Population In Vitro-In Vivo Correlation Model Linking Gastrointestinal Transit Time, pH, and Pharmacokinetics: Itraconazole as a Model Drug

In Vitro-In Vivo Correlation Of Amorphous Solid Dispersion Enabled Itraconazole Tablets

PURPOSE

There are scarce reports on in vitro-in vivo correlation (IVIVC) model development of immediate-release (IR) formulations, and few investigations of the impacts of formulation and process of spray-dried solid dispersions (SDD)-based tablets on human pharmacokinetics (PK), despite commercial product successes. The goal of this study was to investigate the formulation and process factors that impact bioavailability enhancement of IR itraconazole SDD tablets; and to develop an FDA level A IVIVC that would predict in vivo PK performance from in vitro dissolution testing.

METHODS

A direct, differential-equation-based IVIVC model approach was employed, using an oral solution for post-dissolution disposition and Fast-, Medium-, and Slow-release tablets.

RESULTS

The IVIVC met FDA internal predictability for level A IVIVC requirements. The in vitro dissolution employed USP simulated intestinal fluid (phosphate buffer), adjusted pH 6.4, and tablets were triturated into particles prior to their immersion into dissolution media to mimic the attenuated disintegration difference between Medium and Slow in vivo. Credibility assessment of the FDA level A IVIVC model was performed, including model verification and validation considerations in light of the question of interest, the context of use, and model risk.

CONCLUSION

To our knowledge, this is the first and only study that successfully developed an FDA level A IVIVC of an amorphous solid dispersion, which assessed the impact of grades of the same polymer, disintegrant level, and dry granulation processing on the performance of SDD tablets in humans.

SUBA-itraconazole in the treatment of systemic fungal infections

Conventional itraconazole (c-ITZ) can be used for a variety of fungal infections although variable absorption has been a significant limitation. Super-bioavailable itraconazole (SUBA-ITZ) is a novel formulation that overcomes absorption concerns by utilizing a polymer-matrix to disperse active drug and facilitate dissolution. The pH-driven matrix allows concurrent proton pump inhibitor administration without significant effects on drug concentrations. The enhanced bioavailability of SUBA-ITZ allows for lower dosing, while achieving similar serum concentrations as c-ITZ and SUBA-ITZ is now US FDA approved in the treatment of blastomycosis, histoplasmosis and aspergillosis. Common side effects of SUBA-ITZ include gastrointestinal disorders, peripheral edema and drug-induced hypertension. Given the significant differences in pharmacokinetics between the formulations, c-ITZ and SUBA-ITZ capsules are not considered interchangeable. It is important to note that drug errors may occur when transitioning a patient from one formulation to another.

Self-emulsifying micelles as a drug nanocarrier system for itraconazole oral bioavailability enhancement; in vitro and in vivo assessment

Itraconazole (ITZ) is a renowned antifungal medication, however its therapeutic efficacy is limited by low solubility and oral bioavailability. The current research work attempted to augment the oral bioavailability of ITZ by incorporating into self-emulsifying micelles (SEMCs). To fabricate the SEMCs, various preparation techniques including physical mixture, melt-emulsification, solvent evaporation and kneading, were opted by using different weight ratio of drug and solubilizers i.e. Gelucire-50/13 or Gelucire-44/14 and characterized both in vitro and in vivo. The prepared SEMCs were found to be in the size range from 63.4 ± 5.2 to 284.2 ± 19.5 nm with surface charges ranging from -16 ± 1.2 to -27 ± 2.0 mV. The drug solubility was improved to a reasonable extent with all investigated formulations, however, SEMCs in group 6 prepared by kneading method (KMG6) using Gelucire-44/14: drug (10:1 presented 87.6 folds' increase (964.93 ± 2 μg/mL) compared to solubility of crystalline ITZ (11 ± 2 μg/mL) through kneading method. In addition, KMG6 SEMCs shows the fast drug release compared to other SEMCs. Further, KMG6 SEMCs also exhibited 5.12-fold higher relative intestinal serosal fluid absorption compared to crystalline ITZ. The pharmacokinetic parameters such Cmax, AUC and Tmax of KMG6 SEMCs significantly improved compared to crystalline ITZ. In conclusion, the manipulation of ITZ solubility, dissolution rate and absorption using SEMCs is a promising strategy for bioavailability enhancement.

Pharmacokinetics of obese adults: Not only an increase in weight

Obesity is a pathophysiological state defined by a body mass index > 30 kg/m2 and characterized by an adipose tissue accumulation leading to an important weight increased. Several pathologies named comorbidities such as cardiovascular disease, type 2 diabetes and cancer make obesity the fifth cause of death in the world. Physiological changes impact the four main phases of pharmacokinetics of some drugs and leads to an inappropriate drug-dose. For absorption, the gastrointestinal transit is accelerated, and the gastric empty time is shortened, that can reduce the solubilization and absorption of some oral drugs. The drug distribution is probably the most impacted by the obesity-related changes because the fat mass (FM) increases at the expense of the lean body weight (LBW), leading to an important increase of the volume of distribution for lipophilic drugs and a low or moderately increase of this parameter for hydrophilic drugs. This modification of the distribution may require drug-dose adjustments. By various mechanisms, the metabolism and elimination of drugs are impacted by obesity and should be considered as similar or lower than that non-obese patients. To better understand the necessary drug-dose adjustments in obese patients, a narrative review of the literature was conducted to highlight the main elements to consider in the therapeutic management of adult obese patients.

Influence of Gender, Body Mass Index, and Age on the Pharmacokinetics of Itraconazole in Healthy Subjects: Non-Compartmental Versus Compartmental Analysis

Itraconazole is a triazole antifungal agent with highly variable pharmacokinetics, with not yet fully identified factors as the source of this variability. Our study aimed to examine the influence of body mass index, gender, and age on the first dose pharmacokinetics of itraconazole in healthy subjects, using pharmacokinetic modeling, non-compartmental versus compartmental ones. A total of 114 itraconazole and hydroxy-itraconazole sets of plasma concentrations of healthy subjects of both genders, determined using a validated liquid chromatographic method with mass spectrometric detection (LC-MS), were obtained for pharmacokinetic analyses performed by the computer program Kinetica 5®. Genetic polymorphism in CYP3A4, CYP3A5, CYP1A1, CYP2C9, and CYP2C19 was analyzed using PCR-based methods. Multiple linear regression analysis indicated that gender had a significant effect on AUC as the most important pharmacokinetics endpoint, whereas body mass index and age did not show such an influence. Therefore, further analysis considered gender and indicated that both geometric mean values of itraconazole and hydroxy-itraconazole plasma concentrations in men were prominently higher than those in women. A significant reduction of the geometric mean values of Cmax and AUC and increment of Vd in females compared with males were obtained. Analyzed genotypes and gender differences in drug pharmacokinetics could not be related. Non-compartmental and one-compartmental models complemented each other, whereas the application of the two-compartmental model showed a significant correlation with the analysis of one compartment. They indicated a significant influence of gender on itraconazole pharmacokinetics after administration of the single oral dose of the drug, given under fed conditions. Women were less exposed to itraconazole and hydroxy-itraconazole than men due to poorer absorption of itraconazole, its more intense pre-systemic metabolism, and higher distribution of both drug and its metabolite.

Population Pharmacokinetics and Pharmacodynamics of Itraconazole for Disseminated Infection Caused by Talaromyces marneffei

First-line treatment of talaromycosis with amphotericin B deoxycholate (DAmB) is labor-intensive and toxic. Itraconazole is an appealing alternative antifungal agent. Pharmacokinetic data were obtained from 76 patients who were randomized to itraconazole in the Itraconazole versus Amphotericin B for Talaromycosis (IVAP) trial. Plasma levels of itraconazole and its active metabolite, hydroxyitraconazole, were analyzed alongside longitudinal fungal CFU counts in a population model. Itraconazole and hydroxyitraconazole pharmacokinetic variability was considerable, with areas under the concentration-time curve over 24 h (AUC24) of 3.34 ± 4.31 mg·h/liter and 3.57 ± 4.46 mg·h/liter (mean ± standard deviation), respectively. Levels of both analytes were low; itraconazole minimum concentration (Cmin) was 0.11 ± 0.16 mg/liter, and hydroxyitraconazole Cmin was 0.13 ± 0.17 mg/liter. The mean maximal rates of drug-induced killing were 0.206 and 0.208 log10 CFU/ml/h, respectively. There were no associations between itraconazole Cmin/MIC and time to sterilization of the bloodstream (hazard ratio [HR], 1.01; 95% confidence interval [CI], 0.99 to 1.03; P = 0.43), time to death (HR, 0.99; 95% CI, 0.96 to 1.02; P = 0.77), or early fungicidal activity (EFA) (coefficient, -0.004; 95% CI, -0.010 to 0.002; P = 0.18). Similarly, there was no relationship between AUC/MIC and time to sterilization of the bloodstream (HR, 1.00; 95% CI, 0.99 to 1.00; P = 0.50), time to death (HR, 1.00; 95% CI, 0.99 to 1.00; P = 0.91), or EFA (coefficient, -0.0001; 95% CI, -0.0003 to 0.0001; P = 0.19). This study raises the possibility that the failure of itraconazole to satisfy noninferiority criteria against DAmB for talaromycosis in the IVAP trial was a pharmacokinetic and pharmacodynamic failure.

An Open-Label, Randomized, Double-Arm Clinical Trial to Compare the Effectiveness and Safety of Super Bioavailable Itraconazole Capsules and Itraconazole Capsules in the Management of Dermatophytosis in India

Purpose

A new oral formulation of itraconazole, called super bioavailable itraconazole (SBITZ), has been launched in India, exhibiting greater bioavailability than conventional itraconazole (CITZ). No clinical studies on its effectiveness and safety in dermatophytosis in comparison with CITZ have been conducted in India. Hence, the aim of this clinical study was to compare the effectiveness and safety of SBITZ capsules and CITZ capsules in dermatophytosis.

Patients and Methods

This was an open-label, randomized, double-arm clinical study in which 70 patients (≥18 years of age) of either gender and diagnosed with tinea cruris, tinea corporis, and/or tinea faciei were included. The study was divided into two parts, the first part comprising a treatment period of 4 weeks and the second part an observation period for recurrence, comprised of another 4 weeks, thus making an entire study duration of 8 weeks.

Results

Of the 70 patients enrolled in this study, 59 (33 patients in the CITZ group and 26 patients in the SBITZ group) were included in the final analysis. In both groups, most patients were diagnosed with tinea cruris et corporis, with five or more lesions. At week 4, 11 patients (33.33%) and 17 patients (65.38%) had achieved complete cure (p<0.05), whereas 22 patients (66.67%) and 22 patients (84.61%) had achieved mycological cure (p=0.14), in the CITZ and SBITZ groups, respectively. During the observation period, recurrence was seen in 1/11 and 4/17 completely cured patients in the CITZ and SBITZ groups, respectively (p=0.15). A significant difference was noted in resolution of symptoms as well as lesions of dermatophytosis in the SBITZ group (p<0.05). Both treatments were found to be safe and well tolerated.

Conclusion

In the light of real-world evidence on effectiveness and safety, SBITZ should be considered as a potent therapeutic choice to effectively control the current menace of dermatophytosis in India.

Computational disease model of phenobarbital-induced acute attacks in an acute intermittent porphyria mouse model

INTRODUCTION

Acute intermittent porphyria (AIP) is characterized by hepatic over-production of the heme precursors when aminolevulinic acid (ALA)-synthase 1 is induced by endogenous or environmental factors. The aim of this study was to develop a semi-mechanistic computational model to characterize urine accumulation of heme precursors during acute attacks based on experimental pharmacodynamics data and support the development of new therapeutic strategies.

METHODS

Male AIP mice received recurrent phenobarbital challenge starting on days 1, 9, 16 and 30. 24-h urine excretion of ALA, porphobilinogen (PBG) and porphyrins from challenges D1, D9 and D30 constituted the training data set to build the mechanistic model using the population approach. In a second study, porphyrin and porphyrin precursor excretion from challenge D16 were used as a validation data set.

RESULTS

The computational model presented the following features: (i) urinary excretion of ALA, PBG and porphyrins was governed by unmeasured circulating heme precursor amounts, (ii) the circulating amounts of ALA and PBG were the precursors of circulating amounts of PBG and porphyrins, respectively, and (iii) the phenobarbital effect linearly increased the synthesis of circulating ALA and PBG levels. The model displayed good parameter precision (coefficient of variation below 32% in all parameters), and adequately described the experimental data. Finally, a theoretical hemin effect was implemented to illustrate the applicability of the model to dosage optimization in drug therapies.

CONCLUSIONS

A semi-mechanistic disease model was successfully developed to describe the temporal evolution of urinary heme precursor excretion during recurrent biochemical-induced acute attacks in AIP mice. This model represents the first computational approach to explore and optimize current and new therapies.

Physiologically Relevant In Vitro-In Vivo Correlation (IVIVC) Approach for Sildenafil with Site-Dependent Dissolution

This study aimed to establish a physiologically relevant in vitro-in vivo correlation (IVIVC) model reflecting site-dependent dissolution kinetics for sildenafil based on population-pharmacokinetic (POP-PK) modeling. An immediate release (IR, 20 mg) and three sustained release (SR, 60 mg) sildenafil tablets were prepared by wet granulation method. In vitro dissolutions were determined by the paddle method at pH 1.2, 4.5, and 6.8 media. The in vivo pharmacokinetics were assessed after oral administration of the prepared IR and SR formulations to Beagle dogs (n = 12). The dissolution of sildenafil from SR formulations was incomplete at pH 6.8, which was not observed at pH 1.2 and pH 4.5. The relative bioavailability was reduced with the decrease of the dissolution rate. Moreover, secondary peaks were observed in the plasma concentration-time curves, which may result from site-dependent dissolution. Thus, a POP-PK model was developed to reflect the site-dependent dissolution by separately describing the dissolution and absorption processes, which allowed for estimation of the in vivo dissolution of sildenafil. Finally, an IVIVC was established and validated by correlating the in vitro and in vivo dissolution rates. The present approach may be applied to establish IVIVC for various drugs with complex dissolution kinetics for the development of new formulations.

Defining level A IVIVC dissolution specifications based on individual in vitro dissolution profiles of a controlled release formulation

Regulatory guidelines recommend that, when a level A IVIVC is established, dissolution specification should be established using averaged data and the maximum difference between AUC and C_max between the reference and test formulations cannot be greater than 20%. However, averaging data assumes a loss of information and may reflect a bias in the results. The objective of the current work is to present a new approach to establish dissolution specifications using a new methodology (individual approach) instead of average data (classical approach). Different scenarios were established based on the relationship between in vitro-in vivo dissolution rate coefficient using a level A IVIVC of a controlled release formulation. Then, in order to compare this new approach with the classical one, six additional batches were simulated. For each batch, 1000 simulations of a dissolution assay were run. C_max ratios between the reference formulation and each batch were calculated showing that the individual approach was more sensitive and able to detect differences between the reference and the batch formulation compared to the classical approach. Additionally, the new methodology displays wider dissolution specification limits than the classical approach, ensuring that any tablet from the new batch would generate in vivo profiles which its AUC or C_max ratio will be out of the 0.8-1.25 range, taking into account the in vitro and in vivo variability of the new batches developed.

An updated overview with simple and practical approach for developing in vitro-in vivo correlation

Preclinical Research & Development An in vitro-in vivo correlation (IVIVC) is as a predictive mathematical model that demonstrates a key role in the development, advancement, evaluation and optimization of extended release, modified release and immediate release pharmaceutical formulations. A validated IVIVC model can serve as a surrogate for bioequivalence studies and subsequently save time, effort and expenditure during pharmaceutical product development. This review discusses about different levels of correlations, general approaches to develop an IVIVC by mathematical modelling, validation, data analysis and various applications. In the current setting, the dearth of success associated with IVIVC is due to complexity of underlying scientific principles as well as the practice of fitting/matching in vivo plasma level-time data with in vitro dissolution profile. Hence, a simple, straightforward practical means to predict plasma drug levels by convolution technique and percentage drug absorbed computed from in vitro dissolution profile based on deconvolution method are illustrated. The bioavailability/bioequivalence assessment and evaluation are frequently validated by the pharmacokinetic parameters such as maximum concentration, time to reach maximum concentration, and area under the curve. The implementation of a quality by design manufacturing based on in vivo bioavailability and clinically relevant dissolution specification are recommended because corresponding design safe space will guarantee that all batches from relevant products are met with sufficient quality and bioperformance. Recently, United States Food and Drug Administration and European Medicines Agency have proposed that in silico/physiologically based pharmacokinetic modelling can be used in decision making during preclinical experiments as well as to recognize the dissolution profiles that can forecast and ensure the desired clinical performance.

Reactive oxygen species modulate itraconazole-induced apoptosis via mitochondrial disruption in Candida albicans

Itraconazole (ITC), a well-known fungistatic agent, has potent fungicidal activity against Candida albicans. However, its mechanism of fungicidal activity has not been elucidated yet, and we aimed to identify the mechanism of ITC against C. albicans. ITC caused cell shrinkage via potassium leakage through the ion channel. Since shrunken cells could indicate apoptosis, we investigated apoptotic features. Annexin V-FITC and TUNEL assays indicated that fungicidal activity of ITC was involved in apoptosis. Subsequently, we confirmed an intracellular factor that could cause apoptosis. ITC treatment caused reactive oxygen species (ROS) accumulation. To confirm whether ROS is related with ITC-triggered cell death, cell viability was examined using the ROS scavenger N-acetylcysteine (NAC). NAC pretreatment recovered ITC-induced cell death, indicating that antifungal activity of ITC is associated with ROS, which is also confirmed by impaired glutathione-related antioxidant system and oxidized intracellular lipids. Moreover, ITC-induced mitochondrial dysfunction, in turn, triggered cytochrome c release and metacaspase activation, leading to apoptosis. Unlike the only ITC-treatment group, cells with NAC pretreatment did not show significant damage to mitochondria, and attenuated apoptotic features. Therefore, our results suggest that ITC induces apoptosis as fungicidal mechanism, and intracellular ROS is major factor to trigger the apoptosis by ITC in C. albicans.

Therapeutic drug monitoring for invasive mould infections and disease: pharmacokinetic and pharmacodynamic considerations

Therapeutic drug monitoring (TDM) may be required to achieve optimal clinical outcomes in the setting of significant pharmacokinetic variability, a situation that applies to a number of anti-mould therapies. The majority of patients receiving itraconazole should routinely be managed with TDM. Voriconazole exhibits highly variable inter-individual pharmacokinetics, and a trough concentration of 1.0-5.5 mg/L is widely accepted although it is derived from relatively low-quality evidence. The case for TDM of posaconazole is currently in a state of flux following the introduction of a newer tablet formulation with improved oral bioavailability, but it may be indicated when used for either prophylaxis or treatment of established disease. The novel broad-spectrum azole drug isavuconazole does not currently appear to require TDM but 'real-world' data are awaited and TDM could be considered in selected clinical cases. For both polyene and echinocandin agents, there are insufficient data regarding the relationship between serum concentrations and therapeutic outcomes to support the routine use of TDM. A number of practical challenges to the implementation of TDM in the treatment of invasive mould infections remain unsolved. The delivery of TDM as a future standard of care will require real-time measurement of drug concentrations at the bedside and algorithms for dosage adjustment. Finally, measures of pharmacodynamic effect are required to deliver therapy that is truly individualized.