Modeling of the pharmacokinetic/pharmacodynamic interaction between irbesartan and hydrochlorothiazide in normotensive subjects

Analytical quality by design approach to develop an eco-friendly RP-HPLC method for estimation of irbesartan in chitosan polymeric nanoparticles: forced degradation studies and assessment of in vitro release mathematical modelling

Irbesartan is an angiotensin converting enzyme blocker, primarily utilized for the management of hypertension and the mitigation of diabetic nephropathy progression. The present study introduces rapid, robust and environmentally sustainable reverse phase high performance liquid chromatography (RP-HPLC) validated under the analytical quality by design (AQbD) framework according to ICH guidelines. Utilizing a central composite design, the method's systemic optimization was achieved, ensuring reproducibility and accuracy. Chromatographic separation was accomplished utilizing an ethanol and sodium acetate buffer (60 : 40 v/v) isocratic mobile phase system on a zorbax sb C18 column, with a flow rate of at 0.6 mL min-1. Studies on forced degradation outlined stability of irbesartan and its degradation processes, enhancing our understanding of its chemical robustness under varied conditions. Complementing the green chemistry paradigm, the method's environmental impact was critically assessed, affirming its alignment with sustainability objectives. The validated method proved pivotal in determining the percent entrapment and loading efficiency of the formulated nanoparticles and holds potential for application in biological matrices. Furthermore, the encapsulation of IRB within chitosan nanoparticles was explored to assess release kinetics and enhance bioavailability. This study not only advances the analytical sciences by merging eco-friendly practices with method development but also broadens the applicative landscape of HPLC methodologies in drug delivery research.

Overview of the pharmacokinetics and pharmacodynamics of URAT1 inhibitors for the treatment of hyperuricemia and gout

INTRODUCTION

Hyperuricemia is a common metabolic disease, which is a risk factor for gouty arthritis and ureteral stones and may also lead to cardiovascular and chronic kidney disease (CDK). Therefore, hyperuricemia should be treated early. Xanthine oxidase inhibitors (XOIs) and uricosuric agents (UAs), which target uric acid, are two types of medications that are used to treat gout and hyperuricemia. XOIs stop the body from producing excessive uric acid, while UAs eliminate it rapidly via the kidneys. Urate transporter 1 (URAT1) belongs to the organic anion transporter family (OAT) and is specifically localized to the apical membrane of the epithelial cells of proximal tubules. Unlike other organic anion transporter family members, URAT1 identifies and transports organic anions that are primarily responsible for urate transport.

AREAS COVERED

This article reviews the pharmacokinetics and pharmacodynamics of the existing URAT1 inhibitors to serve as a reference for subsequent drug studies.

EXPERT OPINION

The URAT1 inhibitors that are currently used as clinical drugs mainly include dotinurad, benzbromarone, and probenecid. Results indicate that RDEA3170 may be the most promising inhibitor, in addition to SHR4640, URC-102, and MBX-102, which are in the early stages of development.

Oral Formulation Based on Irbesartan Nanocrystals Improve Drug Solubility, Absorbability, and Efficacy

We previously reported that the bioavailability (BA) of irbesartan (IRB), a BSC class II drug, was improved by preparing nanocrystalline suspensions. However, nanocrystalline suspensions have chemical and physical instabilities and must be converted into tablets through drying approaches in order to overcome such instabilities. In this study, we attempted to design a molded tablet based on nanocrystalline IRB suspensions (IRB-NP tablet) and investigated the effects of this IRB-NP tablet on blood pressure (BP) in a stroke-prone spontaneously hypertensive (SHR-SP) rat. The IRB-NP tablet (with a hardness of 42.6 N) was developed by combining various additives (methylcellulose, 2-hydroxypropyl-β-cyclodextrin HPβCD, D-mannitol, polyvinylpyrrolidone, and gum arabic) followed by bead-milling and freeze-drying treatments. The mean particle size in the redispersions of the IRB-NP tablet was approximately 118 nm. The solubility and intestinal absorption of IRB in the IRB-NP tablet were significantly enhanced in comparison with the microcrystalline IRB tablet (IRB-MP tablet), and both solubility and clathrin-dependent endocytosis helped improve the low BA of the IRB. In addition, the BP-reducing effect of the IRB-NP tablet was significantly higher than that of the IRB-MP tablet. These results provide useful information for the preservation of nanocrystalline suspensions of BCS class II drugs, such as IRB.

Influence of release rate, dose and co-administration on pharmacokinetics, pharmacodynamics and PK-PD relationship of tanshinone IIA and tanshinol

The present study aims to investigate the influence of release rate, dose and co-administration on pharmacokinetics (PK) and pharmacodynamics (PD) of tanshinone IIA (TA) and tanshinol (TS), and reveal the changes in their PK-PD relationships. Sustained and immediate release pellets of TS and TA were prepared respectively, and oral administrated to angina model rabbits according to the experimental design. The administration dose of TS was 50, 35 or 20 mg/kg and that of TA was 30 mg/kg. Then, plasma concentrations of TS and TA were measured to evaluate the pharmacokinetics. Pharmacodynamic biomarkers including cardiac troponin (cTn-I), creatine kinase (CK-MB), superoxide dismutase (SOD) and nitric oxide (NO) were measured to evaluated the effects of cardioprotection, amelioration of oxidative stress and vasorelaxation of TS and TA. Parameters such as maximum plasma concentration (C_max), maximum effect (E_max), time to C_max or E_max (TC_max or TE_max), areas under the plasma concentration or effect curves (AUC_0-∞ or AUEC) and pharmacodynamic efficiency (EFF) were calculated based on non-compartmental analysis. Beside, PK-PD relationship/hysteresis was evaluated. The TE_max was less sensitive than TC_max to changes in release rate. The E_max, AUEC and EFF showed increasing trend as the decrease of release rate even that the AUC_0-∞ showed no significant difference. In addition, slow drug release decreased the magnitude of hysteresis of TS and TA. The sensitivities of E_max and AUEC of four biomarkers to changes in dose were varied and relatively lower than those of C_max and AUC_0-∞. The EFF decreased and the magnitude of hysteresis increased for high dose. The C_max and AUC_0-∞ of TS and TA showed little difference after co-administration. The E_max and AUEC of four biomarkers increased for immediate release pellets (P < 0.05 or P < 0.01) and generally decreased for sustained release pellets (P < 0.05 or P < 0.01) after co-administration. In addition, the magnitudes of hysteresis of four biomarkers decreased for immediate release pellets and generally increased for sustained release pellets after co-administration. In summary, the dissociated and unstable PK-PD relationship should be considered during optimization of dosage forms and regimens to make sure the rationality, safety and efficacy. These findings could also provide some valuable information for the development and clinical therapy of other drugs.

Validation of population pharmacokinetic models: a comparison of internal and external validation approaches for hydrochlorothiazide

1. Model evaluation is an important issue in population analyses. Our aim was to perform and illustrate metrics and techniques for internal and external evaluation with an application to population pharmacokinetics of hydrochlorothiazide (HCTZ).2. A nonlinear mixed effects model was used to study the pharmacokinetics of HCTZ. In addition, different types of internal assessment tools and external metrics were used for model evaluation. External evaluation was performed using an alternative dataset that included data from an independent group of subjects. For comparison, a previously published population pharmacokinetic model for HCTZ was applied to the same data.3. A two-compartment model with first-order oral absorption using a constant time delay between administration and absorption and first-order elimination best described HCTZ pharmacokinetics. Age had a statistically significant effect on HCTZ clearance. The final model performed adequately in the internal and external assessment tests. The final model showed better predictive performance than the other previously published HCTZ model.4. Finally, a robust population pharmacokinetic model for HCTZ in adults was constructed and validated internally and externally. Incorporating analytical assessment of nonlinear pharmacokinetics into the modelling may be a promising approach to improve the predictive power of the model.

Pharmacokinetic study on the interaction between succinic acid and irbesartan in rats and its potential mechanism

CONTEXT

Succinic acid and irbesartan are commonly used drugs in cardiovascular disease treatment. The interaction might occur during their co-administration, which was still unclear.

OBJECTIVE

To reveal the effect of succinic acid on the metabolism of irbesartan and its potential mechanism.

MATERIALS AND METHODS

The Sprague-Dawley rats (n = 6) were treated with a single dose of 30 mg/kg irbesartan (control) or the co-administration with the pre-treatment of 200 mg/kg succinic acid for 7 d. The effect of succinic acid on the metabolic stability and the activity of CYP2C9 was evaluated in rat liver microsomes.

RESULTS

Succinic acid increased the AUC (5328.71 ± 959.31 μg/L × h vs. 3340.23 ± 737.75 μg/L × h) and prolonged the half-life of irbesartan (from 12.79 ± 0.73 h to 20.59 ± 6.35 h). The T_max (2.83 ± 0.75 h vs. 3.83 ± 1.10 h) and clearance rate (3.46 ± 1.13 L/h/kg vs. 6.91 ± 1.65 L/h/kg) of irbesartan was reduced by succinic acid. Consistently, succinic acid improved the metabolic stability (half-life from 23.32 ± 3.46 to 27.35 ± 2.15 min, intrinsic clearance rate from 59.43 ± 6.12 to 50.68 ± 5.64 μL/min/mg protein). Succinic acid was also found to inhibit the activity of CYP2C9 with the IC₅₀ value of 13.87 μM.

DISCUSSION AND CONCLUSIONS

Succinic acid increased the system exposure of irbesartan via inhibiting CYP2C9. The experiment design of this study also provides a reference for the further validation of this interaction in humans.

Nanocrystalline Suspensions of Irbesartan Enhance Oral Bioavailability by Improving Drug Solubility and Leading Endocytosis Uptake into the Intestine

We attempted to design irbesartan nanocrystalline (IRB-NC) suspensions by the bead mill method, and we evaluated the bioavailability (BA) in the oral administration of the nanocrystalline drug. The mean particle size of the IRB-NC suspensions was approximately 140 nm, and the crystalline structure of irbesartan in these suspensions was different using the bead mill method. The aggregation and degradation of irbesartan were not observed for one month, and the solubility increased. Moreover, the inclusion complex formation of IRB-NC suspensions with 2-hydroxypropyl-β-cyclodextrin was higher than that in traditional IRB powder (IRB-P). In addition, the intestinal absorption of IRB-NC suspensions was higher than that of IRB-P suspensions, and the reducing effect on blood pressure in spontaneously hypertensive SHR-SP rats orally administered IRB-NC suspensions was significantly higher than in those administered IRB-P suspensions. On the other hand, the intestinal penetration of IRB-NC suspensions was attenuated by the inhibitors of clathrin-dependent endocytosis (CME). In conclusion, we improved the low oral BA of irbesartan by preparing IRB-NC suspensions and showed that both the solubility and CME are related to the enhanced intestinal absorption of IRB-NC suspensions, resulting in an increase in their antihypertensive effect. These findings provide significant information for the development of oral nanomedicines.

Physicochemical Characterization of a Co-Amorphous Atorvastatin-Irbesartan System with a Potential Application in Fixed-Dose Combination Therapy

The aim of this study was to characterize a 1:1 molar ratio of a pharmacologically relevant co-amorphous atorvastatin-irbesartan (ATR-IRB) system obtained by quench cooling of the crystalline ATR/IRB physical mixture for potential use in the fixed-dose combination therapy. The system was characterized by employing standard differential scanning calorimetry (DSC), Fourier transform-infrared spectroscopy (FT-IR), and intrinsic dissolution rate studies. Quantum mechanical calculations were performed to obtain information regarding intermolecular interactions in the studied co-amorphous ATR-IRB system. The co-amorphous formulation showed a significant improvement in the intrinsic dissolution rate (IDR) of IRB over pure crystalline as well as its amorphous counterpart. An unusual behavior was observed for ATR, as the IDR of ATR in the co-amorphous formulation was slightly lower than that of amorphous ATR alone. Short-term physical aging studies of up to 8 h proved that the ATR-IRB co-amorphous system remained in the amorphous form. Furthermore, no physical aging occurred in the co-amorphous system. FT-IR, density functional theory calculations, and analysis of T_g value of co-amorphous system using the Couchman–Karasz equation revealed the presence of molecular interactions between APIs, which may contribute to the increased physical stability.

Delay differential equations for the description of Irbesartan pharmacokinetics: A population approach to model absorption complexities leading to dual peaks

Irbesartan is a poorly soluble BCS class II compound with weak acidic properties. After oral administration, dual peaks are noted in its concentration (C) - time (t) profile, a phenomenon that may be attributed to enterohepatic recirculation, gastric emptying and/or other absorption complexities related to its pH- and buffer capacity-dependent dissolution behavior. A population pharmacokinetic model, encompassing delay differential equations, was found the most appropriate approach to describe dual peaks in irbesartan's C-t profiles. Parameters estimated were: the absorption rate constant in the central compartment (ka = 0.304 h^-1), the constant time delay between the administration and the absorption (T=1.68 h), the apparent volume of distribution of the central (V1/F = 13.8 L) and peripheral (V2/F = 85.8 L) compartment, the apparent clearance from the central compartment (CL/F = 13.5 L/h), and the inter-compartmental clearance (Q/F = 17.7 L/h). Using simulations, it was made evident that changing the time delay results in significant changes of peak plasma concentrations but not of its blood pressure-lowering effect. In conclusion, delay differential equations may be useful to model dual peaks arising from absorption complexities, while changes of the time delay that reflect physiological processes that take place before absorption may have significant implications in proving bioequivalence.

The Cancer Drug Fraction of Metabolism Database

This study aims to create a database for quantifying the fraction of metabolism of cytochrome P450 isozymes for cancer drugs approved by the US Food and Drug Administration. A reproducible data collection protocol was developed to extract essential information, including both substrate-depletion and metabolite-formation data from publicly available in vitro selective cytochrome P450 enzyme inhibition studies. We estimated the fraction of metabolism from the curated data. To demonstrate the utility of this database, we conducted an in vitro drug interaction prediction for the 42 cancer drugs. In the drug-drug interaction prediction, we identified 31 drug pairs with at least one cancer drug in each pair that had predicted area under concentration ratios > 2. We further found clinical drug interaction pieces of evidence in the literature to support 20 of these 31 drug-drug interaction pairs.

Formulation and performance of Irbesartan nanocrystalline suspension and granulated or bead-layered dried powders - Part I

Nanocrystalline suspensions offer a promising approach to improve the dissolution rate of BCS Class II/IV drugs and hence oral bioavailability. Irbesartan (crystalline Form B), a poorly soluble drug substance was chosen as a model compound for the study. The objectives of the study were to formulate Irbesartan nanocrystalline suspension via media milling, study the effects of process and formulation variables on particle size reduction, and evaluate bead layering or spray granulation as drying processes. A Design of Experiment approach was utilized to understand the impact of formulation variables on particle size reduction via media milling. Drug concentration and type of stabilizer were found to be significant in particle size reduction. Optimized Irbesartan nanocrystalline suspension (i.e. at 10% w/w with 1% w/w poloxamer 407) showed superior in vitro dissolution profile compared to unmilled suspension. Optimized Irbesartan nanocrystalline suspension was converted into dried powders either by bead layering (with microcrystalline cellulose) or by spray granulation (either with mannitol or microcrystalline cellulose). DSC and PXRD studies revealed that Irbesartan remained crystalline post drying. Microcrystalline cellulose beads layered with Irbesartan nanocrystals showed about 65% drug dissolution within the first 10 min of dissolution study. Mannitol granules containing Irbesartan nanocrystals were fast dissolving (i.e. >90% drug dissolution within 10 min) compared to microcrystalline cellulose granules (i.e. approx. 46% drug dissolution within 10 min). Irbesartan nanocrystalline suspension had the fastest dissolution rates (i.e. >90% drug dissolution in two minutes) followed by mannitol-based granules containing dried Irbesartan nanocrystals (i.e. >90% drug dissolution in ten minutes).