (45.7%, 100%, 100%, 89.1%), Quik Chek Complete GDH (97.1%, 99.4%, 97.1%, 99.4%), Xpert CD (94.3%, 100%, 100%, 98.7%), and toxigenic culture (91.4%, 100%, 100%, 98.1%). A two-step algorithm performed identically with Xpert CD assay.

CONCLUSION

Our data showed that most C. difficile isolates from adult patients were toxigenic. We demonstrated that a two-step algorithm based on GDH/CDT assay followed by Xpert CD assay as a confirmatory test was rapid, reliable, and cost effective for diagnosis of CDI in an adult patient setting with high prevalence of toxigenic C. difficile.

Performance evaluation of Mindray CAL 8000(BC-6800 and SC-120) hematology analyzer and slidemaker/stainer

INTRODUCTION

The Mindray CAL 8000 is a cellular analysis line that consists of the BC-6800, an automated hematology analyzer, and the SC-120, an automated slidemaker/stainer. We evaluated the performances of the BC-6800 and the SC-120.

METHODS

Four hundred and eight normal and abnormal samples were analyzed. The performance of the BC-6800 and Sysmex XE-2100 were compared, and blood films by the SC-120 and manual method were compared according to the CLSI guideline H26-A2 and H20-A2.

RESULTS

Most parameters measured by the BC-6800 matched well with the XE-2100 and manual differential. The flag efficiency of the BC-6800 for blasts (95.3%) and atypical lymphocytes (92.6%) were higher while immature granulocytes (89.7%) and NRBCs (94.1%) were lower than that of the XE-2100. Additionally, the BC-6800 detected four of five samples infected with plasmodium parasites. The SC-120 showed no carry-over and expected repeatability. There was good agreement on the five-part differential including abnormal cells between blood films by the SC-120 and manually prepared blood films. The shape of the RBC was also comparable between blood films.

CONCLUSION

The CAL-8000 analysis line is beneficial for precise, fast hematology work, and even more useful in malaria endemic areas.

Prognostic significance of PCR-based molecular staging in patients with diffuse large B-cell lymphoma treated with R-CHOP immunochemotherapy

The prognostic role of detecting clonal immunoglobulin gene rearrangement (IgR) from bone marrow (BM) aspirates was evaluated by BIOMED-2 PCR in 97 patients with diffuse large B-cell lymphoma (DLBCL) treated with rituximab-CHOP immunochemotherapy. Sixteen (16.5%) patients had BM involvement (BMI) defined by BM biopsy (MOR+) and 39 (40.2%) had positive IgR (PCR+). Patients with MOR + BMI showed inferior event-free survival (EFS) compared to those with MOR-/PCR- (p < 0.001) or those with MOR-/PCR + BMI (p = 0.002), while no significant difference in EFS was observed between patients with MOR-/PCR + and those with MOR-/PCR - BMI (p = 0.497). Use of the BIOMED-2 for PCR resulted in significant increase in detection of BMI. However, the increased sensitivity by PCR did not translate into improved prediction of prognosis, emphasizing the essential role of histopathological review of trephine biopsy for the detection of BMI.

Prognostic impact of concordant and discordant bone marrow involvement and cell-of-origin in Korean patients with diffuse large B-cell lymphoma treated with R-CHOP

AIMS

Previous studies have suggested many prognostic factors in diffuse large B-cell lymphoma (DLBCL), but the prognostic importance of cell-of-origin and discordant bone marrow involvement remains unclear. The aim of this study was to evaluate the prognostic impact of bone marrow involvement histological subtype, cell-of-origin subtype and international prognostic index (IPI) scores in patients with DLBCL.

METHODS

Patients who were newly diagnosed with DLBCL and treated with rituximab plus cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP) were analysed. Clinical information was reviewed retrospectively. Patients were classified into negative, concordant and discordant bone marrow involvement by histological review. The cell-of-origin types were defined using immunohistochemical analysis.

RESULTS

Both concordant and discordant bone marrow involvement had a negative prognostic impact on progression-free survival, independent of the standard and National Comprehensive Cancer Network (NCCN) IPI scores and cell-of-origin. Patients with non-germinal centre B-cell type showed significantly shorter progression-free survival than those with germinal centre B-cell type. However, non-germinal centre B-cell type did not have a prognostic impact on progression-free survival or overall survival after controlling for the standard and NCCN-IPI and bone marrow involvement.

CONCLUSIONS

Both concordant and discordant bone marrow involvement had an adverse prognostic impact on progression-free survival and overall survival; this was independent of the standard and NCCN-IPI and cell-of-origin (non-germinal centre B-cell type). The NCCN-IPI had more powerful prognostic value than the standard IPI (sIPI). The non-germinal centre B-cell type lost significant prognostic impact on progression-free survival after adjustment for standard and NCCN-IPI and bone marrow involvement.

Effectiveness and safety of varenicline as an aid to smoking cessation: results of an inter-Asian observational study in real-world clinical practice

AIMS

To evaluate the effectiveness and safety of varenicline for smoking cessation among Asian adult smokers in real-world clinical practice.

METHODS

A multicentre, prospective, non-comparative, observational study conducted in China, India, Philippines and Korea. Adult smokers, willing to make a quit attempt, who reached a joint decision with the investigators to take varenicline received 1 mg twice daily (after 1-week titration) for 12 weeks. No exclusion criteria were specified. Effectiveness evaluations included smoking abstinence status for the 7-day period before the Week 12 visit and the last observed study visit, determined by verbal reporting using a nicotine use inventory and carbon monoxide levels if part of usual practice (end of study only). The safety profile of varenicline was also assessed.

RESULTS

Of 1377 subjects enrolled in the study, 1373 (99.7%) received varenicline and were evaluated for safety and effectiveness. Overall, 46.4% [95% confidence interval (CI): 43.73-49.07] of subjects successfully quit smoking by the end of the treatment phase at Week 12. When analysed by country, 57.1% (95% CI: 53.55-60.65) of subjects from China, 52.8% (95% CI: 45.21-60.25) of subjects from India, 51.0% (95% CI: 36.60-65.25) of subjects from Philippines and 20.3% (95% CI: 16.29-24.73) of subjects from Korea had quit smoking at Week 12. The most commonly reported treatment-related adverse event was nausea (11.5%).

CONCLUSIONS

This study demonstrates the effectiveness and acceptable safety profile of varenicline for smoking cessation in a real-world setting among Asian populations, with results consistent with those of varenicline randomised controlled trials.

Effect of Quercetin on the Pharmacokinetics of Rosiglitazone, a CYP2C8 Substrate, in Healthy Subjects

Previous in vitro studies have demonstrated that quercetin inhibits CYP2C8, but there are no available data to indicate that quercetin inhibits CYP2C8 in vivo. The effect of long-term use of quercetin on the pharmacokinetics of rosiglitazone was evaluated. After administration of quercetin or matched placebo for 3 weeks in a crossover manner, rosiglitazone 4 mg was administered, and the pharmacokinetics of rosiglitazone and N-desmethylrosiglitazone were determined. For AUCinfinity, AUClast, and Cmax, the geometric mean ratios (90% confidence interval) for (quercetin + rosiglitazone/placebo + rosiglitazone) were 0.98 (0.92, 1.05), 0.99 (0.92, 1.05), and 1.01 (0.88, 1.14), respectively. Metabolic conversion based on the AUC ratio of N-desmethylrosiglitazone/rosiglitazone in the quercetin phase (0.49 +/- 0.17) was similar to that of the placebo phase (0.47 +/- 0.14) (P = .574). Even though the acute interaction that would occur during the first few days of concurrent administration of quercetin cannot be excluded, these results indicate that long-term use of quercetin does not inhibit CYP2C8 activity, and the usage has little possibility of interacting with drugs that are metabolized by CYP2C8, including rosiglitazone.

Prognostic role of serum lactate dehydrogenase beyond initial diagnosis: a retrospective analysis of patients with diffuse large B cell lymphoma

BACKGROUND/AIMS

Baseline serum lactate dehydrogenase (LDH) level is a well-known prognostic factor in patients with non-Hodgkin's lymphoma; however, its role beyond initial diagnosis has not yet been defined.

METHODS

This study was conducted as a retrospective analysis of patients with diffuse large B cell lymphoma (DLBCL) treated with R-CHOP21, who had undergone regular checks for LDH during immunochemotherapy (n = 119) and during the posttreatment follow-up period after complete remission (CR; n = 100). The 119 patients were classified into 4 groups according to their baseline and change in LDH level during treatment, and an analysis of tumor response and survival was performed. The value of LDH as a predictor for relapse was evaluated among the patients with regular follow-up visits after achieving CR.

RESULTS

An increased LDH level during immunochemotherapy had no impact on tumor response or survival, and only the LDH status 'before' treatment was a prognostic marker. The sensitivity, specificity, positive predictive value and negative predictive value of serum LDH for detecting relapse after CR were 47.4, 86.5, 9.3 and 98.3%, respectively.

CONCLUSION

The measurement of LDH level beyond initial diagnosis has no clear benefit in predicting disease progression or relapse in patients with DLBCL treated with R-CHOP21.

Interaction between brain-derived neurotrophic factor Val66Met polymorphism and recent negative stressor in harm avoidance

There have been controversial results regarding the association between brain-derived neurotrophic factor (BDNF) Val66Met polymorphism and anxiety-related traits such as harm avoidance (HA). We aimed to investigate the interaction between BDNF Val66Met polymorphism and negative life stressors in HA. BDNF Val66Met polymorphism was genotyped in 391 community-dwelling Koreans (152 males, 239 females; 43.2 +/- 14.1 years old). The Temperament and Character Inventory (TCI) and the Center for Epidemiological Studies for Depression Scale (CES-D) were self applied. The Structured Clinical Interview for DSM-IV axis I disorders and face-to-face interviews investigating negative life stressors within the last 6 months were also performed. There was no significant difference in TCI score, major depressive disorder prevalence and CES-D score among the 3 genotypes (94 Met/Met, 188 Val/Met and 109 Val/Val subjects). There was no significant difference in TCI scores between subjects with stressors and those without stressors, while more common major depressive episodes (p = 0.03) and higher CES-D scores (p < 0.001) were found in subjects with stressors. However, there was a significant interaction between the BDNF genotype and negative life stressors in HA (p = 0.02). Only subjects with the Val/Val genotype showed higher HA with recent negative stressors. Our finding suggests that BDNF Val66Met polymorphism might influence HA by interacting with recent negative stress experience.

Effect of cytochrome P450 3A5*3 genotype on the stereoselective pharmacokinetics of amlodipine in healthy subjects

Amlodipine is a racemic mixture composed of S- and R-form and metabolized stereoselectively. Cytochrome P450 3A (CYP3A) including CYP3A5 are involved in the metabolism of amlodipine and it was reported that polymorphic CYP3A5 genotype modulates the plasma levels of amlodipine and thus affect its pharmacokinetics. This study was conducted to find whether stereoselective pharmacokinetics of amlodipine was affected by the polymorphic CYP3A5 genotype. Seventeen healthy subjects were genotyped for CYP3A5*3 variant. After a single dose of 10-mg amlodipine, enantiomers of amlodipine were analyzed using HPLC-MS/MS equipped with an AGP column. Amlodipine showed stereoselective pharmacokinetics. S-amlodipine exhibited higher plasma levels than R-amlodipine in both genotype groups. S-amlodipine showed 15% higher mean peak plasma concentrations (Cmax) in CYP3A5*1/*3 carriers (3.28 ng/ml) than CYP3A5*3/*3 carriers (2.85 ng/ml) (P = 0.194) and R-amlodipine also showed 21% higher Cmax in CYP3A5*1/*3 carriers (3.33 ng/ml) than CYP3A5*3/*3 carriers (2.75 ng/ml) (P = 0.114). CYP3A5*1/*3 carriers also have 23 and 12% higher mean area under the time versus concentration curve of R-amlodipine and S-amlodipine than CYP3A5*3/*3 carriers, respectively (for R-amlodipine, 147.1 ng*h/ml for CYP3A5*1/*3 carriers versus 121.8 ng*h/ml for CYP3A5*3/*3 carriers, P = 0.234; for S-amlodipine, 161.6 ng*h/ml for CYP3A5*1/*3 carriers vs. 144.2 ng*h/ml for CYP3A5*3/*3 carriers, P = 0.353). Other pharmacokinetic parameters also showed no significant difference between them. In conclusion, the present study showed that despite the evidence that amlodipine is stereoselectively metabolized, CYP3A5*3 genotype did not affect stereoselective disposition of amlodipine. It provides the evidence that CYP3A5*3genotype plays a minor role in the interindividual variability of stereoselective disposition of amlodipine in humans.

Effect of rifampin, an inducer of CYP3A and P-glycoprotein, on the pharmacokinetics of risperidone

The authors studied the effect of rifampin, a dual inducer of CYP3A and P-glycoprotein, on the pharmacokinetics and pharmacodynamics of risperidone in humans. Ten healthy male subjects were treated daily for 7 days with 600 mg rifampin or with placebo. On day 6, a single dose of 1 mg risperidone was administered. Plasma risperidone and 9-hydroxyrisperidone concentrations were measured. Rifampin significantly decreased the mean area under the plasma concentration-time curve by 51% for risperidone, by 43% for 9-hydroxyrisperidone, and by 45% for the active moieties (risperidone + 9-hydroxyrisperidone). Rifampin also decreased the peak plasma concentration of risperidone by 38%, 9-hydroxyrisperidone by 46%, and the active moieties by 41%. The apparent oral clearance of risperidone approximately doubled after rifampin treatment. Thus, rifampin reduced the exposure to risperidone, probably because of a decrease in its bioavailability through the induction of CYP3A and probably P-glycoprotein.

Effect of polymorphic CYP3A5 genotype on the single-dose simvastatin pharmacokinetics in healthy subjects

Simvastatin, a cholesterol-lowering agent, is mainly metabolized by CYP3A4/5. The objective of this study was to investigate the effect of CYP3A5*3 genotype on the pharmacokinetics of simvastatin in humans. Twenty-two men with CYP3A5*1/*1 (n = 4), CYP3A5*1/*3 (n = 8), or CYP3A5*3/*3 (n = 10) genotypes were enrolled. Each subject ingested a 20-mg dose of simvastatin, and plasma simvastatin concentrations were measured for 12 hours after dosing. The mean (+/-SD) area under the plasma concentration-time curve for simvastatin in the CYP3A5*1/*1 carriers (4.94 +/- 2.25 ng x h/mL) was significantly lower than CYP3A5*3/*3 carriers (16.35 +/- 6.37 ng x h/mL; P = .013, Bonferroni test). The mean (+/-SD) oral clearance was also significantly different between CYP3A5*1/*1 carriers (4.80 +/- 2.35 L/h) and CYP3A5*3/*3 carriers (1.35 +/- 0.61 L/h; P < .05, Dunn's test). However, other pharmacokinetic parameters including peak plasma concentrations and half-life did not show any difference between genotype groups. These findings suggest that the polymorphic CYP3A5 gene affects the disposition of simvastatin and provides a plausible explanation for interindividual variability of simvastatin disposition.

Effect of CYP3A53 genotype on the pharmacokinetics and pharmacodynamics of amlodipine in healthy Korean subjects

BACKGROUND AND OBJECTIVE

1,4-Dihydropyridine calcium channel blockers, including amlodipine, are mainly metabolized by cytochrome P450 (CYP) 3A. We investigated the effect of CYP3A5*3 genotype on the pharmacokinetics and pharmacodynamics of amlodipine in healthy Korean male subjects.

METHODS

Forty healthy male participants were enrolled and genotyped for the CYP3A5*3 gene. Each subject ingested a 5-mg dose of amlodipine, and plasma amlodipine concentrations were measured for 144 hours after dosing. Blood pressure and pulse rate were also measured for pharmacodynamic analysis.

RESULTS

Among the 40 volunteers, 24 were CYP3A5*3/*3 carriers and 16 were CYP3A5*1 carriers (CYP3A5*1/*1 in 2 and CYP3A5*1/*3 in 14). The difference in the oral clearance of amlodipine approached statistical significance between the 2 major genotype groups, with CYP3A5*1 carriers (27.0 +/- 8.2 L/h) showing 20% lower clearance than CYP3A5*3/*3 carriers (32.4 +/- 10.2 L/h) (P = .063). However, the mean area under the plasma concentration-time curve of amlodipine was 200.9 +/- 61.9 ng . h/mL for CYP3A5*1 carriers and 167.6 +/- 45.0 ng . h/mL for CYP3A5*3/*3 carriers (P = .029). Moreover, the peak plasma concentration was significantly higher in CYP3A5*1 carriers (3.8 +/- 1.1 ng/mL) than in CYP3A5*3/*3 carriers (3.1 +/- 0.8 ng/mL) (P = .037). Pharmacodynamically, blood pressure and pulse rate were not significantly different between the 2 groups.

CONCLUSIONS

CYP3A5*3/*3 carriers exhibited lower plasma amlodipine concentrations than CYP3A5*1 carriers. These findings suggest that the polymorphic CYP3A5 gene affects the disposition of amlodipine and provides a plausible explanation for interindividual variability in amlodipine disposition.

Comparative pharmacokinetic and pharmacodynamic characteristics of amlodipine besylate and amlodipine nicotinate in healthy subjects

BACKGROUND AND AIM

Amlodipine, a dihydropyridine calcium antagonist, is prescribed for the management of angina and hypertension, and is sold as amlodipine besylate. However, a new salt formulation, amlodipine nicotinate, has recently been developed. Here, we evaluated the comparative pharmacokinetic and pharmacodynamic characteristics of the nicotinate and besylate forms of amlodipine.

SUBJECTS AND METHODS

A randomized, 2-way crossover study was conducted in 18 healthy male volunteers to compare the pharmacokinetics and pharmacodynamics of these two forms, i.e. amlodipine nicotinate (test) and amlodipine besylate (reference), after administration of a single dose of 5 mg of each drug and a washout period between doses of 4 weeks. Blood samples for the pharmacokinetic analysis of amlodipine were obtained over the 144-hour period after administration. Systolic and diastolic blood pressures and pulse rates were recorded immediately prior to each blood sampling.

RESULTS

All participants completed both treatment periods, and no serious adverse events occurred during the study period. After administering a single dose of each formulation, mean AUC0-infinity and Cmax values were 190.91+/-60.49 ng x h/ml and 3.87+/-1.04 ng/ml for the test formulation and 203.15+/-52.05 ng x h/ml and 4.01+/-0.60 ng/ml for the reference formulation, respectively. The 90% confidence intervals of test/reference mean ratios for AUC0- infinity and Cmax fell within the predetermined equivalence range of 80 - 125%. Pharmacodynamic profiles including systolic and diastolic blood pressures and pulse rates exhibited no significant differences between the two formulations.

CONCLUSION

The two amlodipine formulations showed similar pharmacokinetic and pharmacodynamic characteristics and the new amlodipine formulation, amlodipine nicotinate, was found to be equivalent for pharmacokinetics to the currently available amlodipine besylate with respect to the rate and extent of amlodipine absorption.

Pharmacokinetic and pharmacodynamic characteristics of a new S-amlodipine formulation in healthy Korean male subjects: A randomized, open-label, two-period, comparative, crossover study

BACKGROUND

Amlodipine, a dihydropyridine calcium channel antagonist, is prescribed for the management of angina and hypertension. It is used therapeutically as a racemic mixture, composed of S- and R-enantiomers, but its calcium channel-blocking effect is confined to S-amlodipine; R-amlodipine has 1000-fold less activity than its S-enantiomer.

OBJECTIVE

The objective of this study was to compare the pharmacokinetic and pharmacodynamic properties and safety profiles of a newly developed amlodipine formulation, composed wholly of S-amlodipine, with those of the conventionally prescribed racemic formulation.

METHODS

This randomized, open-label, 2-period, comparative, crossover study was conducted with healthy volunteers at the Gil Medical Center and Gachon Medical School, Incheon, Korea. Male subjects, aged 20 to 50 years, were eligible to participate if their weight was within 20% of ideal body weight and if they were judged by physicians to be healthy. All subjects were randomly assigned in a 1:1 ratio to 1 of 2 treatment sequences: (1) a single dose of the test amlodipine formulation (S-enantiomer amlodipine 5 mg p.o.) (Lodien [Hanlim Pharmaceutical Co., Seoul, Korea]) in the first study period, followed by a single dose of the reference amlodipine formulation (racemate 10 mg p.o.) (Norvasc [Pfizer Pharmaceuticals Korea Ltd., Seoul, Korea]) in the second study period, or (2) a single dose of the reference formulation in the first study period, followed by a single dose of the test formulation in the second period. A 3-week washout occurred between study periods. Blood samples for pharmacokinetic analysis of S-amlodipine were collected at 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 24, 48, 72, 96, 120, 144, and 168 hours after drug administration. Pharmacodynamic variables (ie, systolic and diastolic blood pressure and heart rate) were measured at 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 24, 48, and 72 hours after administration. Safety profiles were also assessed. Hematology, biochemistry, electrocardiography, and urinalysis were performed at baseline and end of study. Adverse events were monitored throughout the study period. Pharmacokinetic characteristics were compared using noncompartmental analysis. Pharmacokinetic equivalence was concluded if the geometric mean ratios of the plasma Cmax and AUC were within the predetermined range of 80% to 125%.

RESULTS

Twenty-six healthy Korean male volunteers were screened and 18 subjects (mean [SD] age, 23.4 [1.5] years [range, 21-26 years]; mean [SD] weight, 69.3 [6.8] kg [range, 60-88 kg]) were enrolled and completed the study. The plasma concentration-time profiles of S-amlodipine were comparable after administration of both formulations. The mean (SD) values for Cmax AUC from time 0 to the last available measurement (AUC(last)), and AUC from 0 to infinity (AUC(0-infinity)) for the reference formulation (3.0 [0.6] ng/mL, 151.4 [35.7] ng x h/mL, and 175.3 [45.1] ng x h/mL, respectively) did not differ significantly from those for the test formulation (3.1 [0.6] ng/mL, 139.7 [40.3] ng x h/mL, and 161.7 [43.8] ng x h/mL, respectively). The calculated 90% Cls for the corresponding ratios of log-transformed Cmax, AUCO(0-infinity), and AUC(last) were 97.56% to 112.51%, 86.31% to 98.74%, and 83.46% to 100.04%, respectively, which met the predetermined criteria for pharmacokinetic equivalence. Despite the single administration, significant changes in maximal blood pressure and heart rate were observed after drug administration for both formulations, compared with baseline values (all, P < 0.001). However, no significant differences were observed between the 2 formulations in terms of pharmacodynamic profiles, and no clinically relevant changes were observed for either formulation with respect to physical examination, hematology, biochemistry, electrocardiography, or urinalysis. Neither formulation caused any serious adverse events.

CONCLUSIONS

Two amlodipine formulations were found to be equivalent in terms of the pharmacokinetics of S-amlodipine. The newly developed formulation, comprised of only S-amlodipine, had pharmacodynamic profiles comparable to those of the conventional racemic amlodipine formulation in these healthy Korean male subjects. Both formulations were well tolerated.

Effect of multiple doses of montelukast on the pharmacokinetics of rosiglitazone, a CYP2C8 substrate, in humans

AIMS

To investigate the effect of multiple dosing with montelukast, a selective leukotriene-receptor antagonist, on the pharmacokinetics of rosiglitazone, a CYP2C8 substrate, in humans.

METHODS

A two-period, randomized crossover study was conducted in 10 healthy subjects. After administration of oral doses of placebo or 10 mg montelukast daily for 6 days, 4 mg rosiglitazone was administered and plasma samples were obtained for 24 h and analyzed for rosiglitazone and N-desmethylrosiglitazone using high-performance liquid chromatography with fluorescence detection.

RESULTS

During the montelukast phase, the total area under the time-concentration curve (AUC) and peak plasma concentration of rosiglitazone were 102% (90% CI 98, 107%) and 98% (90% CI 92, 103%) of the corresponding values during the placebo phase, respectively. Multiple dosing with montelukast did not affect the oral clearance of rosiglitazone significantly (90% CI 94, 105%; P = 0.50). The AUC ratio and plasma concentration ratios of N-desmethylrosiglitazone : rosiglitazone were not changed by multiple dosing with montelukast (90% CI 90, 103%; P = 0.14).

CONCLUSIONS

Multiple doses of montelukast do not inhibit CYP2C8-mediated rosiglitazone metabolism in vivo despite in vitro findings indicating that montelukast is a selective CYP2C8 inhibitor.

Effect of ABCB1 (MDR1) haplotypes derived from G2677T/C3435T on the pharmacokinetics of amlodipine in healthy subjects

AIM

We aimed to investigate the effect of the ABCB1 gene on the pharmacokinetics of amlodipine.

METHODS

Based on polymorphisms of the ABCB1 gene at positions 2677 and 3435, 26 healthy male participants were divided into three groups: subjects with 2677GG/3435CC (n = 9), 2677GT/3435CT (n = 9) and 2677TT/3435TT (n = 8). After a single-dose administration of 5 mg amlodipine, plasma concentrations of amlodipine were measured and its pharmacokinetic characteristics were compared according to ABCB1 genotype.

RESULTS

The area under the plasma concentration-time curve was significantly lower in subjects with 2677TT/3435TT (140.8 +/- 35.6 ng h(-1) ml(-1)) and 2677GT/3435CT (149.8 +/- 40.1 ng h(-1) ml(-1)) than in those with 2677GG/3435CC (208.6 +/- 39.2 ng h(-1) ml(-1)) [95% confidence interval (CI) on the difference, 2677GG/3435CC vs. 2677GT/3435CT 12.0, 105.6, P < 0.01; 2677GG/3435CC vs. 2677TT/3435TT 19.6, 116.0, P < 0.01; 2677GT/3435CT vs. 2677TT/3435TT - 39.2, 57.2, P > 0.05]. The peak plasma concentrations were highest in subjects with 2677GG/3435CC (3.8 +/- 0.5 ng ml(-1)), lower in subjects with 2677GT/3435CT (3.2 +/- 0.5 ng ml(-1)) and 2677TT/3435TT (2.7 +/- 0.5 ng ml(-1)) in rank and showed a significant difference between those with 2677GG/3435CC and with 2677TT/3435TT (95% CI on the difference 0.4, 2.0, P < 0.01). However, the oral clearance was higher in subjects with 2677TT/3435TT (37.7 +/- 10.2 l h(-1)) than in those with 2677GT/3435CT (35.7 +/- 9.9 l h(-1)) and with 2677GG/3435CC (24.8 +/- 5.4 l h(-1)) and exhibited a significant difference between ABCB1 genotype groups (95% CI on the difference, 2677GG/3435CC vs. 2677GT/3435CT - 21.5, - 0.3, P < 0.05; 2677GG/3435CC vs. 2677TT/3435TT - 23.8, - 2.0, P < 0.05).

CONCLUSION

Amlodipine pharmacokinetics was affected by the genetic polymorphisms of the ABCB1 gene in humans. These findings may provide a plausible explanation for interindividual variation in the disposition of amlodipine, although our study could not explain the exact mechanism(s) by which the polymorphic ABCB1 gene paradoxically reduces the plasma levels of amlodipine. Further evaluation is thus warranted.

Effect of CYP3A5*3 genotype on the pharmacokinetics and pharmacodynamics of alprazolam in healthy subjects

OBJECTIVE

Our objective was to evaluate the effect of the CYP3A5 genotype on the pharmacokinetics and pharmacodynamics of alprazolam in healthy volunteers.

METHODS

Nineteen healthy male volunteers were divided into 3 groups on the basis of the genetic polymorphism of CYP3A5. The groups comprised subjects with CYP3A5*1/*1 (n=5), CYP3A5*1/*3 (n=7), or CYP3A5*3/*3 (n=7). After a single oral 1-mg dose of alprazolam, plasma concentrations of alprazolam were measured up to 72 hours, together with assessment of psychomotor function by use of the Digit Symbol Substitution Test, according to CYP3A5 genotype.

RESULTS

The area under the plasma concentration-time curve for alprazolam was significantly greater in subjects with CYP3A5*3/*3 (830.5+/-160.4 ng . h/mL [mean+/-SD]) than in those with CYP3A5*1/*1 (599.9+/-141.0 ng . h/mL) (P=.030). The oral clearance of alprazolam was also significantly different between the CYP3A5*1/*1 group (3.5+/-0.8 L/h) and CYP3A5*3/*3 group (2.5+/-0.5 L/h) (P=.036). Although a trend was noted for the area under the Digit Symbol Substitution Test score change-time curve (area under the effect curve) to be greater in subjects with CYP3A5*3/*3 (177.2+/-84.6) than in those with CYP3A5*1/*1 (107.5+/-44), the difference did not reach statistical significance (P=.148).

CONCLUSIONS

The CYP3A5*3 genotype affects the disposition of alprazolam and thus influences the plasma levels of alprazolam.

Effect of high-dose aspirin on CYP2E1 activity in healthy subjects measured using chlorzoxazone as a probe

The authors evaluated the effect of high-dose aspirin at a therapeutic dose, using chlorzoxazone as a probe for CYP2E1 enzyme activity. In a randomized, open-label, 2-way crossover study, 10 healthy men were treated 3 times daily for 6 days with 1 g aspirin or placebo. On day 7, 1 dose of 400 mg chlorzoxazone was administered orally. Plasma concentrations of chlorzoxazone and its metabolite, 6-hydroxychlorzoxazone, were measured. During the aspirin phase, the area under the time-concentration curve (AUC) and peak plasma concentration of chlorzoxazone were 95% (90% confidence interval [CI], 87%-103%) and 90% (90% CI, 80%-101%) of the values during the placebo phase, respectively. High-dose aspirin did not affect the oral clearance of chlorzoxazone significantly (90% CI, 98%-120%; P = .24). The AUC ratio and plasma concentration ratios of 6-hydroxychlorzoxazone/chlorzoxazone were not changed significantly by high-dose aspirin. High-dose aspirin at a therapeutic dose does not affect CYP2E1 activity in humans.

A complex, four-way variant t(15;17) in acute promyelocytic leukemia

Complex variant 15;17 translocations are increasingly recognized in acute promyelocytic leukemia (APL). We report the case of a 47-year-old woman with APL harboring a novel four-way translocation. She presented with persistent bleeding after a tooth extraction. Blood cell counts at admission were hemoglobin at 9.0 g/dL, platelets at 15 x 10(9)/L, and white blood cells at 0.460 x 10(9)/L with abnormal promyelocytes. Most nucleated cells of bone marrow aspirates were abnormal promyelocytes with Auer rods. Chromosome analysis of unstimulated bone marrow cell cultures revealed a variant t(15;17) in the form of t(10;17;15;22)(q22;q21;q22;q11.2). Fluorescence in situ hybridization with a PML/RARA dual-color DNA probe showed the fusion signals on der(15) and the residual PML signals on der(22). RT-PCR showed long-form PML/RARA fusion transcripts. A complete remission was attained with a course of conventional chemotherapy including ATRA. A literature review revealed that our case is one of the very rare four-way translocations and the first report of the involvement of chromosomes 10 and 22 in a variant t(15;17).

Cytochrome P450 3A inhibitor itraconazole affects plasma concentrations of risperidone and 9-hydroxyrisperidone in schizophrenic patients

BACKGROUND AND OBJECTIVE

Despite the belief that cytochrome P450 (CYP) 2D6 alone is responsible for the metabolism of risperidone, several studies suggest that CYP3A may be involved. The aim of this study was to evaluate the effect of itraconazole, a CYP3A inhibitor, on the plasma concentrations of risperidone and 9-hydroxyrisperidone in schizophrenic patients in relation to CYP2D6 genotype.

METHODS

Nineteen schizophrenic patients treated with 2 to 8 mg/d of risperidone received 200 mg/d of itraconazole for a week. Plasma concentrations of risperidone and 9-hydroxyrisperidone were measured immediately before and after itraconazole treatment, as well as at 1 week after itraconazole treatment was stopped, together with clinical assessment by use of the Udvalg for Kliniske Undersøgelser Side Effect Rating Scale and the Brief Psychiatric Rating Scale.

RESULTS

Dose-normalized plasma concentrations of risperidone and 9-hydroxyrisperidone before itraconazole treatment (0.9 +/- 0.8 ng.mL(-1).mg(-1) and 6.9 +/- 3.3 ng.mL(-1).mg(-1), respectively) were significantly elevated after itraconazole treatment (1.6 +/- 1.3 ng.mL(-1).mg(-1) and 11.3 +/- 4.5 ng.mL(-1).mg(-1)) and decreased 1 week after its discontinuation (1.0 +/- 0.8 ng.mL(-1).mg(-1) and 7.2 +/- 3.7 ng.mL(-1).mg(-1)) (P < .01). However, the ratio of risperidone/9-hydroxyrisperidone, an index of CYP2D6 activity, did not differ before itraconazole treatment (0.14 +/- 0.13), after itraconazole treatment (0.15 +/- 0.13), and 1 week after discontinuation (0.14 +/- 0.13) (P > .05). Itraconazole increased the concentrations of risperidone by 69% (P < .001) and 75% (P < .01) in CYP2D6 extensive and poor metabolizers, respectively. In addition, the active moiety (risperidone plus 9-hydroxyrisperidone) also increased similarly, by 71% (P < .001) and 73% (P < .05), respectively, with itraconazole, without a significant difference between CYP2D6 genotypes. The scores on the Brief Psychiatric Rating Scale decreased significantly but only by 6% after itraconazole treatment (P < .05); however, the scores on the Udvalg for Kliniske Undersøgelser Side Effect Rating Scale were not changed.

CONCLUSIONS

Our results provide in vivo evidence of the involvement of CYP3A in the disposition of risperidone and 9-hydroxyrisperidone. In addition to CYP2D6, treatment with CYP3A inhibitor(s) including itraconazole may influence clinical symptoms and risperidone side effects.

Genetic polymorphisms and linkage disequilibrium of sulfotransferase SULT1A1 and SULT1A2 in a Korean population: comparison of other ethnic groups

AIMS

To determine the allele frequencies of sulfotransferases (SULTs) 1A1 and 1A2 and their linkage disequilibrium in a Korean population and compare them with those of other ethnic groups.

METHODS

Genotypes of the SULT1A1*1, *2, and *3 and SULT1A2*1, *2, and *3 allelic variants were determined in 234 Korean subjects using polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) methods.

RESULTS

Allele frequencies for SULT1A1*1 and *2 were 0.876 [95% confidence interval (CI), 0.843-0.905] and 0.124 (95% CI, 0.096-0.157), respectively. Similarly, those for SULT1A2*1 and *2 were 0.885 (95% CI, 0.852-0.912) and 0.115 (95% CI, 0.088-0.150), respectively. However, no subject with SULT1A1*3 or SULT1A2*3 was detected. These genotype distributions are similar to those of Asian populations including the Chinese and Japanese, but quite different from other ethnic groups such as African-Americans and Caucasians. The expected allelic frequencies of SULT1A1 and SULT1A2 at Hardy-Weinberg equilibrium are quite similar to the observed distributions in the population. SULT1A1*2 and SULT1A2*2, the most common variant alleles of these two genes, are strongly and positively linked in the Korean population (D' = 0.8919, chi2 = 343.24, P = 0.0034).

CONCLUSIONS

SULT1A1*2 and SULT1A2*2 are the major allelic variants in the Korean population, whereas the SULT1A1*3 and SULT1A2*3 alleles were not found. SULT1A1*2 and SULT1A2*2 are strongly linked.

Effect of probenecid on the pharmacokinetics of carbamazepine in healthy subjects

OBJECTIVES

Carbamazepine (CBZ) undergoes biotransformation by CYP3A4 and CYP2C8, and glucuronide conjugation. There has been no clear demonstration to reveal the role of glucuronidation in the disposition of CBZ. We evaluated the effect of probenecid, a UDP-glucuronosyltransferase inhibitor, on the pharmacokinetics of CBZ in humans.

METHODS

In a randomized, open-label, two-way crossover study, ten healthy male subjects were treated twice daily for 10 days with 500 mg probenecid or with a matched placebo. On day 6, a single dose of 200 mg CBZ was administered orally. Concentrations of CBZ and CBZ 10,11-epoxide (CBZ-E) in plasma and urine were measured.

RESULTS

Probenecid decreased the area under the plasma concentration-time curve (AUC) of CBZ from 1253.9 micromol h/l to 1020.7 micromol h/l (P < 0.001) while increasing that of CBZ-E from 137.6 micromol h/l to 183.5 micromol h/l (P = 0.033). The oral clearance of CBZ was increased by probenecid by 26% (90% confidence interval, 17-34%; P < 0.001). Probenecid increased the AUC ratio of CBZ-E/CBZ from 0.11 to 0.16 (P < 0.001). However, probenecid had minimal effect on the recovery of the conjugated and free forms of CBZ and CBZ-E in urine.

CONCLUSION

Although probenecid showed a minimal effect on the glucuronidation of CBZ and CBZ-E, it increased CBZ biotransformation to CBZ-E, most likely reflecting the induction of CYP3A4 and CYP2C8 activities, in humans. These results demonstrate that glucuronide conjugation plays a minor role in the metabolism of CBZ and CBZ-E in humans, and that probenecid has an inducing effect on the disposition of CBZ.

Relative bioavailability and pharmacokinetics of a new sibutramine formulation in healthy male subjects: a randomized, open-label, two-period, comparative crossover study

BACKGROUND

Sibutramine is an orally administered, centrally acting antiobesity drug. Sibutramine hydrochloride monohydrate is the conventional formulation, whereas sibutramine mesylate hemihydrate is a newly developed formulation. Drugs formed from different salts may differ in their solubility profiles and dissolution rates, which may affect their rate of absorption and thus their onset, duration, and intensity of effect.

OBJECTIVE

This study was conducted to compare the relative bioavailability and pharmacokinetics of the new sibutramine formulation (test) with those of the conventional formulation (reference).

METHODS

: This was a single-center, randomized, open-label, 2-period, comparative crossover study in healthy male subjects. All subjects received a single 15-mg oral dose of sibutramine hydrochloride monohydrate (reference) and a single 17.3-mg oral dose of sibutramine mesylate hemihydrate (test), both containing 12.55 mg sibutramine base. The 2 doses were separated by a 2-week washout period. Blood samples for pharmacokinetic analysis were collected during a 72-hour period after treatment. Safety parameters were assessed, including adverse events, hematology and biochemistry, urinalysis, and electrocardiography. Plasma concentrations of the active metabolites of sibutramine (desmethylsibutramine [M1] and didesmethylsibutramine [M2]) were determined, and the pharmacokinetic characteristics of the 2 formulations were compared using noncompartmental analysis.

RESULTS

Sixteen subjects (mean [SD] age, 24.3 [2.3] years [range, 20-25 years]; mean [SD] body weight, 66.1 [5.1] kg [range, 57-77 kg]) were enrolled in and completed the study. The plasma concentration-time profiles of M1 and M2 were similar after administration of both formulations. The reference and test formulations showed pharmacokinetic equivalence with respect to M1 and M2. The relative bioavailability of the test drug was 117.6% for M1 and 102.4% for M2. The 90% Cls for the ratios of the log-transformed C(max) and AUC values were within the predetermined equivalence range of 80% to 125%. There were no significant changes in physical, biochemical, hematologic, or urinalysis variables during the study. Neither formulation was associated with any serious adverse events.

CONCLUSION

In this study in healthy male subjects, the 2 sibutramine formulations were pharmacokinetically equivalent, and the newly developed formulation had a safety profile comparable to that of the conventional formulation.

Randomized, open-label, two-period crossover comparison of the pharmacokinetic and pharmacodynamic properties of two amlodipine formulations in healthy adult male Korean subjects

BACKGROUND

Amlodipine, a third-generation dihydropyridine calcium antagonist, is prescribed in the management of angina and hypertension. A newly developed amlodipine formulation (amlodipine camsylate) is associated with similar physical properties, melting point, and solubility-and improved stability against long-term stability test and accelerated temperature test-compared with the conventional formulation (amlodipine besylate).

OBJECTIVE

This study was performed to compare the pharmacokinetic (PK) and pharmacodynamic (PD) properties and safety profiles of a newly developed amlodipine formulation with a conventional formulation in healthy male subjects.

METHODS

This randomized, open-label, 2-period crossover comparative study was conducted at the Clinical Trial Center, Gil Medical Center, Gachon Medical School (Incheon, Korea). Eighteen healthy male Korean subjects aged 20 to 40 years were enrolled. All subjects received a single oral dose (5-mg tablet) of a conventional (reference) or newly developed (test) amlodipine formulation. Blood samples for PK analysis of amlodipine were obtained during the 144-hour period after dosing. Systolic and diastolic blood pressure (BP) (SBP and DBP, respectively) and pulse rate (PR) were measured just before each blood sampling. Assessment of safety profiles, including hematology and biochemistry, electrocardiography, urinalysis, and monitoring of adverse events (AEs), was performed.

RESULTS

All participants completed both treatment periods. Their mean (SD) age was 22.3 (1.5) years (range, 20-25 years) and their mean (SD) body weight was 67.9 (5.6) kg (range, 57-77 kg). The plasma concentration-time profiles of amlodipine were similar after administration of the 2 formulations. The reference and test formulations were pharmacokinetically equivalent. The 90% CIs for the mean treatment ratios of the log-transformed peak plasma concentration and the area under the plasma concentration-time curve were within the predetermined equivalence range of 80% to 125%. Despite administration of a single dose, significant maximal changes in SBP, DBP, and PR were achieved after drug administration for both formulations compared with baseline values (all, P < 0.001). No significant differences in PD profiles were found between the 2 formulations. No clinically relevant changes were observed in physical, biochemical, hematologic, electrocardiographic, or urinalysis findings during the study. Neither formulation caused any AEs during the study.

CONCLUSIONS

The 2 amlodipine formulations were pharmacokinetically equivalent and showed similar PD characteristics in these healthy male subjects.

Quantification of gliclazide by semi-micro high-performance liquid chromatography: application to a bioequivalence study of two formulations in healthy subjects

The objective of the present study was to evaluate the bioequivalence of two formulations of gliclazide in healthy human volunteers. Bioequivalence of the two formulations was determined in 20 healthy subjects with a single-dose, two-period, crossover study. A new high-performance liquid chromatographic method for the pharmacokinetic analysis of gliclazide was developed, using a semi-micro column to quantify gliclazide in plasma samples. Chromatographic separation was achieved with a semi-micro C18 column and 40 mM KH2PO4 (pH 4.6)-acetonitrile-isopropyl alcohol (5:4:1, v/v/v) as the mobile phase, and with UV detection at 229 nm. The method displayed good precision (coefficients of variation (CV < 8.0%)), was fast (total analysis time 8 min), and required only a small amount of mobile phase (0.22 ml/min), with a reasonable limit of quantification (0.1 microg/ml). The calibration curve was linear in the concentration range 0.1-10 microg/ml. When the pharmacokinetic parameters of gliclazide in the two formulations were calculated and compared statistically using crossover analysis of variance, they were similar, with no statistically significant difference. Ninety percent confidence intervals for AUC0-last, AUC0-infinity, and Cmax, used to evaluate bioequivalence, were in the stipulated range of 0.80-1.25. This result suggests that two formulations are bioequivalent when administered orally at a dose of 80 mg gliclazide.

Effect of rifampin on the pharmacokinetics and pharmacodynamics of gliclazide

OBJECTIVE

Our objective was to investigate the effect of rifampin (INN, rifampicin) on the pharmacokinetics and pharmacodynamics of gliclazide, a sulfonylurea antidiabetic drug.

METHOD

In a randomized 2-way crossover study with a 4-week washout period, 9 healthy Korean subjects were treated once daily for 6 days with 600 mg rifampin or with placebo. On day 7, a single dose of 80 mg gliclazide was administered orally. Plasma gliclazide, blood glucose, and insulin concentrations were measured.

RESULTS

Rifampin decreased the mean area under the plasma concentration-time curve for gliclazide by 70% (P <.001) and the mean elimination half-life from 9.5 to 3.3 hours (P <.05). The apparent oral clearance of gliclazide increased about 4-fold after rifampin treatment (P <.001). A significant difference in the blood glucose response to gliclazide was observed between the placebo and rifampin phases.

CONCLUSION

The effect of rifampin on the pharmacokinetics and pharmacodynamics of gliclazide suggests that rifampin affects the disposition of gliclazide in humans, possibly by the induction of cytochrome P450 2C9. Concomitant use of rifampin with gliclazide can considerably reduce the glucose-lowering effects of gliclazide.

Exploitation of syndecan-1 shedding by Pseudomonas aeruginosa enhances virulence

Cell-surface heparan sulphate proteoglycans (HSPGs) are ubiquitous and abundant receptors/co-receptors of extracellular ligands, including many microbes. Their role in microbial infections is poorly defined, however, because no cell-surface HSPG has been clearly connected to the pathogenesis of a particular microbe. We have previously shown that Pseudomonas aeruginosa, through its virulence factor LasA, enhances the in vitro shedding of syndecan-1-the predominant cell-surface HSPG of epithelia. Here we show that shedding of syndecan-1 is also activated by P. aeruginosa in vivo, and that the resulting syndecan-1 ectodomains enhance bacterial virulence in newborn mice. Newborn mice deficient in syndecan-1 resist P. aeruginosa lung infection but become susceptible when given purified syndecan-1 ectodomains or heparin, but not when given ectodomain core protein, indicating that the ectodomain's heparan sulphate chains are the effectors. In wild-type newborn mice, inhibition of syndecan-1 shedding or inactivation of the shed ectodomain's heparan sulphate chains prevents lung infection. Our findings uncover a pathogenetic mechanism in which a host response to tissue injury-syndecan-1 shedding-is exploited to enhance microbial virulence apparently by modulating host defences.

Volume reduction surgery for end-stage heart failure: experience in Korea

Partial left ventriculectomy (PLV) is regarded as one of the alternatives to heart transplantation for idiopathic dilated cardiomyopathy (d-CMP). Between June 1996 and March 2000, 20 patients underwent left ventricular volume reduction surgery at five major cardiac centers in Korea. PLV was performed in 16 patients with d-CMP and in 1 patient with ischemic CMP. The modified Dor procedure was performed in three patients; two patients with d-CMP and one patient with ischemic CMP. Median age was 35 years (range 3-64 years). There were 13 male and 7 female patients; there were 4 patients in Class III and 16 patients in Class IV. Among the 16 patients in Class IV, 5 patients were inotropic dependent, 2 patients were resuscitated from cardiac arrest or shock in hospital, and 1 patient was treated with intra-aortic balloon pumping. Operative technique for PLV was the same as described by Batista and colleagues. For the modified Dor procedures, the apical left ventricle was opened and a circumferential pursestring suture was placed at the base of both papillary muscles to reduce the diameter of the left ventricle concomitant with mitral annuloplasty. Mitral valve repair was performed in 15 patients and mitral valve replacement was performed in 1 patient. Moderate-to-severe tricuspid regurgitation was noted in 12 patients (with tricuspid annuloplasty in 11 of these patients and replacement in 1 patient). Postoperatively, there were seven operative deaths after PLV and one death after the modified Dor procedure. Cause of death after PLV was right heart failure in four of the seven cases, sepsis in one case, and ventricular tachyarrhythmia in the remaining two cases. After the modified Dor procedure, there was one operative death with left ventricular failure. Postoperatively, mean ventricular end-diastolic dimension markedly decreased from 75.3 mm to 50.9 mm. However, this dimension had increased slightly to 58.2 mm, an average observed 22 months later. Mean left ventricular ejection fraction (LVEF) improved significantly from 20.6% to 33.5% (p < 0.0001), but decreased to 28.5% on average 22 months later (p = 0.058). Eleven patients were discharged from the hospital and followed-up for a mean of 20.2 months (range 1-41 months). During the early postoperative period, most were in good condition. However, heart failure progressed with mitral regurgitation in four patients, two of whom underwent heart transplantation. In conclusion, PLV for d-CMP seems to be an effective alternative surgical procedure to heart transplantation in Korea. The modified Dor procedure may be another alternative to transplantation for left ventricular volume reduction. However, in patients showing progression of heart failure, early intervention with ventricular assist or heart transplantation will be necessary. Also, further studies will be necessary for selection criteria and for prevention of ventricular tachyarrhythmia.

Homologous monocuspid valve patch in right ventricular outflow tract reconstruction

BACKGROUND

In the surgical repair of tetralogy of Fallot or pulmonary atresia, pulmonary regurgitation may be detrimental in the postoperative period. We have used homograft monocuspid valve patch to prevent pulmonary insufficiency.

METHODS

From September 1996 to December 1998, twenty-five patients, 4 months to 8 years of age (median 10.1 months) had homograft monocuspid valve in the procedure of right ventricular outflow tract reconstruction. The function of the monocuspid valve was assessed by echocardiogram and graded as trivial to mild, mild to moderate, moderate, and severe. We evaluated the degree of pulmonary insufficiency before discharge, at 3-6 months, and at 12 months after the operation.

RESULTS

There was one hospital death due to fulminate adeno viral pneumonia. On echocardiogram, 21 patients (88%, 21/24) had no significant pulmonary insufficiency. Only one patient (4.5%) showed a moderate degree of pulmonary insufficiency. At 3-6 months, seventeen of twenty-one (81%) patients had no significant pulmonary insufficiency. There were fourteen patients who had follow-up over 1 year, and no patients showed newly developed significant pulmonary insufficiency.

CONCLUSIONS

We concluded that the homograft monocuspid valve patch for right ventricular outflow tract reconstruction has provided excellent early results for the prevention of pulmonary insufficiency. However these effects are limited in duration and further close follow-up should be needed.

Functions of cell surface heparan sulfate proteoglycans

The heparan sulfate on the surface of all adherent cells modulates the actions of a large number of extracellular ligands. Members of both cell surface heparan sulfate proteoglycan families, the transmembrane syndecans and the glycosylphosphoinositide-linked glypicans, bind these ligands and enhance formation of their receptor-signaling complexes. These heparan sulfate proteoglycans also immobilize and regulate the turnover of ligands that act at the cell surface. The extracellular domains of these proteoglycans can be shed from the cell surface, generating soluble heparan sulfate proteoglycans that can inhibit interactions at the cell surface. Recent analyses of genetic defects in Drosophila melanogaster, mice, and humans confirm most of these activities in vivo and identify additional processes that involve cell surface heparan sulfate proteoglycans. This chapter focuses on the mechanisms underlying these activities and on the cellular functions that they regulate.

Organo-axial volvulus of the stomach with diaphragmatic eventration

Gastric volvulus occurs when the stomach rotates about its longitudinal axis (organo-axial volvulus), or about an axis joining the lesser and greater curvatures (mesentero-axial volvulus). Primary gastric volvulus, making up one third of cases, occurs when the stabilizing ligaments are too lax as a result of congenital or acquired causes. Secondary gastric volvulus, making up the remainder of cases, occurs in association with a paraesophageal hernia or other congenital or acquired diaphragmatic defects. While gastric volvulus may occur acutely, especially in children, it may not be clinically apparent and discovered incidentally. The authors present a case of chronic organo-axial volvulus of the stomach secondary to left hemidiaphragmatic eventration with a review of the relevant literature.

Syndecan-1 shedding is enhanced by LasA, a secreted virulence factor of Pseudomonas aeruginosa

Microbial pathogens frequently take advantage of host systems for their pathogenesis. Shedding of cell surface molecules as soluble extracellular domains (ectodomains) is one of the host responses activated during tissue injury. In this study, we examined whether pathogenic bacteria can modulate shedding of syndecan-1, the predominant syndecan of host epithelia. Our studies found that overnight culture supernatants of Pseudomonas aeruginosa and Staphylococcus aureus enhanced the shedding of syndecan-1 ectodomains, whereas culture supernatants of several other Gram-negative and Gram-positive bacteria had only low levels of activity. Because supernatants from all tested strains of P. aeruginosa (n = 9) enhanced syndecan-1 shedding by more than 4-fold above control levels, we focused our attention on this Gram-negative bacterium. Culture supernatants of P. aeruginosa increased shedding of syndecan-1 in both a concentration- and time-dependent manner, and augmented shedding by various host cells. A 20-kDa shedding enhancer was partially purified from the supernatant through ammonium sulfate precipitation and gel chromatography, and identified by N-terminal sequencing as LasA, a known P. aeruginosa virulence factor. LasA was subsequently determined to be a syndecan-1 shedding enhancer from the findings that (i) immunodepletion of LasA from the partially purified sample resulted in abrogation of its activity to enhance shedding and (ii) purified LasA increased shedding in a concentration-dependent manner. Our results also indicated that LasA enhances syndecan-1 shedding by activation of the host cell's shedding mechanism and not by direct interaction with syndecan-1 ectodomains. Enhanced syndecan-1 shedding may be a means by which pathogenic bacteria take advantage of a host mechanism to promote their pathogenesis.

Characterization of the elastin binding domain in the cell-surface 25-kDa elastin-binding protein of staphylococcus aureus (EbpS)

Our previous studies have established that a cell-surface 25-kDa elastin-binding protein of Staphylococcus aureus (EbpS) mediates binding of this pathogen to the extracellular matrix protein elastin. Results from binding assays examining the activity of various EbpS fragments suggested that the elastin recognition domain is contained within the first 59 amino acids. In this report, we have used functional analyses with synthetic peptides and recombinant truncated forms of EbpS to localize the elastin binding domain to a 21-amino acid region contained within residues 14-34 of EbpS. Further evidence for the importance of this domain was obtained by demonstrating that the inhibitory activity of anti-EbpS antibodies on staphylococcal elastin binding was neutralized when these antibodies were pre-absorbed with a truncated recombinant EbpS construct containing residues 1-34. Overlapping synthetic peptides corresponding to EbpS residues 14-36 were then generated and tested for elastin binding activity to define further the elastin binding domain, and results from these studies showed that sequences spanning amino acids Gln14-Asp23, Asp17-Asp23, and Thr18-Glu34 inhibit binding of Staphylococcus aureus to elastin. Our analyses indicate that the hexameric sequence Thr18-Asn-Ser-His-Gln-Asp23 is the minimal sequence common to all active synthetic peptides, proteolytic fragments, and recombinant constructs of EbpS. Furthermore, substitution of Asp23 with Asn abrogated the blocking activity of the synthetic peptides, demonstrating the requirement for a charged amino acid at this location. The composite data indicate that staphylococcal elastin binding is mediated by a discrete domain defined by short peptide sequences in the amino-terminal extracellular region of EbpS.

MR imaging of non-visualized pulmonary arteries at angiography in patients with congenital heart disease

The aim of this study was to evaluate whether MR could depict pulmonary arterial anatomy in more detail than routine angiography in patients with congenital interruption or acquired occlusion of the left pulmonary artery or pulmonary atresia. This study included 10 patients with tetralogy of Fallot (n=6) or pulmonary atresia with ventricular septal defect (n=3) or aorticopulmonary window (n=1) diagnosed by cardiac angiography and MR. Surgical confirmation was made in seven patients. Interruption of the proximal left pulmonary artery, diagnosed at the time of evaluation, was found in seven patients and acquired obstruction of the hilar pulmonary artery (PA) was found in two at cardiac angiography. In the remaining one patient with pulmonary atresia and an occluded palliative shunt, the central PA was not visualized at angiography. MR showed 3-6 mm-sized hilar PAs in five and a central PA in a patient with pulmonary atresia. In 4 of 6 (67%) surgically-proven patients with congenital or acquired left PA obstruction, the status of the PA distal to the obstruction was correctly diagnosed with MR. In conclusion, MR is an effective modality in depicting sizable PAs when routine angiography fails to visualize the PA anatomy.

Video-assisted thoracic surgery as a primary therapy for primary spontaneous pneumothorax. Decision making by the guideline of high-resolution computed tomography

BACKGROUND

Because blebs are confirmed in most of the patients undergoing thoracotomy, identification of blebs by high-resolution computed tomography (HRCT) can be proposed as a surgical indication in primary spontaneous pneumothorax (PSP). If an apical bleb is identified, we treat the patient by video-assisted thoracic surgery (VATS).

METHODS

From May 1995 to September 1997, 61 patients (21.9 +/- 4.6 years) were seen for initial episodes of PSP. Only seven showed bullae on simple chest radiography. However, by HRCT, 48 had sizable blebs (>5 mm), and 45 were treated surgically by VATS.

RESULTS

The mean duration of chest tube use after surgery was 3.2 +/- 1.9 days, and the mean hospital stay was 4.5 +/- 1.9 days. Only one recurrence developed 5 weeks after VATS.

CONCLUSIONS

Our protocol is effective in controlling an initial episode of PSP. It shortens the observation time before definitive surgical treatment, shortens the hospital stay, and decreases the likelihood of recurrence.