Pharmacokinetics of single‐dose rosiglitazone in chronic ambulatory peritoneal dialysis patients

Background: End‐stage renal disease (ESRD) is associated with marked alterations in the pharmacokinetics of many drugs, not only from reduction in renal clearance but also from changes in metabolic activity, bioavailability, volume of distribution and plasma protein binding. Objective: To study the pharmacokinetics of a single 8‐mg oral dose of rosiglitazone in patients with ESRD and requiring long‐term chronic ambulatory peritoneal dialysis (CAPD). Method: The medication was administered just before the first exchange of peritoneal dialysis fluid on the day that blood and peritoneal dialysate collection was performed. Results: In our CAPD patients the mean (±SD) T_max and T_1/2 of rosiglitazone were 1·20 ± 0·26 and 21·38 ± 21·96 h respectively. These values were different to those reported for healthy volunteers reported in previous studies. The mean area under the concentration–time curve (AUC_(0–∞)) and an average maximum observed plasma concentration (C_max) of rosiglitazone in our CAPD patients were 4203·56 ± 2916·97 ng h/mL and 409·67 ± 148·89 ng/mL respectively. These appear no different from those reported in healthy volunteers . Conclusion: The apparently significant difference in T_1/2 of rosiglitazone in CAPD patients compared with healthy volunteers suggest that dose adjustment may be necessary in order to avoid toxicity.     

Pharmacokinetics and safety of bromotetrandrine (BrTet, W198) after single-dose intravenous administration in healthy Chinese volunteers

Objective: To investigate the safety and pharmacokinetics of bromotetrandrine (BrTet, W198), a novel inhibitor of P‐glycoprotein (P‐gp), after single‐dose i.v. infusion in healthy Chinese volunteers. Methods: We conducted a randomized, dose‐escalating, phase I clinical study for that purpose. Thirty healthy subjects received BrTet at the doses of 10, 20 or 30 mg/m² by i.v. infusion. Plasma and urine concentrations of bromotetrandrine were determined by using a liquid chromatography–tandem mass spectrometric (LC/MS/MS) method. AUC was calculated by the trapezoidal rule extrapolation method. C_max, T_max, t_1/2α, t_1/2β, Cl and V_d were compiled from the plasma concentration–time data. Results: Bromotetrandrine was generally well tolerated at all doses. No serious or severe adverse events were found in the study. The pharmacokinetic parameters of BrTet after single i.v. infusion doses of BrTet 10, 20 and 30 mg/m² were as follows: T_max were 1·5 h in three groups, C_max were 24·79, 39·59 and 64·31 μg/L, t_1/2α were 0·37, 0·29 and 0·30 h, t_1/2β were 62·88, 56·45 and 52·20 h. AUC_0–194h were 345·83, 688·15 and 1096·28 μg h/L, Cl were 23·68, 25·69 and 25·66 L h/m², V_d were 157·73,156·96 and 140·73 L/m². In urine, the total eliminate rate of originate compound was 0·61 ± 0·19%. Conclusions: This study suggested that bromotetrandrine was well tolerated in healthy volunteers within the dose range evaluated. The pharmacokinetics parameters of bromotetrandrine indicated that the compound was rapidly distributed and accumulated in the tissues, and slowly cleared from plasma, which supported the use of BrTet for a once or twice dosing per chemotherapy cycle.     

Smoking behaviour modulates pharmacokinetics of orally administered clopidogrel

Background and objectives: Clopidogrel is an important antiplatelet drug that is effective in preventing thrombotic events, especially for patients undergoing percutaneous coronary intervention. The therapeutic usefulness of clopidogrel has been limited by documented inter‐individual heterogeneity in platelet inhibition, which may be attributable to known clopidogrel pharmacokinetic variability. The objective of this study was to assess the influence of smoking cigarettes and abnormal body weight on the pharmacokinetics of clopidogrel. Methods: Seventy‐six healthy adult male volunteers were selected randomly. Each subject received a single 75 mg oral dose of clopidogrel after overnight fast. Clopidogrel carboxylate plasma levels were measured and non‐compartmental analysis was used to determine peak plasma concentration (C_max), time to peak plasma concentration (T_max), elimination half‐life (t_1/2e), and area under the curve (AUC_0→∞). Results: One‐third of volunteers were smokers (n = 27) and one‐half had abnormal body weight (n = 39). Smokers had lower AUC_0→∞ (smokers: 6·24 ± 2·32 μg/h/mL vs. non‐smokers: 8·93 ± 3·80 μg/h/mL, P < 0·001) and shorter half‐life (smokers: 5·46 ± 2·99 vs. non‐smokers: 8·43 ± 4·26, P = 0·001). Smoking behaviour had no influence on C_max (P = 0·3) and T_max (P = 0·7). There was no statistically significant difference in C_max, AUC_0→∞, T_max and t_1/2e between volunteers with abnormal body weight and normal body weight. However the difference in body weight of the two groups was relatively narrow (mean ± SE; 26·93 ± 0·16 vs. 23·11 ± 0·27). In general, the pharmacokinetic parameters were characterized by considerable inter‐individual differences (C_max = 3·09 ± 0·99 μg/mL, CV = 32%), (T_max =0·76 ± 0·24 h, CV = 31·6%), (AUC_0→∞ = 7·98 ± 3·58 μg/h/mL, CV = 44·8%), and (t_1/2e = 7·38 ± 4·10 h, CV = 55·6%). Conclusion: Smoking is a significant factor affecting the pharmacokinetics of clopidogrel, following administration of a single 75 mg dose in healthy young volunteers. The study supports smoking‐cessation recommendations. Further studies are required to evaluate the influence of smoking and body weight on the pharmacokinetics of the active metabolite of clopidogrel and on the clinical effects of any differences observed.     

Effect of levofloxacin on lithium – a pharmacokinetic study in rabbits

The aim of this study was to evaluate potential drug–drug interaction between lithium and levofloxacin. The study was conducted on New Zealand white rabbits with three groups having two subgroups each (n = 12). The first group compared the pharmacokinetic (Pk) parameters of lithium when lithium was given as a single dose (56 mg/kg) and when lithium was co‐administered with levofloxacin (35 mg/kg). The second group compared the Pk parameters of lithium when lithium was given for 6 days alone and when levofloxacin was given on the sixth day after lithium steady‐state levels were achieved. The third group compared the Pk parameters of lithium when lithium was given alone for 8 days and levofloxacin was given on days 6, 7, and 8 along with lithium. Apart from this, creatinine levels were also measured to detect nephrotoxicity effects because of this co‐administration. It was found that there was increase in lithium levels in all three groups. The increase was significant when a single dose of levofloxacin was administered with steady‐state level of lithium (C_max of lithium: 2.54 ± 0.15 vs 2.79 ± 0.12 mm , P < 0.001 and AUC_0‐α of lithium: 24.36 ± 3.68 vs 31.88 ± 4.83 mmol/mL h, P < 0.001). The increase in lithium levels was also significant when levofloxacin was coprescribed for 3 days after lithium steady‐state levels were achieved (C_max increased from 2.72 ± 0.29 to 3.96 ± 0.29 mm , P < 0.001 and AUC_0‐α increased from 27.1 ± 4.96 to 42.64 ± 4.94 mmol/mL h). Levofloxacin increases lithium levels when they are co‐administered, and this interaction might be clinically significant as they may be coprescribed.     

Effect of cytochrome P450 3A4 inhibitor ketoconazole on risperidone pharmacokinetics in healthy volunteers

What is known and objective: Risperidone is an atypical antipsychotic agent used for the treatment of schizophrenia. It is mainly metabolized by human cytochrome P450 CYP2D6 and partly by CYP3A4 to 9‐hydroxyrisperidone. Ketoconazole is used as a CYP3A4 inhibitor probe for studying drug–drug interactions. We aim to investigate the effect of ketoconazole on the pharmacokinetics of risperidone in healthy male volunteers. Methods: An open‐label, randomized, two‐phase crossover design with a 2‐week washout period was performed in 10 healthy male volunteers. The volunteers received a single oral dose of 2 mg of risperidone alone or in combination with 200 mg of ketoconazole, once daily for 3 days. Serial blood samples were collected at specific periods after ingestion of risperidone for a period of 96 h. Plasma concentrations of risperidone and 9‐hydroxyrisperidone were determined using a validated HPLC–tandem mass spectrometry method. Results and discussion: After pretreatment with ketoconazole, the clearance of risperidone decreased significantly by 34·81 ± 15·10% and the T_1/2 of risperidone increased significantly by 28·03 ± 40·60%. The AUC_0–96 and AUC_0–∞ of risperidone increased significantly by 66·61 ± 43·03% and 66·54 ± 39·76%, respectively. The Vd/f of risperidone increased significantly by 39·79 ± 53·59%. However, the C_max and T_max of risperidone were not significantly changed, indicating that ketoconazole had minimal effect on the absorption of risperidone. The C_max, T_max and T_1/2 of 9‐hydroxyrisperidone did not decrease significantly. However, the Cl/f of 9‐hydroxyrisperidone increased significantly by 135·07 ± 124·68%, and the Vd/f of 9‐hydroxyrisperidone decreased significantly by 29·47 ± 54·64%. These changes led to a corresponding significant decrease in the AUC_0–96 and AUC_0–∞ of 9‐hydroxyrisperidone by 47·76 ± 22·39% and 48·49 ± 20·03%, respectively. Ketoconazole significantly inhibited the metabolism of risperidone through the inhibition of hepatic CYP3A4. Our results suggest that besides CYP2D6, CYP3A4 contributes significantly to the metabolism of risperidone. What is new and Conclusion: The pharmacokinetics of risperidone was affected by the concomitant administration of ketoconazole. If a CYP3A4 inhibitor is used concomitantly with risperidone, it is necessary for the clinicians to monitor their patients for signs of adverse drug reactions.     

Pharmacokinetic comparison of a new glimepiride 1-mg + metformin 500-mg combination tablet formulation and a glimepiride 2-mg + metformin 500-mg combination tablet formulation: A single-dose,randomized, open-label,two-period,two-way crossover study in healthy,fasting Korean male volunteers

Background: Coadministration of glimepiride and metformin has been used to achieve glucose control. Because compliance with a multiple medication regimen can be difficult for some patients, combination tablets of glimepiride + metformin might be a suitable alternative for these patients.Objective: This study was conducted to compare the pharmacokinetics of test and reference formulations of glimepiride + metformin fixed-dose combination tablets under fasting conditions to meet the regulatory requirements for marketing approval of a new drug in Korea.Methods: This was a single-dose, randomized, open-label, 2-period, 2-way crossover study conducted between March 2007 and May 2007. Healthy fasting Korean men were randomized to 1 of 2 dosing sequences: a single oral administration of a fixed-dose glimepiride 1-mg + metformin 500-mg combination tablet (test) followed by single oral administration of a fixed-dose glimepiride 2 mg + metformin 500 mg combination tablet (reference), separated by a 1-week washout period between doses; or a single oral administration of a fixed-dose glimepiride 2-mg + metformin 500-mg combination tablet followed by single oral administration of a fixed-dose glimepiride 1 mg + metformin 500-mg combination tablet, separated by a 1-week washout period between doses. Serial samples of blood were collected up to 24 hours after oral administration, and drug concentrations in plasma were determined by HPLC-MS/MS. Tolerability was assessed based on adverse events and changes in clinical parameters. Serious adverse events included those that resulted in death, a life-threatening condition, congenital anomaly or birth defect, or required hospitalization or prolongation of existing hospitalization.Results: A total of 30 healthy male subjects (mean age, 25.6 years [range, 20–36 years]; weight, 69.5 kg [range, 58.2–90.7 kg]) participated in the study. After administration of the test and reference formulations, glimepiride was rapidly absorbed, reaching C_max with a median T_max of 1.75 and 2.0 hours, respectively, and then declined exponentially with an average t½ of 8.2 and 8.5 hours. The individual C_max and AUC_last of glimepiride were observed to be proportionally increased according to the administered glimepiride dose. The mean (SD) dose-normalized Cmax values of glimepiride 1 and 2 mg were 168.2 (54.9) and 149.9 (47.4) ng/mL/mg, respectively; the mean dose-normalized AUC_last values of glimepiride 1 and 2 mg were 681.5 (190.3) and 635.8 (194.1) ng · h/mL/mg. Individual plots of dose-normalized C_max and AUC_last values identified a similarity between the 2 groups but no significant between-group differences. A total of 25 adverse events (12 after the test dose and 13 after the reference dose) were reported by 13 of the 30 subjects. All adverse events were considered mild. Twenty-one adverse events were considered related to the study drug (8 after the test dose and 13 after the reference dose). Adverse events believed to be related to the test formulation were diarrhea (4 cases), dizziness (1), headache (1), tingling sensation (1), and weakness (1). Adverse events believed to be related to the reference formulation were diarrhea (6 cases), headache (3), cold sweats (1), dyspepsia (1), epigastric discomfort (1), and lethargy (1). There were no clinically significant findings in the laboratory test results or vital sign monitoring during the study. There were no serious adverse events reported.Conclusions: The C_max and AUC_last of glimepiride increased proportionally according to the administered glimepiride dose in this study of healthy, fasting Korean men. The safety profiles of the 2 combination tablets were comparable.     

OATP1B1 388A>G polymorphism and pharmacokinetics of pitavastatin in Chinese healthy volunteers

Purpose: To investigate the contribution of the most frequent single nucleotide polymorphism (SNPs) of the organic anion transporting polypeptide 1B1 (OATP1B1) 388A>G to the pharmacokinetics of pitavastatin in Chinese healthy volunteers. Methods: Eighteen healthy volunteers participated in this study. Group 1 consisted of nine subjects who were of 388AA wild‐type OATP1B1 genotype. Group 2 consisted of seven subjects with the 388GA genotype and two 388GG homozygotes. Two milligram of pitavastatin was administered orally to the volunteers. The plasma concentration of pitavastatin was measured for up to 48 h by liquid chromatography–mass spectrometry (LC–MS). Results: The pharmacokinetic parameters of pitavastatin were significantly different between the two genotyped groups. The concentration (C_max) value was higher in the 388GA + 388GG group than that in the 388AA group (39·22 ± 8·45 vs. 22·90 ± 4·03 ng/mL, P = 0·006). The area under the curve to the last measurable concentration (AUC_0–48) and area under the curve extrapolated to infinity (AUC_0–∞) of pitavastatin were lower in the 388AA group than in the 388GA + 388GG group (100·42 ± 21·19 vs. 182·19 ± 86·46 ng h/mL, P = 0·024; 108·12 ± 24·94 vs. 199·64 ± 98·70ng h/mL, P = 0·026) respectively. The oral clearance (Cl/F) was lower in the 388GA + 388GG group than that in the 388AA group (12·46 ± 4·79 vs. 19·21 ± 3·74/h, P = 0·012). The elimination of half‐life (t_1/2) and peak concentration times (T_max) values showed no difference between these groups. Conclusions: The OATP 388A>G polymorphism causes significant alterations in the pharmacokinetics of pitavastatin in healthy Chinese volunteers and this may well be clinically significant.     

Pharmacokinetic Interaction Among Telmisartan,Amlodipine, and Hydrochlorothiazide After a Single Oral Administration in Healthy Male Subjects

PurposeHypertension is a major risk factor for cardiovascular diseases, necessitating hypertension control. Antihypertensive drugs are more potent when administered in combinations of 2 or 3 different classes of drugs. One such therapy includes a combination of an angiotensin receptor blocker, a calcium channel blocker, and a diuretic. The objective of this study was to evaluate the pharmacokinetic interaction among telmisartan, amlodipine, and hydrochlorothiazide.Methods: A randomized, open-label, 3-period, 6-sequence, 3-treatment, single-dose crossover study was conducted in healthy male subjects. Subjects were randomly assigned to 1 of 6 sequences and one of the following treatments was administered in each period: treatment A, co-administration of one tablet of telmisartan 80 mg and one tablet of amlodipine 10 mg; treatment B, one tablet of hydrochlorothiazide 25 mg alone; and treatment C, co-administration of all 3 investigational products. Serial blood samples were collected up to 144 hours postdose. Plasma drug concentrations were measured by using LC/MS–MS. Pharmacokinetic parameters, including C_max and AUC_0–last, were determined by using noncompartmental analysis. The geometric least squares mean ratios and associated 90% CIs of log-transformed C_max and AUC_0–last for separate administration or co-administration were calculated to evaluate pharmacokinetic interactions.FindingsTwenty-seven subjects completed the study. The geometric least squares mean ratios and 90% CIs of C_max and AUC_0–last were 1.02 (0.85–1.21) and 1.04 (0.97–1.13) for telmisartan; 1.00 (0.95–1.04) and 0.95 (0.91–0.99) for amlodipine; and 0.88 (0.82–0.96) and 0.86 (0.82–0.90) for hydrochlorothiazide, respectively. No serious adverse events were recorded, and all reported adverse events were of mild intensity.ImplicationsThe pharmacokinetic parameters of telmisartan, amlodipine, and hydrochlorothiazide when administered separately or co-administered were compared, and all the parameters met the criteria for pharmacokinetic equivalence. Combination therapy of these 3 drugs had no significant impact on the pharmacokinetic parameters of each drug. (ClinicalTrials.gov Identifier: NCT03889145)     

Evaluation of the Pharmacokinetics, Food Effect, Pharmacodynamics, and Tolerability of DA-1229, a Dipeptidyl Peptidase IV Inhibitor, in Healthy Volunteers: First-in-Human Study

BackgroundInhibitors of dipeptidyl peptidase (DPP) IV are a class of oral hypoglycemic agents that increase glucagon-like peptide-1 (GLP-1) levels by inhibiting its degradation.ObjectiveThis study evaluated the pharmacokinetics, pharmacodynamics, and tolerability of DA-1229, which is a newly developed DPP IV inhibitor. This study was planned as part of a product development project at the request of the Korean regulatory agency.MethodsA 7 parallel arm dose-escalation study was conducted in healthy Korean male volunteers. A single oral dose of DA-1229 or placebo was given to 10 subjects (8 active + 2 placebo) in each dose group of 1.25, 2.5, 5, 10, 20, 40, or 60 mg. To assess the effects of food, the subjects in the 10-mg dose group received a single dose of DA-1229 10 mg after a high-fat meal, crossing over from the administration of DA-1229 under a fasting state, after a 7-day washout period. Serial blood samples were collected up to 120 hours after drug administration for pharmacokinetic analysis and the assessment of DPP IV activity, and blood samples were collected up to 2 hours after each meal until the next morning of drug administration to evaluate active GLP-1, glucose, and insulin levels.ResultsSeventy-two subjects, aged 20 to 39 years and weighing 52.1 to 79.8 kg, participated in this study. Twenty-one adverse events were reported; all were mild, and all subjects recovered spontaneously. DA-1229 reached a peak at 3.0 to 5.5 hours after a single oral dose and the concentrations declined, with a terminal t_½ from 32.5 to 39.8 hours. The %CV of C_max and AUC_0–last ranged from 11.1% to 54.6%. Dose-proportional pharmacokinetics were confirmed within the dose range by using a linear regression analysis, and the 95% CIs of the slope of the log-transformed C_max and AUC_0–last included 1.0. The pharmacokinetics of DA-1229 were unchanged by food. The degree of DPP IV inhibition was dependent on the dose, and groups receiving ≥10 mg exhibited >80% DPP IV inhibition for >24 hours. The %CV of the time of the last quantifiable concentration ranged from 4.6% to 15.2%. C_max of active GLP-1 was achieved at 30 minutes after meal intake. The active GLP-1 levels were enhanced in groups receiving ≥5 mg. There were no changes in the glucose and insulin levels after DA-1229 administration.ConclusionsDA-1229 was well tolerated within the dose range of 1.25 to 60 mg. DA-1229 pharmacokinetics suggested dose proportionality, and dose-dependent DPP IV inhibition was exhibited. ClinicalTrials.gov identifier: NCT00961025.     

Pharmacokinetics,safety, and tolerability of sulcardine sulfate: an open‐label,single‐dose,randomized study in healthy Chinese subjects

Sulcardine sulfate (Sul) is a novel anti‐arrhythmic agent as a potential treatment for atrial fibrillation and ventricular arrhythmias. This study was conducted to investigate the pharmacokinetic profile, safety, and tolerability of Sul in healthy Chinese subjects. In this open‐label, single‐dose, randomized study, 10 healthy subjects were assigned to receive Sul doses of 200, 400, and 800 mg under fasting conditions (Cohorts A, B, and C, respectively) or 400 mg under fed conditions (Cohort D). The study incorporated a crossover design, separated by a seven‐day washout period. Blood samples were collected before treatment and at successive time intervals up to 48 h after treatment. Sul concentrations in plasma samples were determined using a validated LC‐MS/MS method. Tolerability was determined by clinical evaluation and adverse event (AE) monitoring. Pharmacokinetic results demonstrated that C_max and AUC_(0–t) of Sul increased with an increasing dose. The mean t_1/2 values for Cohorts A, B, and C were 16.85, 17.66, and 11.87 h, respectively. No statistically significant differences were observed between men and women for the main pharmacokinetic parameters, with the exception of t_1/2 in Cohorts B and C. No significant differences were observed in the absorption and bioavailability of Sul between the fed and fasted states (P > 0.05). Four subjects reported mild AEs during the study. No serious AEs were reported. Sul was shown to be safe and well tolerated in healthy Chinese subjects. Pharmacokinetics studies demonstrated that Sul has adequate oral absorption and bioavailability properties.     

Pharmacokinetics,safety and tolerability of the novel,selective mineralocorticoid receptor antagonist finerenone – results from first‐in‐man and relative bioavailability studies

The safety, tolerability and pharmacokinetics of the selective nonsteroidal mineralocorticoid receptor antagonist finerenone were evaluated in healthy male volunteers in two randomized, single‐centre studies. Study 1 was a first‐in‐man, single‐blinded, placebo‐controlled, parallel‐group, dose‐escalation study. Fasted participants (n = 45) received single oral doses of finerenone 1–40 mg polyethylene glycol (PEG) solution or placebo. Study 2 was a relative bioavailability study comparing a finerenone 10 mg immediate‐release (IR) tablet with finerenone 10 mg PEG solution in the fasted state, investigating the effect of a high‐fat/high‐calorie meal on the pharmacokinetics of the IR tablet and assessing a further dose escalation to finerenone 80 mg (eight × finerenone 10 mg IR tablets), in an open‐label, fourfold crossover design (n = 15). Finerenone was rapidly absorbed from PEG solution (median time to maximum plasma concentration [t_max]: 0.500–1.00 h), exhibited dose‐linear pharmacokinetics and was rapidly eliminated from plasma (geometric mean terminal half‐life [t_½]: 1.70–2.83 h). Finerenone IR tablets demonstrated similar pharmacokinetics (median t_max: 0.750–2.50 h; geometric mean t_½: 1.89–4.29 h) with, however, enhanced bioavailability versus PEG solution (least‐squares mean tablet/solution ratio of 187% for area under the plasma–concentration curve [AUC] and maximum plasma concentration [C_max]). High‐fat/high‐calorie food affected the rate but not the extent of finerenone absorption. Finerenone was well tolerated and did not influence clinical laboratory parameters, blood pressure, heart rate, urinary electrolytes or neurohormones, including serum aldosterone and angiotensin II. In conclusion, finerenone has favourable pharmacokinetics and tolerability in healthy men, and is suitable for dosing independent of food intake.     

Nonlinear pharmacokinetic properties of mildronate capsules: a randomized,open‐label,single‐ and multiple‐dose study in healthy volunteers

Mildronate has been used as antianginal drug in parts of Europe for many years, but its pharmacokinetic (PK) properties in humans remain unclear. This study was designed to assess and compare the PK properties of mildronate capsules after single escalating oral dose and multiple doses in healthy Chinese volunteers. Volunteers were randomly assigned to receive a single dose of 250, 500, 1000, 1250 or 1500 mg of mildronate capsules. Those who received the 500‐mg dose continued on the multiple‐dose phase and received 500 mg three times a day for 13 days. Plasma drug concentrations were analysed by ultraperformance liquid chromatography coupled with tandem mass spectrometry (UPLC‐MS/MS). Tolerability was assessed throughout the study. A total of 40 Chinese volunteers were enrolled in the study. No period or sequence effect was observed. Area under the concentration and C_max were increased proportionally with the dose levels, whereas t_1/2 and V_d/f were dependent on the dose. Nonlinear PK properties were found at doses of 250–1500 mg. There was an accumulation after multiple‐dose administration. No serious adverse events (AEs) were reported in the PK study. The formulation was well tolerated.     

Pharmacokinetics of losartan and its active carboxylic acid metabolite E-3174 in five ethnic populations of China

What is known and Objective: Interethnic variability in drug pharmacokinetics is well known. Our aim was to investigate whether the pharmacokinetics of losartan and its active carboxylic acid metabolite E‐3174 vary between subjects of five Chinese ethnicities (Han, Mongolian, Korean, Hui and Uigur). Methods: Fifty healthy subjects (five men and five women of each ethnicity) were recruited, and each received 50‐mg dose of losartan in tablet form. Fourteen blood samples were collected for each subject over a 24‐h period after drug administration. The concentrations of losartan and its active carboxylic acid metabolite E‐3174 in plasma were determined by high‐performance liquid chromatography/fluorescence (HPLC/FLU) method, and the pharmacokinetic parameters were calculated by DAS 2.0 software and compared by SPSS 16.0 software. Pharmacokinetic parameters, including area under the curve from 0 h to the last measured point 24 h [AUC_(0–24)], area under the curve from 0 h to infinite time [AUC_(0–∞)], peak plasma concentration (C_max), time to reach C_max (t_max), oral clearance (CL), oral volume of distribution (V_d) and elimination half‐life (t_1/2), were determined following a single oral dose of losartan. Results and Discussion: The t_1/2 values of losartan and its active carboxylic acid metabolite E‐3174 showed significant differences across the five ethnicities. After normalization by weight, no ethnicity‐based difference was noted in the pharmacokinetic parameters of losartan. However, there were significant differences in C_max and V_d of the active carboxylic acid metabolite E‐3174 for Han and Mongolian subjects, compared with the other three ethnic groups. There was a high linear correlation between weight and C_max, AUC_(0–24), AUC_(0–∞), CL and V_d. What is new and Conclusion: Ethnicity was associated with significant differences in the single‐dose pharmacokinetics of losartan’s active carboxylic acid metabolite E‐3174 in healthy subjects of the five main ethnic groups in China.     

Pharmacogenetic determinants for interindividual difference of tacrolimus pharmacokinetics 1 year after renal transplantation

What is known and objective: Tacrolimus, a widely used immunosuppressive agent in organ transplantation, has a narrow therapeutic window. It has been suggested that its interaction with lansoprazole could be dependent on polymorphisms of CYP3A5 and CYP2C19. The objective of this study was to investigate how, 1 year after renal transplantation, CYP3A5 and CYP2C19 polymorphisms, biochemical parameters and coadministration with lansoprazole, influenced tacrolimus pharmacokinetics. Methods: The pharmacokinetics of tacrolimus was studied 1 year after renal transplantation, in 75 recipients who were all receiving continuation treatment with 12‐hourly oral tacrolimus, and 30 mg lansoprazole daily (Group 1; n = 20) or, 10 mg rabeprazole daily or no proton pump inhibitor (Group 2; n = 55). Results: There were no significant differences in the dose‐adjusted area under the plasma concentration–time curve (AUC_0–12) and maximum plasma concentration (C_max) of tacrolimus between CYP2C19 genotype groups, but there were significant differences between CYP3A5 genotypes groups (*1/*1 + *1/*3 vs. *3/*3 = 45·2 ± 20·0 vs. 71·0 ± 34·1 ng·h/mL/mg, P < 0·0001 and 6·3 ± 2·6 vs. 9·3 ± 7·0 ng/mL/mg, P = 0·0017, respectively) and between co‐administration with and without lansoprazole (74·5 ± 34·0 vs. 52·4 ± 27·4 ng·h/mL/mg, P = 0·0054 and 10·9 ± 8·8 vs. 6·7 ± 3·0 ng/mL/mg, P = 0·0024, respectively). In a multiple regression analysis, the dose‐adjusted AUC_0–12 and C_max of tacrolimus were associated with CYP3A5*3/*3 and co‐administration with lansoprazole. What is new and conclusion: CYP2C19 does not seem to contribute to the interaction between tacrolimus and lansoprazole. The long‐term combination of tacrolimus and lansoprazole requires careful monitoring of patients with the CYP3A5*3/*3 genotype.     

A randomized crossover study to assess the pharmacokinetics of a novel amphetamine extended-release orally disintegrating tablet in healthy adults

Objectives: In this pharmacokinetic (PK) study in healthy adults, we sought to: (1) compare the PK properties of a novel amphetamine extended-release orally disintegrating tablet formulation (Adzenys XR-ODT? [AMP XR-ODT]) to a reference extended-release mixed amphetamine salts (MAS ER) formulation and (2) assess the effect of food on AMP XR-ODT.

Methods: Forty-two adults were enrolled in a single-dose, open-label, 3-period, 3-treatment, randomized crossover study and received an 18.8-mg dose of AMP XR-ODT (fasted or fed) or equivalent dose (30 mg) of MAS ER (fasted). Plasma samples were analyzed for d-and l-amphetamine. Maximum plasma concentration (C_max), time to maximum plasma concentration (T_max), elimination half-life (T_1/2), area under the concentration-time curve from time zero to last quantifiable concentration (AUC_last), from time zero to infinity (AUC_inf), relevant partial AUCs, and weight-normalized clearance (CL/F/kg) were assessed. The PK parameters were compared across treatments using an ANOVA. Safety was also assessed.

Results: A total of 39 adults completed this study. The geometric mean ratios (90% confidence interval [CI]) for AMP XR-ODT/MAS ER C_max, AUC_5-last, AUC_last, and AUC_inf were within 80%–125% for both d-and l-amphetamine. The 90% CIs for AUC_0-5 were slightly below the 80%–125% range. When AMP XR-ODT was administered with food, there was a slight decrease in the d-and l-amphetamine C_max and approximately a 2-hour delay in T_max. The most common adverse events reported (>5% of participants) were dry mouth, palpitations, nausea, dizziness, headache, anxiety, and nasal congestion.

Conclusions: AMP XR-ODT displayed a PK profile similar to MAS ER, and no clinically relevant food effect was observed.     

Pharmacokinetics and metabolism of Chf197, a ligustrazine derivative,in rats

Ligustrazine is the most abundant and bioactive ingredient in Rhizoma Chuanxiong, a Chinese medicinal herb commonly used for the treatment of cardiovascular diseases. Chf197 is one of the structurally modified ligustrazine derivatives in a purpose of overcoming the rapid metabolism and short half‐life of original. The plasma and urine pharmacokinetics of Chf197 in rats were studied after intravenous or intraperitoneal injection of Chf197 with the validated RP‐HPLC method. The pharmacokinetic parameters of Chf197 injected intravenously 20 mg/kg were as follows: C_max, 1.44 ± 0.4 mg/L; T_max, 0.08 h; t_1/2, 3.03 ± 1.67 h; AUC, 3.85 ± 3.88 h/L; V_d, 31.66 ± 11.79L/kg; and CL, 9.29 ± 4.92 l/h/kg. Dose‐dependent pharmacokinetics was observed, and a significantly higher dose‐normalized AUC after intravenous administration was obtained than that after intraperitoneal administration. A possible metabolite was detected at about 3.1 min, and full‐scan mass spectrum was adopted to predict its possible structure.     

Pharmacodynamic comparison of two formulations of Acarbose 100-mg tablets

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

Comparison of the Pharmacokinetics,Safety, and Tolerability of Vitamin D3 in DP-R206 (150-mg Ibandronate/24,000-IU Vitamin D3 Tablet) and as Monotherapy (24,000 IU) in Healthy Male Korean Adults

Background

Combined treatment with a bisphosphonate and vitamin D has been proposed for postmenopausal osteoporosis. A new, fixed-dose combination tablet of ibandronate plus vitamin D₃ has been developed for monthly administration to treat postmenopausal osteoporosis.

Objectives

The main objective of the present study was to compare the pharmacokinetics of vitamin D₃ administered in 2 forms: a newly developed ibandronate 150-mg/vitamin D₃ 24,000-IU tablet (DP-R206, test drug) and a stand-alone vitamin D₃ 24,000-IU tablet (reference drug). A secondary objective was to evaluate the safety and tolerability of DP-R206 in healthy adult male Korean volunteers.

Methods

This study was a single-dose, open-label, randomized-sequence, 2-treatment, 2-way crossover trial. Blood samples were collected from 24 hours’ predose to 120 hours’ postdose. The plasma concentrations of vitamin D₃ were analyzed by using a validated HPLC-MS/MS method. Pharmacokinetic parameters were calculated, and the 90% CIs of the ratios of the geometric means of the parameters were determined from the logarithmically transformed data by using ANOVA.

Results

Thirty-sex healthy adult male Korean volunteers with a mean (SD) age of 25.8 (2.7) years, a mean height of 174.0 (5.9) cm, and a mean weight of 69.1 (6.2) kg were enrolled; 29 participants completed the study. The 90% CIs of the ratios of the geometric means (test drug/reference drug) of the baseline-corrected C_max, AUC_0–last, and AUC_0–∞ values were 0.93 to 1.24, 0.89 to 1.19, and 0.87 to 1.18, respectively. The 90% CIs of the ratios of the geometric means (test drug/reference drug) of the baseline-uncorrected C_max, AUC_0–last, and AUC_0–∞ values were 0.93 to 1.24, 0.88 to 1.19, and 0.87 to 1.18, respectively. Eighty-four adverse events (AEs) were reported in 24 of 32 subjects receiving DP-R206, and 14 AEs were reported in 8 of 29 subjects receiving the vitamin D₃ 24,000-IU tablet. All of the subjects who experienced AEs recovered without sequelae, and no serious AEs were observed.

Conclusions

The vitamin D₃ pharmacokinetics were similar for DP-R206 and the 24,000-IU vitamin D₃ tablet. DP-R206 was well tolerated. ClinicalTrials.gov identifier: NCT01577849.     

Determination of glycyrrhetic acid in human plasma by HPLC-MS method and investigation of its pharmacokinetics

Objective: To develop a high performance liquid chromatography mass spectrometry (HPLC‐MS) method for the determination of the glycyrrhetic acid (GA) in human plasma and for the investigation of its pharmacokinetics after the oral administration of 150 mg diammonium glycyrrhizinate test and reference capsule formulations. Methods: The GA in plasma was extracted with ethyl acetate, separated on a C₁₈ column with a mobile phase of methanol (5 mmol/L ammonium acetate)–water (85 : 15, V/V) and analysed using a MS detector. Ursolic acid (UA) was used as internal standard. The target ions were m/z 469·5 for GA and m/z 455·6 for UA, the fragment voltages were 200 V and 100 V for GA and UA respectively. Results: The calibration curve was linear over the range of 0·5–200 ng/mL (r = 0·9974). The limit of quantification for GA in plasma was 0·5 ng/mL, the recovery was 76·0–80·0%, and the inter‐ and intra‐day relative standard deviations (RSD) were <12%. The pharmacokinetic parameters of GA after a single dose of 150 mg diammonium glycyrrhizinate test and reference were as follows: the half life (t_1/2) 9·65 ± 3·54 h and 9·46 ± 2·85 h, the time to peak concentration (T_max) 10·95 ± 1·32 h and 11·00 ± 1·30 h, the peak concentration (C_max) 95·57 ± 43·06 ng/mL and 103·89 ± 49·24 ng/mL; the area under time‐concentration curve (AUC_0–48 and AUC_0–∞) 1281·84 ± 527·11 ng·h/mL and 1367·74 ± 563·27 ng·h/mL, 1314·32 ± 566·40 ng·h/mL and 1396·97 ± 630·06 ng·h/mL. The relative bioavailability of diammonium glycyrrhizinate capsule was 98·88 ± 12·98%. Conclusion: The assay was sensitive, accurate and convenient, and can be used for the determination of GA in human plasma. Comparison of the bioavailability and pharmacokinetic profile of GA indicated that the test and reference capsules were bioequivalent.     

Results of a single-center,single-dose,randomized-sequence,open-label,two-way crossover bioequivalence study of two formulations of valsartan 160-mg tablets in healthy volunteers under fasting conditions

Background: Valsartan is a nonpeptide, orally active angiotensin II type 1 receptor blocker used to treat hypertension alone or in combination with other antihypertensive agents.Objective: The aim of this study was to compare the relative bioavailability of a new valsartan 160-mg formulation (ie, test drug) and that of a reference formulation so that bioequivalence could be assessed, as required by European regulatory authorities for the marketing of a generic product.Methods: This was a single-center, single-dose, randomized-sequence, open-label, 2-way crossover study with a minimum washout period of 7 days; drug was administered to healthy volunteers under fasting conditions. Blood samples were collected up to 36 hours postadministration, and valsartan levels were gauged from plasma by reverse liquid chromatography and tandem mass spectrometry detection (ie, the LC-MS/MS method). Pharmacokinetic parameters were calculated from valsartan concentration data using noncompartmental analysis. AUC_last, AUC_∞, and C_max were analyzed. The 90% CIs of the ratios of the testversus-reference pharmacokinetic parameters (AUC_last, AUC_∞, and C_max) were obtained by ANOVA on Intransformed data. The 90% CIs were required to be within 80.00% to 125.00% of the 90% CI to meet the criteria for bioequivalence. Tolerability was monitored using physical examination (including vital-sign measurements) and ECG performed at screening, as well as laboratory analysis, including biochemistry tests, hematology tests, and urinalysis, which were performed at screening and during the study period.Results: Thirty-eight white (90.5%), 2 black (4.8%), and 2 Hispanic subjects (4.8%) enrolled in the study; the sample included a total of 27 men and 15 women. The mean (SD) age was 37 (11) years and mean weight was 65.4 (7.6) kg. The 90% CI values for pharmacokinetic measurements were as follows: AUC_last, 94.45% to 118.59%; AUC_∞, 93.58% to 116.51%; and C_max, 93.61% to 122.02%. Thus, they were all within the predefined 80.00% to 125.00% range. Thirty-six postadministration adverse events were reported; the most common was blood pressure decrease. A decrease of blood pressure was experienced by 6 subjects (14.6%) after the administration of the test formulation, and by 5 subjects (12.5%) after the administration of the reference formulation. Thirtythree of these adverse events were graded as mild and 3 as moderate; 11 were judged as probably related, 12 as possibly related, 3 as remotely related, and 10 as unrelated to the study medication.Conclusions: In this open-label study of healthy volunteers, the test and reference formulations of valsartan 160 mg met the European regulatory definition of bioequivalence, based on the rate and extent of absorption of a single dose under fasting conditions. Both formulations were well tolerated.