Preparation and characterization of hydroxypropyl methyl cellulose films containing stable BCS Class II drug nanoparticles for pharmaceutical applications

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.

Fenofibrate Nanocrystals Embedded in Oral Strip-Films for Bioavailability Enhancement

The aim of the present study was to make a fenofibrate (FNB) nanocrystal (NC) by wet media milling, characterizations and formulates into oral strip-films (OSFs). Mechanical properties, redispersion study, and solid-state characterizations results suggested that reduction of drug crystal size at nanoscale and incorporation into OSFs does not affect the solid-state properties of the drug. In vitro dissolution kinetics showed enhanced dissolution rate was easily manipulated by changing the thickness of the OSF. In situ UV-imaging was used to monitor drug dissolution qualitatively and quantitatively in real time. Results confirm that the intrinsic dissolution rates and surface drug concentration measured with this device were in agreement with the USP-IV dissolution profiles. In vivo pharmacokinetics in rabbits showed a significant difference in the pharmacokinetics parameter (1.4 fold increase bioavailability) of FNB NC-loaded OSFs as compared to the marketed formulation “Tricor” and as-received (pristine) drug. This approach of drug nanocrystallization and incorporation into OSFs may have significant applications in cost-effective tools for bioavailability enhancement of FNB.

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.

Quality by Design approach for studying the impact of formulation and process variables on product quality of oral disintegrating films

The present investigation was carried out to understand the impact of formulation and process variables on the quality of oral disintegrating films (ODF) using Quality by Design (QbD) approach. Lamotrigine (LMT) was used as a model drug. Formulation variable was plasticizer to film former ratio and process variables were drying temperature, air flow rate in the drying chamber, drying time and wet coat thickness of the film. A Definitive Screening Design of Experiments (DoE) was used to identify and classify the critical formulation and process variables impacting critical quality attributes (CQA). A total of 14 laboratory-scale DoE formulations were prepared and evaluated for mechanical properties (%elongation at break, yield stress, Young's modulus, folding endurance) and other CQA (dry thickness, disintegration time, dissolution rate, moisture content, moisture uptake, drug assay and drug content uniformity). The main factors affecting mechanical properties were plasticizer to film former ratio and drying temperature. Dissolution rate was found to be sensitive to air flow rate during drying and plasticizer to film former ratio. Data were analyzed for elucidating interactions between different variables, rank ordering the critical materials attributes (CMA) and critical process parameters (CPP), and for providing a predictive model for the process. Results suggested that plasticizer to film former ratio and process controls on drying are critical to manufacture LMT ODF with the desired CQA.

Novel strategies for the formulation and processing of poorly water-soluble drugs

Low aqueous solubility of active pharmaceutical ingredients presents a serious challenge in the development process of new drug products. This article provides an overview on some of the current approaches for the formulation of poorly water-soluble drugs with a special focus on strategies pursued at the Center of Pharmaceutical Engineering of the TU Braunschweig. These comprise formulation in lipid-based colloidal drug delivery systems and experimental as well as computational approaches towards the efficient identification of the most suitable carrier systems. For less lipophilic substances the preparation of drug nanoparticles by milling and precipitation is investigated for instance by means of microsystem-based manufacturing techniques and with special regard to the preparation of individualized dosage forms. Another option to overcome issues with poor drug solubility is the incorporation into nanospun fibers.

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.

Tandem modification of amphiphilic cellulose ethers for amorphous solid dispersion via olefin cross-metathesis and thiol-Michael addition

Tandem olefin cross-metathesis (CM) and thiol-Michael addition for modification of cellulose derivatives”.

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.

Formulation of orodispersible films for paediatric therapy: investigation of feasibility and stability for tetrabenazine as drug model

Objectives

Orodispersible films (ODF) were formulated to facilitate tetrabenazine (TBZ) administration to paediatric population for the treatment of hyperkinetic movement disorders.

Methods

ODF were obtained by solvent casting/evaporation method using four different polymers (HPMC, PVP, pullulan and HEC). Physicochemical, mechanical and biopharmaceutical characterizations as well as API state in ODF by thermal analysis were investigated to define and compare formulations. ODF stability was also monitored during 6 months to follow evolution of properties.

Key findings

Analyses at T0 showed few differences between formulations: results of physicochemical and mechanical characterizations were almost similar for each formulation and TBZ appeared at the amorphous state in all cases. ODF delivery system allowed a major improvement of TBZ dissolution profile in buccal conditions compared with pure drug. However, after 3 and 6 months of stability, a TBZ recrystallization occurred for formulations based on PVP and HEC associated with a decrease of drug release in saliva conditions.

Conclusions

HPMC-ODF (F1) appeared as the best formulation. Indeed, physicochemical, mechanical and biopharmaceutical characteristic remained intact. In addition, TBZ remained in amorphous state during stability study.

Efficient production of nanoparticle-loaded orodispersible films by process integration in a stirred media mill

Orodispersible films possess a great potential as a versatile platform for nanoparticle-loaded oral dosage forms. In this case, poorly water-soluble organic materials were ground in a stirred media mill and embedded into a polymer matrix. The aim of this study was the shortening of this manufacturing process by the integration of several process steps into a stirred media mill without facing disadvantages regarding the film quality. Furthermore, this process integration is time conserving due to the high stress intensities provided in the mill and applicable for high solids contents and high suspension viscosities. Two organic materials, the model compound Anthraquinone and the active pharmaceutical ingredient Naproxen were investigated in this study. Besides the impact of the film processing on the crystallinity of the particles in the orodispersible film, a particle load of up to 50% was investigated with the new developed processing route. Additionally, a disintegration test was developed, combining an appropriate amount of saliva substitute and a clear endpoint determination. In summary, high nanoparticle loads in orodispersible films with good particle size preservation after film redispersion in water as well as a manufacturing of the film casting mass within a few minutes in a stirred media mill was achieved.

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

Recent studies have demonstrated polymer films to be a promising platform for delivery of poorly water-soluble drug particles. However, the impact of critical material attributes, for example plasticizer, on the properties of and drug release from such films has yet to be investigated. In response, this study focuses on the impact of plasticizer and plasticizer concentration on properties and dissolution rate of polymer films loaded with poorly water-soluble drug nanoparticles. Glycerin, triacetin, and polyethylene glycol were selected as film plasticizers. Griseofulvin was used as a model Biopharmaceutics Classification System class II drug and hydroxypropyl methylcellulose was used as a film-forming polymer. Griseofulvin nanoparticles were prepared via wet stirred media milling in aqueous suspension. A depression in film glass transition temperature was observed with increasing plasticizer concentration, along with a decrease in film tensile strength and an increase in film elongation, as is typical of plasticizers. However, the type and amount of plasticizer necessary to produce strong yet flexible films had no significant impact on the dissolution rate of the films, suggesting that film mechanical properties can be effectively manipulated with minimal impact on drug release. Griseofulvin nanoparticles were successfully recovered upon redispersion in water regardless of plasticizer or content, even after up to 6months' storage at 40°C and 75% relative humidity, which contributed to similar consistency in dissolution rate after 6months' storage for all films. Good content uniformity (<4% R.S.D. for very small film sample size) was also maintained across all film formulations.

Nanomilling of Drugs for Bioavailability Enhancement: A Holistic Formulation-Process Perspective

Preparation of drug nanoparticles via wet media milling (nanomilling) is a very versatile drug delivery platform and is suitable for oral, injectable, inhalable, and buccal applications. Wet media milling followed by various drying processes has become a well-established and proven formulation approach especially for bioavailability enhancement of poorly water-soluble drugs. It has several advantages such as organic solvent-free processing, tunable and relatively high drug loading, and applicability to a multitude of poorly water-soluble drugs. Although the physical stability of the wet-milled suspensions (nanosuspensions) has attracted a lot of attention, fundamental understanding of the process has been lacking until recently. The objective of this review paper is to present fundamental insights from available published literature while summarizing the recent advances and highlighting the gap areas that have not received adequate attention. First, stabilization by conventionally used polymers/surfactants and novel stabilizers is reviewed. Then, a fundamental understanding of the process parameters, with a focus on wet stirred media milling, is revealed based on microhydrodynamic models. This review is expected to bring a holistic formulation-process perspective to the nanomilling process and pave the way for robust process development scale-up. Finally, challenges are indicated with a view to shedding light on future opportunities.

Recent developments in the Raman and infrared investigations of amorphous pharmaceuticals and protein formulations: A review

The success rate for drug discovery and the development of innovative therapeutic strategies are intimately related to the physical properties of the solid-state condensed matter, which have direct influence on the bioavailability of Active Pharmaceutical Ingredients. In order to transform a new molecule in efficient drug, the material is brought into an amorphous state using various manufacturing processes including freeze drying, spray drying, hot melt extrusion and loading in different delivery devices. The infrared and Raman spectroscopic analyses used for exploring disordered and amorphous states, for the monitoring of the drug physical stability in drug delivery systems are described in this review.

An Intensified Vibratory Milling Process for Enhancing the Breakage Kinetics during the Preparation of Drug Nanosuspensions

As a drug-sparing approach in early development, vibratory milling has been used for the preparation of nanosuspensions of poorly water-soluble drugs. The aim of this study was to intensify this process through a systematic increase in vibration intensity and bead loading with the optimal bead size for faster production. Griseofulvin, a poorly water-soluble drug, was wet-milled using yttrium-stabilized zirconia beads with sizes ranging from 50 to 1500 μm at low power density (0.87 W/g). Then, this process was intensified with the optimal bead size by sequentially increasing vibration intensity and bead loading. Additional experiments with several bead sizes were performed at high power density (16 W/g), and the results were compared to those from wet stirred media milling. Laser diffraction, scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, and dissolution tests were used for characterization. Results for the low power density indicated 800 μm as the optimal bead size which led to a median size of 545 nm with more than 10% of the drug particles greater than 1.8 μm albeit the fastest breakage. An increase in either vibration intensity or bead loading resulted in faster breakage. The most intensified process led to 90% of the particles being smaller than 300 nm. At the high power intensity, 400 μm beads were optimal, which enhanced griseofulvin dissolution significantly and signified the importance of bead size in view of the power density. Only the optimally intensified vibratory milling led to a comparable nanosuspension to that prepared by the stirred media milling.

Preparation and characterization of fast dissolving pullulan films containing BCS class II drug nanoparticles for bioavailability enhancement

The aim of this study is to assess pullulan as a novel steric stabilizer during the wet-stirred media milling (WSMM) of griseofulvin, a model poorly water-soluble drug, and as a film-former in the preparation of strip films via casting-drying the wet-milled drug suspensions for dissolution and bioavailability enhancement. To this end, pullulan films, with xanthan gum (XG) as thickening agent and glycerin as plasticizer, were loaded with griseofulvin nanoparticles prepared by WSMM using pullulan in combination with sodium dodecyl sulfate (SDS) as an ionic stabilizer. The effects of drug loading and milling time on the particle size and suspension stability were investigated, as well as XG concentration and casting thickness on film properties and dissolution rate. The nanosuspensions prepared with pullulan-SDS combination were relatively stable over 7 days; hence, this combination was used for the film preparation. All pullulan-based strip films exhibited excellent content uniformity (most <3% RSD) despite containing only 0.3-1.3 mg drug, which was ensured by the use of precursor suspensions with >5000 cP viscosity. USP IV dissolution tests revealed fast/immediate drug release (t80 < 30 min) from films <120 μm thick. Thinner films, films with lower XG loading, or smaller drug particles led to faster drug dissolution, while drug loading had no discernible effect. Overall, these results suggest that pullulan may serve as an acceptable stabilizer for media milling in combination with surfactant as well as a fast-dissolving film former for the fast release of poorly water-soluble drug nanoparticles.

Particle size tailoring of ursolic acid nanosuspensions for improved anticancer activity by controlled antisolvent precipitation

The present study was aimed at tailoring the particle size of ursolic acid (UA) nanosuspension for improved anticancer activity. UA nanosuspensions were prepared by antisolvent precipitation using a four-stream multi-inlet vortex mixer (MIVM) under defined conditions of varying solvent composition, drug feeding concentration or stream flow rate. The resulting products were characterized for particle size and polydispersity. Two of the UA nanosuspensions with mean particle sizes of 100 and 300 nm were further assessed for their in-vitro activity against MCF-7 breast cancer cells using fluorescence microscopy with 4',6-diamidino-2-phenylindole (DAPI) staining, as well as flow cytometry with propidium (PI) staining and with double staining by fluorescein isothiocyanate. It was revealed that the solvent composition, drug feeding concentration and stream flow rate were critical parameters for particle size control of the UA nanosuspensions generated with the MIVM. Specifically, decreasing the UA feeding concentration or increasing the stream flow rate or ethanol content resulted in a reduction of particle size. Excellent reproducibility for nanosuspension production was demonstrated for the 100 and 300 nm UA preparations with a deviation of not more than 5% in particle size from the mean value of three independent batches. Fluorescence microscopy and flow cytometry revealed that these two different sized UA nanosuspensions, particularly the 300 nm sample, exhibited a higher anti-proliferation activity against the MCF-7 cells and afforded a larger population of these cells in both early and late apoptotic phases. In conclusion, MIVM is a robust and pragmatic tool for tailoring the particle size of the UA nanosuspension. Particle size appears to be a critical determinant of the anticancer activity of the UA nanoparticles.

Nanosuspensions of poorly water-soluble drugs prepared by bottom-up technologies

In recent years, nanosuspension has been considered effective in the delivery of water-soluble drugs. One of the main challenges to effective drug delivery is designing an appropriate nanosuspension preparation approach with low energy input and erosion contamination, such as the bottom-up method. This review focuses on bottom-up technologies for preparation of nanosuspensions. The features and advantages of drug nanosuspension, including bottom-up methods as well as the corresponding characterization techniques, solidification methods, and drug delivery dosage forms, are discussed in detail. Certain limitations of commercial nanosuspension products are also reviewed.

Raman imaging of drug delivery systems

This review article includes an introduction to the principals of Raman spectroscopy, an outline of the experimental systems used for Raman imaging and the associated important considerations and limitations of this method. Common spectral analysis methods are briefly described and examples of interesting published studies which utilised Raman imaging of pharmaceutical and biomedical devices are discussed, along with summary tables of the literature at this point in time.

Polymer strip films as a robust, surfactant-free platform for delivery of BCS Class II drug nanoparticles

The robustness of the polymer strip film platform to successfully deliver a variety of BCS Class II drug nanoparticles without the need for surfactant while retaining positive characteristics such as nanoparticle redispersibility and fast dissolution is demonstrated. Fenofibrate (FNB), griseofulvin (GF), naproxen (NPX), phenylbutazone (PB), and azodicarbonamide (AZD) were considered as model poorly water-soluble drugs. Their aqueous nanosuspensions, produced via wet stirred media milling, were mixed with hydroxypropyl methylcellulose solution containing glycerin as plasticizer, followed by casting and drying to form films. For the purpose of comparison, sodium dodecyl sulfate (SDS) was used as surfactant, but was found to be unnecessary for achieving fast dissolution (t80 between 18 and 28 min) for all five drugs. Interestingly, SDS was required for the full recovery of nanoparticles for PB, yet lack of it did not impact the dissolution. Interactions between drug and polymer were investigated with FTIR spectroscopy whereas drug crystallinity within the film was investigated via Raman spectroscopy. Films for all drugs, even for very small samples, exhibited excellent content uniformity (RSD <4%) regardless of use of surfactant. Overall, these results demonstrate the novelty and robustness of the polymer strip film platform for fast release of poorly water-soluble drugs without requiring any surfactants.

Raman spectroscopy for in-line and off-line quantification of poorly soluble drugs in strip films

Raman spectroscopy was used as a process analytical technology (PAT) tool for in-line measurement of active pharmaceutical ingredient (API) content during continuous manufacturing of strip films containing nanoparticles of poorly water-soluble APIs. Fenofibrate and naproxen were used as model APIs, whose concentrations ranged from 3% to 26% (w/w) in the model calibration. For both in-line and off-line measurements, calibration models employed partial least square (PLS) analysis, yielding correlation coefficients (R(2)) greater than 0.9946 and root mean squared error of calibration (RMSEC) of about 0.44%, indicating the validity and accuracy of the calibration. The robustness of Raman spectroscopy as a PAT tool was established by considering three processing parameters after substrate interference correction: sensing location, substrate speed and film thickness. Calibration models for each API were validated using a separate batch of strip films by predicting the API concentrations to within ±1.3%. Principal component analysis (PCA) was used to explain the interactions between processing variables and calibration models, which suggest that besides API concentration, film thickness could also be monitored using Raman spectroscopy. The results demonstrate the potential of Raman spectroscopy as an effective PAT tool for novel strip film manufacturing process, facilitating detection of drug form and concentration in real-time.

A brief literature and patent review of nanosuspensions to a final drug product

Particle size reduction can be used for enhancing the dissolution of poorly water-soluble drugs in order to enhance bioavailability. In nanosuspensions, the particle size of the drug is reduced to nanometer size. Nanosuspensions after downstream processing into drug products have successfully shown its impact on formulation design, the augmentation of product life cycle, patent life, and therapeutic efficacy. Formulation considerations for the nanosuspension formulation, its processing into a solid form, and aspects of material characterization are discussed. Technology assessments and feasibility of upstream processes for nanoparticle creation, and subsequently transformation into a drug product via the downstream processes have been reviewed. This paper aims to bridge formulation and process considerations along with patent reviews and may provide further insight into understanding the science and the white space. An analysis of current patent outlook and future trends is described to fully understand the limitations and opportunities in intellectual property generation.

Engineered nanocrystal technology: in-vivo fate, targeting and applications in drug delivery

Formulation of nanocrystals is a robust approach which can improve delivery of poorly water soluble drugs, a challenge pharmaceutical industry has been facing since long. Large scale production of nanocrystals is done by techniques like precipitation, media milling and, high pressure homogenization. Application of appropriate stabilizers along with drying accords long term stability and commercial viability to nanocrystals. These can be administered through oral, parenteral, pulmonary, dermal and ocular routes showing their high therapeutic applicability. They serve to target drug molecules in specific regions through size manipulation and surface modification. This review dwells upon the in-vivo fate and varying applications in addition to the facets of drug nanocrystals stated above.