UI14SDF100CW is a chewable tablet of sildenafil citrate, which was developed to improve compliance through convenience of administration. The purpose of this study was to compare the pharmacokinetic (PK) properties of sildenafil citrate chewable tablets (UI14SDF100CW) and conventional sildenafil citrate film-coated tablets (Viagra®, Pfizer). A randomized, open-label, single dose, two-treatment, two-period, two-way crossover study was conducted in 60 healthy male volunteers. In each period, the subjects received a single oral dose of UI14SDF100CW or Viagra® (both tablets contain 140.45 mg of sildenafil citrate, which is equivalent to 100 mg of sildenafil). Serial blood samples were collected up to 24 h post-dose for PK analysis. The plasma concentration of sildenafil was determined using a validated HPLC-MS/MS assay. PK parameters of sildenafil were calculated using non-compartmental methods. The plasma concentration-time profiles of sildenafil in both formulations were similar. For UI14SDF100CW, the C(max) and AUC(last) of sildenafil were 1068.69 ± 458.25 (mean ± standard deviation) mg/L and 3580.59 ± 1680.29 h·mg/L, and the corresponding values for Viagra® were 1146.84 ± 501.70 mg/L and 3406.35 ± 1452.31 h·/L, respectively. The geometric mean ratios (90% confidence intervals) of UI14SDF100CW to Viagra® for C(max) and AUC(last) were 0.933 (0.853–1.021) and 1.034 (0.969–1.108), respectively, which met the bioequivalence criteria of Korean regulatory agency. In conclusion, UI14SDF100CW and Viagra® showed similar PK properties. Therefore, UI14SDF100CW can be an alternative to sildenafil for the treatment of erectile dysfunction, providing better compliance.
Compliance ; Cross-Over Studies ; Erectile Dysfunction ; Humans ; Male* ; Pharmacokinetics ; Plasma ; Sildenafil Citrate* ; Tablets* ; Therapeutic Equivalency ; Volunteers

This study focused on the role of cytochrome P450 2D6 (CYP2D6) genotypes to predict phenotypes in the metabolism of dextromethorphan. CYP2D6 genotypes and metabolic ratios (MRs) of dextromethorphan were determined in 201 Koreans. Unsupervised clustering algorithms, hierarchical and k-means clustering analysis, and color visualizations of CYP2D6 activity were performed on a subset of 130 subjects. A total of 23 different genotypes were identified, five of which were observed in one subject. Phenotype classifications were based on the means, medians, and standard deviations of the log MR values for each genotype. Color visualization was used to display the mean and median of each genotype as different color intensities. Cutoff values were determined using receiver operating characteristic curves from the k-means analysis, and the data were validated in the remaining subset of 71 subjects. Using the two highest silhouette values, the selected numbers of clusters were three (the best) and four. The findings from the two clustering algorithms were similar to those of other studies, classifying *5/*5 as a lowest activity group and genotypes containing duplicated alleles (i.e., CYP2D6*1/*2N) as a highest activity group. The validation of the k-means clustering results with data from the 71 subjects revealed relatively high concordance rates: 92.8% and 73.9% in three and four clusters, respectively. Additionally, color visualization allowed for rapid interpretation of results. Although the clustering approach to predict CYP2D6 phenotype from CYP2D6 genotype is not fully complete, it provides general information about the genotype to phenotype relationship, including rare genotypes with only one subject.
Alleles ; Classification ; Cluster Analysis* ; Cytochrome P-450 CYP2D6* ; Dextromethorphan ; Genotype ; Metabolism ; Phenotype* ; ROC Curve

Caffeine is a naturally-occurring central nervous system stimulant found in plant constituents including coffee, cocoa beans, and tea leaves. Consumption of caffeine through imbibing caffeinated drinks is rapidly growing among children, adolescents, and young adults, who tend to be more caffeine-sensitive than the rest of the general public; consequently, caffeine-related toxicities among these groups are also growing in number. However, a quantitative and interactive tool for predicting the plasma caffeine concentration that may lead to caffeine intoxication has yet to be developed. Using the previously established population-pharmacokinetic model, we developed “caffsim” R package and its web-based applications using Shiny and EDISON (EDucation-research Integration through Simulation On the Net). The primary aim of the software is to easily predict and calculate plasma caffeine concentration and pharmacokinetic parameters and visualize their changes after single or multiple ingestions of caffeine. The caffsim R package helps understand how plasma caffeine concentration changes over time and how long toxic concentration of caffeine can last in caffeine-sensitive groups. It may also help clinical evaluation of relationship between caffeine intake and toxicities when suspicious acute symptoms occur.
Adolescent ; Cacao ; Caffeine* ; Central Nervous System ; Child ; Coffee ; Humans ; Pharmacokinetics ; Plants ; Plasma* ; Tea ; Young Adult

Rivaroxaban is a new oral anticoagulant used for the prevention of stroke in patients with atrial fibrillation. Hemorrhagic pericarditis is known to occur with rivaroxaban; however, only a few case reports in the literature describe such events. Recently, we experienced hemorrhagic pericarditis that treated with rivaroxaban for anticoagulation of newly diagnosed, non valvular AF patients with pacemaker. An 83 year old male with permanent pacemaker receiving rivaroxaban 20 mg daily once for 3 months presented at our emergency department complaining of exertional dyspnea. ECG showed intermittent atrial pacing failure and echocardiography showed large amount of pericardial effusion. After urgent pericardiocentesis, which resulted in removal of 500cc bloody fluid, there was an immediate and dramatic improvement in the patient's clinical state. He was discharged without anticoagulation therapy due to concern for further bleeding. This case highlight the potential for bleeding complications associated with novel anticoagulants. Rivaroxaban is being used with increasing frequently in outpatient care. However, no available laboratory test specifically measures the anticoagulant effect of rivaroxaban. Also, in the events of serious bleeding, no specific antidotes, reversal agents were available. Clinicians should be aware of the possibility of hemopericardium in patients treated with anticoagulants, including rivaroxaban who presented with cardiomegaly.
Ambulatory Care ; Anticoagulants ; Antidotes ; Atrial Fibrillation* ; Cardiomegaly ; Dyspnea ; Echocardiography ; Electrocardiography ; Emergency Service, Hospital ; Hemorrhage ; Humans ; Male ; Pericardial Effusion ; Pericardiocentesis ; Pericarditis* ; Rivaroxaban* ; Stroke

We report a case of Waldenström's macroglobulinemia (WM) treated using clarithromycin (CAM) and prednisolone (PSL). An 84-year-old woman was admitted to our hospital for bleeding after a tooth extraction and hematuria. Computed tomography showed multiple ill-defined nodules in the omentum (omental cake). Although the cause of the omental cake remained unclear, the patient was diagnosed with WM, based on the detection of M-protein of immunoglobulin (Ig) M in serum and lymphoplasmacytes in bone marrow. The bleeding tendency in the patient may have been due to acquired hemophilia and/or hyper IgM-induced platelet dysfunction. The patient was treated using CAM (800 mg/day) and PSL (10 mg/day). As a result, IgM levels gradually decreased. Because the omental cake contracted along with improvement in IgM, it was thought to be lymphoplasmacytic lymphoma-like lymphoma. This case shows that treatment using CAM and PSL may be effective in some cases of WM.
Aged, 80 and over ; Blood Platelets ; Bone Marrow ; Clarithromycin* ; Female ; Hematuria ; Hemophilia A ; Hemorrhage ; Humans ; Immunoglobulin M ; Immunoglobulins ; Lymphoma ; Omentum ; Prednisolone* ; Tooth Extraction ; Waldenstrom Macroglobulinemia*

In this tutorial, we introduce a differential equation simulation model for use in pharmacometrics involving NONMEM, Berkeley Madonna, and R. We report components of the simulation code and similarities/differences between software, rather than how to use each software. Depending on the purpose of the simulation, an appropriate tool can be selected for effective communication.
Computer Simulation ; Software

Atorvastatin and ezetimibe are frequently co-administered to treat patients with dyslipidemia for the purpose of low-density lipoprotein cholesterol control. However, pharmacokinetic (PK) drug interaction between atorvastatin and ezetimibe has not been evaluated in Korean population. The aim of this study was to investigate PK drug interaction between two drugs in healthy Korean volunteers. An open-label, randomized, multiple-dose, three-treatment, three-period, Williams design crossover study was conducted in 36 healthy male subjects. During each period, the subjects received one of the following three treatments for seven days: atorvastatin 40 mg, ezetimibe 10 mg, or a combination of both. Blood samples were collected up to 96 h after dosing, and PK parameters of atorvastatin, 2-hydroxyatorvastatin, total ezetimibe (free ezetimibe + ezetimibe-glucuronide), and free ezetimibe were estimated by non-compartmental analysis in 32 subjects who completed the study. Geometric mean ratios (GMRs) with 90% confidence intervals (CIs) of the maximum plasma concentration (C(max,ss)) and the area under the curve within a dosing interval at steady state (AUC(τ,ss)) of atorvastatin when administered with and without ezetimibe were 1.1087 (0.9799–1.2544) and 1.1154 (1.0079–1.2344), respectively. The corresponding values for total ezetimibe were 1.0005 (0.9227–1.0849) and 1.0176 (0.9465–1.0941). There was no clinically significant change in safety assessment related to either atorvastatin or ezetimibe. Co-administration of atorvastatin and ezetimibe showed similar PK and safety profile compared with each drug alone. The PK interaction between two drugs was not clinically significant in healthy Korean volunteers.
Atorvastatin Calcium* ; Cholesterol ; Cross-Over Studies ; Drug Interactions* ; Dyslipidemias ; Ezetimibe* ; Humans ; Lipoproteins ; Male ; Pharmacokinetics ; Plasma ; Volunteers*

JOINS (SKI306X) is an herbal anti-arthritic medicine that is widely used with aceclofenac for treating osteoarthritis in Korea. A fixed-dose combination (FDC) tablet containing SKI306X and aceclofenac was developed to improve patient compliance. This study aimed to compare the pharmacokinetics (PK) and safety of the FDC tablet with those of co-administered SKI306X and aceclofenac in healthy subjects. In this randomized, open-label, two-way crossover, single-dose study, the FDC tablet (SKI306X 300 mg/aceclofenac 100 mg) (test) was given or co-administration of 300 mg of SKI306X and 100 mg of aceclofenac (reference) was performed followed by a 7-day wash-out period. Blood samples were collected before and after drug administration to evaluate aceclofenac PK parameters, and safety was assessed throughout the study. A total of 54 healthy male subjects were enrolled in and completed the study. T(max) and t(1/2) of aceclofenac of the FDC tablet were similar to those of aceclofenac co-administered with SKI306X (T(max): test 2.96 h and reference 2.14 h; t(1/2): test 3.46 h and reference 4.04 h). The geometric mean ratios (90% confidence intervals) of C(max) and AUC(last) (T/R) were 0.85 (0.81 to 0.91) and 1.03 (1.01 to 1.06) respectively; these results were within the predefined range (0.8 to 1.25). There was only one drug-related adverse event (dizziness) occurred after administration of the FDC tablet; however, it was mild in severity and resolved without any complications. The FDC tablet was well tolerated and exhibited an absorption rate and extent comparable to those of SKI306X and aceclofenac administered simultaneously.
Absorption ; Healthy Volunteers* ; Humans ; Korea ; Male ; Osteoarthritis ; Patient Compliance ; Pharmacokinetics* ; Tablets*

Two separate studies were conducted to establish bioequivalence (BE) for two doses of atorvastatin/metformin sustained-release (SR) fixed dose combination (FDC) versus the same dosage of the individual component (IC) tablets in healthy male subjects under fed conditions (study 1, BE of atorvastatin/metformin SR 20/500 mg FDC; study 2, BE of atorvastatin/metformin SR 20/750 mg FDC). Each study was a randomized, open-label, single oral dose, two-way crossover design. Serial blood samples were collected pre-dose and up to 36 hours post-dose for atorvastatin and 24 hours for metformin. Plasma concentrations of atorvastatin, 2-OH atorvastatin and metformin were analyzed using a validated liquid chromatography tandem mass-spectrometry. A non-compartmental analysis was used to calculate pharmacokinetic (PK) variables and analysis of variance was performed on the lognormal-transformed PK variables. A total of 75 subjects completed the study 1 (36 subjects) and study 2 (39 subjects). The 90% confidence intervals for the adjusted geometric mean ratio of Cmax and the AUC0-t were within the predefined 0.80 to 1.25 range. The number of subjects reporting at least one adverse event following FDC treatments was comparable to that following IC treatments. The two treatments were well tolerated. Therefore, atorvastatin/metformin SR 20/500 mg and 20/750 mg FDC tablets are expected to be used as alternatives to IC tablets to decrease the pill burden and increase patient compliance.
Atorvastatin Calcium* ; Chromatography, Liquid ; Cross-Over Studies* ; Humans ; Male* ; Metformin* ; Patient Compliance ; Pharmacokinetics* ; Plasma ; Tablets* ; Therapeutic Equivalency

This study describes the development of an analytical method to determine radotinib levels in human plasma using high performance liquid chromatography (HPLC) coupled with triple quadrupole tandem mass spectrometry (MS/MS) for pharmacokinetic application. Plasma samples were sequentially processed by liquid-liquid extraction using methyl tert-butyl ether, evaporation, and reconstitution. Analytes were separated and analyzed using HPLC-MS/MS in selected reaction monitoring mode, monitoring the specific transitions of m/z 531 to 290 for radotinib and m/z 409 to 238 for amlodipine (internal standard). The HPLC-MS/MS analytical method was validated with respect to selectivity, linearity, sensitivity, accuracy, precision, recovery, and stability. Calibration curves were linear over a concentration range 5–3,000 ng/mL with correlation coefficients (r) > 0.998. The lower limit of quantification for radotinib in plasma was 5 ng/mL. The accuracy and precision of the analytical method were acceptable within 15% at all quality control levels. This method was suitable to determine radotinib levels in human plasma because of its simplicity, selectivity, precision, and accuracy.
Amlodipine ; Calibration ; Chromatography, Liquid ; Ether ; Humans* ; Liquid-Liquid Extraction ; Mass Spectrometry* ; Methods* ; Plasma* ; Quality Control ; Tandem Mass Spectrometry