On the usefulness of compendial setups and tiny-TIM system in evaluating the in vivo performance of oral drug products with various release profiles in the fasted state: Case example sodium salt of A6197

The revival of the mini-tablets: Recent advancements, classifications and expectations for the future

Mini-tablets have recently raised huge interest in pharmaceutical industry. The present review aims to identify the rational, the opportunities and challenges of this emerging small solid drug dosage form by a structured literature review following the PRISMA algorithm. In total, more than 5,000 literature and patent sources have been found starting with the very first in the 60s of the past century, followed by the first multiparticular products using mini-tablets with pancreatin (Panzytrat® by the former BASF subsidiary Knoll/Nordmark) authorized in 1985. There seems to be a second boost of common interest in the 2000s when clinical studies demonstrated that one or more mini-tablets could enable superior drug administration even in very young patients including neonates over the former gold standard, a liquid drug preparation. Several pharmaceutical companies immediately started clinical development programs using the mini-tablet concept and the first products have been recently authorized by the competent authorities. Superiority was given as the mini-tablets ease the swallowing procedure compared to conventional tablets, enable various modified drug release opportunities including taste-masking by film-coating technology and provide excellent drug stability compared to liquid oral dosage forms. Due to these product attributes they are particularly beneficial to children and their caregivers. Furthermore, there is potential for precise individual drug dosing by counting adequate amounts of the multiple drug carriers. Most recently, two novel products with different concepts were authorized by the EMA and entered the market which are highlighted in this review: the first orodispersible mini-tablet with enalapril maleate for congenital heart failure (Aqumeldi® from Proveca Pharma) and the first single unit mini-tablet with matrix-type controlled melatonin release for insomnia (Slenyto® from Neurim Pharmaceuticals). Our review reveals, that the majority of the published scientific papers use co-processed, ready-to-use excipients for the orodispersible mini-tablet formulations. However, traditional fillers such as microcrystalline cellulose or lactose have also been used for immediate release mini-tablets after adding a (super)disintegrant and a lubricant. The manufacturing of mini-tablets is conducted on conventional rotary tablet presses, predominantly equipped with multi-tip toolings to improve the yield or production speed. Scaling-up has been successfully realized from compaction simulators to pilot and production scale. Film-coatings enabling gastric resistance, taste masking or sustained-release properties have been realized in both fluid-bed and drum coaters using the same polymers as for conventional tablets. There is still a significant lack in regulatory guidance despite the recent success of the mini-tablet concept, starting from suitable characterization methods in the pharmacopoeias up to the design and conduct of clinical studies on mini-tablets.

Digitalizing the TIM-1 Model Using Computational Approaches─Part Two: Digital TIM-1 Model in GastroPlus

A TIM-1 model is an in vitro gastrointestinal (GI) simulator considering crucial physiological parameters that will affect the in vivo drug release process. The outcome of these experiments can indicate the critical bioavailability attributes (CBAs) that will impact the fraction absorbed in vivo. The model is widely used in the nonclinical stage of drug product development to assess the bioaccessible fraction of drugs for numerous candidate formulations. In this work, we developed a digital TIM-1 model in the GastroPlus platform. In a first step, we performed validation experiments to assess the luminal concentrations and bioaccessible fractions for two marker compounds. The digital TIM-1 was able to adequately reflect the luminal concentrations and bioaccessible fractions of these markers under different prandial conditions, confirming the appropriate integration of mass transfer in the TIM-1 model. In a second set of experiments, a case example with PF-07059013 was performed, where luminal concentrations and bioaccessible fractions were predicted for 200 and 1000 mg doses under fasted and achlorhydric conditions. Experimental and simulated data pointed out that the achlorhydric effect was more pronounced at the 1000 mg dose, showing a solubility-limited dissolution and, consequently, decreased bioaccessible fraction. Toward future applications, the digital TIM-1 model will be thoroughly applied to explore a link between in vitro and in vivo outcomes based on more case examples with model compounds with the access of TIM-1 and plasma data. Ideally, this digital TIM-1 can be directly used in GastroPlus to explore an in vitro-in vivo correlation (IVIVC) between the fraction dissolved (digital TIM-1 settings) and the fraction absorbed (human PBPK settings).

Application of biorelevant in vitro assays for the assessment and optimization of ASD-based formulations for pediatric patients

Amorphous solid dispersions (ASD) have been a successful formulation strategy to overcome the poor aqueous solubility of many novel drugs, but the development of pediatric formulations presents a special challenge due to variable gastrointestinal conditions in children. It was the aim of this work to design and apply a staged biopharmaceutical test protocol for the in vitro assessment of ASD-based pediatric formulations. Ritonavir was used as a model drug with poor aqueous solubility. Based on the commercial ASD powder formulation, a mini-tablet and a conventional tablet formulation were prepared. Drug release from the three formulations was studied in different biorelevant in vitro assays (i.e. MicroDiss, two-stage, transfer model, tiny-TIM) to consider different aspects of human GI physiology. Data from the two-stage and transfer model tests indicated that by controlled disintegration and dissolution excessive primary precipitation can be prevented. However, this advantage of the mini-tablet and tablet formulation did not translate into better performance in tiny-TIM. Here, the in vitro bioaccessibility was comparable for all three formulations. In the future, the staged biopharmaceutical action plan established herein will support the development of ASD-based pediatric formulations by improving the mechanistic understanding so that formulations are developed for which drug release is robust against variable physiological conditions.

Evaluating effect of salt leaching method on release and swelling rate of metformin nanoparticles loaded-chitosan/polyvinyl alcohol porous composite

In this study, salt leaching (SL) technique was used to prepare a chitosan/polyvinyl alcohol (CS/PVA) polymeric composite in order to load metformin nanoparticles (METNPs). Sodium chloride was added to the CS/PVA (0.5:0.1) composite to create a porous hydrogel using the SL technique. METNPs were then prepared by water/oil (w/o) method and loaded into the hydrogel structure. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis confirmed that >80 % of the METNPs were in the range of 10 nm. As a result, encapsulation increased due to the increase in surface-to-volume ratio. Scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) results confirmed that creating porosity in the polymer composition by the SL method led to increased CS/PVA polymer chain mobility. The drug encapsulation increased due to more porosity, and the release in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) was according to the controlled diffusion kinetics. Furthermore, the drug release from CS/PVA composite was anomalous carrier type that could be attributed to the addition of salt. However, due to the increase the amount of PVA and the creation of a monotonous composite structure, encapsulation of drug decreased, which is in accordance with the polymer relaxation mechanism.

Using Tiny-TIM Dissolution and In Silico Simulation to Accelerate Oral Product Development of a BCS Class II Compound

Though oral drug delivery is the most preferred route of administration, there is high drug pharmacokinetic variability associated with the oral route. Change in drug substance particle size distribution, formulation composition, or manufacturing process may impact the dissolution and, hence, the systemic drug absorption in biopharmaceutics classification system class II compounds. In the present research, using a Boehringer Ingelheim investigational drug substance as the model compound, the tiny-TIM in vitro data and in silico pharmacokinetic model were used to establish in vitro-in vivo correlation and to predict the oral bioavailability. The level C in vitro-in vivo correlation between in vivo AUC and in vitro amount dissolved in both fasted and fed states could be established. Furthermore, level A in vitro-in vivo correlation was established between in vivo fraction absorbed and bioaccessibility from tiny-TIM dissolution in both fasted and fed states. Prediction of positive food effect from tiny-TIM dissolution was consistent with conclusion from clinical studies. Such predictive models developed using the minimum clinical data and the in vitro tiny-TIM data have the potential to reduce the animal and human experiments and to expedite the overall drug development process.

Mucin-Protected Caco-2 Assay to Study Drug Permeation in the Presence of Complex Biorelevant Media

The poor solubility and permeability of compounds beyond Lipinski’s Rule of Five (bRo5) are major challenges for cell-based permeability assays. Due to their incompatibility with gastrointestinal components in biorelevant media, the exploration of important questions addressing food effects is limited. Thus, we established a robust mucin-protected Caco-2 assay to allow the assessment of drug permeation in complex biorelevant media. To do that, the assay conditions were first optimized with dependence of the concentration of porcine mucin added to the cells. Mucin-specific effects on drug permeability were evaluated by analyzing cell permeability values for 15 reference drugs (BCS class I–IV). Secondly, a sigmoidal relationship between mucin-dependent permeability and fraction absorbed in human (f_a) was established. A case study with venetoclax (BCS class IV) was performed to investigate the impact of medium complexity and the prandial state on drug permeation. Luminal fluids obtained from the tiny-TIM system showed a higher solubilization capacity for venetoclax, and a better read-out for the drug permeability, as compared to FaSSIF or FeSSIF media. In conclusion, the mucin-protected Caco-2 assay combined with biorelevant media improves the mechanistic understanding of drug permeation and addresses complex biopharmaceutical questions, such as food effects on oral drug absorption.

Development of In Vitro Dissolution Testing Methods to Simulate Fed Conditions for Immediate Release Solid Oral Dosage Forms

In vitro dissolution testing is widely used to mimic and predict in vivo performance of oral drug products in the gastrointestinal (GI) tract. This literature review assesses the current in vitro dissolution methodologies being employed to simulate and predict in vivo drug dissolution under fasted and fed conditions, with emphasis on immediate release (IR) solid oral dosage forms. Notable human GI physiological conditions under fasted and fed states have been reviewed and summarized. Literature results showed that dissolution media, mechanical forces, and transit times are key dissolution test parameters for simulating specific postprandial conditions. A number of biorelevant systems, including the fed stomach model (FSM), GastroDuo device, dynamic gastric model (DGM), simulated gastrointestinal tract models (TIM), and the human gastric simulator (HGS), have been developed to mimic the postprandial state of the stomach. While these models have assisted in expanding physiological relevance of in vitro dissolution tests, in general, these models lack the ability to fully replicate physiological conditions/processes. Furthermore, the translatability of in vitro data to an in vivo system remains challenging. Additionally, physiologically based pharmacokinetic (PBPK) modeling has been employed to evaluate the effect of food on drug bioavailability and bioequivalence. Here, we assess the current status of in vitro dissolution methodologies and absorption PBPK modeling approaches to identify knowledge gaps and facilitate further development of in vitro dissolution methods that factor in fasted and fed states. Prediction of in vivo drug performance under fasted and fed conditions via in vitro dissolution testing and modeling may potentially help efforts in harmonizing global regulatory recommendations regarding in vivo fasted and fed bioequivalence studies for solid oral IR products.

Best practices in current models mimicking drug permeability in the gastrointestinal tract - an UNGAP review

The absorption of orally administered drug products is a complex, dynamic process, dependent on a range of biopharmaceutical properties; notably the aqueous solubility of a molecule, stability within the gastrointestinal tract (GIT) and permeability. From a regulatory perspective, the concept of high intestinal permeability is intrinsically linked to the fraction of the oral dose absorbed. The relationship between permeability and the extent of absorption means that experimental models of permeability have regularly been used as a surrogate measure to estimate the fraction absorbed. Accurate assessment of a molecule's intestinal permeability is of critical importance during the pharmaceutical development process of oral drug products, and the current review provides a critique of in vivo, in vitro and ex vivo approaches. The usefulness of in silico models to predict drug permeability is also discussed and an overview of solvent systems used in permeability assessments is provided. Studies of drug absorption in humans are an indirect indicator of intestinal permeability, but in vitro and ex vivo tools provide initial screening approaches are important tools for direct assessment of permeability in drug development. Continued refinement of the accuracy of in silico approaches and their validation with human in vivo data will facilitate more efficient characterisation of permeability earlier in the drug development process and will provide useful inputs for integrated, end-to-end absorption modelling.

Prediction of in vivo supersaturation and precipitation of poorly water-soluble drugs: Achievements and aspirations

This review focuses on options available to a pharmaceutical scientist to predict in vivo supersaturation and precipitation of poorly water-soluble drugs. As no single device or system can simulate the complex gastrointestinal environment, a combination of appropriate in vitro tools may be utilized to get optimal predictive information. To address the empirical issues encountered during small-scale and full-scale in vitro predictive testing, theoretical background and relevant case studies are discussed. The practical considerations for selection of appropriate tools at various stages of drug development are recommended. Upcoming technologies that have potential to further reduce in vivo studies and expedite the drug development process are also discussed.

Impact of polymer type, ASD loading and polymer-drug ratio on ASD tablet disintegration and drug release

Amorphous solid dispersion (ASD) has become an attractive strategy to enhance solubility and bioavailability of poorly water-soluble drugs. To facilitate oral administration, ASDs are commonly incorporated into tablets. Disintegration and drug release from ASD tablets are thus critical for achieving the inherent solubility advantage of amorphous drugs. In this work, the impact of polymer type, ASD loading in tablet and polymer-drug ratio in ASD on disintegration and drug release of ASD tablets was systematically studied. Two hydrophilic polymers PVPVA and HPMC and one relatively hydrophobic polymer HPMCAS were evaluated. Dissolution testing was performed, and disintegration time was recorded during dissolution testing. As ASD loading increased, tablet disintegration time increased for all three polymer-based ASD tablets, and this effect was more pronounced for hydrophilic polymer-based ASD tablets. As polymer-drug ratio increased, tablet disintegration time increased for hydrophilic polymer-based ASD tablets, however, it remained short and largely unchanged for HPMCAS-based ASD tablets. Consequently, at high ASD loadings or high polymer-drug ratios, HPMCAS-based ASD tablets showed faster drug release than PVPVA- or HPMC-based ASD tablets. These results were attributed to the differences between polymer hydrophilicities and viscosities of polymer aqueous solutions. This work is valuable for understanding the disintegration and drug release of ASD tablets and provides insight to ASD composition selection from downstream tablet formulation perspective.

The Introduction of a New Flexible In Vivo Predictive Dissolution Apparatus, GIS-Alpha (GIS-α), to Study Dissolution Profiles of BCS Class IIb Drugs, Dipyridamole and Ketoconazole

The physiological pH changes and peristalsis activities in gastrointestinal (GI) tract have big impact on the dissolution of oral drug products, when those oral drug products include APIs with pH-dependent solubility. It is well documented that predicting the bioperformance of those oral drug products can be challenging using compendial methods. To overcome this limitation, in vivo predictive dissolution apparatuses, such as the transfer model, have been developed to predict bioperformance of oral formulation candidates and drug products. In this manuscript we utilize a new transfer-model dissolution apparatus, the gastrointestinal simulator-α (GIS-α), to characterize its behavior in terms of transfer kinetics and pH, assess its reproducibility and adaptability to mimic different transfer conditions, as well as study dissolution of ketoconazole and dipyridamole as model BCS class IIb compounds. Availability of commercially available dissolution transfer systems with similar configuration to compendial dissolution apparatus, may be helpful to simplify and standardize in vivo predictive dissolution methodologies for BCS class IIb compounds in the future.

Dissolution testing of modified release products with biorelevant media: An OrBiTo ring study using the USP apparatus III and IV

During the OrBiTo project, our knowledge on the gastrointestinal environment has improved substantially and biorelevant media composition have been refined. The aim of this study was to propose optimized biorelevant testing conditions for modified release products, to evaluate the reproducibility of the optimized compendial apparatus III (USP apparatus III) and compendial apparatus IV (USP apparatus IV, open-loop mode) dissolution methods and to evaluate the usefulness of these methods to forecast the direction of food effects, if any, based on the results of two «ring» studies and by using two model modified release (MR) products, Ciproxin / Cipro XR and COREG CR. Six OrBiTo partners participated in each of the ring studies. All laboratories were provided with standard protocols, pure drug substance, and dose units. For the USP apparatus III, the dissolution methods applied to Ciproxin / Cipro XR, a monolithic MR product of an active pharmaceutical ingredient (API) with moderate aqueous solubility, were robust with low intra- and inter-laboratory data variability. Data from all partners were in line on a qualitative basis with food effect data in humans. For the USP apparatus IV, the dissolution methods applied to COREG CR, a multiparticulate, pH dependent, MR product of an API with low and pH dependent solubility led to high intra- and inter- laboratory data variability. Data from all partners were in line, on a qualitative basis, with the previously observed food effects in humans.