Absolute bioavailability and pharmacokinetics of the angiotensin II receptor antagonist fimasartan in healthy subjects

Solidification of deep eutectic solvent containing fimasartan through wet impregnation and exploration of flow attributes by modified SeDeM-SLA expert system

The solidification of deep eutectic solvent (DES) through wet impregnation techniques on inert solid carriers is an interesting approach that offers better processing attributes and excellent stability. Herein, DES of Fimasartan (FS) was developed to improve its solubility and bioavailability. The selected DES-FS was solidified by wet impregnation method employing Nesulin US2 and Aerosil 200. The SeDeM-SLA (solid-liquid adsorption) system was employed to investigate flow attributes of solidified DES-FS. Further, the selected solidified DES-FS (A) was characterized by Fourier transforms infrared spectroscopy (FTIR), Powder X-ray diffraction (PXRD), Differential scanning calorimetry (DSC), Scanning electron microscopy (SEM). The DES comprising Choline Chloride (ChCl): Glycerol (Gly) (1:3) revealed maximum drug solubility (35.6 ± 2.2 mg/mL) and thus opted for solidification. Solidification through wet impregnation was employed using 1:0.5 ratios (DES-FS to carriers). The Index of Good Flow (IGF) value was calculated from the SeDeM-SLA expert system, which indicates the better flow characteristics of solidified DES-FS, particularly with Neusilin US2 [SDES-FS (A)]. The solid-state evaluation data of SDS-FS (A) suggested a transition of FS to an amorphous form, resulting in an increment in solubility and dissolution. A similar trend was reported in the in vivo pharmacokinetic study, which indicated a 2.9 folds increment in the oral bioavailability of FS. Furthermore, excellent stability, i.e., a shelf life of 28.44 months, reported by SDES-FS (A) in accelerated stability studies, suggests better formulation perspectives. In a nutshell, the present study evokes the potentiality of performing solidification through wet impregnation and successful implementation of the SeDeM-SLA expert model, which could find wide applications in pharmaceutical science.

Multivariate Assessment for Bioequivalence Based on the Correlation of Random Effect

Background and Objective

Bioequivalence tests are fundamental step in assessing the equivalence in bioavailability between a test and reference product. In practice, two separate linear mixed models (LMMs) with random subject effects, which have an area under the concentration-time curve (AUC) and the peak concentration (C_max) as the responses, have become the gold standard for evaluating bioequivalence. Recently, Lee et al developed a multivariate hierarchical generalized linear model (HGLM) for several responses that modeled correlations among multivariate responses via correlated random effects. The objective of this study was to apply this multivariate analysis to the bioequivalence test in practice and to compare the performance of multivariate HGLM and separate LMMs.

Methods

Three pharmacokinetic datasets, fixed-dose combination (naproxen and esomeprazole), tramadol and fimasartan data were analyzed. We compared the 90% confidence interval (CI) for the geometric mean ratio (GMR) of a test product to a reference product using the multivariate HGLM and two conventional separate LMMs.

Results

We found that the 90% CIs for the GMRs of both AUC and C_max from the multivariate HGLM were narrower than those from the separate LMMs: (0.843, 1.152) vs (0.825, 1.177) for C_max of esomeprazole in fixed-dose combination data; (0.805, 0.931) vs (0.797, 0.941) for C_max in tramadol data; (0.801, 1.501) vs (0.762, 1.578) for C_max and (1.163, 1.332) vs (1.009, 1.341) for AUC in fimasartan data, consistent with the random subject effects from two separate LMMs being highly correlated in the three datasets (correlation coefficient r = 0.883; r = 0.966; r = 0.832).

Conclusion

This multivariate HGLM had good performance in the bioequivalence test with multiple endpoints. This method would provide a more reasonable option to reduce the 90% CI by adding correlation parameters and thus an advantage especially in evaluating the bioequivalence of highly variable drugs with broad 90% CIs.

A Pharmacokinetic Drug Interaction Between Fimasartan and Linagliptin in Healthy Volunteers

Objective

Fimasartan, an angiotensin II type 1 receptor blocker, and linagliptin, a dipeptidyl-peptidase-4 inhibitor, are frequently coadministered to treat patients with hypertension and diabetes, respectively. This study sought to evaluate the pharmacokinetic interactions between fimasartan and linagliptin after co-administration in healthy Korean subjects.

Methods

The overall study was divided into two separate parts, with each part designed as an open-label, multiple-dose, two-period, and single-sequence study. In Part A, to investigate the effect of linagliptin on fimasartan, 25 subjects received 120 mg fimasartan alone once daily for seven days during Period I, and 120 mg fimasartan with 20 mg linagliptin for seven days during Period II. In Part B, to examine the effect of fimasartan on linagliptin, 12 subjects received only linagliptin once daily for seven days during Period I, followed by concomitant administration of fimasartan for seven days during Period II, at the same doses used in Part A. Serial blood samples were collected at scheduled intervals for up to 24 h after the last dose to determine the steady-state pharmacokinetics of both drugs.

Results

Thirty-six subjects completed the study. The geometric mean ratio and 90% confidence intervals for maximum plasma concentration at steady state (C_max,ss) and area under the concentration–time curve at steady state (AUC_τ,ss) of fimasartan with or without linagliptin were 1.2633 (0.9175–1.7396) and 1.1740 (1.0499–1.3126), respectively. The corresponding values for C_max,ss and AUC_τ,ss of linagliptin with or without fimasartan were 0.9804 (0.8480–1.1336) and 0.9950 (0.9322–1.0619), respectively. A total of eight adverse events (AEs) were reported and the incidence of AEs did not increase significantly with co-administration of the drugs.

Conclusion

Our results suggest that there are no clinically significant pharmacokinetic interactions between fimasartan and linagliptin when co-administered. Treatments were well tolerated during the study, with no serious adverse effects.

Clinical Trial Registry

http://clinicaltrials.gov, NCT03250052.

Pharmacokinetic comparison between a fixed-dose combination of fimasartan/amlodipine/hydrochlorothiazide 60/10/25 mg and a corresponding loose combination of fimasartan/amlodipine 60/25 mg and hydrochlorothiazide 25 mg in healthy subjects

For the treatment of hypertension, fixed-dose combinations (FDCs) of antihypertensive drugs can provide complementary benefits from improved compliance and cost-effectiveness compared with loose combinations of corresponding drugs. A new FDC of fimasartan/amlodipine/hydrochlorothiazide 60/10/25 mg is undergoing clinical development. A randomized, open-label, single-dose, 3-period, 3-sequence, partially replicated crossover phase 1 study was conducted to compare the pharmacokinetics (PKs) between the FDC of fimasartan/amlodipine/hydrochlorothiazide 60/10/25 mg and a loose combination of a dual-combination FDC (fimasartan/amlodipine 60/10 mg) and hydrochlorothiazide 25 mg. Sixty healthy subjects were randomized, and 55 subjects completed the study. Serial blood samples were collected, and plasma concentrations of fimasartan, amlodipine and hydrochlorothiazide were measured to analyze PK parameters. The PK profiles of the FDC were similar to those of the loose combinations. The geometric mean ratios (GMRs) and 90% confidence intervals (CIs) of the FDC to loose combinations for the maximum plasma concentration (C_max) and area under the curve until the last measurable time point (AUC_last) were within the conventional bioequivalent range of 0.80 to 1.25. The GMRs and 90% CIs of fimasartan, amlodipine and hydrochlorothiazide were 1.0163 (0.8681–1.1898), 0.9595 (0.9256–0.9946), and 1.1294 (1.0791–1.1821) for C_max and 1.0167 (0.9347–1.1059), 0.9575 (0.9317–0.9841), and 1.0561 (1.0170–1.0967) for AUC_last, respectively. Both the FDC and loose combinations were well tolerated. In conclusion, the FDC of fimasartan/amlodipine/hydrochlorothiazide 60/10/25 mg showed similar PK profiles to those of the corresponding loose combination, and both treatments were well tolerated.

Predicting the Human Hepatic Clearance of Acidic and Zwitterionic Drugs

Prospective predictions of human hepatic clearance for anionic/zwitterionic compounds, which are oftentimes subjected to transporter-mediated uptake, are challenging in drug discovery. We evaluated the utility of preclinical species, rats and cynomolgus monkeys [nonhuman primates (NHPs)], to predict the human hepatic clearance using a diverse set of acidic/zwitterionic drugs. Preclinical clearance data were generated following intravenous dosing in rats/NHPs and compared to the human clearance data (n = 18/27). Single-species scaling of NHP clearance with an allometric exponent of 0.50 allowed for good prediction of human clearance (fold error ∼2.1, bias ∼1.0), with ∼86% predictions within 3-fold. In comparison, rats underpredicted the clearance of lipophilic acids, while overprediction was noted for hydrophilic acids. Finally, an in vitro clearance assay based on human hepatocytes, which is routinely used in discovery setting, markedly underpredicted human clearance (bias ∼0.12). Collectively, this study provides insights into the usefulness of the preclinical models in enabling pharmacokinetic optimization for acid/zwitterionic drug candidates.

Simultaneous determination of sacubitrilat and fimasartan in rat plasma by a triple quad liquid chromatography-tandem mass spectrometry method utilizing electrospray ionization in positive mode

An LC-tandem mass spectrometry method was developed and validated for the simultaneous quantitation of fimasartan and sacubitrilat using positive ion mode. The protein precipitation method was employed for the extraction of fimasartan, sacubitrilat and alprazolam (internal standard) from rat heparinized plasma. Baseline separation of the analytes was accomplished using an ACE-5, C₁₈ (4.6 × 50 mm) column and gradient elution of mobile phase A (5 mm ammonium formate and 0.1% formic acid in purified water) and B (acetonitrile:methanol, 80:20; v/v). All peaks of interest were eluted within a 5-min runtime. The quantitation was achieved in the selected reaction monitoring mode. The developed method was validated as per US Food and Drug Administration guidelines and met the pre-defined acceptance criteria. The method showed linearity from 5 to 10,000 ng/mL. The accuracy/precision of intra- and inter-batch assays was 96.64%/2.05% to 109.17%/13.70% and 100.74%/3.76% to 106.39%/9.75% for fimasartan and 100.02%/1.49% to 113.80%/9.38% and 100.75%/2.31% to 108.40%/7.74% for sacubitrilat, respectively, in rat plasma. Fimasartan and sacubitrilat remained stable in rat plasma at different experimental conditions up to 21 days. The developed method was sensitive, selective and applied successfully to monitor plasma concentrations of fimasartan and sacubitrilat in an oral rat pharmacokinetic study.

Comparison of the Pharmacokinetics of Highly Variable Drugs in Healthy Subjects Using a Partial Replicated Crossover Study: A Fixed-Dose Combination of Fimasartan 120 mg and Atorvastatin 40 mg versus Separate Tablets

Purpose

A fixed-dose combination (FDC) of fimasartan and atorvastatin is used to treat hypertension and dyslipidemia. The peak plasma concentration (C_max) of fimasartan and atorvastatin has a large intra-subject variability with a maximum coefficient of variation of 65% and 48%, respectively. Therefore, both drugs are classified as highly variable drugs. The purpose of this study was to compare the pharmacokinetics (PK) between a FDC of fimasartan 120 mg and atorvastatin 40 mg versus separate tablets in healthy male Korean subjects.

Subjects and Methods

A randomized, single-dose, two-treatment, three-sequence, three-period, partial replicated crossover study was conducted with a 7-day washout interval between periods. Blood samples for fimasartan and atorvastatin were collected until 48 hours after administration in each period. PK parameters were calculated using the non-compartmental method. Geometric mean ratios (GMRs) for PK parameters of FDC to loose combination and their 90% confidence intervals (90% CIs) were estimated.

Results

A total of 56 subjects completed the study. GMRs (90% CIs) of the C_max for fimasartan and atorvastatin were 1.08 (0.93–1.24) and 1.02 (0.92–1.13), respectively. The expanded 90% CIs of both drugs using the intra-subject variability was calculated range of 0.70–1.43 and 0.73–1.38, respectively. The corresponding values of area under the concentration–time curve from zero to the last measurable time point were 1.02 (0.97–1.08) and 1.02 (0.98–1.07), respectively.

Conclusion

FDC of fimasartan 120 mg and atorvastatin 40 mg between their loose combination showed similar PK characteristics.

Pharmacokinetic comparison between fixed-dose combination of fimasartan/amlodipine 60/10 mg and the corresponding loose combination through partial replicated crossover study in healthy subjects

Combination therapies of antihypertensive drugs are recommended in cases where hypertension is not controlled by monotherapy. This study aimed to compare the pharmacokinetics (PKs) between fixed-dose combination (FDC) of fimasartan/amlodipine 60/10 mg and the corresponding loose combination. Because of the high intra-subject variability for maximum plasma concentration (Cmax) of fimasartan, a randomized, open-label, 3×3 partial replicated crossover design was adopted. Subjects received a single dose of FDC of fimasartan/amlodipine 60/10 mg or the corresponding loose combination in each period. Blood samples for PK analysis were collected up to 48 hours for fimasartan and 144 hours for amlodipine, respectively. Geometric mean ratios (GMRs) and its 90% confidence intervals (CIs) of the FDC to the loose combination for Cmax and area under the concentration-time curve from time 0 to the last quantifiable time point (AUClast) were calculated. Sixty healthy subjects were randomized, and 57 subjects completed the study. The concentration-time profiles of fimasartan and amlodipine were similar between the FDC and loose combination. The GMRs (90% CIs) of the FDC to the loose combination for Cmax and AUClast were 1.0440 (0.9202-1.1844) and 1.0412 (0.9775-1.1090) for fimasartan, and 1.0430 (1.0156-1.0711) and 1.0339 (1.0055-1.0631) for amlodipine, respectively. The GMRs and its 90% CIs for Cmax and AUClast of fimasartan and amlodipine were included not only in the scaled bioequivalence criteria but also in the conventional bioequivalence criteria. In conclusion, FDC of fimasartan/amlodipine 60/10 mg showed comparable PK profiles with the corresponding loose combination, which suggests their bioequivalence.

Regional Absorption of Fimasartan in the Gastrointestinal Tract by an Improved in situ Absorption Method in Rats

The aim of the present study was to assess the regional absorption of fimasartan by an improved in situ absorption method in comparison with the conventional in situ single-pass perfusion method in rats. After each gastrointestinal segment of interest was identified, fimasartan was injected into the starting point of each segment and the unabsorbed fimasartan was discharged from the end point of the segment. Blood samples were collected from the jugular vein to evaluate the systemic absorption of the drug. The relative fraction absorbed (F_abs,relative) values in the specific gastrointestinal region calculated based on the area under the curve (AUC) values obtained after the injection of fimasartan into the gastrointestinal segment were 8.2% ± 3.2%, 23.0% ± 12.1%, 49.7% ± 11.5%, and 19.1% ± 11.9% for the stomach, duodenum, small intestine, and large intestine, respectively, which were comparable with those determined by the conventional in situ single-pass perfusion. By applying the fraction of the dose available at each gastrointestinal segment following the oral administration, the actual fraction absorbed (F′_abs) values at each gastrointestinal segment were estimated at 10.9% for the stomach, 27.1% for the duodenum, 40.7% for the small intestine, and 5.4% for the large intestine, which added up to the gastrointestinal bioavailability (F_X·F_G) of 84.1%. The present method holds great promise to assess the regional absorption of a drug and aid to design new drug formulations.

Pharmacokinetic interaction between fimasartan and atorvastatin in healthy male volunteers

Introduction

Major cardiovascular risk factors, including hypertension and dyslipidemia, are often comorbidities, frequently leading to concurrent prescription of angiotensin receptor blockers and 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (statins). The study’s objective was to evaluate the effect of coadministration of fimasartan and atorvastatin on their pharmacokinetics (PKs).

Subjects and methods

In a randomized, open-label, three-period, six-sequence, crossover, multiple-dose study, 36 healthy subjects received 120 mg fimasartan, 40 mg atorvastatin, or both (based on their assigned sequence) once daily for 7 days in each period, with a 7-day washout between periods. Blood samples for the PK analysis of fimasartan, atorvastatin, and the 2-hydroxy atorvastatin metabolite were collected up to 48 h after the last dose.

Results

The coadministration of fimasartan and atorvastatin was well tolerated and led to an increase in the peak concentration and area under the concentration–time curve at steady state of fimasartan by 2.18-fold (95% confidence interval [CI], 1.79–2.65) and 1.35-fold (95% CI, 1.26–1.43) and those of atorvastatin increased by 1.82-fold (95% CI, 1.51–2.18) and 1.12-fold (95% CI, 1.04–1.22), respectively.

Conclusion

Coadministration increased the systemic exposures of fimasartan and atorvastatin, but the clinical significance of this finding needs to be evaluated with respect to exposure responses and clinical outcomes.

PK/PD evaluation of fimasartan for the treatment of hypertension Current evidences and future perspectives

INTRODUCTION

Fimasartan is the ninth and latest Angiotensin Receptor Blockers for the treatment of hypertension. Fimasartan is a derivative of losartan in which the imidazole ring has been replaced. It provides a selective type 1 angiotensin II receptor antagonist effect with noncompetitive, in surmountable binding. Fimasartan is rapidly absorbed following oral administration with an oral bioavailability of 18.6 ± 7.2%. Fimasartan is relatively stable in terms of metabolism and more than 90% of circulating fimasartan moieties in the plasma are in the parent form; fecal elimination and biliary excretion are the predominant elimination pathways of fimasartan. Areas covered: We reviewed data from clinical trials that investigated safety and efficacy of fimasartan in hypertension. Expert opinion: Fimasartan proved good efficacy in blood pressure reduction. In large clinical studies,fimasartan showed an excellent safety profile and when combined with hydrochlorothiazide oram lodipine, it showed a better effect on controlling blood pressure than monotherapy. Fimasartan 60-120 mg once daily has also shown an antihypertensive effect over 24-h. Moreover, preclinical studies demonstrated organ-protecting effects of fimasartan. These results make fimasartan an attractive candidate for the treatment of hypertension. However, it remains to test the benefit of using fimasartan on clinical outcomes.

Renal Drug Transporters and Drug Interactions

Transporters in proximal renal tubules contribute to the disposition of numerous drugs. Furthermore, the molecular mechanisms of tubular secretion have been progressively elucidated during the past decades. Organic anions tend to be secreted by the transport proteins OAT1, OAT3 and OATP4C1 on the basolateral side of tubular cells, and multidrug resistance protein (MRP) 2, MRP4, OATP1A2 and breast cancer resistance protein (BCRP) on the apical side. Organic cations are secreted by organic cation transporter (OCT) 2 on the basolateral side, and multidrug and toxic compound extrusion (MATE) proteins MATE1, MATE2/2-K, P-glycoprotein, organic cation and carnitine transporter (OCTN) 1 and OCTN2 on the apical side. Significant drug-drug interactions (DDIs) may affect any of these transporters, altering the clearance and, consequently, the efficacy and/or toxicity of substrate drugs. Interactions at the level of basolateral transporters typically decrease the clearance of the victim drug, causing higher systemic exposure. Interactions at the apical level can also lower drug clearance, but may be associated with higher renal toxicity, due to intracellular accumulation. Whereas the importance of glomerular filtration in drug disposition is largely appreciated among clinicians, DDIs involving renal transporters are less well recognized. This review summarizes current knowledge on the roles, quantitative importance and clinical relevance of these transporters in drug therapy. It proposes an approach based on substrate-inhibitor associations for predicting potential tubular-based DDIs and preventing their adverse consequences. We provide a comprehensive list of known drug interactions with renally-expressed transporters. While many of these interactions have limited clinical consequences, some involving high-risk drugs (e.g. methotrexate) definitely deserve the attention of prescribers.

Management of Hypertension Using Olmesartan Alone or in Combination

Hypertension is one of the most significant and consistent risk factors for many cardiovascular diseases. The global prevalence of hypertension has dramatically increased over recent years. Life-style and genetic factors are generally considered to be primarily responsible for the incidence of hypertension. Concerning the high morbidity rate, setting up an updated standard for hypertensive patients becomes indispensable. According to the widely accepted standard treatments for hypertension, these four basic principles should be taken into account: low dosage; medication should provide long term-control; combination therapies are becoming common; personalized treatments are a newer approach. In most patients with hypertension, adequate control of BP can be achieved with combined therapy. Therefore, antihypertensive agents with complementary mechanisms are now recommended. In this review, we focus on the pharmacology, antihypertensive efficacy, and adverse events (AEs) of olmesartan medoxomil, either alone or in combination with other antihypertensive medications. In conclusion, olmesartan medoxomil, is an angiotensin II receptor blocker with an excellent efficacy in the reduction and stabilization of blood pressure. When combined with calcium channel blockers (CCBs) and diuretics, olmesartan medoxomil has a better effect on controlling BP and reducing AEs in patients.

Decreased potency of fimasartan in liver cirrhosis was quantified using mixed-effects analysis

Fimasartan is a nonpeptide angiotensin II receptor blocker. In a previous study that compared the pharmacokinetics (PK) of fimasartan between patients with hepatic impairment (cirrhosis) and healthy subjects, the exposure to fimasartan was found to be higher in patients, but the decrease of blood pressure (BP) was not clinically significant in those with moderate hepatic impairment. The aims of this study were to develop a population PK-pharmacodynamic (PD) model of fimasartan and to evaluate the effect of hepatic function on BP reduction by fimasartan using previously published data. A 2-compartment linear model with mixed zero-order absorption followed by first-order absorption with a lag time adequately described fimasartan PK, and the effect of fimasartan on BP changes was well explained by the inhibitory sigmoid function in the turnover PK-PD model overlaid with a model of circadian rhythm (NONMEM version 7.2). According to our PD model, the lower BP responses in hepatic impairment were the result of the increased fimasartan EC₅₀ in patients, rather than from a saturation of effect. This is congruent with the reported pathophysiological change of increased plasma ACE and renin activity in hepatic cirrhosis.

Fimasartan: A New Angiotensin Receptor Blocker

Fimasartan is the ninth, and most recent, angiotensin II receptor antagonist approved as an antihypertensive agent. Fimasartan, a pyrimidin-4(3H)-one derivative of losartan with the imidazole ring replaced, which enables higher potency and longer duration than losartan. Fecal elimination and biliary excretion are the predominant elimination pathways of fimasartan and the urinary excretion was found to be less than 3 % 24 h after administration. Fimasartan is primarily catabolized by cytochrome P450 isoform 3A and no significant drug interaction was observed when used in combination with hydrochlorothiazide, amlodipine, warfarin, or digoxin. Fimasartan at a dosage range of 60-120 mg once daily showed an antihypertensive effect over 24 h. In a large, population-based observational study, fimasartan showed an excellent safety profile. Anti-inflammatory and organ-protecting effects of fimasartan have been shown in various preclinical studies, including aortic balloon injury, myocardial infarct ischemia/reperfusion, doxorubicin cardiotoxicity, and ischemic stroke models.