Effect of nanonization on absorption of 301029: ex vivo and in vivo pharmacokinetic correlations determined by liquid chromatography/mass spectrometry

Vitamin D loaded into lipid nanoparticles shows insulinotropic effect in INS-1E cells

Increasing evidence suggests a beneficial role of vitamin D (VitD) supplementation in addressing the widespread VitD deficiency, but currently used VitD3 formulations present low bioavailability and toxicity constrains. Hence, poly(L-lactide-co-glycolide) (PLGA) nanoparticles (NPs), solid-lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) were investigated to circumvent these issues. PLGA NPs prepared by emulsification or nanoprecipitation presented 74 or 200 nm, and association efficiency (AE) of 68 % and 17 %, respectively, and a rapid burst release of VitD3. Both SLN and NLCs presented higher polydispersity and larger NPs size, around 500 nm, which could be reduced to around 200 nm by use of hot high-pressure homogenization in the case of NLCs. VitD3 was efficiently loaded in both SLNs and NLCs with an AE of 82 and 99 %, respectively. While SLNs showed burst release, NLCs allowed a sustained release of VitD3 for nearly one month. Furthermore, NLCs showed high stability with maintenance of VitD3 loading for up to one month at 4 °C and no cytotoxic effects on INS-1E cells up to 72 h. A trending increase (around 30 %) on glucose-dependent insulin secretion was observed by INS-1E cells pre-treated with VitD3. This effect was consistently observed in the free form and after loading on NLCs. Overall, this work contributed to further elucidation on a suitable delivery system for VitD3 and on the effects of this metabolite on β cell function.

Enhanced biopharmaceutical performance of brick dust molecule nilotinib via stabilized amorphous nanosuspension using a facile acid-base neutralization approach

"Brick dust" compounds have high lattice energy as manifested by the poor aqueous solubility and suboptimal bioavailability. Nilotinib being a weakly basic brick dust molecule exhibits erratic and limited absorption during gastrointestinal transit, attributed to pre-absorptive factors like pH-dependent solubility, poor dissolution kinetics, and post-absorptive factors including P-gp-mediated drug efflux. In our study, these problems are addressed holistically by the successful fabrication of amorphous nanosuspension by an acid-base neutralization approach. The nanosuspension was obtained via rapid precipitation of nilotinib in an amorphous form and the generated in situ sodium chloride salt assisted in stabilizing the drug-loaded nanosuspension in a cage of salt and micellar stabilizer. Soluplus® and hypromellose acetate succinate (HPMCAS) were employed as a novel combination of stabilizers. Systematic optimization was carried out by employing the I-optimal method using Design Expert® software with a concentration of HPMCAS and Soluplus® as independent variables and evaluating them for responses viz particle size, polydispersity index (PDI), and zeta potential. The resultant nanosuspension showed a mean particle size of 130.5 ± 1.22 nm with a PDI value of 0.27 ± 0.01, and a zeta potential of - 5.21 ± 0.91 mV. The nanosuspension was further characterized for morphology, dissolution, and in vivo pharmacokinetics study. X-ray powder diffraction study of the nano-formulation displayed a halo pattern revealing the amorphous form. Stability studies showed that the nanosuspension remained stable at 40 °C ± 2 °C and 75% RH ± 5% RH for a period of three months. In vitro drug release and solubility study showed threefold and 36-fold enhancement in dissolution and solubility of the nanosuspension. Furthermore, an in vivo pharmacokinetic study in Sprague-Dawley rats following oral administration displayed a 1.46-fold enhancement in the relative bioavailability of the nanosuspension in contrast to neat nilotinib.

Leveraging the use of in vitro and computational methods to support the development of enabling oral drug products: An InPharma commentary

Due to the strong tendency towards poorly soluble drugs in modern development pipelines, enabling drug formulations such as amorphous solid dispersions, cyclodextrins, co-crystals and lipid-based formulations are frequently applied to solubilize or generate supersaturation in gastrointestinal fluids, thus enhancing oral drug absorption. Although many innovative in vitro and in silico tools have been introduced in recent years to aid development of enabling formulations, significant knowledge gaps still exist with respect to how best to implement them. As a result, the development strategy for enabling formulations varies considerably within the industry and many elements of empiricism remain. The InPharma network aims to advance a mechanistic, animal-free approach to the assessment of drug developability. This commentary focuses current status and next steps that will be taken in InPharma to identify and fully utilize 'best practice' in vitro and in silico tools for use in physiologically based biopharmaceutic models.

Nanoparticles Formulation Improves the Antifibrogenic Effect of Quercetin on an Adenine-Induced Model of Chronic Kidney Disease

Renal fibrosis is the final stage of chronic kidney injury characterized by glomerulosclerosis and tubulointerstitial fibrosis with parenchymal destruction. Quercetin belongs to the most studied flavonoids with antioxidant, anti-inflammatory, antifibrogenic, and antitumor activity. It modifies the TGF-β/Smad signaling pathway, decreasing profibrogenic expression molecules and inducing the expression of antioxidant, anti-inflammatory, and antifibrogenic molecules. However, quercetin exhibits poor water solubility and low absorption and bioavailability. This limitation was solved by developing a nanoparticles formulation that improves the solubility and bioavailability of several bioactive compounds. Therefore, we aimed to investigate the in vivo antifibrogenic effect of a quercetin nanoparticles formulation. Male C57BL/6 mice were induced into chronic renal failure with 50 mg/kg of adenine for four weeks. The animals were randomly grouped and treated with 25, 50, or 100 mg/kg of quercetin, either macroparticles or nanoparticles formulation. We performed biochemical, histological, and molecular analyses to evaluate and compare the effect of macroparticles versus nanoparticles formulation on kidney damage. Here, we demonstrated that smaller doses of nanoparticles exhibited the same beneficial effect as larger doses of macroparticles on preventing kidney damage. This finding translates into less quercetin consumption reaching the desired therapeutic effect.

Immobilized Alcalase on Micron- and Submicron-Sized Alginate Beads as a Potential Biocatalyst for Hydrolysis of Food Proteins

Enzymatic hydrolysis of food proteins is convenient method to improve their functional properties and physiological activity. Herein, the successful covalent attachment of alcalase on alginate micron and submicron beads using the carbodiimide based chemistry reaction and the subsequent application of the beads for egg white and soy proteins hydrolysis were studied. In addition to the electrostatic extrusion technique (EE) previously used by others, the potential utilization of a novel ultrasonic spray atomization technique without drying (UA) and with drying (UAD) for alginate submicron beads production has been attempted. The immobilization parameters were optimized on microbeads obtained by EE technique (803 ± 23 µm) with respect to enzyme loading and alcalase activity. UA and UAD techniques resulted in much smaller particles (607 ± 103 nm and 394 ± 51 nm in diameter, respectively), enabling even higher enzyme loading of 671.6 ± 4 mg g−1 on the carrier and the highest immobilized alcalase activity of 2716.1 IU g−1 in the standard reaction. The UAD biocatalyst exhibited also better performances in the real food system based on egg white or soy proteins. It has been shown that the immobilized alcalase can be reused in seven successive soy protein hydrolysis cycles with a little decrease in the activity.

Intestinal absorption of BCS class II drugs administered as nanoparticles: A review based on in vivo data from intestinal perfusion models

An established pharmaceutical strategy to increase oral drug absorption of low solubility–high permeability drugs is to create nanoparticles of them. Reducing the size of the solid-state particles increases their dissolution and transport rate across the mucus barrier and the aqueous boundary layer. Suspensions of nanoparticles also sometimes behave differently than those of larger particles in the fed state. This review compares the absorption mechanisms of nano- and larger particles in the lumen at different prandial states, with an emphasis on data derived from in vivo models. Four BSC class II drugs—aprepitant, cyclosporine, danazol and fenofibrate—are discussed in detail based on information from preclinical intestinal perfusion models.

Eliminating blood oncogenic exosomes into the small intestine with aptamer-functionalized nanoparticles

There are disease-causing biohazards in the blood that cannot be treated with modern medicines. Here we show that an intelligently designed safe biomaterial can precisely identify, tow and dump a targeted biohazard from the blood into the small intestine. Positively charged mesoporous silica nanoparticles (MSNs) functionalized with EGFR-targeting aptamers (MSN-AP) specifically recognize and bind blood-borne negatively charged oncogenic exosomes (A-Exo), and tow A-Exo across hepatobiliary layers and Oddi's sphincter into the small intestine. MSN-AP specifically distinguish and bind A-Exo from interfering exosomes in cell culture and rat and patient blood to form MSN-AP and A-Exo conjugates (MSN-Exo) that transverse hepatocytes, cholangiocytes, and endothelial monolayers via endocytosis and exocytosis mechanisms, although Kupffer cells have been shown to engulf some MSN-Exo. Blood MSN-AP significantly decreased circulating A-Exo levels, sequentially increased intestinal A-Exo and attenuated A-Exo-induced lung metastasis in mice. This study opens an innovative avenue to relocate blood-borne life-threatening biohazards to the intestine.

Ginkgolides-loaded soybean phospholipid-stabilized nanosuspension with improved storage stability and in vivo bioavailability

The purpose of this study was to investigate the effects of soybean phospholipid, as a steric stabilizer, on improving dissolution rate, storage stability and bioavailability of ginkgolides. The ginkgolides coarse powder, hydroxypropyl methylcellulose (HPMC), soybean phospholipid and sodium dodecyl sulfate (SDS) were mixed and wet-milled to prepare nanosuspension S1. Nanosuspension S2 was obtained by the same technique except adding the soybean phospholipid. Results of particle size showed that particle size (D50) of S1 significantly decreased from 44.25 μm to 0.373 μm. Results of differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD) and transmission electron microscope (TEM) showed that ginkgolides in nanosuspension still maintained its crystallinity, and the nanoparticles were all nearly circular and uniformly dispersed. Then, pellets F1 and F2 were prepared by layering S1 and S2 onto the microcrystalline cellulose (MCC) spheres, respectively. The dissolution rate of ginkgolide A (GA) and ginkgolide B (GB) in F1 was 98.3% and 97.7% in 30 min, respectively. It was much higher than F2 (89.0% and 86.5%) and coarse powder of ginkgolides (22.3% and 24.6%). According to the results of stability test, the storage stability of F1 was improved compared with F2. In addition, compared with coarse powder of ginkgolides, the relative bioavailability of GA and GB in F1 were up to (221.84 ± 106.67) % and (437.45 ± 336.43) %, respectively. The above results demonstrated that soybean phospholipid added to the nanosuspension played an important role in improving drug dissolution rate, storage stability and in vivo bioavailability: (1) The amphiphilic soybean phospholipid interacted with the drug, with the hydrophobic part adsorbed on the surface of the poorly soluble drug and the hydrophilic part exposed to the aqueous medium. This increases the wettability of the nanoparticles, which ensure a good redispersibility of the drug particles. (2) It could self-assemble to form an interfacial phospholipid film by surrounding the individual nanoparticles, which can produce enough steric hindrance to prevent nanoparticles from aggregation and ensure a rapid dissolution rate. (3) Soybean phospholipid and its hydrolysate formed strong micellar solubilizing vehicles with bile salts in vivo, stimulated the absorption process of ginkgolides. Thus, soybean phospholipid was a promising steric stabilizer in nanosuspension drug delivery system.

Risk assessment and QbD based optimization of an Eprosartan mesylate nanosuspension: In-vitro characterization, PAMPA and in-vivo assessment

Quality by design (QbD) principles were implemented to understand the product and process variables of sonoprecipitation technique, for preparation of eprosartan mesylate (EM) nanosuspension. Quality risk management approach was utilized to identify and assess high-risk attributes affecting critical quality attributes (CQA's), prioritizing the number of experiments. The effect of critical material attributes (CMA's) and critical process parameters (CPP's) (soluplus concentration, drug concentration ultrasonication amplitude) on z-average particle size and PDI were investigated using a central composite face-centered design (CCF). Further, design space with criteria set of CMA's and CPP's was established to offer assurance of quality. The optimal formulation, identified using numerical optimization method, was further lyophilized and evaluated for redispersibility, solubility saturation, dissolution kinetic and in-vitro dissolution behavior. The EM nanoparticles were in an amorphous state as confirmed by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) studies. The stability study conducted for a span of 6 months attests physical and chemical stability of EM dry nanosuspension in an amorphous state when stored at 4 °C. The enhanced solubility and in-vitro dissolution of EM nanosuspension may be attributed to the reduced particle size and alteration of the physical state from a crystalline to an amorphous state. Further, the optimized formulation was subjected to in-vitro and ex-vivo transport study using parallel artificial membrane permeability assay (PAMPA) and rat everted gut sac model respectively. The transport studies revealed successful permeation enhancement of EM nanoparticle when compared with EM API and physical mixture (PM). The absolute bioavailability of EM API was 7.1% and improved to 39.9% for EM nanosuspension, suggesting that nanoformulation had overcome solubility and permeability limited bioavailability which was observed with EM API.

Enhanced dissolution/caco-2 permeability, pharmacokinetic and pharmacodynamic performance of re-dispersible eprosartan mesylate nanopowder

Eprosartan mesylate is an angiotensin receptor blocker which suffers from extremely poor bioavailability owing to its poor solubility and poor permeability. The rationale of the present work was to design the drug delivery system capable of overcoming these constraints. Nanoformulation of eprosartan mesylate was developed using ultrasonic wave-assisted liquid-antisolvent technique. Nanoformulation was further freeze dried with the addition of 1% of mannitol resulting in formation of re-dispersible EPM nanopowder. To prove our proof of principle, the re-dispersed nanopowder with z-average particle size 165.2 ± 1.8 nm was evaluated enormously for in-vitro dissolution behaviour and permeability assay through Caco-2 cell model. In-vitro dissolution study was performed at pH 1.2, pH 4.5 and pH 6.8. Result demonstrates enhanced dissolution from EPM nanopowder with negligible pH dependence. Transport studies accomplished using validated Caco-2 based cell model showed 11-fold enhanced apparent permeability of redispersed nanopowder when compared to pure EPM and corresponding physical mixture (p < 0.0001). In-vivo study reveals, exceptionally strong variations in plasma concentration of EPM through nanopowder (62 mg/kg) formulation when compared with physical mixture and pure EPM (62 mg/kg) group. Moreover, study manifests that 5-fold lower dose (12.4 mg/kg) of developed formulation yields higher exposure (4600 ± 36 ng·mL^-1·h) than pure EPM (2349 ± 34 ng·mL^-1·h) and corresponding physical mixture (2456 ± 49 ng·mL^-1·h) at therapeutic dose (62 mg/kg). Further, L-NAME induced hypertensive model was undertaken to investigate effect of reduced dose of EPM nanopowder on systolic blood pressure, biochemical analysis and histopathology of heart. Results revealed pronounced antihypertensive potential of re-dispersed EPM nanopowder at 5-fold lower dose (12.4 mg/kg). In conclusion, our study indicates that nanopowder delivery might be the promising approach for providing enhanced oral bioavailability at lower dose.

Fabrication and Evaluation of Lambda-Cyhalothrin Nanosuspension by One-Step Melt Emulsification Technique

Recent years have witnessed significant progress in nanotechnology and pesticide research in pest control and crop protection. There are more motivations to develop nanoformulations that are less harmful to environment than conventional formulations. The use of nanosuspension has been proposed as a novel formulation to process poorly soluble pesticides. In this study, the lambda-cyhalothrin nanosuspension (LCNS) was prepared in a melt emulsification method. The prepared nanosuspension had a mean particle size of 12.0 ± 0.1 nm and a polydispersity index of 0.279 ± 0.135. The smaller particle size and polydispersity confer better wettability, stability and bioavailability than conventional suspension concentrates. The excellent properties of the nanosuspension were attributed to the reduced particle size and the emulsification and dispersion of the surfactants. The LCNS eliminates the need for organic solvents and significantly reduces the amount of surfactant required. The simple production process of LCNS saves production and equipment costs. The results indicate that lambda-cyhalothrin nanosuspensions would have a broad application prospect in agricultural production systems.

Sex-related pharmacokinetic differences and mechanisms of metapristone (RU486 metabolite)

Metapristone is the primary metabolite of the abortifacient mifepristone (RU486), and is being developed as a safe and effective cancer metastatic chemopreventive agent for both sexes. Here, we systematically investigated the sex-related pharmacokinetics of metapristone in both rats and dogs, and explored the related mechanisms of actions. Administration of metapristone to rats and dogs showed that plasma concentrations of metapristone (AUC, C _max ) were significantly higher in female dogs and rats than in males. The sex-related differences in pharmacokinetics become more significant after ten consecutive days of oral administration. Female liver microsomes metabolized metapristone significantly slower than the male ones. The results from P450 reaction phenotyping using recombinant cDNA-expressed human CYPs in conjunction with specific CYP inhibitors suggested that CYP1A2 and CYP3A4 are the predominant CYPs involved in the metapristone metabolism, which were further confirmed by the enhanced protein levels of CYP1A2 and CYP3A4 induced by 1-week oral administration of metapristone to rats. The highest tissue concentration of metapristone was found in the liver. The study demonstrates, for the first time, the sex-related pharmacokinetics of metapristone, and reveals that activities of liver microsomal CYP1A2 and CYP3A4 as well as the renal clearance are primarily responsible for the sex-related pharmacokinetics.

Improving cyclodextrin complexation of a new antihepatitis drug with glacial acetic acid

The purpose of this study was to develop and evaluate a solid nonaqueous oral dosage form for a new hepatitis C drug, PG301029, which is insoluble and unstable in water. Hydroxypropyl-β-cyclodextrin (HPβCD) and PG301029 were dissolved in glacial acetic acid. The acetic acid was removed by rotoevaporation such that the drug exists primarily in the complexed form. The stability of formulated PG301029 was determined upon dry storage and after reconstitution in simulated intestinal fluid (SIF), simulated gastric fluid (SGF), and water. Formulated PG301029 was found to be stable upon storage and can be reconstituted with water to a concentration 200 times that of the intrinsic solubility. Once reconstituted, the powder dissolves rapidly and PG301029 remains stable for 21 hours in SGF, SIF, and water. The unique use of acetic acid and HPβCD results in a solid dosage form of PG301029 that is both soluble and stable in water.

Annonaceous acetogenins (ACGs) nanosuspensions based on a self-assembly stabilizer and the significantly improved anti-tumor efficacy

Annonaceous acetogenins (ACGs) have exhibited antitumor activity against various cancers. However, these substances' poor solubility has limited clinical applications. In this study, hydroxypropyl-beta-cyclodextrin (HP-β-CD) and soybean lecithin (SPC) were self-assembled into an amphiphilic complex. ACGs nanosuspensions (ACGs-NSps) were prepared with a mean particle size of 144.4nm, a zeta potential of -22.9mV and a high drug payload of 46.17% using this complex as stabilizer. The ACGs-NSps demonstrated sustained release in vitro and good stability in plasma as well as simulated gastrointestinal fluid, and met the demand of both intravenous injection and oral administration. The ACGs-NSps demonstrated significantly increased cytotoxicity against Hela and HepG2 cancer cell lines compared to ACGs in solution (in vitro cytotoxicity assay). An in vivo study with H22-tumor bearing mice demonstrated that nanosuspensions significantly improved ACGs' antitumor activity. When orally administered, ACGs-NSps achieved a similar tumor inhibition rate at 1/10th the dose of ACGs in an oil solution (47.94% vs. 49.74%, p>0.05). Improved therapeutic efficacy was further achieved when the ACGs-NSps were intravenously injected into mice (70.31%). With the help of nanosuspension technology, ACGs may be an effective antitumor drug for clinic use.

Gastrointestinal behavior of nano- and microsized fenofibrate: In vivo evaluation in man and in vitro simulation by assessment of the permeation potential

INTRODUCTION

The purpose of this study was (i) to evaluate the gastrointestinal behavior of micro- and nanosized fenofibrate in humans and (ii) to develop a simple yet qualitatively predictive in vitro setup that simulates the observed absorption-determining factors.

MATERIALS AND METHODS

Commercially available micro- and nanoparticles of fenofibrate (Lipanthyl® and Lipanthylnano®, respectively) were administered orally to five healthy volunteers in fasting and postprandial conditions. Intraluminal and systemic drug concentrations were determined as reference data for the development of a predictive in vitro setup. To capture the observed solubility/permeability interplay, in vitro dissolution testing was performed in the presence of a permeation bag with sink conditions.

RESULTS

In fasting conditions, intake of nanosized fenofibrate generated increased duodenal concentrations compared to microsized fenofibrate, which was reflected in an improved systemic exposure. In postprandial conditions, duodenal concentrations were greatly enhanced for both formulations, however without an accompanying increase in systemic exposure. It appeared that micellar encapsulation of the highly lipohilic fenofibrate limited its potential to permeate from fed state intestinal fluids. To capture these in vivo observations in an in vitro setup, classic dissolution testing was combined with permeation assessment into a permeation bag with sink conditions. In case of fasting conditions, the dissolution/permeation approach allowed for an improved discriminative power between micro- and nanosized fenofibrate by better simulating the dynamic interplay of dissolution and absorption. In case of postprandial conditions, the observed solubility-permeability interplay could be simulated using the dissolution/permeation approach in combination with biorelevant media (FeSSGFFortimel and FeSSIF-V2) to mimic micellar entrapment and reduced permeation potential of fenofibrate.

CONCLUSION

For the first time, reduced permeation of a lipophilic drug despite increased intraluminal concentrations, was demonstrated in humans. Dissolution testing using biorelevant media in combination with permeation assessment into a sink permeation bag appeared to be a simple yet pragmatic approach to capture this solubility-permeability interplay in early formulation evaluation.

Fabrication of isradipine nanosuspension by anti-solvent microprecipitation-high-pressure homogenization method for enhancing dissolution rate and oral bioavailability

The aim of this study was to develop a nanosuspension of a highly hydrophobic drug, isradipine (ISR) by combination of anti-solvent microprecipitation and high-pressure homogenization to achieve the superior in vitro dissolution and in vivo pharmacokinetic profile. The nanosuspension was formulated using combination of stabilizers as vitamin E TPGS and sodium lauryl sulfate. The developed nanosuspension was characterized for particle size, shape, and zeta potential. The particle size of the developed ISR nanosuspension was observed to be approximately 538 nm (by laser diffraction) and 469 nm (by photon correlation spectroscopy) with -33.3 mV zeta potential. Scanning electron microscopy study revealed the good correlation with particle size measured by photon correlation spectroscopy and laser diffraction. The X-ray diffraction and differential scanning calorimetry showed that ISR was present as an amorphous state in the lyophilized form of nanosuspension. In vitro dissolution and saturation solubility study showed the dissolution rate of nanosuspensions (98.60 %) and saturation solubility (98.76 μg/ml) compared with the coarse drug (11.53 % and 14.1 μg/ml, respectively) had been significantly enhanced. The pharmacokinetic study showed that the nanosuspension exhibits increased in AUC0-48 by 2.0-fold compared to coarse suspension. Further, there was increased in C max and decreased in t max of ISR nanosuspension compared to coarse suspension of ISR. These studies proved that particle size reduction can influence ISR absorption in gastrointestinal tract and thus nanosuspension technology is responsible for enhancing oral bioavailability in rats.

Preparation and optimization of resveratrol nanosuspensions by antisolvent precipitation using Box-Behnken design

Resveratrol, a natural polyphenolic component, has inspired considerable interest for its extensive physiological activities. However, the poor solubility of resveratrol circumscribes its therapeutic applications. The purpose of this study was to optimize and prepare resveratrol nanosuspensions using the antisolvent precipitation method. The effects of crucial formulation and process variables (drug concentration, stabilizer, and surfactant contents) on particle size were investigated by utilizing a three-factor three-level Box-Behnken design (BBD) to perform this experiment. Different mathematical polynomial models were used to identify the impact of selected parameters and to evaluate their interrelationship for predictive formulation purposes. The optimal formulation consisted of drug 29.2 (mg/ml), polyvinylpyrrolidone (PVP) K17 0.38%, and F188 3.63%, respectively. The morphology of nanosuspensions was found to be near-spherical shaped by scanning electron microscopy (SEM) observation. The X-ray powder diffraction (XRPD) and differential scanning calorimetry (DSC) analysis confirmed that the nanoparticles were in the amorphous state. Furthermore, in comparison to raw material, resveratrol nanosuspensions showed significantly enhanced saturation solubility and accelerated dissolution rate resulting from the decrease in particle size and the amorphous status of nanoparticles. Meanwhile, resveratrol nanosuspensions exhibited the similar antioxidant potency to that of raw resveratrol. The in vivo pharmacokinetic study revealed that the C max and AUC0→∞ values of nanosuspension were approximately 3.35- and 1.27-fold greater than those of reference preparation, respectively. Taken together, these results suggest that this study provides a beneficial approach to address the poor solubility issue of the resveratrol and affords a rational strategy to widen the application range of this interesting substance.

A nanoparticulate drug-delivery system for 20(S)-protopanaxadiol: formulation, characterization, increased oral bioavailability and anti-tumor efficacy

As with many other hydrophobic anticancer agents, 20(S)-protopanaxadiol (PPD) has a very low oral bioavailability. In this study, a precipitation-combined ultrasonication technique was used to prepare PPD nanosuspensions. The mean particle size of the nanosuspensions was approximately 222 ± 12 nm, the drug payload achieved 50% after lyophilization and the maximum PPD concentration can reach 100 mg/ml, which is over 30 000 times the solubility of PPD in aqueous solution (3 μg/ml). After oral administration, the C_max and AUC_last values of PPD nanosuspensions were approximately 3.66-fold and 3.48-fold as those of PPD coarse suspensions, respectively. In contrast to the free drug solution, PPD nanosuspensions showed higher in vitro anti-tumor activity against HepG-2 cells (an IC₅₀ value of 1.40 versus 5.83 μg/ml at 24 h, p < 0.01). The in vivo study in H22-tumor-bearing mice demonstrated that PPD nanosuspensions showed good anti-tumor efficacy with an inhibition rate of 79.47% at 100 mg/kg, while 50 mg/kg of cyclophosphamide was displayed as positive control, and the inhibition rate was 87.81%. Considering the highest drug payload, oral bioavailability reported so far, significant anti-tumor efficacy and excellent safety of encapsulated drugs, PPD nanosuspensions could be used in potential effective strategies for anticancer therapy; further investigation is ongoing.

Characterization and evaluation in vivo of baicalin-nanocrystals prepared by an ultrasonic-homogenization-fluid bed drying method

AIM

To improve the absorption and bioavailability of baicalin using a nanocrystal (or nanosuspension) drug delivery system.

METHODS

A tandem, ultrasonic-homogenization-fluid bed drying technology was applied to prepare baicalin-nanocrystal dried powders, and the physicochemical properties of baicalin-nanocrystals were characterized by scanning electron microscopy, photon correlation spectroscopy, powder X-ray diffraction, physical stability, and solubility experiments. Furthermore, in situ intestine single-pass perfusion experiments and pharmacokinetics in rats were performed to make a comparison between the microcrystals of baicalin and pure baicalin in their absorption properties and bioavailability in vivo.

RESULTS

The mean particle size of baicalin-nanocrystals was 236 nm, with a polydispersity index of 0.173, and a zeta potential value of -34.8 mV, which provided a guarantee for the stability of the reconstituted nanosuspension. X-Ray diffraction results indicated that the crystallinity of baicalin was decreased through the ultrasonic-homogenization process. Physical stability experiments showed that the prepared baicalin-nanocrystals were sufficiently stable. It was shown that the solubility of baicalin in the form of nanocrystals, at 495 μg·mL(-1), was much higher than the baicalin-microcrystals and the physical mixture (135 and 86.4 μg·mL(-1), respectively). In situ intestine perfusion experiments demonstrated a clear advantage in the dissolution and absorption characteristics for baicalin-nanocrystals compared to the other formulations. In addition, after oral administration to rats, the particle size decrease from the micron to nanometer range exhibited much higher in vivo bioavailability (with the AUC(0-t) value of 206.96 ± 21.23 and 127.95 ± 14.41 mg·L(-1)·h(-1), respectively).

CONCLUSION

The nanocrystal drug delivery system using an ultrasonic-homogenization-fluid bed drying process is able to improve the absorption and in vivo bioavailability of baicalin, compared with pure baicalin coarse powder and micronized baicalin.

Nanocrystal-based per-oral itraconazole delivery: superior in vitro dissolution enhancement versus Sporanox® is not realized in in vivo drug absorption

Nanoscience holds true promise in enabling efficient formulation development and in vivo delivery of poorly water soluble drugs. The objective of this study was to formulate solid oral nanocrystal delivery systems of itraconazole, and thus enhance the oral bioavailability of the very poorly soluble drug. Nanocrystal suspensions were prepared by a rapid wet milling technique, after which the suspensions were transformed into solid dosage forms by both freeze drying and granulating. Finally, the obtained nanocrystalline powders were capsule-packed as well as compacted to tablets. After in vitro analysis, the formulations (nanocrystal suspension (NPs), freeze dried NPs, granulated NPs) were tested in vivo in a rat model, and compared with commercial itraconazole formulation (Sporanox). Importantly, the results indicated rapid dissolution of the nanocrystalline itraconazole with enhanced bioavailability compared to physical mixture. Drug dissolution in vitro was immediate from NPs and freeze dried powder, and differed significantly from the marketed product (P=0.004 and 0.002, correspondingly) until 30min. Freeze drying was detected to be especially advantageous for the solid dosage forms. It is possible to maintain the original character of the nanocrystals, e.g. rapid dissolution, even after tableting of the nanocrystalline powders. Interestingly, the marketed product out-performed the nanocrystalline formulations in vivo, even though the nanocrystals provided reasonable bioavailability of itraconazole absorption as well. The efficient in vitro dissolution enhancement of the nanocrystalline formulations compared to Sporanox® was not realized in in vivo drug absorption.

Evaluation of exposure properties after injection of nanosuspensions and microsuspenions into the intraperitoneal space in rats

In the present paper, BA99 and AC88 were used as model compounds for intraperitoneal (i.p.) administration to Sprague-Dawley rats. A major problem for the compounds, like many others newly developed pharmaceutical drugs, is the poor solubility in water. To solve solubility related problems, development of nanosuspensions is an attractive alternative. Both compounds are suitable for nanosuspensions, using the milling approach. After 2 weeks in freezer, the nanoparticles aggregated to form particles in the 400-2000 nm interval. However, following a 20 s ultrasonication step, the original particle sizes (about 200 nm) were obtained. Adding 5% mannitol before the samples were frozen abolished aggregation. It is also possible to freeze-dry the nanosuspension in the presence of 5% mannitol and re-disperse the formulation in water. Nanosuspensions of both compounds were injected i.p. to rats at 5 and 500 µmoL/kg. At the low dose, also a microsuspension was administered. I.p. administration resulted in overall improved C(max) for both AC88 and BA99 compared to s.c. and oral administration. I.p. is the preferred route of administration of tolerable drugs when a fast onset of action is desired and when a significant first passage metabolism occurs. The net charge of the active molecule appeared to affect the absorption kinetics. In the present work, the neutral molecule was favored over the negatively charged one.

Effect of fixed aqueous layer thickness of polymeric stabilizers on zeta potential and stability of aripiprazole nanosuspensions

The aim of this study was to evaluate the effect of the thickness of adsorbed polymer layer (also known as Fixed Aqueous Layer Thickness, FALT) of polymeric stabilizers on zeta potential and stability of nanoparticles in a suspension. Aripiprazole, a poorly water soluble drug was used as a model drug to evaluate rationale for increased FALT and to understand the effect of hydrophilicity and hydrophobicity of polymeric stabilizers on FALT of aripiprazole nanosuspensions. The nanosuspensions were prepared by media milling and Pluronic F68, Pluronic F127, Hydroxypropyl methylcellulose (HPMC) and Hydroxypropyl cellulose (HPC) were used as polymeric stabilizers. The particle size (immediately after preparation and after 1 week of storage at 25°C) and zeta potential of aripiprazole nanosuspensions were determined. For Pluronics, FALT was determined theoretically whereas for HPMC and HPC it was calculated as Debye Huckel parameter from the zeta potential dependence on the ionic strength. An increase in FALT resulted in reduced zeta potential. With an increase in FALT of polymers used, the stability of nanosuspensions showed improvement. Furthermore, a linear correlation was shown to exist between the FALT and length of hydrophilic chains in Pluronics.

Nanosuspension: An approach to enhance solubility of drugs

One of the major problems associated with poorly soluble drugs is very low bioavailability. The problem is even more complex for drugs like itraconazole, simvastatin, and carbamazepine which are poorly soluble in both aqueous and nonaqueous media, belonging to BCS class II as classified by biopharmaceutical classification system. Formulation as nanosuspension is an attractive and promising alternative to solve these problems. Nanosuspension consists of the pure poorly water-soluble drug without any matrix material suspended in dispersion. Preparation of nanosuspension is simple and applicable to all drugs which are water insoluble. A nanosuspension not only solves the problems of poor solubility and bioavailability, but also alters the pharmacokinetics of drug and thus improves drug safety and efficacy. This review article describes the preparation methods, characterization, and applications of the nanosuspension.

Crystalline nanosuspensions as potential toxicology and clinical oral formulations for BCS II/IV compounds

Nanosuspensions, formulations based on the reduction of the active pharmaceutical ingredient (API) particle size in the sub-micron range and most typically around 100-200 nm, represent a valuable option for formulators to facilitate oral absorption of Biopharmaceutics Classification System class II and IV compounds. Their ability to increase the API dissolution rate and subsequent absorption and thus oral bioavailability has been demonstrated in preclinical and clinical settings. This review summarizes the current experience in the biopharmaceutic field with the use of nanosuspensions as oral delivery formulations. The principles behind nanosuspensions as well as the in vitro and in silico evaluation are discussed, while examples are presented highlighting both successes as well as limitations in their application as either toxicology or clinical formulations.

Assembling nanoparticle coatings to improve the drug delivery performance of lipid based colloids

Lipid based colloids (e.g. emulsions and liposomes) are widely used as drug delivery systems, but often suffer from physical instabilities and non-ideal drug encapsulation and delivery performance. We review the application of engineered nanoparticle layers at the interface of lipid colloids to improve their performance as drug delivery systems. In addition we focus on the creation of novel hybrid nanomaterials from nanoparticle-lipid colloid assemblies and their drug delivery applications. Specifically, nanoparticle layers can be engineered to enhance the physical stability of submicron lipid emulsions and liposomes, satbilise encapsulated active ingredients against chemical degradation, control molecular transport and improve the dermal and oral delivery characteristics, i.e. increase absorption, bioavailability and facilitate targeted delivery. It is feasible that hybrid nanomaterials composed of nanoparticles and colloidal lipids are effective encapsulation and delivery systems for both poorly soluble drugs and biological drugs and may form the basis for the next generation of medicines. Additional pre-clinical research including specific animal model studies are required to advance the peptide/protein delivery systems, whereas the silica lipid hybrid systems have now entered human clinical trials for poorly soluble drugs.

A novel strategy to produce highly stable and transparent aqueous 'nanosolutions' of water-insoluble drug molecules

A surprisingly large proportion of new drug candidates emerging from drug discovery programmes are water-insoluble and, as a result, have poor oral bioavailability. To overcome insolubility, the drug particles are usually dispersed in a medium during product formation, but large particles that are formed may affect product performance and safety. Many techniques have been used to produce nanodispersions-dispersions with nanometre-scale dimensions-that have properties similar to solutions. However, making nanodispersions requires complex processing, and it is difficult to achieve stability over long periods. In this paper, we report a generic method for preparing drug nanoparticles with a combination of antisolvent precipitation in the presence of water-soluble matrices and spray-drying. The spray-dried powder composites (solid dispersion) are microspherical, highly stable and thus form transparent nanodispersions or so-called 'nanosolutions' of water-insoluble drug when simply added to water. Aqueous nanodispersions of silybin (a kind of water-insoluble drug for liver protection) with an average size of 25 nm produced with this approach display a 10 times faster dissolution rate than that of raw drug. This has great potential to offer a novel solution for innovative drugs of the future.

Enhanced antihypertensive activity of candesartan cilexetil nanosuspension: formulation, characterization and pharmacodynamic study

The objective of the present investigation was to enhance the oral bioavailability of practically insoluble Candesartan cilexetil [CC] by preparing nanosuspension. The nanosuspension was prepared by media milling using zirconium oxide beads and converted to solid state by spray drying. The spray dried nanosuspension of CC [SDCN] was evaluated for particle size, zeta potential, saturation solubility, crystallanity, surface morphology and dissolution behavior. SDCN showed particle size of 223.5±5.4 nm and zeta potential of −32.2±0.6 mV while saturation solubility of bulk CC and SDCN were 125±6.9 μg/ml and 2805±29.5 μg/ml respectively, showing more than 20 times increase in solubility. Differential Scanning Calorimetry [DSC] and X-ray diffraction [XRD] analysis showed that crystalline state of CC remained unchanged in SDCN. Dissolution studies in phosphate buffer pH 6.5 containing 0.7% Tween 20 showed that 53±5% of bulk drug dissolved in 15 min whereas SDCN was almost completely dissolved exhibiting higher dissolution velocity and solubility. Transmission electron microscopy [TEM] revealed that nanocrystals were not of uniform size, and approximately of oval shape. Pharmacodynamic study based on deoxycorticosterone acetate [DOCA] salt model was performed in rats to evaluate in-vivo performance, which showed 26.75±0.33% decrease in systolic blood pressure for nanosuspension while plain drug suspension showed 16.0±0.38% reduction, indicating that increase in dissolution velocity and saturation solubility leads to enhancement of bioavailability of SDCN when compared to bulk CC suspension. Thus, the results conclusively demonstrated a significant enhancement in antihypertensive activity of candesartan when formulated as nanosuspension.

Controlled delivery systems: from pharmaceuticals to cells and genes

During the last few decades, a fair amount of scientific investigation has focused on developing novel and efficient drug delivery systems. According to different clinical needs, specific biopharmaceutical carriers have been proposed. Micro- and nanoparticulated systems, membranes and films, gels and even microelectronic chips have been successfully applied in order to deliver biopharmaceuticals via different anatomical routes. The ultimate goal is to deliver the potential drugs to target tissues, where regeneration or therapies (chemotherapy, antibiotics, and analgesics) are needed. Thereby, the bioactive molecule should be protected against environmental degradation. Delivery should be achieved in a dose- and time-correct manner. Drug delivery systems (DDS) have been conceived to provide improvements in drug administration such as ability to enhance the stability, absorption and therapeutic concentration of the molecules in combination with a long-term and controlled release of the drug. Moreover, the adverse effects related with some drugs can be reduced, and patient compliance could be improved. Recent advances in biotechnology, pharmaceutical sciences, molecular biology, polymer chemistry and nanotechnology are now opening up exciting possibilities in the field of DDS. However, it is also recognized that there are several key obstacles to overcome in bringing such approaches into routine clinical use. This review describes the present state-of-the-art DDS, with examples of current clinical applications, and the promises and challenges for the future in this innovative field.

Usefulness of a nanoparticle formulation to investigate some hemodynamic parameters of a poorly soluble compound

Drug solubility is an important issue when progressing investigational compounds into clinical candidates. The present paper describes the development and characterization of a nanosuspension that was formulated to overcome problems with poor water solubility and possible adverse events caused by cosolvent mixtures, using ticagrelor as a model compound. A homogeneous nanosuspension of ticagrelor was formed using a wet milling approach, which yielded particle sizes around 230 nm. The nanosuspensions were chemically stable for at least 10 months at both room temperature and when refrigerated, and physically (i.e., particle size) stable for at least 10 months under refrigeration, and approximately 3 years at room temperature and when frozen. One rat model and two dog models were used to assess the pharmacokinetics and hemodynamic-related effects following intravenous administration of nanoparticles. There were no biologically consistent or dose-dependent effects of the nanoparticles on the hemodynamic parameters tested, that is, heart rate, mean aortic pressure, cardiac output, left femoral artery blood flow, or cardiac inotropy (measured as max dP/dt). In conclusion, a stable ticagrelor nanosuspension formulation was developed, suitable for intravenous administration. At the doses evaluated, this formulation was without hemodynamic effects in three sensitive preclinical models.

Particle size reduction and pharmacokinetic evaluation of a poorly soluble acid and a poorly soluble base during early development

AIM

The aim of the present study was to find out if nanosuspensions were a better choice compared with microsuspensions, for the present substances with water solubility in the order of 2-3 μM (pH 6.8, small intestinal pH) and no permeability limitations. The ambition was also to understand what the higher solubility in the stomach for BA99 means in terms of absorption properties of the substance.

METHOD

The pharmacokinetic parameters of a poorly soluble acid (AC88) and a poorly soluble base (BA99) administered orally as nanosuspensions have been compared with those from microsuspensions using rat as in vivo species.

RESULTS

A significant difference was observed between the two suspensions for AC88 already at the lowest dose, 5 μmol/kg (the particle size of the nanosuspensions and the microsuspensions was about 200 nm and 14 μm, respectively). These results were further confirmed at a high dose (500 μmol/kg). However, for BA99, there were no significant differences between the two formulations at any dose investigated (the particle size of the nanosuspensions and the microsuspensions was about 280 nm and 12 μm, respectively).

CONCLUSIONS

The study demonstrated a clear correlation between particle size and in vivo exposures for an acidic compound, the nanosuspensions providing the highest exposure. For a basic compound, on the other hand, with the present properties and doses, a microsuspension was sufficient. In the latter case, the higher solubility at gastric pH, because of the basic pK(a), limits the need for particle reduction.

A formulation comparison between micro- and nanosuspensions: the importance of particle size for absorption of a model compound, following repeated oral administration to rats during early development

AIM

The aim of this study was to maximize the exposure of a model compound (MC) for forthcoming high-dose toxicological studies with the physical form of the original compound unaffected.

METHOD

The two evaluated formulation approaches for the present poorly water-soluble compound were micro- and nanosuspensions.

RESULTS

The particle size was about 280 nm for the nanosuspensions and about 4 μm for the microsuspensions. The crystallinity and the crystalline form of the ground samples were conserved. The physical and the chemical stabilities of the two kinds of suspensions were unaffected during the investigated time period. The in vivo results of the study showed that the pharmacokinetic parameters investigated were comparable at the low-dose level (6 μmol/kg) for both formulations after single administration. However, at the two higher doses (60 and 300 μmol/kg), a significant difference in exposure was observed between the two suspensions with an improved exposure for smaller particles. After Day 7 of repeated administration, a significant difference in exposure was observed at all dose levels. The overall exposures were higher on Day 7, compared to the exposures on Day 1 (most significant for nanoparticles), due to an accumulation of compound in the body.

CONCLUSIONS

The nanoparticles have a larger surface, resulting in faster in vivo dissolution rate, faster absorption, and increased bioavailability, compared to microparticles. The differences in systemic exposure of model compound, following oral administration of nano- or microparticles of the drug substance, are probably caused by differences in the in vivo dissolution rate and possibly further enhanced by saturation of the systemic elimination.