In vitro and in vivo evaluation of amorphous solid dispersions generated by different bench-scale processes, using griseofulvin as a model compound

Optimization of Spray-Drying Parameters for Formulation Development at Preclinical Scale

Spray-drying dispersion (SDD) is a well-established manufacturing technique used to prepare amorphous solid dispersions (ASDs), allowing for poorly soluble drugs to have improved bioavailability. However, the process of spray-drying with multiple factors and numerous variables can lead to a lengthy development timeline with intense resource requirements, which becomes the main obstacle limiting spray-drying development at the preclinical stage. The purpose of this work was to identify optimized preset parameters for spray-drying to support the early development of ASDs suitable for most circumstances rather than individual optimization. First, a mini-DoE (Design of Experiment) study was designed to evaluate the critical interplay of two key variables for spray-drying using a BUCHI B-290 mini spray dryer: solid load and atomizing spray gas flow. The critical quality attributes (CQAs) of the ASDs, including yield, particle size, morphology, and in vitro release profile, were taken into account to identify the impact of the key variables. The mini-DoE results indicated that a 5% solid load (w/v %) and 35 mm height atomizing spray gas flow were the most optimized parameters. These predefined values were further verified using different formulation compositions, including various polymers (Eudragit L100-55, HPMCAS-MF, PVAP, and PVP-VA64) and drugs (G-F, GEN-A, Indomethacin, and Griseofulvin), a range of drug loading (10 to 40%), and scale (200 mg to 200 g). Using these predefined parameters, all ASD formulations resulted in good yields as well as consistent particle size distribution. This was despite the differences in the formulations, making this a valuable and rapid approach ideal for early development. This strategy of leveraging the preset spray-drying parameters was able to successfully translate into a reproducible and efficient spray-drying platform while also saving material and reducing developmental timelines in early-stage formulation development.

Amorphous Solid Dispersions: Utilization and Challenges in Preclinical Drug Development within AstraZeneca

The poor aqueous solubility of many active pharmaceutical ingredients (APIs) dominates much of the early drug development portfolio and poses a major challenge in pharmaceutical development. Polymer-based amorphous solid dispersions (ASDs) are becoming increasingly common and offer a promising formulation strategy to tackle the solubility and oral absorption issues of these APIs. This review discusses the design, manufacture, and utilisation of ASD formulations in preclinical drug development, with a key focus on the pre-formulation assessments and workflows employed at AstraZeneca.

Hierarchical Particle Approach for Co-Precipitated Amorphous Solid Dispersions for Use in Preclinical In Vivo Studies

Amorphous solid dispersions (ASD) have become a well-established strategy to improve exposure for compounds with insufficient aqueous solubility. Of methods to generate ASDs, spray drying is a leading route due to its relative simplicity, availability of equipment, and commercial scale capacity. However, the broader industry adoption of spray drying has revealed potential limitations, including the inability to process compounds with low solubility in volatile solvents, inconsistent molecular uniformity of spray dried amorphous dispersions, variable physical properties across batches and scales, and challenges containing potent compounds. In contrast, generating ASDs via co-precipitation to yield co-precipitated amorphous dispersions (cPAD) offers solutions to many of those challenges and has been shown to achieve ASDs comparable to those manufactured via spray drying. This manuscript applies co-precipitation for early safety studies, developing a streamlined process to achieve material suitable for dosing as a suspension in conventional toxicity studies. Development targets involved achieving a rapid, safely contained process for generating ASDs with high recovery yields. Furthermore, a hierarchical particle approach was used to generate composite particles where the cPAD material is incorporated in a matrix of water-soluble excipients to allow for rapid re-dispersibility in the safety study vehicle to achieve a uniform suspension for consistent dosing. Adopting such an approach yielded a co-precipitated amorphous dispersion with comparable stability, thermal properties, and in vivo pharmacokinetics to spray dried amorphous materials of the same composition.

Selective Laser Sintering 3-Dimensional Printing as a Single Step Process to Prepare Amorphous Solid Dispersion Dosage Forms for Improved Solubility and Dissolution Rate

This study reports the development of ritonavir-copovidone amorphous solid dispersions (ASDs) and dosage forms thereof using selective laser sintering (SLS) 3-dimensional (3-D) printing in a single step, circumventing the post-processing steps required in common techniques employed to make ASDs. For this study, different drug loads of ritonavir with copovidone were processed at varying processing conditions to understand the impact, range, and correlation of these parameters for successful ASD formation. Further, ASDs characterized using conventional and advanced solid-state techniques including wide-angle X-ray scattering (WAXS), solid-state nuclear magnetic resonance (ssNMR), revealed the full conversion of the crystalline drug to its amorphous form as a function of laser-assisted selective fusion in a layer-by-layer manner. It was observed that an optimum combination of the powder flow properties, surface temperature, chamber temperature, laser speed, and hatch spacing was crucial for successful ASD formation, any deviations resulted in print failures or only partial amorphous conversion. Moreover, a 21-fold increase in solubility was demonstrated by the SLS 3-D printed tablets. The results confirmed that SLS 3-D printing can be used as a single-step platform for creating ASD-based pharmaceutical dosage forms with a solubility advantage.

Hypromellose - A traditional pharmaceutical excipient with modern applications in oral and oromucosal drug delivery

Hydroxypropylmethylcellulose (HPMC), also known as Hypromellose, is a traditional pharmaceutical excipient widely exploited in oral sustained drug release matrix systems. The choice of numerous viscosity grades and molecular weights available from different manufacturers provides a great variability in its physical-chemical properties and is a basis for its broad successful application in pharmaceutical research, development, and manufacturing. The excellent mucoadhesive properties of HPMC predetermine its use in oromucosal delivery systems including mucoadhesive tablets and films. HPMC also possesses desirable properties for formulating amorphous solid dispersions increasing the oral bioavailability of poorly soluble drugs. Printability and electrospinnability of HPMC are promising features for its application in 3D printed drug products and nanofiber-based drug delivery systems. Nanoparticle-based formulations are extensively explored as antigen and protein carriers for the formulation of oral vaccines, and oral delivery of biologicals including insulin, respectively. HPMC, being a traditional pharmaceutical excipient, has an irreplaceable role in the development of new pharmaceutical technologies, and new drug products leading to continuous manufacturing processes, and personalized medicine. This review firstly provides information on the physical-chemical properties of HPMC and a comprehensive overview of its application in traditional oral drug formulations. Secondly, this review focuses on the application of HPMC in modern pharmaceutical technologies including spray drying, hot-melt extrusion, 3D printing, nanoprecipitation and electrospinning leading to the formulation of printlets, nanoparticle-, microparticle-, and nanofiber-based delivery systems for oral and oromucosal application. Hypromellose is an excellent excipient for formulation of classical dosage forms and advanced drug delivery systems. New methods of hypromellose processing include spray draying, hot-melt extrusion, 3D printing, and electrospinning.

Formulation and evaluation of cyclodextrin-based nanosponges of griseofulvin as pediatric oral liquid dosage form for enhancing bioavailability and masking bitter taste

The aim of this study was the development of griseofulvin (GRI) loaded β-cyclodextrin (β–CD) based nanosponges for bitter taste masking, improving dissolution rate and oral bioavailability. Plain NS (NS1 NS2 and NS3) were fabricated by reacting β-CD with the cross-linker diphenyl carbonate at different molar ratios (1:2, 1:4 and 1:6, respectively) using ultrasonication method. The NS2 provided both highest %yield and GRI solubilization enhancement. Thus, the drug was loaded in NS2 at different NS2: drug weight ratios in presence or absence of 0.25%w/w polyvinylpyrolidone (PVP k30). The GRI loaded NS (F1) that provided highest drug loading capacity and entrapment efficiency (47.20 ± 0.38%, 84.91 ± 0.30%, respectively) was morphologically examined using scanning electron microscopy (SEM). Also, Particle size, zeta potential, differential scanning calorimetry (DSC), Fourier transform infra-red (FT-IR), nuclear magnetic resonance (NMR) spectroscopy, in-vitro release, taste masking potential were evaluated. Moreover, in-vivo Pharmacokinetic studies were performed on rats. The F1 showed particle size 665.9 ± 13.8 nm and zeta potential −21.5 ± 0.7 mV. The DSC and FT-IR analysis confirmed the complexation of GRI with NS2. Nanosponges (F1) provided 3.19, folds increase in dissolution efficiency %, 2.13 and 3.78 folds increase in C_max and AUC_0-48 compared to plain GRI. Taste masking evaluation confirmed the potential of GRI nanosponges (F1) in masking the bitter taste of GRI completely. The study confirmed that complexation of GRI with NS would be a viable approach for masking the bitter taste of GRI and improving oral bioavailability, that Cmax, Tmax and AUC 0–48 were significantly higher for the developed formulation (F1).

Miniaturized Measurement of Drug-Polymer Interactions via Viscosity Increase for Polymer Selection in Amorphous Solid Dispersions

Drug-polymer interactions have a substantial impact on stability and performance of amorphous solid dispersions (ASD) but are difficult to analyze. Whereas there are many screening methods described for polymer selection based for example on glass forming ability, drug-polymer miscibility, supersaturation, or inhibition of recrystallization, the distinct detection of physico-chemical interactions mostly lacks miniaturized techniques. This work presents an interaction screening assessing the relative viscosity increase between highly concentrated polymer solutions with and without the model drug ketoconazole (KTZ). The fluorescent molecular rotor 9-(2-carboxy-2-cyanovinyl)julolidine was added to the solutions in a miniaturized setup in μL-scale. Due to its environment-sensitive emission behavior, the integrated fluorescence intensity can be used as a viscosity dye within this screening approach (FluViSc). Differences in relative viscosity increases through addition of KTZ were proposed to rank polymers regarding KTZ-polymer interactions. Absolute viscosities were measured with a cone-plate rheometer as a complimentary method and supported the results acquired by the FluViSc. Solid-state nuclear magnetic resonance (ss-NMR) relaxation time measurements and Raman spectroscopy were utilized to investigate drug-polymer interactions at a molecular level. Whereas Raman spectroscopy was not suited to reveal KTZ-polymer interactions, ss-NMR relaxation time measurements differentiated between the selected polymeric carriers hydroxypropylmethylcellulose acetate succinate (HPMCAS) and polyvinylpyrrolidone vinyl acetate 60:40 (PVP-VA64). Interactions were detected for HPMCAS/KTZ ASD while there was no hint for interactions between KTZ and PVP-VA64. These results were in correlation with the FluViSc. The findings were correlated with the dissolution performance of ASD and found to be predictive for supersaturation and inhibition of precipitation during dissolution.

Spray drying OZ439 nanoparticles to form stable, water-dispersible powders for oral malaria therapy

Background

OZ439 is a new chemical entity which is active against drug-resistant malaria and shows potential as a single-dose cure. However, development of an oral formulation with desired exposure has proved problematic, as OZ439 is poorly soluble (BCS Class II drug). In order to be feasible for low and middle income countries (LMICs), any process to create or formulate such a therapeutic must be inexpensive at scale, and the resulting formulation must survive without refrigeration even in hot, humid climates. We here demonstrate the scalability and stability of a nanoparticle (NP) formulation of OZ439. Previously, we applied a combination of hydrophobic ion pairing and Flash NanoPrecipitation (FNP) to formulate OZ439 NPs 150 nm in diameter using the inexpensive stabilizer hydroxypropyl methylcellulose acetate succinate (HPMCAS). Lyophilization was used to process the NPs into a dry form, and the powder’s in vitro solubilization was over tenfold higher than unprocessed OZ439.

Methods

In this study, we optimize our previous formulation using a large-scale multi-inlet vortex mixer (MIVM). Spray drying is a more scalable and less expensive operation than lyophilization and is, therefore, optimized to produce dry powders. The spray dried powders are then subjected to a series of accelerated aging stability trials at high temperature and humidity conditions.

Results

The spray dried OZ439 powder’s dissolution kinetics are superior to those of lyophilized NPs. The powder’s OZ439 solubilization profile remains constant after 1 month in uncapped vials in an oven at 50 °C and 75% RH, and for 6 months in capped vials at 40 °C and 75% RH. In fasted-state intestinal fluid, spray dried NPs achieved 80–85% OZ439 dissolution, to a concentration of 430 µg/mL, within 3 h. In fed-state intestinal fluid, 95–100% OZ439 dissolution is achieved within 1 h, to a concentration of 535 µg/mL. X-ray powder diffraction and differential scanning calorimetry profiles similarly remain constant over these periods.

Conclusions

The combined nanofabrication and drying process described herein, which utilizes two continuous unit operations that can be operated at scale, is an important step toward an industrially-relevant method of formulating the antimalarial OZ439 into a single-dose oral form with good stability against humidity and temperature.

Electronic supplementary material

The online version of this article (10.1186/s12967-019-1849-8) contains supplementary material, which is available to authorized users.

Relative Bioavailability Risk Assessment: A Systematic Approach to Assessing In Vivo Risk Associated With CM&C-Related Changes

Relative bioavailability (RBA) studies are often carried out to bridge changes made between drug products used for clinical studies. In this work, we describe the development of a risk assessment (RA) tool that comprehensively and objectively assesses the risk of noncomparable in vivo performance associated with Chemistry, Manufacturing, and Controls (CM&C)-related changes. The RA tool is based on a risk grid that provides a quantitative context to facilitate discussions to determine the need for an in vivo RBA study. Relevant regulatory guidances and the required in vitro and in silico absorption modeling data, on which the RA is based, are discussed. In addition, an analysis of previously executed RBA studies at Eli Lilly and Company over a period of several years is presented. The risk grid incorporates individual risk factors for a given study and provides a recommendation on the risk associated with bypassing an RBA study. The outcome of an RA results in 1 of 3 possible risk zones; lower tier risk, intermediate tier risk, and upper tier risk. In cases where the outcome from the RA falls into the intermediate tier risk zone, further in depth data analysis is required.

A rational approach towards development of amorphous solid dispersions: Experimental and computational techniques

The purpose of this study was to determine the drug-polymer miscibility of GENE-A, a Genentech molecule, and hydroxypropyl methylcellulose-acetate succinate (HPMC-AS), a polymer, using computational and experimental approaches. The Flory-Huggins interaction parameter,χ, was obtained by calculating the solubility parameters for GENE-A and HPMC-AS over the temperature range of 25-100°C to obtain the free energy of mixing at different drug loadings (0-100%) using the Materials Studio modeling and simulation platform (thermodynamic approach). Solid-state nuclear magnetic spectroscopy (ssNMR) was used to measure the proton relaxation times for both drug and polymer at different drug loadings (up to 60%) at RT (kinetic approach). Thermodynamically, the drug and polymer were predicted to show favorable mixing as indicated by a negative Gibbs free energy of mixing from 25 to 100°C. ssNMR showed near identical relaxation times for both drug and polymer in the solid dispersion at RT and 40°C for a period up to 6 months showing phase mixing between the API and polymer on <10nm scale. Orthogonal computational and experimental approaches indicate phase mixing of the system components.

In vitro and in vivo effects of morin on the intestinal absorption and pharmacokinetics of olmesartan medoxomil solid dispersions

PURPOSE

In-situ evaluation to corroborate morin effects on the intestinal absorption and pharmacokinetic behavior of freeze-dried OLM-loaded solid dispersions with Caco-2 and in-vivo studies Methods: Intestinal transport and absorption studies were examined by Caco-2 permeability, in-situ single pass perfusion and closed-loop models along with in-vivo pharmacokinetic studies to evaluate and confirm the effect of P-gp-mediated activity of morin. We evaluated the intestinal membrane damage in the presence of morin by measuring the release of protein and lactate dehydrogenase (LDH) followed by using qualitative and quantitative morphometric analysis to describe the surface characteristics of intestinal epithelium.

RESULTS

Morin showed the highest P_eff value 13.8 ± 0.34 × 10^-6cm/s in jejunum than ileum (p < .01) at 100 µM with absorption enhancement of 1.31-fold together with enhanced (p < .01) secretory transport of 6.27 ± 0.27 × 10 ^-6cm/s in Caco-2 monolayer cells. Our findings noticed 2.37 (in-situ); 2.39 (in-vivo) and 1.43 (in-situ); 1.36 (in-vivo) fold increase in AUC_0-t with elevated C_max and shortened T_max for freeze-dried solid dispersion in the presence of morin as compared to pure OLM and freeze-dried solid dispersions without morin, respectively.

CONCLUSIONS

Our study demonstrated that increased solubilization through freeze-dried OLM-loaded solid dispersion together with efflux inhibition improved intestinal permeability to one system that might lead to novel solubilization and efflux pump inhibition as a novel alternative potential to increase oral absorption and bioavailability of OLM.

Hot melt extruded Aprepitant-Soluplus solid dispersion: preformulation considerations, stability and in vitro study

CONTEXT

Solubility limitation of BCS class II drugs pose challenges to in vitro release.

OBJECTIVE

To investigate the miscibility of Aprepitant (APR) and Soluplus(®) (SOL) for hot melt extrusion (HME) viability and improved in vitro release of APR.

METHODS

Solubility parameters of APR and SOL from group contribution methods were evaluated. Heat-cool-heat differential scanning calorimetry (DSC) scans were assessed for determining the glass forming ability (GFA) and glass stability (GS) of APR. An optimum HME temperature was selected based on melting point depression in physical mixtures. Moisture sorption isotherms were collected using a dynamic vapor sorption (DVS) analyzer at 25 °C. A 1:4 APR:SOL physical mixture was extruded in a co-rotating 12 mm twin screw extruder and in vitro release was assessed in fasted state simulated intestinal fluid (FaSSIF) with 0.25% SLS. Extrudates were analyzed using TGA, DSC, XRD and FTIR.

RESULTS

APR was classified as a class II glass former. APR and SOL had composition dependent miscibility based on Gibb's free energy of mixing. Extrudate prepared using HME had an amorphous as well as a crystalline phase that showed good stability in accelerated stability conditions. Smaller particle size extrudates exhibited a higher % moisture uptake and in vitro release compared to larger particle size extrudates. Enhanced in vitro release of APR from extrudates was attributed to amorphization of APR, solubilization as well as crystal growth inhibition effect of SOL due to H-bond formation with APR.

CONCLUSIONS

A solid dispersion of APR with improved in vitro release was successfully developed using HME technology.

Enhancement of docetaxel solubility using binary and ternary solid dispersion systems

CONTEXT

Poor biopharmaceutical properties and toxicities associated with the intravenous formulation of docetaxel (DTX) necessitate the exploration of an alternate oral route of delivery.

OBJECTIVE

This study aims at enhancing the solubility of poorly soluble drug, DTX with the help of solid dispersion (SD) technique.

METHOD

DTX SDs were formulated with selected solubilizers, including Kollidon 12PF, Lutrol F68, Soluplus and Hydroxypropyl-β-cyclodextrin in different weight ratios. Freeze-drying method was used to prepare the binary and ternary SDs. Kinetic solubility of the SDs was evaluated in order to select best DTX-solubilizer combination. Best performing combination was then characterized using differential scanning calorimeter (DSC), powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM).

RESULTS AND DISCUSSION

Among all SDs tested, Soluplus outperformed all the excipients at equivalent weight ratio. Binary SD of DTX and Soluplus (1:10) resulted in the highest improvement in solubility (362.93 ± 11.01 µg/mL). This is approximately a 93-fold increment as compared to the solubility of crystalline DTX (3.9 ± 0.2 µg/mL). This exceptional performance can be attributed to solid-state transformation as well as micellization.

CONCLUSION

Among all the excipients tested, Soluplus dispersion is the most promising candidate for oral formulation development.

Amorphous solid dispersions: a robust platform to address bioavailability challenges

Amorphous solid dispersions (ASDs) are being used with increasing frequency for poorly soluble pharmaceutical compounds in development. These systems consist of an amorphous active pharmaceutical ingredient stabilized by a polymer to produce a system with improved physical and solution stability. ASDs are commonly considered as a means of improving the apparent solubility of an active pharmaceutical ingredient. This review will discuss methods of preparation and characterization of ASDs with an emphasis on understanding and predicting stability. Theoretical understanding of supersaturation and predicting in vivo performance will be stressed. Additionally, a summary of preclinical and clinical development efforts will be presented to give the reader an understanding of risks and key pitfalls when developing an ASD.