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YH4808 is a novel potassium-competitive acid blocker developed for gastric acid-related disorders. Previous studies indicate its potential to improve symptoms of gastric acid-related disorders. The current study was aimed to find the optimal regimen of YH4808 for night time pH control. This study was performed in two parts. Each was a randomized, open-label, active-controlled, multiple-doses, two-treatment, two-period crossover study conducted in 20 healthy Korean volunteers. Subjects were randomly assigned to one of the four groups. The three groups received different dosage regimens of YH4808 (100 mg twice a day, 200 mg once a day, or 200 mg twice a day), and the fourth group received esomeprazole 40 mg twice a day. The pharmacokinetic parameters demonstrated that the systemic exposure of YH4808 increased in a dose-proportional manner. The difference in the proportion of time above pH 4 over 24 h from the baseline was the greatest in the group receiving YH4808 200 mg twice a day. The values of the area under the effect curve at night time (12 A.M.-7 A.M.) were higher in all YH4808 groups than in the esomeprazole group. However, the differences among the YH4808 groups were not statistically significant (p > 0.05). YH4808 exhibited potential for better pH control during the night in comparison to esomeprazole. The optimal regimen for night time pH control among all the YH4808 regimens was 200 mg twice a day. Trial Registration ClinicalTrials.gov Identifier: NCT01761513.

YH12852, a novel, highly selective 5‐hydroxytryptamine 4 (5‐HT4) receptor agonist, is currently under development to treat patients with functional constipation. In this study, we aimed to develop a pharmacokinetic (PK)–pharmacodynamic (PD) model that adequately described the time courses of the plasma concentrations of YH12852 and its prokinetic effect as assessed by the Gastric Emptying Breath Test (GEBT) and to predict the prokinetic effect of YH12852 at higher doses through PD simulation. We used the plasma concentrations of YH12852 from patients with functional constipation and healthy subjects and the GEBT results from healthy subjects obtained from a phase I/IIa trial. The PK‐PD modeling and covariate analysis were performed using NONMEM software. The prokinetic effect of YH12852 was described using a semimechanistic multicompartment PD model and an empirical model by Ghoos et al. A two‐compartment model with first‐order absorption adequately described the observed concentration‐time profiles of YH12852. The semimechanistic multicompartment PD model and the revised Ghoos model with two slope parameters adequately described the observed kPCDt (the percent dose of 13C excreted in the exhaled air at minute t after completing the test meal, multiplied by 1000) values. YH12852 accelerated gastric emptying even at low doses of 0.05–0.1 mg, and its prokinetic effect was greater in subjects suffering from more severe functional constipation. The PD simulation experiments revealed that the change from baseline in the half time for gastric emptying induced by YH12852 increased in a dose‐dependent manner at 0.05–5 mg although the results at doses >0.1 mg were extrapolated. We also showed that the empirical Ghoos model is a special case of the general semimechanistic multicompartment PD model for gastric emptying.

A physiologically-based pharmacokinetic (PBPK) model was developed for YH4808, a novel potassium-competitive acid blocker, using the SimCYP® Simulator based on the physicochemical, in vitro preclinical and clinical data of YH4808. The PBPK model was optimized using YH4808 concentrations obtained from the single-dose phase I clinical trial. Overall, the PBPK model adequately predicted the observed pharmacokinetic profiles of YH4808 in humans. The pharmacokinetic profiles of YH4808 after multiple oral administrations were predicted using a refined PBPK model. The ratios of model-predicted to observed Cmax, AUCinf and AUCτ values on Day 1 and Day 7 at 100 mg were 0.7–1.0. However, the model failed to predict a decreased exposure after multiple oral administration particularly at higher doses of 200 and 400 mg. The reduced solubility of YH4808 at higher pH was hypothesized as the main cause of the reduction in exposure such that absorption was decreased as pH was increased. This hypothesis was confirmed by PBPK modeling and simulation, where intragastric pH was increased by YH4808.

Purpose A new sustained-release (SR) pregabalin formulation (YHD1119) designed for once-daily dosing has recently been developed to improve patient adherence. This study aimed to compare the pharmacokinetics of pregabalin SR and immediate-release (IR) formulations after multiple oral doses and to assess the effect of food on the pharmacokinetic profile of the pregabalin SR formulation after a single dose in healthy individuals. Methods Two clinical trials were conducted: a randomized, open-label, multiple-dose, 2-treatment, 2-period crossover study to evaluate the steady-state pharmacokinetic properties of SR treatment (pregabalin SR 300 mg once daily for 3 days) and IR treatment (pregabalin IR 150 mg twice daily for 3 days) under fed conditions and a randomized, open-label, single-dose, 2-treatment, 2-period, crossover study to evaluate the effect of food intake on the pharmacokinetic properties of the pregabalin SR formulation. Plasma concentrations of pregabalin were measured using LC-MS/MS. The AUC and Cmax for pregabalin were calculated using noncompartmental method and compared between treatments in each study. Findings Thirty-one individuals in the bioequivalence study and 23 in the food effect study completed the pharmacokinetic sampling. The geometric mean ratios of Cmax,ss and AUC0–τ between the SR and IR formulations were 1.1642 (90% CI, 1.1043–1.2272) and 0.9704 (90% CI, 0.9372–1.0047), respectively. The geometric mean ratios of Cmax and AUC0–last between the SR formulation in the fed state and in the fasted state were 1.6514 (90% CI, 1.3820-1.9732) and 1.7899 (90%CI, 1.4499-2.2097), respectively. Implications The bioavailability of the pregabalin SR 300 mg formulation is increased if taken with a high-fat meal. Once-daily pregabalin SR 300 mg is bioequivalent to twice-daily pregabalin IR 150 mg under fed conditions at steady state. The pregabalin SR formulation is expected to improve patient adherence. ClinicalTrials.gov identifiers: NCT02783183 (bioequivalence study) and NCT03191136 (food effect study).

Jin Ah Jung,1 Soo-Yun Lee,2 Jung-Ryul Kim,1 Jae-Wook Ko,1,2 Seong Bok Jang,3 Su Youn Nam,3 Wooseong Huh1,41Department of Clinical Pharmacology and Therapeutics, Samsung Medical Center, 2Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, 3Yuhan Research Institute, Yuhan Corporation, 4Department of Internal Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, KoreaPurpose: Valsartan, an angiotensin-receptor blocker, and rosuvastatin, a competitive inhibitor of the 3-hydroxy-3-methylglutaryl coenzyme A reductase, are frequently coadministered to treat patients with hypertension and dyslipidemia. The study reported here sought to evaluate the pharmacokinetic and pharmacodynamic interactions between rosuvastatin and valsartan in healthy Korean subjects. Subjects and methods: Thirty healthy male Korean subjects were administered with rosuvastatin (20 mg/day), valsartan (160 mg/day), and both drugs concomitantly for 4 days in a randomized, open-label, multiple-dose, three-treatment, three-period crossover study. Plasma concentrations of rosuvastatin, N-desmethyl rosuvastatin, and valsartan were determined using validated high-performance liquid chromatography with tandem mass spectrometry. Lipid profiles and vital signs (systolic and diastolic blood pressure and pulse rate) were measured for the pharmacodynamic assessment.Results: For rosuvastatin, the geometric mean ratios (90% confidence intervals [CIs]) of coadministration to mono-administration were 0.8809 (0.7873-0.9857) for maximum plasma concentration at steady state and 0.9151 (0.8632-0.9701) for area under the concentration–time curve (AUC) over a dosing interval at steady state. For valsartan, the geometric mean ratios (90% CIs) of those were 0.9300 (0.7946-1.0884) and 1.0072 (0.8893-1.1406), respectively. There were no significant differences in the metabolic ratio of N-desmethyl rosuvastatin AUC to rosuvastatin AUC between coadministration and rosuvastatin alone. No interaction was found in terms of systolic or diastolic blood pressure or lipid profiles. Combined treatment with valsartan and rosuvastatin was generally well tolerated without serious adverse events.Conclusion: The pharmacokinetic profiles of rosuvastatin and valsartan in combination were comparable with those of rosuvastatin and valsartan administered individually, suggesting that their individual pharmacokinetics were not affected by their coadministration. No dose adjustment was required and the results are supportive of a study in a larger patient population.Keywords: pharmacokinetics, pharmacodynamics, hypertension, dyslipidemia&nbsp

Purpose Rosuvastatin is indicated for hypercholesterolemia or dyslipidemia and metformin mainly for type 2 diabetes. These 2 drugs are frequently prescribed in combination due to the high comorbidity of the 2 diseases. However the nature of pharmacokinetic interaction between the 2 drugs has not been previously investigated. The purpose of our study was to investigate the pharmacokinetic interaction between rosuvastatin and metformin in healthy Korean male volunteers. Methods This was a randomized, open-label, 6-sequence, 3-period, crossover, multiple-dose study. Eligible subjects, aged 20 to 50 years and within 20% of the ideal body weight, received 1 of the following 3 treatments for each period once daily for 5 consecutive days with a 10-day washout period between the treatments: monoadministration of rosuvastatin 10 mg tablet, monoadministration of metformin 750 mg tablet, and coadministration of rosuvastatin 10 mg tablet with metformin 750 mg tablet. Blood samples were collected up to 72 hours after the last dose and pharmacokinetic parameters for rosuvastatin and metformin were compared between combination and monotherapy. Adverse events were investigated and evaluated based on subject interviews and physical examinations. Findings Among the 36 enrolled subjects, 31 completed the study. The coadministration of rosuvastatin with metformin produced a significant pharmacokinetic interaction in rosuvastatin C ss,max , with the 90% CI for the geometric mean ratio (coadministration:monoadministration) being 110.27% to 136.39% ( P = 0.0029), whereas no significant interaction was observed in rosuvastatin AUC tau , yielding the 90% CI of 104.41% to 118.95%. When metformin was coadministered with rosuvastatin, no significant pharmacokinetic interaction was observed for C ss,max and AUC tau of metformin, yielding the 90% CIs of the geometric mean ratio for coadministration to monoadministration as 87.38% to 102.54% and 86.70% to 99.08%, respectively. Overall, 19 mild and 1 moderate adverse events occurred in 12 subjects, with no significant differences in the incidence among the 3 treatments. Implications Although the C ss,max of rosuvastatin was significantly influenced by coadministration with metformin, the degree of interaction seen was considered clinically insignificant, with no significant interaction observed in the other pharmacokinetic measures between the 2 drugs. These results imply that drug effects of rosuvastatin and metformin will also not be significantly influenced by coadministration of the 2 drugs. All treatments were well tolerated and no serious adverse events occurred. ClinicalTrials.gov identifier: NCT01526317.

Background To date, no definitive treatment of functional dyspepsia (FD) has been proven to be effective and reasonably well-tolerated. Proton pump inhibitors (PPIs) combined with prokinetic agents are considered an effective option. Revaprazan is a selective potassium-competitive acid blocker that reversibly inhibits gastric H + /K + -ATPase and shows effective acid suppression comparable to PPIs. Itopride is a prokinetic agent that has anticholinesterase activity as well as dopamine D 2 receptor antagonistic activity. For this reason, revaprazan and itopride have been prescribed for FD; however, no available studies have reported the pharmacokinetic interactions of these 2 drugs. Objective The objective of this study was to compare the bioavailability and tolerability of revaprazan and itopride combination therapy to those of equally dosed monotherapies to acquire basic drug–drug interaction information about revaprazan. Methods This multiple-dose, randomized crossover study was conducted in healthy male Korean subjects. Subjects received, in randomized sequence, a 7-day oral dose of revaprazan 200 mg once daily, itopride 50 mg TID, or both. Each treatment period was separated by a 7-day washout period. Blood samples were collected for up to 24 hours following the last dose at steady state, and drug concentrations were determined using validated LC/MS-MS. Pharmacokinetic properties were obtained using noncompartmental analysis. Drug tolerability was assessed throughout the study, using measurements of vital signs, clinical chemistry testing, and interviews. Results A total of 30 subjects were enrolled in the study. Among them, 28 subjects completed revaprazan treatment, and 27 completed the study (3 subjects were withdrawn). The geometric mean ratios (GMRs) (90% CI) of C max,ss , and AUC τ,ss with revaprazan were 0.92 (0.84–1.00) and 0.96 (0.89–1.03), respectively. The GMRs of C max,ss and AUC τ,ss with itopride were 1.07 (0.96–1.20) and 1.12 (1.06–1.18), respectively. A total of 15 adverse events (AEs) were reported in 8 subjects. All AEs were considered to be mild, and there were no clinically significant differences between treatment groups. Conclusion The findings from this study suggest bioequivalence between revaprazan given as monotherapy and in combination with itopride in these healthy Korean male volunteers, with no clinical significant drug–drug interaction. All treatments in this study was generally well tolerated. ClinicalTrials.gov identifier: NCT0133289.

The investigators quantified the relationship between the genetic polymorphism of HMGCR (3-hydroxy-3-methylglutaryl coenzyme A reductase) and the low-density lipoprotein cholesterol (LDL-C)-lowering effects of atorvastatin in a prospective clinical study. Twenty-four healthy participants were grouped into HMGCR rs3846662 GG (n = 13) and AA (n = 11) genotypes and given atorvastatin (20 mg/d) for 14 days. Serum levels of LDL-C, high-density lipoprotein cholesterol, total cholesterol, triglycerides, and creatinine kinase (CK) were measured before (day 1) and 7, 13, 14, 15, 16, 21, and 28 days after dosing initiation. Blood samples for pharmacokinetics were taken on days 14 through 16. The levels of LDL-C in the GG group were significantly higher than in the AA group at all observation times, with mean differences of 18% to 33% (P < .05). The area under the LDL-C-time curve and the minimum value of LDL-C in the GG group were 24% and 23% higher than in the AA group, respectively (P < .01). There was no significant difference in other lipids, CK, and pharmacokinetic parameters. The HMGCR rs3846662 GG genotype was quantitatively documented to be a significant determinant for higher LDL-C level in basal state and possibly in response to atorvastatin.

OBJECTIVE This study aimed at investigating the influence of demographic and clinical covariates on the population pharmacokinetics of amikacin in Korean patients from routinely collected therapeutic drug monitoring data. MATERIALS AND METHODS Pharmacokinetics was studied in 305 adult Korean patients who received amikacin 125 - 1,000 mg once-daily or every-other- day. Peak and trough plasma levels of steady state were measured. Patients were randomized into an index dataset (n = 197) and a validation dataset (n = 108). Covariates were selected in a step-wise approach using NONMEM 7 software. The predictive performance of the model was evaluated by the percent prediction error and the percent coverage of 95% population prediction interval. RESULTS The covariates significantly influencing amikacin pharmacokinetics were creatinine clearance (p < 0.0001) and ward setting (p = 0.0017) for clearance, and body weight (p < 0.0001) and presence of cholecystitis (p = 0.0135) for volume of distribution. The estimates of pharmacokinetic parameters for a typical individual were 2.82 l/h for clearance, and 18.04 l for volume of distribution. Inter-individual variability (CV%) was 31% for clearance. The mean (SD) of percent prediction errors was 2.1 (26.4)% for peak and -121.5 (460.3)% for trough concentrations. Percent coverage of 95% PPIs for peak and trough concentrations were above 80%. CONCLUSIONS The population pharmacokinetic model developed in this study may be used as a basis for finding optimal amikacin dosing in a Korean patient population without a significant bias. Further studies will be needed to validate these results.

Tacrolimus is metabolized by CYP3A and has highly variable pharmacokinetics. To study the factors contributing to this high variability in pharmacokinetics and to investigate the possibility of genotype-specific clinical applications, the effect of differing CYP3A5 genotypes on the intrasubject coefficients of variation for tacrolimus was investigated. Genotyping for CYP3A5*3 was performed in healthy volunteers who had previously participated in the pharmacokinetic study of 2 tacrolimus formulations with a 2 x 2 cross-over design. Intrasubject coefficients of variation calculated from analysis of variation in CYP3A5*1/*1+*1/*3 (n = 16) and CYP3A5*3/*3 (n = 13) groups were compared. The intrasubject CVs of AUClast and Cmax in the CYP3A5*3/*3 group were about 41.1% and 52.4% greater than those in the CYP3A5*1*1+*1/*3 group. The estimated total sample size for the bioequivalence study of tacrolimus with a 2 x 2 cross-over design was increased by 93.3% for AUClast (n = 30 versus 58) and 121.4% for Cmax (n = 28 versus 62) in the CYP3A5*3/*3 group compared with the CYP3A5*1/*1+*1/*3 group. The intraindividual variability of tacrolimus PK parameters may be associated with the CYP3A5 genotype. We propose that genotyping for CYP3A5 will provide a more efficient approach for bioequivalence designs and therapeutic drug monitoring.

OBJECTIVE This study aimed to evaluate the effect of genetic polymorphisms of SLCO1B1 and ABCB1 on the pharmacokinetics of atorvastatin and its metabolites. METHODS 290 Koreans were genotyped for SLCO1B1, ABCB1 and CYP3A5, and 28 subjects were selected for the pharmacokinetic study. Each subject received a single oral dose of 20 mg atorvastatin and blood samples were collected up to 48 hr after dosing. The relationship between the genotypes and atorvastatin pharmacokinetics was examined. RESULTS For SLCO1B1 genotypes, the mean area under the concentration-time curve from time 0 to infinity (AUC0-infinity) of atorvastatin was 148.2 ng x hr/ml for *15/*15 subjects (n = 3), which was significantly larger than for 1a/*15 and *1b/*15 (n = 8) (80.7 ng x hr/ml, p = 0.0121) and also larger than for *1a/*1a, *1a/*1b and *1b/*1b (n = 17) (66.3 ng x hr/ml, p = 0.0018). The mean AUC0-infinity of 2-hydroxyatorvastatin for *15/*15 was also larger than in *1a/*1a, *1a/*1b and *1b/*1b (p = 0.012). In lactone forms, no significant pharmacokinetic difference was found among the genotypes. For ABCB1 genotypes, the half-lives of atorvastatin, atorvastatin lactone, 2-hydroxyatorvastatin and 2-hydroxyatorvastatin lactone were significantly longer in c.2677TT-c.3435TT (n = 3) vs. c.2677GG-c.3435CC and c.2677GT-c.3435CT (n = 10), yielding p = 0.049, 0.007, 0.007 and 0.007, respectively. CONCLUSION This study shows that the SLCO1B1*15 allele may be associated with the individual difference in the AUC0-infinity of atorvastatin whereas the ABCB1 TT-TT diplotype may affect the elimination half-life of the drug in the Korean population.

Nowadays, attempts to use nanoparticles for medical applications are on the rise. However, the effect of nanoparticles in the body has not been clarified. In this study, we aimed to examine the pharmacokinetics of magnetized nanoparticles. FITC conjugated SA-MnMEIO nanoparticles were prepared for the purpose of tracing. Nanoparticles (15 nm diameter) were injected into the tail vein of BALB/c mice at a dose of 20 mg (Mn+Fe)/kg. A mouse was housed in a metabolic cage and sacrificed serially up to 14 days for the sampling of blood and tissues from various organs (i.e., heart, kidney, liver, and spleen). The concentration of nanoparticles was measured by detecting FITC using spectrofluorophotometer. Nanoparticles showed a half-life of 8.20 h. The fluorescence intensities of nanoparticles in tissues showed different time-dependent patterns among different organs. In the heart and the liver, the fluorescence intensities increased up to 2 weeks of observation, while those in the kidney and the spleen decreased. The results indicate that nanoparticles have unique pharmacokinetic characteristics and suggest that pharmacokinetic study is essential for the development of new nanoparticles for medical use.

A sustained-release (SR) formulation of cilostazol was recently developed in Korea and was expected to yield a lower C(max) and a similar AUC to the immediate-release (IR) formulation.The goal of the present study was to compare the pharmacokinetic profiles of a newly developed SR formulation and an IR formulation of cilostazol after single- and multiple-dose administration and to evaluate the influence of food in healthy Korean subjects. This study was developed as part of a product development project at the request of the Korean regulatory agency.This was a randomized, 3-part, sequential, open-label, 2-period crossover study. Each part consisted of different subjects between the ages of 19 and 55 years. In part 1, each subject received a single dose of SR (200 mg × 1 tablet, once daily) and IR (100 mg × 2 tablets, BID) formulations of cilostazol orally 7 days apart in a fasted state. In part 2, each subject received a single dose of the SR (200 mg × 1 tablet, once daily) formulation of cilostazol 7 days apart in a fasted and a fed state. In part 3, each subject received multiple doses of the 2 formulations for 8 consecutive days 21 days apart. Blood samples were taken for 72 hours after the dose. Cilostazol pharmacokinetics were determined for both the parent drug and its metabolites (OPC-13015 and OPC-13213). Adverse events were evaluated through interviews and physical examinations.Among the 92 enrolled subjects (66 men, 26 women; part 1, n = 26; part 2, n = 26; part 3, n = 40), 87 completed the study. In part 1, all the primary pharmacokinetic parameters satisfied the criterion for assumed bioequivalence both in cilostazol and its metabolites, yielding 90% CI ratios of 0.9624 to 1.2323, 0.8873 to 1.1208, and 0.8919 to 1.1283 for C(max) and 0.8370 to 1.0134, 0.8204 to 0.9807, and 0.8134 to 0.9699 for AUC(0-last) of cilostazol, OPC-13015, and OPC-13213, respectively. In part 2, food intake increased C(max) and AUC significantly (P0.0001), yielding geometric mean ratios of 3.2879, 2.9894, and 3.0592 for C(max) and 1.7001, 1.7689, and 1.6976 for AUC(0-last) of cilostazol, OPC-13015, and OPC-13213. In part 3, only the C(ssmax) of clilostazol in the reference formulation did not satisfy the criterion for assumed bioequivalence, yielding 90% CI ratios of 1.2693 to 1.4238 and 1.2038 to 1.3441, respectively. When each dose was normalized, the C(max) for the SR formulation was significantly lower (P0.005 for cilostazol). Headache was the most frequently noted adverse effect (part 1, a total of 14 subjects with the IR formulation and 14 with the SR formulation; part 2, a total of 10 without food and 23 with a high-fat meal; part 3, a total of 10 with the IR formulation and 24 with the SR formulation), followed by nausea (part 1, none; part 2, only 1 without food and 3 with a high-fat meal; part 3, a total of 3 with the IR formulation and 3 with the SR formulation), and then dizziness (parts 1 and 2, none; part 3, a total of 4 with the IR formulation and 5 with the SR formulation). All other AEs, including fever, cough, vomiting, palpitation, diarrhea, and epigastric pain, occurred in3 subjects.These findings suggest that in this select group of healthy Korean volunteers, the SR formulation of cilostazol was not significantly different in AUC compared with that of the IR formulation, although it did display a significantly lower C(max) per dose in both the single- and multiple-dose groups. Food significantly increased the bioavailability of the SR formulation. The cilostazol SR and IR formulations were well tolerated in all parts of the study, with no serious adverse events reported. ClinicalTrials.gov identifier: NCT01455558.

Sibutramine is a pharmacologic intervention for the treatment of obesity. The effect of CYP2B6 genotypes on the pharmacokinetics of sibutramine and its active metabolites (desmethylsibutramine [M1] and didesmethylsibutramine [M2]) was evaluated in 57 healthy subjects. Each subject received a single oral dose of 10 or 15 mg sibutramine, and blood samples were collected up to 72 hours after dosing. The relationship between the genotypes and the pharmacokinetics of sibutramine, M1, and M2 was examined. A statistically significant difference in the elimination half-life (t 1/2 ) of sibutramine M1 was found among the 3 genotype groups (P = .0006), between the *1/*1 and * 1/ * 6 groups (P = .0001), and between the *1/*4 and *1/*6 groups (P = .012). The mean value of M1 t 1/2 in *1/*6 (33.3 ± 10.5 hours) was about 58% and 61% greater than that of the *1/*1 group (21.0 ± 7.4 hours) and the *1/*4 group (20.7 ± 9.8 hours), respectively. No significant differences in area under the concentration-time curve or maximum plasma drug concentration were observed between thegroups. The CYP2B6* 6 allele may be associated with a lower metabolic clearance of the M1 metabolite of sibutramine in human subjects.

A controlled-release (CR) formulation of simvastatin was recently developed in Korea. The formulation is expected to yield a lower C(max) and similar AUC values compared with the immediate-release (IR) formulation.The goal of this study was to compare the pharmacokinetics of the new CR formulation and an IR formulation of simvastatin after single- and multiple-dose administration in healthy Korean subjects. This study was developed as part of a product development project at the request of the Korean regulatory agency.This was a randomized, open-label, parallelgroup, 2-part study. Eligible subjects were healthy male or female volunteers between the ages of 19 and 55 years and within 20% of their ideal weight. In part I, each subject received a single dose of the CR or IR formulation of simvastatin 40 mg orally (20 mg x 2 tablets) after fasting. In part II, each subject received the same dose of the CR or IR formulation for 8 consecutive days. Blood samples were obtained for 48 hours after the dose in part I and after the first and the last dose in part II. Pharmacokinetic parameters were determined for both simvastatin (the inactive prodrug) and simvastatin acid (the active moiety). An adverse event (AE) was defined as any unfavorable sign (including an abnormal laboratory finding) or symptom, regardless of whether it had a causal relationship with the study medication. Serious AEs were defined as any events that are considered life threatening, require hospitalization or prolongation of existing hospitalization, cause persistent or significant disability or incapacity, or result in congenital abnormality, birth defect, or death. AEs were determined based on patient interviews and physical examinations.Twenty-four healthy subjects (17 men, 7 women; mean [SD] age, 29 [7] years; age range, 22-50 years) were enrolled in part I, and 29 subjects (17 men, 12 women; mean age, 33 [9] years; age range, 19-55 years) were enrolled in part II. For simvastatin acid, C(max) was significantly smaller (1.68 vs 3.62 ng/mL; P0.013) and T(max) and apparent t((1/2)) significantly longer (10.33 vs 4.04 hours [P0.001] and 11.41 vs 4.16 hours [P0.011]) for the CR formulation compared with the IR formulation, respectively, after the single-dose administration. After the multiple-dose administration, for simvastatin acid, the C(max) for the CR formulation was significantly smaller (3.40 vs 5.16 ng/mL; P0.037), while the values for T(max) and apparent t((1/2)) were significantly longer (8.40 vs 4.57 hours and 13.09 vs 4.52 hours; both, P0.001) compared with the IR formulation. There was no significant difference between the CR and the IR formulations for AUC(0-last) and AUC(0-infinity)) during either the single- or multiple-dose testing. Both CR and IR formulations were well tolerated in all subjects, and no serious AEs or adverse drug reactions were found. No subjects reported any AEs during part I of the study. During part II, 6 subjects (3 from each formulation group) reported headache, 1 reported lumbago before the dose, and 1 subject had a hordeolum while receiving the CR formulation.The C(max) of the simvastatin CR formulation was found to be significantly smaller while the AUC of the active moiety did not differ significantly from that of the IR formulation in these healthy Korean subjects. The simvastatin CR and IR formulations were well tolerated, with no serious AEs observed. To evaluate the characteristics of the CR formulation, its clinical efficacy must be examined in patient populations.

What is already known about this subject • It was found that the genetic polymorphisms of CYP3A5, CYP3A4 and MDR1 could affect the pharmacokinetics of tacrolimus. • This study was conducted to find such a possibility in the Korean population. What this study adds • CYP3A5 polymorphisms are likely to be associated with altered pharmacokinetics of tacrolimus in Koreans. • MDR1 polymorphisms have no important role in the pharmacokinetics of tacrolimus. Aims To determine the frequencies of the genotypes of CYP3A5 and MDR1 and to examine the influence of the polymorphisms of these genes on tacrolimus pharmacokinetics in the Korean population. Methods Twenty-nine healthy Koreans who participated in the previous tacrolimus pharmacokinetic study were genotyped for CYP3A4*1B, CYP3A5*3, MDR1 c.1236CT, MDR1 c.2677GA/T and MDR1 c.3435CT. The relationship between the genotypes so obtained and tacrolimus pharmacokinetics observed in the previous study was examined. Results No subject in this study had the CYP3A4*1B variant. The observed frequencies of CYP3A5*1/*1, *1/*3, and *3/*3 were 0.069 [confidence interval (CI) −0.023, 0.161], 0.483 (CI 0.301, 0.665) and 0.448 (CI 0.267, 0.629), respectively. AUC0–∞ for the CYP3A5*1/*1 or *1/*3 genotype was 131.5 ± 44.8 ng h ml−1 (CI 109.6, 153.5), which was much lower compared with the CYP3A5*3/*3 genotype of 323.8 ± 129.3 ng h ml−1 (CI 253.5, 394.1) (P = 2.063E−07). Similarly, Cmax for the CYP3A5*1/*1 or *1/*3 genotype was 11.8 ± 3.4 ng ml−1 (CI 10.1, 13.5), which was also much lower compared with the CYP3A5*3/*3 genotype of 24.4 ± 12.3 ng ml−1 (CI 17.8, 31.1) (P = 0.0001). However, there was no significant difference in tacrolimus pharmacokinetics among the MDR1 diplotypes of CGC-CGC, CGC-TTT, CGC-TGC, TTT-TGC or TTT-TTT (P = 0.2486). Conclusions This study shows that the CYP3A5*3 genetic polymorphisms may be associated with the individual difference in tacrolimus pharmacokinetics. An individualized dosage regimen design incorporating such genetic information would help increase clinical efficacy of the drug while reducing adverse drug reactions.

3 Biocore Corporation, #60-21, Gasan-dong, Geumcheon-gu, Seoul, Korea Background: Olmesartan medoxomil is an angiotensin II receptor blocker commonly used in hypertension. First objective of this study was to evaluate the bioequivalence of two olmesartan formulations, Olmesartan 20 mg and 40 mg tablet (Yuhan, Pharmaceutical Corp. Seoul, Korea) as test drugs and Olmetec ® 20 mg and 40 mg tablet (Daewoong, Pharmaceutical Corp. Seoul, Korea) as reference drugs. Second objective of this study was to evaluate the dose-proportionality of two formulations. Methods: Two studies (20 mg, 40 mg) were conducted as a randomized, open-label, 2-period, crossover design. Each subject received one 20 mg or 40 mg tablet of the reference or test formulation of olmesartan medoxomil in each study. Blood samples were obtained during the 48-hour period after the dose in each treatment period. Wash-out period was 1 week in each study. Concentrations of olmesartan medoxomil in plasma were analyzed using a liquid chromatography system with tandem mass-spectrometric detection (LC/MS/MS). The primary pharmacokinetic parameters were C max (maximum concentration) and AUCt (area under the concentration-time curve from time 0 to the last sampling time). Results: A total number of 40 healthy male volunteers participated in the study and 37 volunteers completed both treatment periods in 20 mg trial. All 40 participants completed both treatment periods in 40 mg trial. The 90 % CIs for the geometric mean ratios of the pharmacokinetic parameters (test:reference drug) were 0.93 ~ 1.04 for AUC t and 0.97 ~ 1.08 for Cmax in 20 mg trial. The 90 CIs were 0.94 ~ 1.02 for AUCt and 1.00 ~ 1.11 for Cmax in 40 mg trial. All parameters of two studies satisfy the range of bioequivalence criterion. Conclusion: The obtained results indicated that pharmacokinetic exposure to Olmesartan 20 mg and 40 mg tablet was bioequivalent to that of Olmetec ® 20 mg and 40 mg tablet, respectively.