Critical material attributes (CMAs) of strip films loaded with poorly water-soluble drug nanoparticles: I. Impact of plasticizer on film properties and dissolution

Design, optimization and pharmaceutical characterization of wound healing film dressings with chloramphenicol and ibuprofen

OBJECTIVE

The aim of the present study was to develop and optimize a wound dressing film loaded with chloramphenicol (CAM) and ibuprofen (IBU) using a Quality by Design (QbD) approach.

SIGNIFICANCE

The two drugs have been combined in the same dressing as they address two critical aspects of the wound healing process, namely prevention of bacterial infection and reduction of inflammation and pain related to injury.

METHODS

Three critical formulation variables were identified, namely the ratios of Kollicoat SR 30D, polyethylene glycol 400 and polyvinyl alcohol. These variables were further considered as factors of an experimental design, and 17 formulations loaded with CAM and IBU were prepared via solvent casting. The films were characterized in terms of dimensions, mechanical properties and bioadhesion. Additionally, the optimal formulation was characterized regarding tensile properties, swelling behavior, water vapor transmission rate, surface morphology, thermal behavior, goniometry, in vitro drug release, cell viability, and antibacterial activity.

RESULTS

The film was optimized by setting minimal values for the folding endurance, adhesive force and hardness. The optimally formulated film showed good fluid handling properties in terms of swelling behavior and water vapor transmission rate. IBU and CAM were released from the film up to 80.9% and 82.5% for 8 h. The film was nontoxic, and the antibacterial activity was prominent against Micrococcus spp. and Streptococcus pyogenes.

CONCLUSIONS

The QbD approach was successfully implemented to develop and optimize a novel film dressing promising for the treatment of low-exuding acute wounds prone to infection and inflammation.

Unmet technological demands in orodispersible films for age-appropriate paediatric drug delivery

Age-appropriateness of a formulation is the ability to deliver variable but accurate doses to the paediatric population in a safe and acceptable manner to improve medical adherence and reduce medication errors. Paediatric drug delivery is a challenging area of formulation research due to the existing gap in knowledge. This includes the unknown safety of excipients in the paediatric population, the need for an age-appropriate formulation, the lack of an effective taste-masking method and the lack of paediatric pharmacokinetic data and patient acceptability. It is equally important to establish methods for predicting the biopharmaceutical performance of a paediatric formulation as a function of age. Overcoming the challenges of existing technologies and providing custom-made solutions for the development of age-appropriate formulation is, therefore, a daunting task. Orodispersible films (ODF) are promising as age-appropriate formulations, an unmet need in paediatric drug delivery. New technological improvements in taste masking, improving solubility and rate of dissolution of insoluble drugs, the flexibility of dosing and extemporaneous preparation of these films in a hospital good manufacturing practises (GMP) setup using 3D printing can increase its acceptance among clinicians, patients and caregivers. The current review discusses the problems and possibilities in ODF technology to address the outstanding issues of age-appropriateness, which is the hallmark of patient acceptance and medical adherence in paediatrics.

The Potential of Films as Transmucosal Drug Delivery Systems

Pharmaceutical films are polymeric formulations used as a delivery platform for administration of small and macromolecular drugs for local or systemic action. They can be produced by using synthetic, semi-synthetic, or natural polymers through solvent casting, electrospinning, hot-melt extrusion, and 3D printing methods, and depending on the components and the manufacturing methods used, the films allow the modulation of drug release. Moreover, they have advantages that have drawn interest in the development and evaluation of film application on the buccal, nasal, vaginal, and ocular mucosa. This review aims to provide an overview of and critically discuss the use of films as transmucosal drug delivery systems. For this, aspects such as the composition of these formulations, the theories of mucoadhesion, and the methods of production were deeply considered, and an analysis of the main transmucosal pathways for which there are examples of developed films was conducted. All of this allowed us to point out the most relevant characteristics and opportunities that deserve to be taken into account in the use of films as transmucosal drug delivery systems.

Concept of Orodispersible or Mucoadhesive “Tandem Films” and Their Pharmaceutical Realization

Orodispersible or mucoadhesive films as a patient-oriented dosage form for low-dosed drugs are usually produced using solvent casting. This paper presents a modification of the solvent casting technique that aimed to divide oral films into two or more compartments. The proposed objectives and fields of applications include improved handling properties and safety of application, the optimization of drug release kinetics and the enhancement of long-term stability when combining two or more active pharmaceutical ingredients into one oral film. A feasibility study for the combination of different film-forming polymers to generate the so-called tandem films was performed. As examples of practical implementation, orodispersible applicator films consisting of a drug-loaded section and a handheld piece were cast, and mucoadhesive buccal tandem films were cast to optimize the dissolution rate of the films.

Orodispersible films: Conception to quality by design

Orodispersible films (ODFs) are ultra-thin, stamp-sized, elegant, portable and patient-centric pharmaceutical dosage forms that do not need water to be ingested. They are particularly useful for paediatric and geriatric patient populations with special needs such as dysphagia, Parkinson's disease, and oral cancer. Accordingly, they hold tremendous potential in gaining patient compliance, convenience and pharmacotherapy. In the present review, conception and evolution of ODFs as a product and its technology are discussed. The review continues by providing overview about the potential of ODFs as carriers for delivering drugs, herbal extracts, probiotics and vaccines. Besides, strategies employed in drug cargo loading, taste masking of bitter drugs and enhancing drug stability are discussed. Finally, the review concludes by providing a brief overview about quality by design (QbD) principles in development of ODFs.

The Impact of the Preparation Method on the Properties of Orodispersible Films with Aripiprazole: Electrospinning vs. Casting and 3D Printing Methods

Orodispersible films (ODFs) address the needs of pediatric and geriatric patients and people with swallowing difficulties due to fast disintegration in the mouth. Typically, they are obtained using the solvent casting method, but other techniques such as 3D printing and electrospinning have already been investigated. The decision on the manufacturing method is of crucial importance because it affects film properties. This study aimed to compare electrospun ODFs containing aripiprazole and polyvinyl alcohol with films prepared using casting and 3D printing methods. Characterization of films included DSC and XRD analysis, microscopic analysis, the assessment of mechanical parameters, disintegration, and dissolution tests. Simplified stability studies were performed after one month of storage. All prepared films met acceptance criteria for mechanical properties. Electrospun ODFs disintegrated in 1.0 s, which was much less than in the case of other films. Stability studies have shown the sensitivity of electrospun films to the storage condition resulting in partial recrystallization of ARP. These changes negatively affected the dissolution rate, but mechanical properties and disintegration time remained at a desirable level. The results demonstrated that electrospun fibers are promising solutions that can be used in the future for the treatment of patients with swallowing problems.

3D Printing of Drug Nanocrystals for Film Formulations

The aim of the study was to prepare indomethacin nanocrystal-loaded, 3D-printed, fast-dissolving oral polymeric film formulations. Nanocrystals were produced by the wet pearl milling technique, and 3D printing was performed by the semi-solid extrusion method. Hydroxypropyl methyl cellulose (HPMC) was the film-forming polymer, and glycerol the plasticizer. In-depth physicochemical characterization was made, including solid-state determination, particle size and size deviation analysis, film appearance evaluation, determination of weight variation, thickness, folding endurance, drug content uniformity, and disintegration time, and drug release testing. In drug nanocrystal studies, three different stabilizers were tested. Poloxamer F68 produced the smallest and most homogeneous particles, with particle size values of 230 nm and PI values below 0.20, and was selected as a stabilizer for the drug-loaded film studies. In printing studies, the polymer concentration was first optimized with drug-free formulations. The best mechanical film properties were achieved for the films with HPMC concentrations of 2.85% (w/w) and 3.5% (w/w), and these two HPMC levels were selected for further drug-loaded film studies. Besides, in the drug-loaded film printing studies, three different drug levels were tested. With the optimum concentration, films were flexible and homogeneous, disintegrated in 1 to 2.5 min, and released the drug in 2–3 min. Drug nanocrystals remained in the nano size range in the polymer films, particle sizes being in all film formulations from 300 to 500 nm. When the 3D-printed polymer films were compared to traditional film-casted polymer films, the physicochemical behavior and pharmaceutical performance of the films were very similar. As a conclusion, 3D printing of drug nanocrystals in oral polymeric film formulations is a very promising option for the production of immediate-release improved- solubility formulations.

Impact of Mixing on Content Uniformity of Thin Polymer Films Containing Drug Micro-Doses

The impact of mixer type and critical process parameters (CPPs) on critical quality attributes (CQAs), including the drug content uniformity (CU) of slurry-cast polymer films loaded with micro-sized poorly water-soluble drugs were investigated. Previously untested hypothesis was that the best mixer at suitable CPPs promotes uniform drug dispersion within film precursors leading to acceptable dried-film CU at low, ~0.6 wt% drug concentrations. Taguchi design was utilized to select the best of three mixers; low-shear impeller, high-shear planetary, and high-intensity vibrational, for dried-film drug concentration of ~23 wt%. As-received fenofibrate, a model poorly water-soluble drug (~6 µm) was directly mixed with the hydroxypropyl methylcellulose (HPMC) and glycerin aqueous solution. Impeller and planetary mixers yielded desirable film relative standard deviation (RSD), while vibrational mixer could not. For the lowest dried-film drug concentration of ~0.6 wt%, only planetary mixer yielded RSD <6%. The precursor drug homogeneity was a sufficient but not a necessary condition for achieving dried-film RSD <6%. Thus, proper selection of mixer and its CPPs assured desirable film CQAs. However, minor drug particle aggregation was identified via re-dispersion testing which also led to incomplete drug release.

Effect of solvents and cellulosic polymers on quality attributes of films loaded with a poorly water-soluble drug

The combined effect of solvent, cellulosic polymer, and a poorly water-soluble drug, fenofibrate (FNB) on solution-cast pharmaceutical film quality attributes, e.g., morphology, drug recrystallization, content uniformity, mechanical properties, dissolution rate and supersaturation level, was investigated. Film morphology, content uniformity, and mechanical properties were impacted by the extent of FNB recrystallization which was strongly affected by FNB solubility in the solvent as compared to the polymer type, hydroxypropyl methylcellulose or hydroxypropyl cellulose. FNB recrystallization affected drug dissolution rates and supersaturation under non-sink conditions. Specifically, the area under the curve linearly correlated with recrystallization. After one-year storage, FNB recrystallization reached very high levels even for the films with no initial recrystallization, suggesting low initial crystallinity does not guarantee stability. Thus, uncontrolled recrystallization and poor time-stability would be unavoidable for solution-cast films. Overall, both the polymer and the solvent strongly impact drug recrystallization, film structure, mechanical properties, dissolution rate, and supersaturation.

Production of Itraconazole Nanocrystal-Based Polymeric Film Formulations for Immediate Drug Release

In order to improve the solubility properties of BCS class II drug itraconazole, fast dissolving oral polymeric film formulations based on itraconazole nanocrystals were produced. Drug nanocrystals were manufactured by the wet pearl milling technique. In polymeric film formulations, hydroxypropyl methyl cellulose (HPMC) was used as a film forming polymer, and glycerin was used as a plasticizer. For nanocrystal suspensions and film formulations, thorough physicochemical characterization was performed, including particle sizing and size deviation, film appearance, weight variation, thickness, folding endurance, drug content uniformity, disintegration time, and dissolution profile. After milling, the nanoparticles were 369 nm in size with a PI value of 0.20. Nanoparticles were stable and after redispersion from film formulations, the particle size remained almost the same (330 nm and PI 0.16). The produced films were flexible, homogeneous, fast disintegrating, and drug release rate from both the nanosuspension and film formulations showed immediate release behavior. Based on the study, the film casting method for production of itraconazole nanocrystal based immediate release formulations is a good option for improved solubility.

Characterization of Orodispersible Films: An Overview of Methods and Introduction to a New Disintegration Test Apparatus Using LDR - LED Sensors

Orodispersible Film (ODF) is a promising and progressive dosage form that offers exceptional drug delivery benefits to patients. Indeed, they are the most transformational alternatives to traditional/conventional dosage forms such as tablets and capsules. ODFs are portable and highly comfortable for self-administration by patients with swallowing problems. The key to gain end-user acceptance is to have an ODF with outstanding quality. Poor quality may lead to choking or spitting, accordingly leading to a lack of compliance. It is vital to employ suitable experimental methodologies that facilitate characterization or determination of the quality of ODF. Nonetheless, there are no standard techniques prescribed in official compendia of any country. But, there is a consensus in the thin-film research community about the characterization techniques that one relies on deciding the quality of an ODF. We review various experimental techniques and highlight its importance in determining the performance and quality of an ODF. We provide a relatively novel and inventive disintegration test apparatus, which works using 'Light Dependent Resistor (LDR) and Light Emitting Diode (LED) sensors' for clear and accurate determination of start and end disintegration time of an ODF.

Fenofibrate Nanocrystal Composite Microparticles for Intestine-Specific Oral Drug Delivery System

Hydrophobic drug nanocrystals (NCs) manufactured by particle engineering have been extensively investigated for enhanced oral bioavailability and therapeutic effectiveness. However, there are significant drawbacks, including fast dissolution of the nanocrystals in the gastric environment, leading to physicochemical instability. To solves this issue, we developed an innovative technique that involves the encapsulation of nanocrystals in composite spherical microparticles (NCSMs). Fenofibrate (FNB) NCs (FNB-NCs) manufactured by a wet stirred media milling (WSMM) technique and an ionotropic crosslinking method were used for FNB-NC encapsulation within gastroresistant NCSMs. Various solid-state methods were used for characterizing NCSMs. The pH-sensitive NCSMs showed a site-specific release pattern at alkaline pH and nearly 0% release at low pH (gastric environment). This phenomenon was confirmed by a real-time in situ UV-imaging system known as the surface dissolution imager (SDI), which was used to monitor drug release events by measuring the color intensity and concentration gradient formation. All these results proved that our NCSM approach is an innovative idea in oral drug delivery systems, as it resolves significant challenges in the intestine-specific release of hydrophobic drugs while avoiding fast dissolution or burst release.

A predictive transport model for convective drying of polymer strip films loaded with a BCS Class II drug

Drying is an important unit operation in the manufacturing of polymer strip films as it affects various film quality attributes. Optimal design and control of convective drying process require models that capture the impact of critical process parameters such as air temperature and velocity on the temporal evolution of film thickness and moisture. Here, a detailed transport model was presented to capture moisture diffusion, heat transfer and moving boundary in convective drying of polymer strip films loaded with griseofulvin (GF), a poorly water-soluble drug. It incorporates a solvent diffusivity model based on free-volume theory. Experimentally, film precursor suspensions were prepared by mixing silica-coated and micronized GF powder with an aqueous solution of hydroxypropyl methylcellulose (HPMC)-glycerin. Films were cast and moisture-time variation during drying was measured. The transport model, whose diffusivity parameters were estimated using drying data at a reference condition, was validated at different drying conditions and wet film thicknesses. It delineates underlying mechanisms of drying kinetics and demarcates a smooth transition from constant-rate to falling-rate period. Overall, our results suggest that the transport model is capable of predicting the temporal evolution of moisture and final film thickness at different drying air velocities and temperatures with reasonable accuracy.

Convective Drying Kinetics of Polymer Strip Films Loaded with a BCS Class II Drug

Polymer strip film is a promising dosage form for oral delivery of poorly water-soluble drugs. Drying is an important step in the production of polymer strip films with significant effects on critical quality attributes (CQAs). In this study, a custom-made batch drying setup was used to study convective drying kinetics of wet polymer strip films loaded with dry-coated micronized griseofulvin (GF) at various drying conditions. A rate-based semi-empirical model was formulated and parameters were estimated by integral method of analysis using a coupled optimizer-ordinary differential equation solver. Despite its simplicity with three parameters, the model could fit the experimental data very well for all drying conditions, which enabled us to examine the effects of air velocity, temperature, and initial wet film thickness on drying kinetics quantitatively. The modeling results clearly delineate a drying mechanism with constant-rate and falling-rate periods. One set of kinetic parameter estimates reasonably predicted the drying kinetics for two different wet film thicknesses in the selected process conditions, which demonstrates the predictive capability of the model. After reporting the limitations of the semi-empirical model, upon future modification and refinement, its potential use in drying process development and process control was highlighted.

Nanocrystals of Poorly Soluble Drugs: Drug Bioavailability and Physicochemical Stability

Many approaches have been developed over time to overcome the bioavailability limitations of poorly soluble drugs. With the advances in nanotechnology in recent decades, science and industry have been approaching this issue through the formulation of drugs as nanocrystals, which consist of “pure drugs and a minimum of surface active agents required for stabilization”. They are defined as “carrier-free submicron colloidal drug delivery systems with a mean particle size in the nanometer range, typically between 10–800 nm”. The primary importance of these nanoparticles was the reduction of particle size to nanoscale dimensions, with an increase in the particle surface area in contact with the dissolution medium, and thus in bioavailability. This approach has been proven successful, as demonstrated by the number of such drug products on the market. Nonetheless, despite the definition that indicates nanocrystals as a “carrier-free” system, surface active agents are necessary to prevent colloidal particles aggregation and thus improve stability. In addition, in more recent years, nanocrystal properties and technologies have attracted the interest of researchers as a means to obtain colloidal particles with modified biological properties, and thus their interest is now also addressed to modify the drug delivery and targeting. The present work provides an overview of the achievements in improving the bioavailability of poorly soluble drugs according to their administration route, describes the methods developed to overcome physicochemical and stability-related problems, and in particular reviews different stabilizers and surface agents that are able to modify the drug delivery and targeting.

Sustained Release of Poorly Water-Soluble Drug from Hydrophilic Polymeric Film Sandwiched Between Hydrophobic Layers

This proof-of-concept study explores the feasibility of using a drug-loaded hydrophilic polymeric layer sandwiched between two hydrophobic layers for improving film drug load while achieving sustained release of poorly water-soluble drug. Such films having total thickness in range ~ 146-250 μm were prepared by slurry-based casting using hydrophilic hydroxypropyl methylcellulose (HPMC) as matrix layer containing fenofibrate (FNB) as the model drug, encased between two very thin rate-limiting layers of 10 μm each of hydrophobic poly-ɛ-caprolactone (PCL). Film precursor slurry consisted of HPMC with plasticizer and water along with micronized FNB powders, which were dry-coated with hydrophilic silica. Characterization techniques demonstrated the presence of homogeneously dispersed crystalline FNB in films. The films are very thin and hence two-dimensional; hence, average drug load per unit area in range ~ 5 to ~ 9 mg/cm² could be achieved by altering the thickness of the drug matrix layer. Drug amount and drug content uniformity were measured through assay of ten circular samples ~ 0.712 cm² in area punched out using a circular-shaped punch tool. Drug release rate was investigated using USP IV flow-through cell and surface dissolution imaging system. Thinner films followed Fickian diffusion, and thicker films followed non-Fickian anomalous diffusion. Overall, the application of middle layer thickness could be used as a tool to manipulate drug load without the need for altering its formulation or precursor preparation by changing its thickness, hence achieving relatively high drug loading yet having sustained release of drug.

Impact of Superdisintegrants and Film Thickness on Disintegration Time of Strip Films Loaded With Poorly Water-Soluble Drug Microparticles

Although strip films are a promising platform for delivery of poorly water-soluble drug particles via slurry casting, the effect of critical material attributes, for example, superdisintegrants (SDIs) on critical quality attributes, including film disintegration time (DT), remains underexplored. A 2-level factorial design is considered to examine the impact of the SDI type (sodium starch glycolate and croscarmellose sodium), their amount, and film thickness. SDIs were used with hydroxypropyl methylcellulose (E15LV) and glycerin solutions along with viscosity matching. Fenofibrate, a model poorly water-soluble drug, was micronized and surface modified via fluid energy milling. Significant decreases in film DT, measured using 3 different methods, were observed due to the addition of SDIs. Percentage reduction in DT was a strong function of SDI amount, and thinner films disintegrated faster. Films with either higher SDI concentrations (>9%) or films under 80 μm, exhibited fast DT (<180 s, European Pharmacopeia). All thin films (50-60 μm) exhibited immediate release (>80% in 10 min). All films achieved good content uniformity, except for those with the lowest amount of SDI, attributed to insufficient viscosity and thickness nonuniformity due to the SDI. Finally, all films achieved adequate mechanical properties, notwithstanding minor negative impact of SDIs.

Design Space and QbD Approach for Production of Drug Nanocrystals by Wet Media Milling Techniques

Drug nanocrystals are nanosized solid drug particles, the most important application of which is the improvement of solubility properties of poorly soluble drug materials. Drug nanocrystals can be produced by many different techniques, but the mostly used are different kinds of media milling techniques; in milling, particle size of bulk sized drug material is decreased, with the aid of milling beads, to nanometer scale. Utilization of Quality by Design, QbD, approach in nanomilling improves the process-understanding of the system, and recently, the number of studies using the QbD approach in nanomilling has increased. In the QbD approach, the quality is built into the products and processes throughout the whole production chain. Definition of Critical Quality Attributes, CQAs, determines the targeted final product properties. CQAs are confirmed by setting Critical Process Parameters, CPPs, which include both process parameters but also input variables, like stabilizer amount or the solid state form of the drug. Finally, Design Space determines the limits in which CPPs should be in order to reach CQAs. This review discusses the milling process and process variables, CPPs, their impact on product properties, CQAs and challenges of the QbD approach in nanomilling studies.

Bioavailability Enhancement of Poorly Water-Soluble Drugs via Nanocomposites: Formulation⁻Processing Aspects and Challenges

Drug nanoparticles embedded in a dispersant matrix as a secondary phase, i.e., drug-laden nanocomposites, offer a versatile delivery platform for enhancing the dissolution rate and bioavailability of poorly water-soluble drugs. Drug nanoparticles are prepared by top-down, bottom-up, or combinative approaches in the form of nanosuspensions, which are subsequently dried to prepare drug-laden nanocomposites. In this comprehensive review paper, the term &ldquo;nanocomposites&rdquo; is used in a broad context to cover drug nanoparticle-laden intermediate products in the form of powders, cakes, and extrudates, which can be incorporated into final oral solid dosages via standard pharmaceutical unit operations, as well as drug nanoparticle-laden strip films. The objective of this paper is to review studies from 2012⁻2017 in the field of drug-laden nanocomposites. After a brief overview of the various approaches used for preparing drug nanoparticles, the review covers drying processes and dispersant formulations used for the production of drug-laden nanocomposites, as well as various characterization methods including quiescent and agitated redispersion tests. Traditional dispersants such as soluble polymers, surfactants, other water-soluble dispersants, and water-insoluble dispersants, as well as novel dispersants such as wet-milled superdisintegrants, are covered. They exhibit various functionalities such as drug nanoparticle stabilization, mitigation of aggregation, formation of nanocomposite matrix⁻film, wettability enhancement, and matrix erosion/disintegration. Major challenges such as nanoparticle aggregation and poor redispersibility that cause inferior dissolution performance of the drug-laden nanocomposites are highlighted. Literature data are analyzed in terms of usage frequency of various drying processes and dispersant classes. We provide some engineering considerations in comparing drying processes, which could account for some of the diverging trends in academia vs. industrial practice. Overall, this review provides rationale and guidance for drying process selection and robust nanocomposite formulation development, with insights into the roles of various classes of dispersants.

Mesoporous silica nanoparticles facilitating the dissolution of poorly soluble drugs in orodispersible films

Orodispersible films (ODF) are immediately dissolving/disintegrating intraoral dosage forms, presented as substitutes of conventional tablets or capsules to ease problems associated with swallowing. Efforts have been made to be able to exploit ODFs as dosage forms for poorly soluble drugs. In the last two decades, mesoporous silica nanoparticles (MSNs) have been extensively used in drug delivery applications to overcome solubility problems of drugs. The tunable features of MSNs make them suitable candidates as drug carriers and solubility enhancers. In this study, the feasibility of MSNs as a carrier of poorly soluble drugs, using prednisolone as a model drug, in ODFs was investigated. Our results revealed that the increased amount of MSNs in ODFs leads to shortening of the disintegration time of the films. Drug content investigations showed that low dose ODFs with prednisolone incorporation efficiencies higher than 80% could be produced. Furthermore, the prednisolone release profile from ODFs can be tuned with the incorporation of MSNs as drug carrier (MSN_pred). The MSN_pred incorporated ODFs yield with immediate release of drug from the ODF, whereby 90% of the prednisolone content could be released in the first minutes. By modifying the MSN_pred design with copolymer surface coating, prednisolone (cop-MSN_pred) release can be modulated into a two-step sustained release profile. To sum up, the MSNs platform does not only provide careful low dose incorporation into ODF with high efficiency, but it also aids in tuning the drug release profiles from ODFs.

Zero-order release of poorly water-soluble drug from polymeric films made via aqueous slurry casting

In spite of significant recent interest in polymeric films containing poorly water-soluble drugs, dissolution mechanism of thicker films has not been investigated. Consequently, release mechanisms of poorly water-soluble drugs from thicker hydroxypropyl methylcellulose (HPMC) films are investigated, including assessing thickness above which they exhibit zero-order drug release. Micronized, surface modified particles of griseofulvin, a model drug of BSC class II, were incorporated into aqueous slurry-cast films of different thicknesses (100, 500, 1000, 1500 and 2000 μm). Films 1000 μm and thicker were formed by either stacking two or more layers of ~500 μm, or forming a monolithic thick film. Compared to monolithic thick films, stacked films required simpler manufacturing process (easier casting, short drying time) and resulted in better critical quality attributes (appearance, uniformity of thickness and drug per unit area). Both the film forming approaches exhibited similar release profiles and followed the semi-empirical power law. As thickness increased from 100 μm to 2000 μm, the release mechanism changed from Fickian diffusion to zero-order release for films ≥1000 μm. The diffusional power law exponent, n, achieved value of 1, confirming zero-order release, whereas the percentage drug release varied linearly with sample surface area, and sample thickness due to fixed sample diameter. Thus, multi-layer hydrophilic polymer aqueous slurry-cast thick films containing poorly water-soluble drug particles provide a convenient dosage form capable of zero-order drug release with release time modulated through number of layers.

Alternative Manufacturing Concepts for Solid Oral Dosage Forms From Drug Nanosuspensions Using Fluid Dispensing and Forced Drying Technology

Flexible manufacturing technologies for solid oral dosage forms with a continuous adjustability of the manufactured dose strength are of interest for applications in personalized medicine. This study explored the feasibility of using microvalve technology for the manufacturing of different solid oral dosage form concepts. Hard gelatin capsules filled with excipients, placebo tablets, and polymer films, placed in hard gelatin capsules after drying, were considered as substrates. For each concept, a basic understanding of relevant formulation parameters and their impact on dissolution behavior has been established. Suitable matrix formers, present either on the substrate or directly in the drug nanosuspension, proved to be essential to prevent nanoparticle agglomeration of the drug nanoparticles and to ensure a fast dissolution behavior. Furthermore, convection and radiation drying methods were investigated for the fast drying of drug nanosuspensions dispensed onto polymer films, which were then placed in hard gelatin capsules. Changes in morphology and in drug and matrix former distribution were observed for increasing drying intensity. However, even fast drying times below 1 min could be realized, while maintaining the nanoparticulate drug structure and a good dissolution behavior.

Incorporation of surface-modified dry micronized poorly water-soluble drug powders into polymer strip films

Recent work has established polymer strip films as a robust platform for delivery of poorly water-soluble drugs via slurry casting, in particular using stable drug nanosuspensions. Here, a simpler, robust method to directly incorporate dry micronized poorly water-soluble drug, fenofibrate (FNB), is introduced. As a major novelty, simultaneous surface modification using hydrophilic silica along with micronization was done using fluid energy mill (FEM) in order to reduce FNB hydrophobicity and powder agglomeration. It is hypothesized that silica coating promotes easy, uniform dispersion of micronized and coated FNB (MC-FNB) during direct mixing with aqueous hydroxypropyl methylcellulose (HPMC-E15LV) and glycerin solutions. Uniform dispersion leads to improved film critical quality attributes (CQAs) such as appearance, drug content uniformity and drug dissolution. The impact of polymer solution viscosity (low and high), mixer type (low versus high shear), and FNB surface modification on film CQAs were also assessed. Films with as-received FNB (AR-FNB) and micronized uncoated FNB (MU-FNB) were prepared as control. When MC-FNB powders were used, films exhibited improved appearance (thickness uniformity, visible lumps/agglomerates), better drug content uniformity (expressed as relative standard deviation), fast and immediate drug release, and enhanced mechanical properties (tensile strength, elongation percentage), regardless of the polymer solution viscosity or mixer type. These results compare favorably with those reported using nanosuspensions of FNB, establishing the feasibility of directly incorporating surface modified-micronized poorly water-soluble drug powders in film manufacturing.

Critical material attributes (CMAs) of strip films loaded with poorly water-soluble drug nanoparticles: III. Impact of drug nanoparticle loading

Polymer strip films have emerged as a robust platform for poorly water-soluble drug delivery. However, the common conception is that films cannot exceed low drug loadings, mainly due to poor drug stability, slow release, and film brittleness. This study explores the ability to achieve high loadings of poorly water-soluble drug nanoparticles in strip films while retaining good mechanical properties and enhanced dissolution rate. Aqueous suspensions containing up to 30wt% griseofulvin nanoparticles were prepared via wet stirred media milling and incorporated into hydroxypropyl methylcellulose (HPMC) films. Griseofulvin loading in films was adjusted to be between 9 and 49wt% in HPMC-E15 films and 30 and 73wt% in HPMC-E4M films by varying the mixing ratio of HPMC solution-to-griseofulvin suspension. All films exhibited good content uniformity and nanoparticle redispersibility up to 50wt% griseofulvin, while E4M films above 50wt% griseofulvin had slightly worse content uniformity and poor nanoparticle redispersibility. Increasing drug loading in films generally required more time to achieve 100% release during dissolution, although polymer-drug clusters dispersed from E4M films above 50wt% griseofulvin, resulting in similar dissolution profiles. While all films exhibited good tensile strength, a significant decrease in percent elongation was observed above 40-50wt% GF, resulting in brittle films.

Critical Material Attributes of Strip Films Loaded With Poorly Water-Soluble Drug Nanoparticles: II. Impact of Polymer Molecular Weight

Recent work established polymer strip films as a robust platform for delivery of poorly water-soluble drug particles. However, a simple means of manipulating rate of drug release from films with minimal impact on film mechanical properties has yet to be demonstrated. This study explores the impact of film-forming polymer molecular weight (MW) and concentration on properties of polymer films loaded with poorly water-soluble drug nanoparticles. Nanoparticles of griseofulvin, a model Biopharmaceutics Classification System class II drug, were prepared in aqueous suspension via wet stirred media milling. Aqueous solutions of 3 viscosity grades of hydroxypropyl methylcellulose (14, 21, and 88 kDa) at 3 viscosity levels (∼9500, ∼12,000, and ∼22,000 cP) were mixed with drug suspension, cast, and dried to produce films containing griseofulvin nanoparticles. Few differences in film tensile strength or elongation at break were observed between films within each viscosity level regardless of polymer MW despite requiring up to double the time to achieve 100% drug release. This suggests film-forming polymer MW can be used to manipulate drug release with little impact on film mechanical properties by matching polymer solution viscosity. In addition, changing polymer MW and concentration had no negative impact on drug content uniformity or nanoparticle redispersibility.