On Absorption Modeling and Food Effect Prediction of Rivaroxaban, a BCS II Drug Orally Administered as an Immediate-Release Tablet

Bioequivalence and Food Effect Assessment Between 2 Oral Tablet Formulations of Rivaroxaban 20 mg in Healthy Chinese Subjects

To evaluate the bioequivalence and safety of oral rivaroxaban tablets between a test formulation and a reference formulation in healthy Chinese subjects, a randomized, open, 2-formulation, 4-cycle, complete repeat crossover study was conducted under both fasting and fed states. Thirty-six healthy participants were enrolled separately for the fasting and fed groups, and each subject received a single oral dose of 20 mg of the test or reference formulation of rivaroxaban tablets per cycle. Blood samples were collected at specified intervals, and rivaroxaban was analyzed using liquid chromatography-tandem mass spectrometry. Under fasting and fed conditions, the 90% confidence intervals (CIs) for the geometric mean ratios of the maximum concentration (Cmax), the area under the plasma concentration-time curve from time 0 to the last measurable time point (AUC0-t), and the area under the curve extrapolated to infinity from time 0 (AUC0-∞) all fell within the 80%-125% CI, and the upper limit of the 90% CIs for the test-to-reference ratio of the within-subject variability was <2.5. This indicated that the test formulation of rivaroxaban is bioequivalent to the reference formulation. Compared to the fasted state, the Cmax, AUC0-t, and AUC0-∞ of rivaroxaban increased significantly by factors of 2, 1.6, and 1.5, respectively, following oral administration of 20 mg of rivaroxaban in the fed state. This suggests that a high-fat diet significantly enhances the exposure to rivaroxaban. No serious adverse events were reported under fasting or fed conditions.

Formulation Strategy of BCS-II Drugs by Coupling Mechanistic In-Vitro and Nonclinical In-Vivo Data with PBPK: Fundamentals of Absorption-Dissolution to Parameterization of Modelling and Simulation

BCS class II candidates pose challenges in drug development due to their low solubility and permeability. Researchers have explored various techniques; co-amorphous and solid dispersion are major approaches to enhance in-vitro drug solubility and dissolution. However, in-vivo oral bioavailability remains challenging. Physiologically based pharmacokinetic (PBPK) modeling with a detailed understanding of drug absorption, distribution, metabolism, and excretion (ADME) using a mechanistic approach is emerging. This review summarizes the fundamentals of the PBPK, dissolution-absorption models, parameterization of oral absorption for BCS class II drugs, and provides information about newly emerging artificial intelligence/machine learning (AI/ML) linked PBPK approaches with their advantages, disadvantages, challenges and areas of further exploration. Additionally, the fully integrated workflow for formulation design for investigational new drugs (INDs) and virtual bioequivalence for generic molecules falling under BCS-II are discussed.

From In Vivo Predictive Dissolution to Virtual Bioequivalence: A GastroPlus®-Driven Framework for Generic Candesartan Cilexetil Tablets

Background: Candesartan cilexetil, a Biopharmaceutics Classification System (BCS) II prodrug, demonstrates compromised bioavailability attributable to its limited aqueous solubility coupled with P-glycoprotein (P-gp)-mediated efflux and hepatic first-pass metabolism, thereby introducing complexities in generic drug bioequivalence assessments. With the rapid advancement of computational technologies, the integration of biorelevant dissolution methodologies with physiologically based pharmacokinetic (PBPK) modeling is emerging as a transformative paradigm in advancing bioequivalence evaluation strategies for generic drug products. This study presents a GastroPlus®-driven framework integrating in vivo predictive dissolution (IPD) and virtual bioequivalence (VBE) to evaluate the quality consistency of generic candesartan cilexetil tablets. Methods: By developing an oral PBPK model in GastroPlus®, we established an IPD method using a phosphate-buffer-based flow-through cell dissolution apparatus. In vitro dissolution profiles of generic tablets from four manufacturers were measured and incorporated into the model to perform VBE simulations. Results: The results demonstrated that only the product from Company A achieved virtual bioequivalence with the reference product, aligning with real-world quality consistency assessments. Conclusions: The proposed framework exhibited robust predictive capability, bridging in vitro dissolution data to in vivo bioequivalence outcomes, thereby offering a cost-effective and efficient strategy for formulation optimization and preclinical bioequivalence evaluation of generic drugs.

RSM and AI based machine learning for quality by design development of rivaroxaban push-pull osmotic tablets and its PBPK modeling

The study is based on applying Artificial Neural Network (ANN) based machine learning and Response Surface Methodology (RSM) as simultaneous bivariate approaches in developing controlled-release rivaroxaban (RVX) osmotic tablets. The influence of different types of polyethylene oxide, osmotic agents, coating membrane thickness, and orifice diameter on RVX release profiles was investigated. After obtaining the trial formulation data sets from Central Composite Design (CCD), an ANN-based model was trained to get the optimized formulations. The Physiological-based Pharmacokinetic (PBPK) modeling of the predicted formulation was performed by GastroPlus™ to simulate in vivo plasma profiles under fasting and fed conditions. In vitro release tests showed zero-order RVX release for up to 12 h. Using graphical and numerical methods, the predicted formulation generated by the prediction profiler was cross-validated by the CCD-based optimized formulation. Analysis of Variance (ANOVA) findings revealed no significant difference between the predicted and optimized formulations and these formulations have a shelf life of 22.47 and 17.87 months, respectively. The PBPK modeling of RVX push-pull osmotic pump (PPOP) tablets suggested enhanced bioavailability in the fasted (up to 82%) and fed (up to 98.5%) state compared to immediate-release tablets. The results indicated that ANN can be effectively used for osmotic systems due to their complex nature and nonlinear interactions between dependent and independent variables.

Preparation and optimisation of solid lipid nanoparticles of rivaroxaban using artificial neural networks and response surface method

AIMS

This study aimed to improve rivaroxaban delivery by optimising solid lipid nanoparticles (SLN) for minimal mean diameter and maximal entrapment efficiency (EE), enhancing solubility, bioavailability, and the ability to cross the blood-brain barrier.

METHODS

A central composite design was employed to synthesise 32 SLN formulations. Response surface methodology (RSM) and artificial neural networks (ANN) models predicted mean diameter and EE based on five independent variables.

RESULTS

The optimised SLN formulation achieved a mean particle diameter of 159.8 ± 15.2 nm, with a Polydispersity index of 0.46, a zeta potential of -28.8 mV, and an EE of 74.3% ± 5.6%. The ANN model showed superior accuracy for both mean diameter and EE, outperforming the RSM model. Structural integrity and stability were confirmed by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and Fourier-transform infrared spectroscopy (FTIR).

CONCLUSION

The high accuracy of the ANN model highlights its potential in optimising pharmaceutical formulations and improving SLN-based drug delivery systems.

Fast onset of thrombolytic effect of efficiently inhalable spray-dried rivaroxaban powder formulations

Pulmonary embolism is a critical medical condition and can lead to cardiovascular arrest or death if left untreated. Pulmonary delivery of an anti-coagulant therapeutic could provide a locally limited and efficient therapy, moreover combined with a potentially fast onset of the therapeutic effect that is demanded in emergency situations. Rivaroxaban (riva) was formulated as an inhalable dry powder that can be administered directly to the lungs in order to reach high local drug doses. Particles obtained spray drying dichloromethane-methanol mixtures yielded an aerodynamic diameter of about or smaller than 5 µm and were found to reach an emitted fine particle fraction (FPFEF) of at least 60 %. Pulmonary administration to rats using a dry powder insufflator revealed a nearly immediate therapeutic onset confirmed by the anticoagulant effects after 5 min in the plasma, followed by a plateau over the next 4 h. Such rivaroxaban particles were further formulated in binary blends using different lactose carriers (Inhalac® 70/251/400). These interactive blends resulted in high emitted fractions of at least 87 %, and furthermore, the highest fine particle fraction - total dose (FPFTD) (60 %) of all tested formulations was achieved by using Inhalac® 400 as a carrier. The data strongly suggest a significant therapeutic potential of a rivaroxaban dry powder formulation, combining fast onset and a plateau of plasma concentrations turning it into a potential first aid therapeutic.

Development and Evaluation of Lactose-Free Single-Unit and Multiple-Unit Preparations of a BCS Class II Drug, Rivaroxaban

Background/Objectives: The aim of the present study was to develop lactose-free formulations of rivaroxaban, a novel oral anticoagulant used for the treatment and prevention of blood clotting. As a BCS Class II drug, rivaroxaban is characterized by poor solubility in aqueous media, posing a significant formulation challenge. Methods: To address this, phosphate-based excipients were employed to prepare both traditional single-unit dosage forms (tablets) and modern multiple-unit pellet systems (MUPS). These formulations were successfully developed and thoroughly evaluated for their physical properties and performance. Results: The resulting formulations demonstrated very good mechanical strength, including appropriate hardness and friability, alongside strong chemical stability. Their dissolution profiles met the requirements of the compendial monograph for Rivaroxaban Tablets and were comparable to those of the reference product, Xarelto® film-coated tablets. Conclusions: This study shows the potential for producing effective, stable, and patient-friendly medications that meet the needs of contemporary society, where an increasing number of individuals suffer from lactose intolerance or seek vegan-friendly alternatives.

Effects of Glass Bead Size on Dissolution Profiles in Flow-through Dissolution Systems (USP 4)

The effects of glass bead size in the conical space of flow-through cells on the dissolution profiles were investigated in a USP apparatus 4. Dissolution tests of disintegrating and non-disintegrating tablets in flow-through dissolution systems were performed using semi-high precision glass beads with diameters ranging from 0.5 mm to 1.5 mm. Computational fluid dynamics (CFD) was used to evaluate the effect of shear stress from the dissolution media flow. The use of smaller glass beads in a larger cell resulted in a faster dissolution of the model formulations under certain test conditions. The effect on the dissolution was highly dependent on the size of the beads in the top layer, including those in contact with the tablets. The absence of a bead-size effect on the dissolution of an orodispersible tablet in a small cell can be explained by the floating fragments during the test. CFD analysis showed that smaller bead diameters led to greater shear stress on the tablet, which was correlated with the dissolution rate. Hence, fluid flow through the narrow gaps between the small beads generated strong local flows, causing shear stress. The size of the glass beads used in flow-through cells affects the dissolution rate of tablets by altering the shear stress on the tablets in certain cases (e.g., direct deposition of the formulation on glass beads, large cells, and very low flow rates). Thus, glass bead size must be considered for a robust dissolution test in a flow-through cell system.

Key Factors for Improving Predictive Accuracy and Avoiding Overparameterization of the PBPK Absorption Model in Food Effect Studies of Weakly Basic Water-Insoluble Compounds in Immediate Release Formulations

Background/Objectives: Physiologically based pharmacokinetic (PBPK) absorption models are instrumental for assessing drug absorption prior to clinical food effect studies, though discrepancies in predictive and actual outcomes are observed. This study focused on immediate release formulations of weakly basic water-insoluble compounds, namely rivaroxaban, ticagrelor, and PB-201, to investigate factors that could improve the predictive accuracy of PBPK models regarding food effects. Methods: Comprehensive in vitro experimental results provided the basis for the development of mechanistic absorption models, which were then combined with mechanistic disposition models to predict the systemic exposure of the model drugs in both fasted and fed states. Results: The developed PBPK models showed moderate to high predictive accuracy for food effects in Caucasian populations. For the Chinese population, the ticagrelor model's initial overestimation of fed-state absorption was addressed by updating the permeability parameters from Caco-2 cell assays to those derived from parallel artificial membrane permeability assays in FaSSIF and FeSSIF media. This refinement was also applied to the rivaroxaban and ticagrelor models, leading to a more accurate representation of absorption in Caucasians. Conclusions: This study highlights the importance of apparent permeability in enhancing the predictive accuracy of PBPK absorption models for weakly basic water-insoluble compounds. Furthermore, the precipitation of PB-201 in the two-stage transfer experiments suggests that precipitation may not be a universal phenomenon for such compounds in vivo. Consequently, the precipitation rate constant, a theoretically essential parameter, should be determined based on experimental evidence to avoid overparameterization and ensure robust predictive accuracy of PBPK models.

In Vitro Lipolysis Model to Predict Food Effect of Poorly Water-Soluble Drugs Itraconazole, Rivaroxaban, and Ritonavir

It is desirable to predict positive food effect of oral formulations due to food mediated dissolution enhancement of lipophilic drugs. The objective was to assess the ability of in vitro lipolysis to anticipate a positive food effect. Tested formulations included rivaroxaban and itraconazole, where some formulations, but not all, exhibit a positive food effect in vivo in humans. Amorphous solid dispersion formulations of ritonavir, which exhibit a negative food effect in vivo in humans, were also studied. Fe-lipolysis and Fa-lipolysis media representing fed and fasted intestinal conditions were used. Results show frequent agreement between in vitro lipolysis predictions and in vivo human outcomes. For rivaroxaban, food effect of unformulated active pharmaceutical ingredient (API) and products were correctly predicted where 2.5 mg and 10 mg strengths did not show any food effect; however, 20 mg did show a positive food effect. For itraconazole, all four products were correctly predicted, with Sporanox, Sempera, and generic capsules having a food effect, but Tolsura not having a positive food effect. For ritonavir, lipolysis predicted a positive food effect for API and Norvir tablet and powder, but Norvir products have negative food effect in vivo in humans. Overall, the lipolysis model showed favorable predictability and merits additional evaluation.

The development of an innovative method to improve the dissolution performance of rivaroxaban

Recent advancements in the formulation of solid dosage forms involving active ingredient-cyclodextrin complexes have garnered considerable attention in pharmaceutical research. While previous studies predominantly focused on incorporating these complexes into solid states, issues regarding incomplete inclusion prompted the exploration of novel methods. In this study, we aimed to develop an innovative approach to integrate liquid-state drug-cyclodextrin inclusion complexes into solid dosage forms. Our investigation centered on rivaroxaban, a hydrophobic compound practically insoluble in water, included in hydroxypropyl-β-cyclodextrin at a 1:1 M ratio, and maintained in a liquid state. To enhance viscosity, hydroxypropyl-cellulose (2 % w/w) was introduced, and the resulting dispersion was sprayed onto the surface of cellulose pellets (CELLETS®780) using a Caleva Mini Coater. The process parameters were meticulously controlled, with atomization air pressure set at 1.1 atm and a fluidizing airflow maintained at 35-45 m3/h. Characterization of the coated cellets, alongside raw materials, was conducted using Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) analyses. Physicochemical evaluations affirmed the successful incorporation of rivaroxaban into hydroxypropyl-β-cyclodextrin, with the final cellets demonstrating excellent flowability, compressibility, and adequate hardness. Quantitative analysis via the HPLC-DAD method confirmed a drug loading of 10 mg rivaroxaban/750 mg coated cellets. In vitro dissolution studies were performed in two distinct media: 0.022 M sodium acetate buffer pH 4.5 with 0.2 % sodium dodecyl sulfate (mirroring compendial conditions for 10 mg rivaroxaban tablets), and 0.05 M phosphate buffer pH 6.8 without surfactants, compared to reference capsules and conventional tablet formulations. The experimental capsules exhibited similar release profiles to the commercial product, Xarelto® 10 mg, with enhanced dissolution rates observed within the initial 10 min. This research presents a significant advancement in the development of solid dosage forms incorporating liquid-state drug-cyclodextrin inclusion complexes, offering a promising avenue for improving drug delivery and bioavailability.

Development of immediate-release formulation with reliable absorption of rivaroxaban in various meal regimes

The bioavailability of rivaroxaban at the higher doses (15 and 20 mg) is considerably reduced when the drug is administered on an empty stomach. This can lead to inadequate anticoagulant effect, and therefore, it is recommended to use the higher doses at fed state. However, proper posology may represent a barrier for some patients. Therefore, the aim of this study was to evaluate innovative rivaroxaban-containing formulations designed to eliminate the food effect to ensure reliable absorption and thus to improve patient adherence with the treatment. Three prototypes (Cocrystal, HPMCP and Kollidon) with rivaroxaban were developed and their bioavailability and food effect in comparison to the reference product was tested in open label, randomized, single oral dose, crossover studies, where test products were administered under fasting and fed conditions and the reference product was administered under fed conditions. Comparable bioavailability for all tested prototypes both under fed and fasting conditions was demonstrated as the 90% confidence intervals of the geometric mean ratios for area under the concentration-time curve remained within the standard acceptance range of 80.00%-125.00%. An innovative immediate release form of rivaroxaban with no food effect on drug bioavailability has been developed, which may represent an important step toward increasing adherence, improving treatment outcome and reducing health care costs.

An extension of biorelevant fed-state dissolution tests to clinical pharmacokinetics - A study on gastrointestinal factors influencing rivaroxaban exposure and efficacy in atrial fibrillation patients

A direct oral anticoagulant rivaroxaban fails to prevent stroke and systemic embolism in one-to-several percent of patients with nonvalvular atrial fibrillation (NVAF), but the reasons are unknown. The study used semi-mechanistic in vitro-in vivo prediction (IVIVP) modeling to explore the reasons for ineffective thrombosis prevention in NVAF patients. Steady-state drug concentrations in plasma were measured at 0 h (Ctrough), 3 h (C3h), and 12 h post-dosing in thirty-four patients treated with 20 mg rivaroxaban daily. The clinical data were compared against "virtual twins" generated with a novel IVIVP model that combined drug dissolution modeling, mechanistic description of gastric drug transit, and population pharmacokinetics defining the variability of drug disposition. The nonresponders had significantly lower C3h and Ctrough than the responders (p < 0.001) and the covariates included in the population pharmacokinetic submodel did not fully explain this difference. Simulations involving varied gastrointestinal parameters in the "virtual twins" revealed that lower small intestinal effective permeability (Peff), rather than a slower stomach emptying rate, could explain low rivaroxaban exposure in the nonresponders. IVIVP modeling was effectively used for exploring pharmacotherapy failure. Low Peff, found as a major determinant of ineffective rivaroxaban treatment, encourages further research to find (pato)physiological factors influencing suboptimal absorption.

A first-in-human phase 1 study of simnotrelvir, a 3CL-like protease inhibitor for treatment of COVID-19, in healthy adult subjects

Safe and efficacious antiviral therapeutics are in urgent need for the treatment of coronavirus disease 2019. Simnotrelvir is a selective 3C-like protease inhibitor that can effectively inhibit severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We evaluated the safety, tolerability, and pharmacokinetics of dose escalations of simnotrelvir alone or with ritonavir (simnotrelvir or simnotrelvir/ritonavir) in healthy subjects, as well as the food effect (ClinicalTrials.gov Identifier: NCT05339646). The overall incidence of adverse events (AEs) was 22.2% (17/72) and 6.3% (1/16) in intervention and placebo groups, respectively. The simnotrelvir apparent clearance was 135-369 L/h with simnotrelvir alone, and decreased significantly to 19.5-29.8 L/h with simnotrelvir/ritonavir. The simnotrelvir exposure increased in an approximately dose-proportional manner between 250 and 750 mg when co-administered with ritonavir. After consecutive twice daily dosing of simnotrelvir/ritonavir, simnotrelvir had a low accumulation index ranging from 1.39 to 1.51. The area under the curve of simnotrelvir increased 44.0 % and 47.3 % respectively, after high fat and normal diet compared with fasted status. In conclusion, simnotrelvir has adequate safety and tolerability. Its pharmacokinetics indicated a trough concentration above the level required for 90 % inhibition of SARS-CoV-2 in vitro at 750 mg/100 mg simnotrelvir/ritonavir twice daily under fasted condition, supporting further development using this dosage as the clinically recommended dose regimen.

Apixaban and rivaroxaban's physiologically-based pharmacokinetic model validation in hospitalized patients: A first step for larger use of a priori modeling approach at bed side

When used in real-world conditions, substantial interindividual variations in direct oral anticoagulant (DOAC) plasma concentrations are observed for a given dose, leading to a risk of over- or under-exposure and clinically significant adverse events. Physiologically-based pharmacokinetic (PBPK) models could help physicians to tailor DOAC prescriptions in vulnerable patient populations, such as those in the hospital setting. The present study aims to validate prospectively PBPK models for rivaroxaban and apixaban in a large cohort of elderly, polymorbid, and hospitalized patients. In using a model of geriatric population integrating appropriate physiological parameters into models first optimized with healthy volunteer data, observed plasma concentration collected in hospitalized patients on apixaban (n = 100) and rivaroxaban (n = 100) were adequately predicted (ratio predicted/observed area under the concentration curve for a dosing interval [AUCtau ] = 0.97 [0.96-0.99] geometric mean, 90% confidence interval, ratio predicted/observed AUCtau  = 1.03 [1.02-1.05]) for apixaban and rivaroxaban, respectively. Validation of the present PBPK models for rivaroxaban and apixaban in in-patients represent an additional step toward the feasibility of bedside use.

Pharmacokinetics, Bioequivalence, and Safety Evaluation of 2 Formulations of 10-mg Rivaroxaban Tablets: A 4-Period Crossover Trial

This study compared the safety, bioequivalence, and pharmacokinetic properties of 2 formulations of 10-mg rivaroxaban tablets in healthy Chinese participants in fasting and fed arms. The trial was an open, randomized, 4-period, replicated crossover scheme, and 36 volunteers were recruited separately for the fasting and fed arms. Volunteers were randomly administered a single dose of the test or reference formulation (10 mg) orally, followed by a 5-day washout period. Rivaroxaban concentrations in the plasma were determined using liquid chromatography-tandem mass spectrometry, and pharmacokinetic parameters were obtained from the concentration-time profiles. The mean values of the test and the reference product for the area under the plasma concentration-time curve from time 0 to the last measurable concentration, area under the plasma concentration-time curve from time 0 to infinity, and maximum plasma concentration were 996 and 1014 ng • h/mL, 1024 and 1055 ng • h/mL, and 150 and 152 ng/mL in the fasting arm, respectively; the values were 1155 and 1167 ng • h/mL, 1160 and 1172 ng • h/mL, and 202 and 193 ng/mL in the fed arm, respectively. All the parameters were within acceptable limits in terms of bioequivalence. No serious adverse events were observed. This study demonstrated that the 2 rivaroxaban tablets were bioequivalent in healthy Chinese participants under fasting and fed conditions.

Assessment of food effects during clinical development

Food-drug interactions frequently hamper oral drug development due to various physicochemical, physiological and formulation-dependent mechanisms. This has stimulated the development of a range of promising biopharmaceutical assessment tools which, however, lack standardized settings and protocols. Hence, this manuscript aims to provide an overview of the general approach and the methodology used in food effect assessment and prediction. For in vitro dissolution-based predictions, the expected food effect mechanism should be carefully considered when selecting the level of complexity of the model, together with its drawbacks and advantages. Typically, in vitro dissolution profiles are then incorporated into physiologically based pharmacokinetic models, which can estimate the impact of food-drug interactions on bioavailability within 2-fold prediction error, at least. Positive food effects related to drug solubilization in the GI tract are easier to predict than negative food effects. Preclinical animal models also provide a good level of food effect prediction, with beagle dogs remaining the gold standard. When solubility-related food-drug interactions have large clinical impact, advanced formulation approaches can be used to improve fasted state pharmacokinetics, hence decreasing the fasted/fed difference in oral bioavailability. Finally, the knowledge from all studies should be combined to secure regulatory approval of the labelling instructions.

Evaluation and prediction of oral drug absorption and bioequivalence with food-drug interaction

This article reviews the impacts on the in vivo prediction of oral bioavailability (BA) and bioequivalence (BE) based on Biopharmaceutical classification systems (BCS) by the food-drug interaction (food effect) and the gastrointestinal (GI) environmental change. Various in vitro and in silico predictive methodologies have been used to expect the BA and BE of the test oral formulation. Food intake changes the GI physiology and environment, which affect oral drug absorption and its BE evaluation. Even though the pHs and bile acids in the GI tract would have significant influence on drug dissolution and, hence, oral drug absorption, those impacts largely depend on the physicochemical properties of oral medicine, active pharmaceutical ingredients (APIs). BCS class I and III drugs are high soluble drugs in the physiological pH range, food-drug interaction may not affect their BA. On the other hand, BCS class II and IV drugs have pH-dependent solubility, and the more bile acid secretion and the pH changes by food intake might affect their BA. In this report, the GI physiological changes between the fasted and fed states are described and the prediction on the oral drug absorption by food-drug interaction have been introduced.

Evaluating the bioequivalence of two pitavastatin calcium formulations based on IVIVC modeling and clinical study

In vitro-in vivo correlation (IVIVC) allows prediction of the in vivo performance of a pharmaceutical product based on its in vitro drug release profiles and can be used to reduce the number of bioequivalence (BE) studies during product development, and facilitate certain regulatory decisions. Here, we developed an IVIVC model for pitavastatin calcium, a basic Biopharmaceutics Classification System (BCS) II lipid-lowering drug, which was then used to predict the BE outcome of formulations manufactured at two manufacturers. In addition, virtual trials using the IVIVC model using pH 4.0 acetate buffer dissolution showed similarity in areas under the curves and maximum plasma concentration (Cmax ) for test and reference tablets under fasting condition. These predicted results were verified in definitive BE study. In conclusion, we demonstrated that for certain BCS II molecules, IVIVC modeling could be used as a priori to predict the BE outcome.

Preparation, characterization, and pharmacokinetics of rivaroxaban cocrystals with enhanced in vitro and in vivo properties in beagle dogs

Rivaroxaban (RIV) is a direct Factor Xa inhibitor anticoagulant, but the oral bioavailability of RIV is estimated to be only 60% due to its poor solubility. The aim of the present study was to improve the solubility and bioavailability of RIV. Five cocrystals—p-hydroxybenzoic acid (HBA), 2,4-dihydroxybenzoic acid (DBA), nicotinamide (NA), isonicotinamide (IA), and succinic acid (SA)—were used as cofomers and were successfully obtained and characterized by powder X-ray diffraction, thermal analysis, and Fourier transform infrared spectra. RIV-DBA and RIV-HBA cocrystals showed obvious improvements in solubility, dissolution (under sink conditions), and intrinsic dissolution rates versus RIV. Moreover, the dissolution of RIV-HBA, RIV-DBA, and RIV-SA cocrystals under non-sink conditions showed obvious “spring and parachute” patterns. The in vitro permeability levels in a Caco-2 cell model of RIV-DBA and RIV-IA cocrystals were significantly improved versus RIV. Pharmacokinetic studies in beagle dogs showed that RIV-DBA and RIV-HBA cocrystals had higher bioavailability than RIV. The enhancements in solubility and bioavailability indicate the potential of RIV cocrystals as a better candidate for the treatment of thrombosis versus RIV.

Application of physiologically-based pharmacokinetic model approach to predict pharmacokinetics and drug-drug interaction of rivaroxaban: A case study of rivaroxaban and carbamazepine

Rivaroxaban (RIV; Xarelto; Janssen Pharmaceuticals, Beerse, Belgium) is one of the direct oral anticoagulants. The drug is a strong substrate of cytochrome P450 (CYP) enzymes and efflux transporters. This study aimed to develop a physiologically-based pharmacokinetic (PBPK) model for RIV. It contained three hepatic metabolizing enzyme reactions (CYP3A4, CYP2J2, and CYP-independent) and two active transporter-mediated transfers (P-gp and BCRP transporters). To illustrate the performance of the developed RIV PBPK model on the prediction of drug-drug interactions (DDIs), carbamazepine (CBZ) was selected as a case study due to the high DDI potential. Our study results showed that CBZ significantly reduces the exposure of RIV. The area under the concentration-time curve from zero to infinity (AUC_inf ) of RIV was reduced by 35.2% (from 2221.3 to 1438.7 ng*h/ml) and by 25.5% (from 2467.3 to 1838.4 ng*h/ml) after the first dose and at the steady-state, respectively, whereas the maximum plasma concentration (C_max ) of RIV was reduced by 37.7% (from 266.3 to 166.1 ng/ml) and 36.4% (from 282.3 to 179.5 ng/ml), respectively. The developed PBPK model of RIV could be paired with PBPK models of other interested perpetrators to predict DDI profiles. Further studies investigating the extent of DDI between CBZ and RIV should be conducted in humans to gain a full understanding of their safety and effects.

Explaining dissolution properties of rivaroxaban cocrystals

The aim of this study was to improve rivaroxaban water-solubility by cocrystal preparation and to understand this process. The screening with water-soluble coformers was performed via both mechanochemical and solution-mediated techniques. Two cocrystals of rivaroxaban with malonic acid and oxalic acid were prepared, and the structure of the cocrystal with oxalic acid was solved. Both cocrystals exhibit improved dissolution properties. The mechanism of the supersaturation maintenance was studied by in-situ Raman spectroscopy. The transformation into rivaroxaban dihydrate was identified as the critical step in the improved dissolution properties of both cocrystals. Moreover, the transformation kinetics and solubilization effects of the coformers were identified as responsible for the differences in the dissolution behavior of the cocrystals. In-vivo experiments proved that the use of cocrystal instead of form I of free API helped to increase the bioavailability ofrivaroxaban.

Development of Extended-Release Mini-Tablets Containing Metoprolol Supported by Design of Experiments and Physiologically Based Biopharmaceutics Modeling

The development of extended-release dosage forms with adequate drug release is a challenge for pharmaceutical companies, mainly when the drug presents high solubility, as in Biopharmaceutics Classification System (BCS) class I. This study aimed to develop extended-release mini-tablets containing metoprolol succinate (MS), while integrating design of experiments (DOE) and physiologically based biopharmaceutics modeling (PBBM), to predict its absorption and to run virtual bioequivalence (VBE) studies in both fasted and fed states. Core mini-tablet formulations (F1, F2, and F3) were prepared by direct compression and coated using nine coating formulations planned using DOE, while varying the percentages of the controlled-release and the pore-forming polymers. The coated mini-tablets were submitted to a dissolution test; additional formulations were prepared that were optimized by simulating the dissolution profiles, and the best one was submitted to VBE studies using GastroPlus® software. An optimized formulation (FO) containing a mixture of immediate and extended-release mini-tablets showed to be bioequivalent to the reference drug product containing MS when running VBE studies in both fasted and fed states. The integration of DOE and PBBM showed to be an interesting approach in the development of extended-release mini-tablet formulation containing MS, and can be used to rationalize the development of dosage forms.

A Combined Pharmacometrics Analysis of Biomarker Distribution Under Treatment With Standard- or Low-Dose Rivaroxaban in Real-World Chinese Patients With Nonvalvular Atrial Fibrillation

Background: The rivaroxaban dose regimen for patients with nonvalvular atrial fibrillation (NVAF) is complex in Asia. Given the high interindividual variability and the risk of bleeding caused by rivaroxaban in Asians, the influencing factors and the relationship between outlier biomarkers and bleeding events need exploration.

Methods: The integrated pharmacokinetics (PK)/pharmacodynamics (PD) models were characterized based on rich PK/PD data from 304 healthy volunteers and sparse PD [anti-factor Xa activity (anti-Xa) and prothrombin (PT)] data from 223 patients with NVAF. The correlations between PD biomarkers and clinically relevant bleedings in 1 year were explored. The final integrated PK/PD model was used to evaluate the influence of dosage and individual covariates on PD parameters.

Results: A two-compartment, linear model with sequential zero-order and first-order absorption was adopted. The dose-specific relative bioavailability (F₁), diet status, creatinine clearance, and body mass index (BMI) improved the model fit. The apparent systemic clearance was 7.39 L/h, and the central and peripheral volumes were 10.9 and 50.9 L, respectively. The linear direct-effects model with shape factor plus the additive (and/or proportional) error model described the correlation between anti-Xa/PT and plasma concentration. Bodyweight, total cholesterol (TCHO), and diet status were selected as the covariates of the anti-Xa/PT model. Anti-Xa was more sensitive to the increase in rivaroxaban exposure compared with PT. An elevated bleeding tendency was seen with higher peak anti-Xa and PT. For a typical Chinese patient, the peak anti-Xa value (median (5%–95% PI)) of 20 and 15 mg were 309 ng/ml (139–597 ng/ml) and 296 ng/ml (138–604 ng/ml), both median values were within the expected range. For patients with CrCL 30–49 ml/min, the median peak anti-Xa with recommended 10 mg other than 15 mg were within the expected range.

Conclusion: Fixed doses of rivaroxaban could be prescribed for patients with NVAF without adjustment for bodyweight, BMI, and TCHO. Randomized studies should be performed to evaluate the efficacy and safety of low-dose rivaroxaban in Chinese patients with NVAF.

A Novel Approach to Justify Dissolution Differences in an Extended Release Drug Product Using Physiologically Based Biopharmaceutics Modeling and Simulation

Dr Reddy's Laboratories Ltd. developed generic version of XYZ extended release tablets (ER) and achieved bioequivalence as per criteria mentioned by USFDA in both fasting and fed conditions for higher strength formulation (1200 mg). However, on comparison of multimedia dissolution profiles in pH 4.5 acetate media, the f2 similarity value was <50. The lower strength formulation (600 mg) demonstrated faster dissolution profile. This was identified as strength-dependent sink condition difference and in vitro multiunit dissolution studies were used to justify sink differences between the higher and lower strengths. Additionally, a Physiologically Based Biopharmaceutics Model (PBBM) was developed using GastroPlus^TM. The validity of this model was established using in-house human pharmacokinetic data. Further, this model was used to justify the insignificant in vivo impact of the faster dissolution profile for the lower strength formulation. This work provides a novel and less explored approach that can be used to obtain biowaiver for lower strength formulations when the standard biowaiver criteria cannot be met. This work also demonstrates the usefulness of PBBM to justify dissolution dissimilarity between dose proportional formulations and to evaluate its biopharmaceutics risk without the need for actual in vivo studies.

Design of Oral Sustained-Release Pellets by Modeling and Simulation Approach to Improve Compliance for Repurposing Sobrerol

Sobrerol, an oral mucolytic agent, in a recent study showed promise for treating multiple sclerosis. A human equivalent dose of 486 mg of sobrerol administered thrice daily (i.e., 1459 mg of daily dose) demonstrated the highest therapeutic efficacy for repurposing use, which also points out the poor compliance of administration. In this study, oral sustained-release pellets of sobrerol were successfully developed with evaluated manufacturing conditions and drug release kinetics. For design of the target drug product, we used a modeling and simulation approach to establish a predictive model of oral pharmacokinetic profile, by exploring the characteristics and correlations corresponding to the pharmacokinetics and pharmacodynamics of sobrerol, such as absorption lag time (0.18 h), time-scaling in vitro–in vivo correlation (t_in-vitro = 0.494 t_in-vivo − 0.0904), gastrointestinal transit time (8 h), minimum effective concentration (1.61 μg/mL), and duration of action (12.8 h). Results showed that the frequency of administration and the daily dose remarkably reduced by 33.3% (i.e., from thrice to twice daily) and 22.8%, respectively, which indicates that this prototype approach can be adopted for rapidly developing a modified-release dosage form of sobrerol, with improvement of compliance of administration and therapeutic efficacy.

Direct Acting Oral Anticoagulants Following Gastrointestinal Tract Surgery

ABSTRACT

Direct-acting oral anticoagulants (DOACs) vary in bioavailability and sites of absorption in the gastrointestinal tract (GIT). Data on DOAC use after major GIT surgery are limited. The aim of this case series was to report the impact of surgical resection or bypass of the GIT on rivaroxaban and apixaban peak plasma concentrations. This was a case series of patients who received rivaroxaban or apixaban after GIT surgery, during the period of July 1, 2019, to December 31, 2020. Peak plasma concentrations of rivaroxaban and apixaban were assessed for the expected concentrations. Of the 27 assessed patients, 18 (66.7%) received rivaroxaban, and 9 (33.3%) received apixaban. After rivaroxaban therapy, 4 of 5 patients (80%) who underwent gastrectomy, and 3 of 3 patients (100%) who underwent duodenum and proximal jejunum exclusion had peak plasma concentrations of rivaroxaban lower than the effective range, whereas 11 of 11 patients (100%) who underwent distal bowel or ileostomy had peak rivaroxaban plasma within the effective range. After apixaban therapy, 5 of 6 patients (83.3%) who underwent total or partial gastrectomy achieved effective peak concentrations. All the patients who underwent proximal and distal bowel resection or bypass had peak concentrations of apixaban within the effective range. In conclusion, surgical resection or bypass of the upper GIT could affect DOAC absorption and subsequently peak plasma concentrations. This effect was more observed among rivaroxaban recipients. An injectable anticoagulant or vitamin K antagonist may be preferred if DOAC concentrations cannot be measured after GIT surgery.

Bioequivalence and Food Effect Assessment of 2 Rivaroxaban Formulations in Healthy Chinese Volunteers: An Open, Randomized, Single-Dose, and 4-Period Crossover Study

Rivaroxaban is a direct factor Xa inhibitor used for the management of thromboembolic disorders. The aim of this study was to evaluate the safety, pharmacokinetic profile, and bioequivalence of a generic and a branded rivaroxaban formulation (Xarelto) under fasted and fed conditions in healthy Chinese volunteers. An open-label, randomized, single-dose, 4-period complete, and replicate crossover study in healthy Chinese volunteers was performed. A single oral dose of 20 mg of 2 rivaroxaban formulations was administered to 72 healthy volunteers, with 36 in the fasted group and 36 consuming a high-fat diet. The evaluated pharmacokinetic parameters, including maximum rivaroxaban concentration, the area under the concentration-time curve (AUC) from time 0 to the last measurable concentration, and AUC from time 0 to infinity, were assessed for BE. The plasma concentrations of rivaroxaban were measured by a validated liquid chromatography-tandem mass spectrometry method. The geometric mean ratios with 90% confidence intervals of the maximum rivaroxaban concentration, AUC from time 0 to the last measurable concentration, and AUC from time 0 to infinity were all within the range of 80% to 125% under fasted and fed conditions. The within-subject variability of the test and reference products was compared, and the upper limit of the 90% confidence intervals for the test-to-reference ratio of the within-subject variability was <2.5, which indicated that the rivaroxaban test and the rivaroxaban reference formulation were bioequivalent. No serious adverse events were reported during either fasted or fed conditions of the study.