Effective polymeric dispersants for vacuum, convection and freeze drying of drug nanosuspensions

Eudragit L100-coated nintedanib nanocrystals improve oral bioavailability by reducing drug particle size and maintaining drug supersaturation

The aim of this study was to prepare nintedanib nanocrystals (BIBF-NCs) to lower the solubility of the drug in the stomach, maintain the supersaturation of the drug in the intestine, and improve the oral absorption of nintedanib (BIBF). In this study, BIBF-NCs were prepared by acid solubilization and alkaline precipitation following nano granding method, with a particle size of 290.80 nm and a zeta potential of -49.13 mV. Subsequently, Nintedanib enteric-coated nanocrystals (BIBF-NCs@L100) were obtained by coating with Eudragit L100. The microscopic morphology, crystalline characteristics, stability, and in vitro dissolution of BIBF-NCs and BIBF-NCs@L100 were also studied. In addition, the in vivo pharmacokinetic behaviors of Samples prepared according to the prescription process of commercially available soft capsules (soft capsules), BIBF-NCs, and BIBF-NCs@L100 were further investigated. The results showed that the oral bioavailability of BIBF-NCs and BIBF-NCs@L100 were increased by 1.43 and 2.58 times, compared with that of the soft capsules. BIBF-NCs@L100 effectively reduced the release of BIBF in the formulation in the stomach, allowing more drug to reach the intestine in the form of nanocrystals, maintaining the supersaturation in the intestine, thereby improving the oral bioavailability of the drug.

Formulation and Characterization of Ursodeoxycholic Acid Nanosuspension Based on Bottom-Up Technology and Box-Behnken Design Optimization

BACKGROUND

Ursodeoxycholic acid (UDCA) is a therapeutic agent used for the treatment of cholestatic hepatobiliary diseases in pediatric patients. It is a bile acid that presents high lipophilicity, and it belongs to Class II of the Biopharmaceutical Classification System (BCS), which exhibits low water solubility and high intestinal permeability, which leads to poor oral absorption. The objective of this work was to design and optimize UDCA nanosuspensions by means of the precipitation-ultrasonication method to improve the solubility, dissolution, and oral bioavailability of UDCA.

METHODS

A three-level, three-factor Box-Behnken design was used to optimize formulation variables and obtain uniform, small-particle-size UDCA nanosuspensions. The independent variables were: stabilizer percentage (X1), amplitude (X2), and sonication time (X3), and the dependent variable was the particle size (Y1). In the precipitation-ultrasonication method, UDCA was dissolved in acetone:PEG 400 (1:1 v/v) and quickly incorporated into the antisolvent (pre-cooled aqueous dispersion of HPMC E-15 0.3%), by means of intense sonication at 50 W for 5 min, controlling temperature through an ice water bath. The lyophilization efficacy was evaluated by means of a cryoprotective efficacy test, working with 10% maltose at -80 °C. The nanosuspensions were characterized by dynamic light scattering (DLS), X-ray diffraction, and scanning electron microscopy (SEM). The physicochemical stability was determined at 25 °C and 4 °C at 7, 14, 30, and 60 days, and the UDCA content was analyzed via HPLC-UV. An in vitro dissolution assay and an oral bioavailability study were performed in male Wistar rats.

RESULTS

A significant impact was achieved in the optimized nanosuspension with 0.3% (stabilizer), 50 W (amplitude), and 5 min (sonication time), with a particle size of 352.4 nm, PDI of 0.11, and zeta potential of -4.30 mV. It presented adequate physicochemical stability throughout the study and the UDCA content was between 90% and 110%. In total, 86% of UDCA was dissolved in the in vitro dissolution test. The relative oral bioavailability was similar without significant statistical differences when comparing the lyophilized nanosuspension and the commercial tablet, the latter presenting a more erratic behavior. The pharmacokinetic parameters of the nanosuspension and the commercial tablet were Tmax (1.0 ± 0.9 h vs. 2.0 ± 0.8 h, respectively), Cmax (0.558 ± 0.118 vs. 0.366 ± 0.113 µM, respectively), ΔCmax (0.309 ± 0.099 vs. 0.232 ± 0.056, respectively), AUC (4.326 ± 0.471 vs. 2.188 ± 0.353 µg/mL.h, respectively, p < 0.02), and IAUC0-24h (2.261 ± 0.187 µg/mL.h vs. 1.924 ± 0.440 µg/mL.h, respectively).

CONCLUSIONS

The developed nanosuspension presents an appropriate dosage and administration for pediatric patients. On the other hand, it exhibits an adequate absorption and UDCA oral bioavailability.

Influence of Polymer Concentration on Drying of SPION Dispersions by Electrospinning

To improve the physical stability of nanoparticle dispersions, several methods for their transformation into stable and easily dispersible dry products have been investigated thus far. Recently, electrospinning was shown to be a novel nanoparticle dispersion drying method, which addresses the crucial challenges of the current drying methods. It is a relatively simple method, but it is affected by various ambient, process, and dispersion parameters, which impact the properties of the electrospun product. The aim of this study was, thus, to investigate the influence of the most important dispersion parameter, namely the total polymer concentration, on the drying method efficiency and the properties of the electrospun product. The formulation was based on a mixture of hydrophilic polymers poloxamer 188 and polyethylene oxide in the weight ratio of 1:1, which is acceptable for potential parenteral application. We showed that the total polymer concentration of prior-drying samples is closely related to their viscosity and conductivity, also affecting the morphology of the electrospun product. However, the change in morphology of the electrospun product does not affect the efficiency of SPION reconstitution from the electrospun product. Regardless of the morphology, the electrospun product is not in powder form and is therefore safer to handle compared to powder nanoformulations. The optimal total polymer concentration in the prior-drying SPION dispersion, which enables the formation of an easily dispersible electrospun product with high SPION-loading (65% (w/w)) and fibrillar morphology, was shown to be 4.2% (w/v).

Development of Fully Redispersible Dried Nanocrystals by Using Sucrose Laurate as Stabilizer for Increasing Surface Area and Dissolution Rate of Poorly Water-Soluble Drugs

There is much interest in converting poorly water-soluble drugs into nanocrystals as they provide extremely high surface area that increases dissolution rate and oral bioavailability. However, nanocrystals are prepared as aqueous suspensions, and once the suspensions are dried for development of solid dosage forms, the nanocrystals agglomerate as large particles to reduce the excess surface energy. For successful development of drug products, it is essential that any agglomeration is reversible, and the dried nanocrystals regain original particle sizes after redispersion in aqueous media. We have established that sucrose laurate serves as a superb stabilizer to ensure complete redispersion of dried nanocrystals in aqueous media with mild agitation. Nanocrystals (150-300 nm) of three neutral drugs (fenofibrate, danazol and probucol) were produced with sucrose laurate by media milling, and suspensions were dried by tray drying under vacuum, spray drying, and lyophilization. Dried solids and their tablets redispersed into original particle sizes spontaneously. Preliminary studies showed that sucrose laurate can also redisperse acidic and basic drugs, indicating its versatile application. Fatty acid ester of another disaccharide, lactose laurate, also performed like sucrose laurate. Thus, we have developed a method of retaining high dissolution rate and, by implication, high bioavailability of nanocrystals from solid formulations.

Impact of Matrix Surface Area on Griseofulvin Release from Extrudates Prepared via Nanoextrusion

We aimed to examine the impact of milling of extrudates prepared via nanoextrusion and the resulting matrix surface area of the particles on griseofulvin (GF, a model poorly soluble drug) release during in vitro dissolution. Wet-milled GF nanosuspensions containing a polymer (Sol: Soluplus^®, Kol: Kolliphor^® P407, or HPC: Hydroxypropyl cellulose) and sodium dodecyl sulfate were mixed with additional polymer and dried in an extruder. The extrudates with 2% and 10% GF loading were milled–sieved into three size fractions. XRPD–SEM results show that nanoextrusion produced GF nanocomposites with Kol/HPC and an amorphous solid dispersion (ASD) with Sol. For 8.9 mg GF dose (non-supersaturating condition), the dissolution rate parameter was higher for extrudates with higher external specific surface area and those with 10% drug loading. It exhibited a monotonic increase with surface area of the ASD, whereas its increase tended to saturate above ~30 × 10⁻³ m²/cm³ for the nanocomposites. In general, the nanocomposites released GF faster than the ASD due to greater wettability and faster erosion imparted by Kol/HPC than by Sol. For 100 mg GF dose, the ASD outperformed the nanocomposites due to supersaturation and only 10% GF ASD with 190 × 10⁻³ m²/cm³ surface area achieved immediate release (80% release within 30 min). Hence, this study suggests that ASD extrudates entail fine milling yielding > ~200 × 10⁻³ m²/cm³ for rapid drug release, whereas only a coarse milling yielding ~30 × 10⁻³ m²/cm³ may enable nanocomposites to release low-dose drugs rapidly.

Freeze-drying of nanoparticles: How to overcome colloidal instability by formulation and process optimization

Lyophilization of nanoparticle (NP) suspensions is a promising technology to improve stability, especially during long-term storage, and offers new routes of administration in solid state. Although considered as a gentle drying process, freeze-drying is also known to cause several stresses leading to physical instability, e.g. aggregation, fusion, or content leakage. NPs are heterogeneous regarding their physico-chemical properties which renders them different in their sensitivity to lyophilization stress and upon storage. But still basic concepts can be deducted. We summarize basic colloidal stabilization mechanisms of NPs in the liquid and the dried state. Furthermore, we give information about stresses occurring during the freezing and the drying step of lyophilization. Subsequently, we review the most commonly investigated NP types including lipophilic, polymeric, or vesicular NPs regarding their particle properties, stabilization mechanisms in the liquid state, and important freeze-drying process, formulation and storage strategies. Finally, practical advice is provided to facilitate purposeful formulation and process development to achieve NP lyophilizates with high colloidal stability.

Cellulose-based dispersants and flocculants

Natural dispersants and flocculants, often referred to as dispersion stabilizers and liquid-solid separators, respectively, have secured a promising role in the bioprocessing community. They have various applications, including in biomedicine and in environmental remediation. A large fraction of existing dispersants and flocculants are synthesized from non-safe chemical compounds such as polyacrylamide and surfactants. Despite numerous advantages of synthetic dispersants and flocculants, issues such as renewability, sustainability, biocompatibility, and cost efficiency have shifted attention towards natural homologues, in particular, cellulose-based ones. Within the past decade, cellulose derivatives, obtained via chemical and mechanical treatments of cellulose fibrils, have successfully been used for these purposes. In this review article, by dividing the functional cellulosic compounds into "polymeric" and "nanoscale" categories, we provide insight into the engineering pathways, the structural frameworks, and surface chemistry of these "green" types of dispersants and flocculants. A summary of their efficiency and the controlling parameters is also accompanied by recent advances in their applications in each section. We are confident that the emergence of cellulose-based dispersing and flocculating agents will extend the boundaries of sustainable green technology.

Optimization, in-vitro Release and in-vivo Evaluation of Gliquidone Nanoparticles

The present work embarks upon increasing the dissolution rate and the bioavailability of model anti-diabetic drug, gliquidone, a sulfonylurea class drug used for treating diabetes mellitus type 2. The gliquidone nanoparticles were prepared by using anti-solvent precipitation technique in which, gliquidone solution in acetone was added at a controlled rate to an aqueous solution containing polyvinylpyrrolidone K25 (PVP K25) as stabilizer. The effect of drug concentration (X1), polymer concentration (X2) and solvent to anti-solvent ratio (X3) on particle size and dissolution was studied using Box-Behnken design. The results revealed that by decreasing the drug concentration and by increasing the stabilizer concentration and solvent/anti-solvent ratio, reduction in the size of the particles was observed. The mentioned parameters were optimised and particle of size about 175 nm was achieved. The relative dissolution rate of prepared gliquidone nanoparticles in phosphate buffer pH 7.4 was ~ 4.7 times faster than original drug at t = 45 min. Further, the gliquidone nanoparticles were characterized by scanning electron microscope (SEM), Fourier transform-infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and X-ray powder diffraction (XRD). The particles revealed to be oval in shape with stabilizer molecules on surface and exhibited decreased crystalline nature when compared to free gliquidone. Finally, the in vivo studies using gliquidone nanoparticles revealed ~ 2.5-fold increase in Cmax when taken orally in the form of hard gelatin capsules in comparison to free gliquidone. Thus, overall investigation suggests that the developed strategy of gliquidone nanoparticles possess a keen potential for exhibiting anti-diabetic effect.

Silica-Lipid Hybrid Microparticles as Efficient Vehicles for Enhanced Stability and Bioaccessibility of Curcumin

Curcumin is an active ingredient with multiple functions, but its application is often restricted due to its poor water solubility, weak stability, and consequently low bioaccessibility. Based on this, the aim of this work is to develop a new vehicle to overcome these restrictions. Here we developed a curcumin-loaded nanoemulsion and then curcumin-loaded silica-lipid hybrid microparticles through emulsification and vacuum drying, respectively. The loading of curcumin in the nanoemulsion and microparticles was (0.30±0.02) and (0.67±0.02) %, respectively. FTIR and XRD analyses of microparticles revealed that curcumin was encapsulated in porous, amorphous silica. In vitro antioxidant activities showed that the encapsulation would not affect the antioxidant activity of curcumin. In vitro simulated digestion indicated that nanoemulsion and microparticles had higher curcumin bioaccessibility than the control group. The storage stability of microparticles remained the same during 6 weeks in the dark at 4, 25 and 40 °C. Moreover, the microparticles had a better chemical stability than nanoemulsion under the light. The cell viability was over 80% when the concentration of nanocarriers was less than 45 μg/mL. Hence, the microparticles could be a promising means to load curcumin and improve its solubility, light stability and bioaccessibility.

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.

Improved stability and oral bioavailability of Ganneng dropping pills following transforming lignans of herpetospermum caudigerum into nanosuspensions

The present study was designed to improve storage stability and oral bioavailability of Ganneng dropping pills (GNDP) by transforming lignans of Herpetospermum caudigerum (HL) composed of herpetrione (HPE) and herpetin (HPN) into nanosuspension (HL-NS), the main active ingredient of GNDP, HL-NS was prepared by high pressure homogenization and lyophilized to transform into solid nanoparticles (HL nanoparticles), and then the formulated HL nanoparticles were perfused into matrix to obtain NS-GNDP by melting method. For a period of 3 months, the content uniformity, storage stability and pharmacokinetics test in vivo of NS-GNDP were evaluated and compared with regular GNDP at room temperature. The results demonstrated that uniformity of dosage units of NS-GNDP was acceptable according to the criteria of Chinese Pharmacopoeia 2015J. Physical stability of NS-GNDP was investigated systemically using photon correlation spectroscopy (PCS), zeta potential measurement, and scanning electron microscopy (SEM). There was a slight increase in particles and PI of HL-NS re-dispersed from NS-GNDP after storage for 3 months, compared with new formulated NS-GNDP, which indicated a good redispersibility of the NS-GNDP containing HL-NS after storage. Besides, chemical stability of NS-GNDP was studied and the results revealed that HPE and HPN degradation was less when compared with that of GNDP, providing more than 99% of drug residue after storage for 3 months. In the dissolution test in vitro, NS-GNDP remarkably exhibited an increased dissolution velocity compared with GNDP and no distinct dissolution difference existed within 3 months. The pharmacokinetic study showed that HPE and HPN in NS-GNDP exhibited a significant increase in AUC_0-t, C_max and decrease in T_max when compared with regular GNDP. These results indicated that NS-GNDP possessed superiority with improved storage stability and increased dissolution rate and oral bioavailability.

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.

Novel nanocrystal-based solid dispersion with high drug loading, enhanced dissolution, and bioavailability of andrographolide

Objective

The current study sought to design a quickly dissolving, high drug loading nanocrystal-based solid dispersion (NC-SD) in order to improve the dissolution of poorly soluble drugs.

Methods

The NC-SD was prepared by means of combination of homogenization and spray-drying. Polymer hydroxypropylmethylcellulose (HPMC) was used as baseline dispersant for NC-SD of the model drug – andrographolide (AG). Three superdisintegrants cohomogenized with HPMC were used as codispersant for AG-NC-SD and compared to common water-soluble dispersants – mannitol and lactose. The dissolution characterization and oral bioavailability of AG-NC-SD were evaluated.

Results

The AG-NC-SD with the higher concentration of HPMC exhibited fast dissolution due to the enhanced wettability of HPMC. The water-soluble codispersants (mannitol and lactose) did not completely prevent AG-NC from aggregation during spray-drying. To achieve much faster AG release, cohomogenized superdisintegrants at a level of 20% must be used along with 25% HPMC. Compared with water-soluble dispersants like mannitol and lactose, superdisintegrants with high swelling capacity were much more effective dispersants for enhancing fast redispersion/dissolution of AG-NC-SD via a swelling-triggered erosion/disintegration mechanism. Surfactant-free AG-NC-SD with 15% cohomogenized sodium carboxymethyl starch combined with 15% HPMC and 10% lactose enhanced the dissolution further, without comprising drug loading, exhibited a barely compromised dissolution rate compared to precursor NC suspensions (f₂>50), and possessed drug loading up to 67.83%±1.26%. The pharmacokinetics results also demonstrated that the AG-NC-SD significantly improved the bioavailability in vivo of AG (P<0.05), compared with to the coarse AG.

Conclusion

This study illustrates that a quickly dissolving, high drug load, surfactant-free NC-SD can be prepared by using a superdisintegrant as codispersant, and provides a feasible strategy to improve the oral bioavailability of poorly soluble drugs.

Design and characterization of loratadine nanosuspension prepared by ultrasonic-assisted precipitation

Nanoparticle engineering is a well-defined technique employed as a novel and effective method in drug design and delivery. It is widely used to control particle size, as well as the morphological and physicochemical properties of active pharmaceutical ingredients. Furthermore, it serves as a method of pre-dispersion preparation for various dosage form developments. Nanotechnology produces nanomaterials with enhanced properties in terms of solubility, dissolution and permeability. In this work, ultrasonic-assisted precipitation was employed to produce nanosuspensions of poorly water-soluble loratadine, using different stabilizers. The objective of our study was attempting to prepare solid nanoparticles of loratadine to be used as a possible intermediate for designing various dosage forms. The effects of the type(s) and concentration(s) of stabilizer(s) on mean particle size were assessed. Optimal process parameters required to produce homogeneous nanoparticles with particle size below 500 nm and polydispersity less than 0.3 were determined both for precipitation and ultrasonication. Pre-dispersions were evaluated for their particle size, polydispersity index and zeta potential. Freeze-drying was employed to produce dry nanoparticles. Particle size, particle size distribution and zeta potential of the dried nanoparticles were measured after reconstitution in water. Besides thermal analysis using DSC and structural analyses (XRPD and FT-IR), the morphological characteristics and dissolution behaviors were also investigated. The selected freeze-dried nanoparticles had a mean particle size range of 353-441 nm, a polydispersity index ranging between 0.167 and 0.229 and a zeta potential between -25.7 and -20.7 mV. These results suggest that material and process parameters were successfully optimized. DSC and XRPD spectra confirmed interactions between the formulation's components during freeze-drying. The solid nanoparticles showed 30-42% of cumulative release after 10 min compared to less than 1% of dissolution characterizing loratadine without pre-processing. This study demonstrates that preparing dried loratadine nanoparticles suitable for designing effective drug preparations is a feasible approach.

Quiescent and Agitated Redispersion as a Tool for Evaluating Dispersant Effectiveness in Dissolution Enhancement of Drug-Laden Nanocomposites

Nanocomposite microparticles (NCMPs) have been used in various solid dosage forms with the goal of enhancing the dissolution rate and bioavailability of poorly water-soluble drugs. Nanoparticle recovery from NCMPs, i.e., redispersion, is the preliminary step in drug dissolution. This study aims at exploring aqueous redispersion of NCMPs with various dispersants under quiescent vs. agitated conditions as potential dispersant screening tool in the development of fast-dissolving NCMP formulations. NCMPs were prepared by coating wet-milled suspensions of a poorly water-soluble drug, griseofulvin (GF), formulated with the dispersants hydroxypropyl cellulose (HPC), sodium dodecyl sulfate (SDS), as-received/wet co-milled croscarmellose sodium (CCS), and mannitol, onto Pharmatose® carrier particles in a fluidized bed dryer. The NCMPs were added to quiescent water kept in a cuvette, and the redispersion was visualized and investigated by turbidimetry and dynamic light scattering. The morphological evolution of a single NCMP exposed to a drop of water was studied via optical microscopy, which provided further insight into the self-redispersibility. As a comparison, the NCMPs were also redispersed in water agitated by a paddle stirrer followed by centrifugation and drug assay of the resultant supernatant, which yielded the percentage of GF recovered as nanoparticles. Both quiescent and agitated redispersion methods yielded similar rank-ordering of the dispersants: NCMPs with either HPC/SDS or HPC/CCS exhibited effective nanoparticle recovery and fast dissolution, whereas those with HPC or HPC/mannitol led to poor redispersibility and slow dissolution. This study demonstrates that both quiescent and agitated redispersion tests could be used for screening/optimizing dispersants for fast-dissolving drug NCMP formulations.

The Roles of Vitrification of Stabilizers/Matrix Formers for the Redispersibility of Drug Nanocrystals After Solidification: a Case Study

To elucidate the roles of vitrification of stabilizers/matrix formers for the redispersibility of drug nanocrystal powder after solidification at storage stress, the influence of different drying methods and storage stresses on stability of drug nanocrystals was systemically investigated. A poorly soluble drug, baicalin, used as model drug was converted into baicalin nanocrystals (BCN-NC). The residual moisture contents of BCN-NC were applied at two different stress conditions defined as "conservative" (<1%) and "aggressive" (>1%), respectively. The influence of different stabilizers, matrix formers, and storage stresses on the redispersibility of BCN-NC powder was systemically investigated, respectively. The results showed that storage stresses had significantly influence the redispersibility of BCN-NC. Aggressive storage temperature and residual moisture could be unfavorable factors for stability of drug nanocrystals, due to the exacerbation of aggregation of BCN-NC induced by vitrification. It was demonstrated that vitrification of spray-dried BCN-NC was dependent on temperature and time. The polymeric stabilizers hydroxypropylmethylcellulose (HPMC) and sodium carboxymethyl starch (CMS-Na) with high glass transition temperature (T _g) played more important role in protecting the BCN-NC from breakage during storage, compared to the surfactants Tween 80, D-α-tocopherol acid polyethylene glycol 1000 succinate (TPGS), or RH 40. Besides, the polyvinylpyrrolidone K30 (PVP K30) and lactose with high T _g were effective matrix formers for preserving the redispersibility of BCN-NC. It was concluded that the vitrification transition of stabilizers/matrix formers could be responsible for aggregation of drug nanocrystals during storage, which was a time-dependent process. The suitable residual moisture contents (RMC) and T _g were very important for preserving the stability of drug nanocrystals during storage.

Panax Notoginseng Saponins as a Novel Nature Stabilizer for Poorly Soluble Drug Nanocrystals: A Case Study with Baicalein

This study is aimed at seeking a nature saponin-based stabilizer for drug nanosuspensions. A poorly soluble drug (baicalein, BCL) was used as a model drug. BCL nanosuspensions with particle size of 156 nm were prepared by means of homogenization and converted into BCL nanocrystals (BCL-NC) stabilized with panax notoginseng saponins (PNS). It was found that PNS was able to prevent the aggregation of BCL-NS during storage and improve the redispersibility of BCL-NC after freeze-drying and spray-drying, compared with polymer stabilizer PVPK30. The freeze-dried and spray-dried BCL-NC with PNS exhibited excellent performance as evidenced by scanning_electron_microscope (SEM) analysis. It was the reason that PNS possessed the interfacial property (41.69 ± 0.32 mN/m) and electrostatic effect (−40.1 ± 1.6 mV), which could easily adsorb onto the surface of hydrophobic BCL nanocrystals and prevent from its aggregation. It is concluded that PNS can be used as an effective nature stabilizer for production of drug nanocrystals.

Stabilizing Agents for Drug Nanocrystals: Effect on Bioavailability

Drug nanocrystals are a versatile option for drug delivery purposes, and while the number of poorly soluble drug materials is all the time increasing, more research in this area is performed. Drug nanocrystals have a simple structure-a solid drug core is surrounded by a layer of stabilizing agent. However, despite the considerably simple structure, the selection of an appropriate stabilizer for a certain drug can be challenging. Mostly, the stabilizer selection is based purely on the requirement of physical stability, e.g., maintaining the nanosized particle size as long as possible after the formation of drug nanocrystals. However, it is also worth taking into account that stabilizer can affect the bioavailability in the final formulation via interactions with cells and cell layers. In addition, formation of nanocrystals is only one process step, and for the final formulation, more excipients are often added to the composition. The role of the stabilizers in the final formulation can be more than only stabilizing the nanocrystal particle size. A good example is the stabilizer's role as cryoprotectant during freeze drying. In this review, the stabilizing effect, role of stabilizers in final nanocrystalline formulations, challenges in reaching in vitro-in vivo correlation with nanocrystalline products, and stabilizers' effect on higher bioavailability are discussed.

Recent advances in the engineering of nanosized active pharmaceutical ingredients: Promises and challenges

The advances in the field of nanotechnology have revolutionized the field of delivery of poorly soluble active pharmaceutical ingredients (APIs). Nanosized formulations have been extensively investigated to achieve a rapid dissolution and therefore pharmacokinetic properties similar to those observed in solutions. The present review outlines the recent advances, promises and challenges of the engineering nanosized APIs. The principles, merits, demerits and applications of the current 'bottom-up' and 'top-down' technologies by which the state of the art nanosized APIs can be produced were described. Although the number of research reports on the nanoparticle engineering topic has been growing in the last decade, the challenge is to take numerous research outcomes and convert them into strategies for the development of marketable products.

Solidification drug nanosuspensions into nanocrystals by freeze-drying: a case study with ursodeoxycholic acid

To elucidate the effect of solidification processes on the redispersibility of drug nanocrystals (NC) during freeze-drying, ursodeoxycholic acid (UDCA) nanosuspensions were transformed into UDCA-NC via different solidification process included freezing and lyophilization. The effect of different concentrations of stabilizers and cryoprotectants on redispersibility of UDCA-NC was investigated, respectively. The results showed that the redispersibility of UDCA-NC was RDI-20 °C < RDI-80 °C < RDI-196 °C during freezing, which indicated the redispersibility of UDCA-NC at the conventional temperature was better more than those at moderate and rigorous condition. Compared to the drying strengthen, the employed amount and type of stabilizers more dramatically affected the redispersibility of UDCA-NC during lyophilization. The hydroxypropylmethylcellulose and PVPK30 were effective to protect UDCA-NC from damage during lyophilization, which could homogeneously adsorb into the surface of NC to prevent from agglomerates. The sucrose and glucose achieved excellent performance that protected UDCA-NC from crystal growth during lyophilization, respectively. It was concluded that UDCA-NC was subjected to agglomeration during solidification transformation, and the degree of agglomeration suffered varied with the type and the amounts of stabilizers used, as well as different solidification conditions. The PVPK30-sucrose system was more effective to protect UDCA-NC from the damage during solidification process.

Polymeric micelles for oral drug administration enabling locoregional and systemic treatments

INTRODUCTION

Amphiphilic block copolymers are recognized components of parenteral drug nanocarriers. However, their performance in oral administration has barely been evaluated to any great extent.

AREAS COVERED

This review provides an overview of the methods used to prepare drug-loaded polymeric micelles and to evaluate their stability in gastrointestinal (GI) fluids, and then analyzes in detail recent in vitro and in vivo results about their performance in oral drug delivery. Oral administration of polymeric micelles has been tested for a variety of therapeutic purposes, namely, to increase apparent drug solubility in the GI fluids and facilitate absorption, to penetrate in pathological regions of the GI tract for locoregional treatment, to carry the drug directly toward the blood stream minimizing presystemic loses, and to target the drug after oral absorption to specific tissue or cells in the body.

EXPERT OPINION

Each therapeutic purpose demands micelles with different performance regarding stability in the GI tract, ability to overcome physiological barriers and drug release patterns. Depending on the block copolymer composition and structure, a wealth of self-assembled micelles with different morphologies and stability can be prepared. Moreover, copolymer unimers can play a role in improving drug absorption through the GI mucosa, either by increasing membrane permeability to the drug and/or the carrier or by inhibiting drug efflux transporters or first-pass metabolism. Therefore, polymeric micelles can be pointed out as versatile vehicles to increase oral bioavailability of drugs that exhibit poor solubility or permeability and may even be an alternative to parenteral carriers when targeting is pursued.

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.

Redispersible fast dissolving nanocomposite microparticles of poorly water-soluble drugs

Enhanced recovery/dissolution of two wet media-milled, poorly water-soluble drugs, Griseofulvin (GF) and Azodicarbonamide (AZD), incorporated into nanocomposite microparticles (NCMPs) via fluidized bed drying (FBD) and spray-drying (SD) was investigated. The effects of drying method, drug loading, drug aqueous solubility/wettability as well as synergistic stabilization of the milled suspensions on nanoparticle recovery/dissolution were examined. Drug nanoparticle recovery from FBD and SD produced NCMPs having high drug loadings was evaluated upon gentle redispersion via optical microscopy and laser diffraction. During wet-milling, hydroxypropyl cellulose (HPC) alone stabilized more wettable drug (AZD) nanoparticles with slight aggregation, but could not prevent aggregation of the GF nanoparticles. In contrast, well-dispersed, stable nanosuspensions of both drugs were produced when sodium dodecyl sulfate (SDS) and HPC were combined. The FBD and SD NCMPs without SDS exhibited incomplete nanoparticle recovery, causing slower dissolution for GF, but not for AZD, likely due to higher aqueous solubility/wettability of AZD. For high active loaded NCMPs (FBD ∼50 wt%, SD ∼80 wt%) of either drug, HPC-SDS together owing to their synergistic stabilization led to fast redispersibility/dissolution, corroborated via optical microscopy and particle sizing. These positive attributes can help development of smaller, high drug-loaded dosage forms having enhanced bioavailability and better patient compliance.

Development and characterization of an orodispersible film containing drug nanoparticles

In this study, a novel orodispersible film (ODF) containing drug nanoparticles was developed with the goal of transforming drug nanosuspensions into a solid dosage form and enhancing oral bioavailability of drugs with poor water solubility. Nanosuspensions were prepared by high pressure homogenization and then transformed into ODF containing drug nanoparticles by mixing with hydroxypropyl methylcellulose solution containing microcrystalline cellulose, low substituted hydroxypropylcellulose and PEG-400 followed by film casting and drying. Herpetrione, a novel and potent antiviral agent with poor water solubility that extracted from Herpetospermum caudigerum, was chosen as a model drug and studied systematically. The uniformity of dosage units of the preparation was acceptable according to the criteria of Japanese Pharmacopoeia 15. The ODF was disintegrated in water within 30s with reconstituted nanosuspensions particle size of 280 ± 11 nm, which was similar to that of drug nanosuspensions, indicating a good redispersibility of the fast dissolving film. Result of X-ray diffraction showed that HPE in the ODF was in the amorphous state. In the in vitro dissolution test, the ODF containing HPE nanoparticles showed an increased dissolution velocity markedly. In the pharmacokinetics study in rats, compared to HPE coarse suspensions, the ODF containing HPE nanoparticles exhibited significant increase in AUC0-24h, Cmax and decrease in Tmax, MRT. The result revealed that the ODF containing drug nanoparticles may provide a potential opportunity in transforming drug nanosuspensions into a solid dosage form as well as enhancing the dissolution rate and oral bioavailability of poorly water-soluble drugs.

Enhanced recovery and dissolution of griseofulvin nanoparticles from surfactant-free nanocomposite microparticles incorporating wet-milled swellable dispersants

Nanocomposite microparticles (NCMPs) incorporating drug nanoparticles and wet-milled swellable dispersant particles were investigated as a surfactant-free drug delivery vehicle with the goal of enhancing the nanoparticle recovery and dissolution rate of poorly water-soluble drugs. Superdisintegrants were used as inexpensive, model, swellable dispersant particles by incorporating them into NCMP structure with or without wet-stirred media milling along with the drug. Suspensions of griseofulvin (GF, model drug) along with various dispersants produced by wet-milling were coated onto Pharmatose® to prepare NCMPs in a fluidized bed process. Hydroxypropyl cellulose (HPC, polymer) alone and with sodium dodecyl sulfate (SDS, surfactant) was used as base-line stabilizer/dispersant during milling. Croscarmellose sodium (CCS, superdisintegrant) and Mannitol were used as additional dispersants to prepare surfactant-free NCMPs. Nanoparticle recovery during redispersion and dissolution of the various GF-laden NCMPs were examined. Suspensions prepared by co-milling GF/HPC/CCS or milling GF/HPC/SDS were stable after 30 h of storage. After drying, due to its extensive swelling capacity, incorporation of wet-milled CCS in the NCMPs caused effective breakage of the NCMP structure and bursting of nanoparticle clusters, ultimately leading to fast recovery of the GF nanoparticles. Optimized wet co-milling and incorporation of CCS in NCMP structure led to superior dispersant performance over incorporation of unmilled CCS or physically mixed unmilled CCS with NCMPs. The enhanced redispersion correlated well with the fast GF dissolution from the NCMPs containing either CCS particles or SDS. Overall, swellable dispersant (CCS) particles, preferably in multimodal size distribution, enable a surfactant-free formulation for fast recovery/dissolution of the GF nanoparticles.

Effervescent redispersion of lyophilized polymeric nanoparticles

Background: Freeze-drying is an attractive method for converting nanoparticulate pharmaceutical dispersions into a stable form with a long shelf life. However, practical challenges in translating laboratory practice to the clinic, such as high protectant osmolarity and infeasible reconstitution methods, currently limit lyophilized formulation development of nanoparticle therapeutics. Results: We demonstrate the use of effervescent redispersion for the reconstitution of lyophilized polymeric nanoparticles and we show that a 3:1 mass ratio of effervescent salt produced the optimum redispersibility. With only low-energy hand agitation, reconstitution to sizes less than 600 nm was achieved. Second, the effect of nanoparticle formulation parameters (dispersion concentration, molecular weight of the stabilizing polymer, and physical state of the nanoparticle core) on particle redispersibility were examined. Conclusion: This novel freeze-drying and reconstitution method offers a route to producing redispersible dry powders of nanoparticle therapeutics.

D-Alpha-tocopherol acid polyethylene glycol 1000 succinate, an effective stabilizer during solidification transformation of baicalin nanosuspensions

Baicalin nanosuspensions, stabilized with 10% TPGS (relative to the weight of baicalin), were transformed into nanosuspensions powders by solidification process. Solidification methods for this transformation included freeze-drying, spray drying or vacuum drying. High pressure homogenization was applied for production of baicalin nanosuspensions used TPGS, SDS, P188, HPMC and MC as stabilizer, respectively. The influence of the different solidification transformation methods on the redispersibility of solid drug nanosuspensions was systemically investigated, such as freeze-drying, spray drying and vacuum drying. Each method was applied with three grades of process stresses called as "conservative", "moderate" and "aggressive" conditions, and the redispersibility index (RDI) of nanosuspensions stabilized by stabilizers (such as TPGS, SDS, P188, HPMC and MC) during those process was investigated. The results showed that there was significant difference in RDI of nanosuspensions after solidification process. The RDI(a) (1.09, 1.01, 1.05, 0.99), RDI(b) (1.03, 0.99, 1.06, 1.02) and RDI(c) (1.01, 1.01, 1.09, 1.08) of nanosuspensions stabilized by TPGS were more small during different solidification process, compared with those of nanosuspensions stabilized by other stabilizer. It was concluded that the baicalin nanosuspensions were subjected to agglomeration or crystal growth during solidification transformation, especially at high aggressive stress conditions. Meanwhile, compared to other stabilizer, the TPGS was more effective for stability of baicalin nanosuspensions, which could exhibit higher affinity to the drug crystal and stronger surface adsorption at different solidification stresses.