Nanocrystalline Formulations Research Articles

The Evolution of Nanocrystalline Drug Delivery System

Developing nanocrystalline drug delivery technologies is a noteworthy advancement in pharmaceutical science. The nanocrystalline formulations aim to improve therapeutic efficacy, pharmaceutical solubility, and bioavailability. We develop many methods for their fabrication, with top-down, bottom-up, and combination procedures, beginning with reasoning behind nanocrystalline approaches. In this type of review, we focused on the progress of nanocrystalline drug delivery systems in various years by applying different techniques which started in 1990 and what dosage forms are still made by this technology. It is found that various other techniques are also there manufacturing of drug Nanocrystals through years of investigation made by specialists. The researchers found methods such as Top-down, bottom-up, combination, solvent displacement technology, fluidised bed technology, freeze drying, spray drying, electrodynamic technique, and melt emulsification. Every process has advantages and disadvantages, therefore selecting the proper technology is critical to produce drug nanocrystals successfully. Keywords: Nanocrysyals, CT, Bottom-up, Top-Down, HPH, Nanocarriers

Evaluation of gender differences in the pharmacokinetics of oral zileuton nanocrystalline formulation using a rat model

Zileuton is a leukotriene inhibitor used to treat asthma. As a BCS class II drug it exhibits challenges with solubility which likely impact its absorption. As patient gender significantly impacts the pharmacokinetics of many drugs, this study aimed to investigate potential gender-based pharmacokinetic differences after oral zileuton administration in rats. Male and female Sprague Dawley rats received single oral gavage doses of pure zileuton as an active pharmaceutical ingredient (30 mg/kg body weight (bw)), physical mixture (PM; at 30 mg/kg bw of the formulation contains zileuton, kollidon VA64 fine, dowfax2A1 and trehalose), and nanocrystalline formulation of zileuton (NfZ; at 30 mg/kg bw of the formulation). Plasma, tissue, and urine concentrations were quantified using high performance liquid chromatography (HPLC). Noncompartmental pharmacokinetic analysis showed higher zileuton levels in the plasma of female versus male rats across all evaluated forms of zileuton (API, PM, and NfZ). Female rats demonstrated higher peak plasma concentrations (Cmax) and increased area under the plasma concentration-time curve (AUC) relative to males, regardless of formulation. These findings reveal substantial gender disparities in the pharmacokinetics of zileuton in the rat model. This study emphasizes the critical need to evaluate gender differences during preclinical drug development to enable gender-based precision dosing strategies for equivalent efficacy/safety outcomes in male and female patients. Additional studies are warranted to investigate underlying mechanisms of such pharmacokinetic gender divergences.

Herbal Medicine Nanocrystals: A Potential Novel Therapeutic Strategy.

Herbal medicines have gained recognition among physicians and patients due to their lower adverse effects compared to modern medicines. They are extensively used to treat various diseases, including cancer, cardiovascular issues, chronic inflammation, microbial contamination, diabetes, obesity, and hepatic disorders, among others. Unfortunately, the clinical application of herbal medicines is limited by their low solubility and inadequate bioavailability. Utilizing herbal medicines in the form of nanocrystals (herbal medicine nanocrystals) has shown potential in enhancing solubility and bioavailability by reducing the particle size, increasing the specific surface area, and modifying the absorption mechanisms. Multiple studies have demonstrated that these nanocrystals significantly improve drug efficacy by reducing toxicity and increasing bioavailability. This review comprehensively examines therapeutic approaches based on herbal medicine nanocrystals. It covers the preparation principles, key factors influencing nucleation and polymorphism control, applications, and limitations. The review underscores the importance of optimizing delivery systems for successful herbal medicine nanocrystal therapeutics. Furthermore, it discusses the main challenges and opportunities in developing herbal medicine nanocrystals for the purpose of treating conditions such as cancer, inflammatory diseases, cardiovascular disorders, mental and nervous diseases, and antimicrobial infections. In conclusion, we have deliberated regarding the hurdles and forthcoming outlook in the realm of nanotoxicity, in vivo kinetics, herbal ingredients as stabilizers of nanocrystals, and the potential for surmounting drug resistance through the utilization of nanocrystalline formulations in herbal medicine. We anticipate that this review will offer innovative insights into the development of herbal medicine nanocrystals as a promising and novel therapeutic strategy.

Preparation and Characterization of Spray-Dried Hybrid Nanocrystal-Amorphous Solid Dispersions (HyNASDs) for Supersaturation Enhancement of a Slowly Crystallizing Drug.

We prepared hybrid nanocrystal-amorphous solid dispersions (HyNASDs) to examine their supersaturation capability in the release of a poorly soluble drug, itraconazole (ITZ), a slow crystallizer during dissolution. The HyNASD formulations included a polymer (HPC: hydroxypropyl cellulose, Sol: Soluplus, or VA64: Kollidon-VA64) and a surfactant (SDS: sodium dodecyl sulfate). Additionally, the dissolution performance of the HyNASDs and ASDs was compared. To this end, wet-milled aqueous nanosuspensions containing a 1:5 ITZ:polymer mass ratio with/without SDS as well as solutions of the same ratio without SDS in dichloromethane were spray-dried. XRPD-DSC confirmed that ASDs were formed upon spray drying the solution-based feeds, whereas HyNASDs (~5-30% amorphous) were formed with the nanosuspension-based feeds. SDS aided to stabilize the ITZ nanosuspensions and increase the amorphous content in the spray-dried powders. During dissolution, up to 850% and 790% relative supersaturation values were attained by HyNASDs with and without SDS, respectively. Due to the stronger molecular interaction between ITZ-Sol than ITZ-HPC/VA64 and micellar solubilization by Sol, Sol-based HyNASDs outperformed HPC/VA64-based HyNASDs. While the ASD formulations generated greater supersaturation values (≤1670%) than HyNASDs (≤790%), this extent of supersaturation from a largely nanocrystalline formulation (HyNASD) has not been achieved before. Overall, HyNASDs could boost drug release from nanoparticle-based formulations and may render them competitive to ASDs.

A Comparative Study between A Protein Based Amorphous Formulation and Other Dissolution Rate Enhancing Approaches: A Case Study with Rifaximin.

Amorphous solid dispersions (ASDs) based on proteins as co-formers have previously shown promising potential to improve the solubility and bioavailability of poorly water-soluble drugs. In particular, whey proteins have shown to be promising co-formers and amorphous stabilizers in ASD formulations, including at high drug loading. In this study, the feasibility of the whey protein β-lactoglobulin (BLG) as a co-former in ASDs was compared to the more traditional ASD co-formers based on synthetic polymers (hydroxypropyl methylcellulose acetate succinate and Eudragit® L) as well as to a nanocrystalline formulation. The poorly water-soluble drug rifaximin (RFX) was chosen as the model drug. All drug/co-former formulations were prepared as fully amorphous ASDs by spray drying at 50% (w/w) drug loading. The BLG-based ASD had the highest glass transition temperature and showed a faster dissolution rate and higher drug solubility in three release media with different pH values (1.2, 4.5, and 6.5) compared to the polymer-based ASDs and the nanocrystalline RFX. In conclusion, BLG is a promising co-former and amorphous stabilizer of RFX in ASD formulations, superior to the selected polymer-based ASD systems or the nanocrystalline formulation.

Albendazole Nanocrystal-Based Dissolving Microneedles with Improved Pharmacokinetic Performance for Enhanced Treatment of Cystic Echinococcosis.

Cystic echinococcosis (CE) is a zoonosis caused by Echinococcus spp., affecting both humans and animals' lives. Current treatment of CE by oral administration of albendazole (ABZ) is hampered by several limitations. The poor aqueous solubility and the rapid metabolism of ABZ in the liver are the main issues, leading to lack of efficacy of the treatment. In the present study, we developed a nanocrystalline (NC) formulation of ABZ to be delivered intradermally using dissolving microneedles (DMNs). The NC formulation was developed using milling in an ultrasmall-scale device. Following several screenings, Pluronic F127 was selected as a suitable stabilizer, producing NCs with around 400 nm in size with narrow particle distribution. The crystallinity of ABZ was maintained as observed by DSC and XRD analysis. The NC approach was able to improve the dissolution percentage of ABZ by approximately three-fold. Furthermore, the incorporation of NCs into DMNs using the combination of poly(vinylpyrrolidone) and poly(vinyl alcohol) formed sharp needles with sufficient mechanical strength and insertion properties. Dermatokinetic studies revealed that >25% of ABZ was localized in the dermis of excised neonatal porcine skin up to 48 h after DMN administration. In in vivo pharmacokinetic studies, the AUC and relative bioavailability values of ABZ delivered by NC-loaded DMNs were found to be significantly higher than those obtained after oral administration of coarse suspension of ABZ or ABZ-NCs, as well as DMNs delivering coarse ABZ as indicated by the relative bioavailability values of >100%. Therefore, the combination approach developed in this study could maintain the systemic circulation of ABZ, which could be possibly caused by avoiding the first-pass metabolism in the liver. This could be beneficial to improve the efficacy of ABZ in CE treatment.

Design and Use of a Thermogelling Methylcellulose Nanoemulsion to Formulate Nanocrystalline Oral Dosage Forms.

Oral drug products have become indispensable in modern medicine because of their exceptional patient compliance. However, poor bioavailability of ubiquitous low-water-soluble active pharmaceutical ingredients (APIs) and lack of efficient oral drug formulations remain as significant challenges. Nanocrystalline formulations are an attractive route to increase API solubility, but typically require abrasive mechanical milling and several processing steps to create an oral dosage form. Using the dual amphiphilic and thermoresponsive properties of methylcellulose (MC), a new thermogelling nanoemulsion and a facile thermal dripping method are developed for efficient formulation of composite particles with the MC matrix embedded with precisely controlled API nanocrystals. Moreover, a fast and tunable release performance is achieved with the combination of a fast-eroding MC matrix and fast-dissolving API nanocrystals. Using the versatile thermal processing approach, the thermogelling nanoemulsion is easily formulated into a wide variety of dosage forms (nanoparticle suspension, drug tablet, and oral thin film) in a manner that avoids nanomilling. Overall, the proposed thermogelling nanoemulsion platform not only broadens the applications of thermoresponsive nanoemulsions but also shows great promise for more efficient formulation of oral drug products with high quality and tunable fast release.

Enabling formulations of aprepitant: in vitro and in vivo comparison of nanocrystalline, amorphous and deep eutectic solvent based formulations

A deep eutectic solvent (DES) is a eutectic system consisting of hydrogen bond donor and acceptor has been suggested as a promising formulation strategy for poorly soluble drugs. A DES consisting of choline chloride and levulinic acid in a 1:2 molar ratio was used to formulate a liquid solution of the model drug aprepitant. This formulation was tested in vitro (drug release and permeability) and in vivo (rat model) and compared with the performance of amorphous aprepitant and the commercial aprepitant nanocrystalline formulation. In this study a DES formulation is compared for the first time directly to other established enabling formulations. The in vitro drug release study demonstrated that the DES formulation and the amorphous form both were able to induce an apparent supersaturation followed by subsequent drug precipitation. To mitigate the risk of precipitation, HPMC was predissolved in the dissolution medium, which successfully reduced the degree of precipitation. In line with the results from the release study, an in vitro permeation study showed superior permeation of the drug from the DES formulation and from the amorphous form compared to the nanocrystalline formulation. However, the promising in vitro findings could not be directly translated into an increased in vivo performance in rats compared to the nanocrystalline formulation. Whilst the DES formulation (34 ± 4%) showed a higher oral bioavailability compared to amorphous aprepitant (20 ± 4%), it was on par with the oral bioavailability obtained from the nanocrystalline formulation (36 ± 2%).

Improvement of Antialveolar Echinococcosis Efficacy of Albendazole by a Novel Nanocrystalline Formulation with Enhanced Oral Bioavailability.

Alveolar echinococcosis (AE) is a chronic infectious parasitic disease that is fatal and still being neglected. Currently, the AE treatment recommended by the WHO is complete excision of the lesions, followed by the oral administration of albendazole (ABZ), the only effective first-line anti-AE drug, for two years. Unfortunately, complete excision of AE lesions is impossible in most cases, leaving the long-term use of ABZ as the only alternative. However, only about one-third of patients experience complete remission or cure with such treatments, largely because of the low oral bioavailability of ABZ caused by its very low solubility. To improve the oral bioavailability of ABZ, a novel nanocrystalline (NC) formulation of ABZ was obtained by spray-drying ABZ with a triblock copolymer poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (Poloxamer 188), and its physical structure was confirmed by scanning electron microscopy (SEM), small-angle X-ray scattering (SAXS), wide-angle X-ray diffraction (WAXRD), and polarized optical microscopy (POM). The significantly reduced ABZ crystallite size coupled with prolonged ABZ supersaturation significantly improved the drug dissolution performance compared with that of the commercial ABZ oral product (Albenda), and the NC formulation showed an approximately 4.2-fold higher AUC than Albenda in a pharmacokinetic comparison in Beagle dogs as measured by the plasma concentration of albendazole sulfoxide, the active antiparasitic metabolite. Even more encouragingly, after 30 days of once-daily oral administration of the NC and Albenda formulations to SD rats with hepatic alveolar echinococcosis, the NC formulation demonstrated a cyst inhibition effect 3.7-fold greater than that of Albenda. We therefore conclude that the NC formulation could potentially be developed into an improved anti-AE drug therapy.

Design of Inhalable Solid Dosage Forms of Budesonide and Theophylline for Pulmonary Combination Therapy.

Corticosteroid resistance poses a major challenge to effective treatment of chronic obstructive pulmonary diseases. However, corticosteroid resistance can be overcome by co-administration of theophylline. The aim of this study was to formulate the corticosteroid budesonide with theophylline into inhalable dry powders intended for pulmonary combination therapy. Four types of spray-dried powders were prepared: (i) budesonide and theophylline co-dissolved and processed using a 2-fluid nozzle spray drier, (ii) budesonide nanocrystals and dissolved theophylline co-dispersed and processed using a 2-fluid nozzle spray drier, (iii) dissolved budesonide and dissolved theophylline processed using a 3-fluid nozzle spray drier, and (iv) budesonide nanocrystals and dissolved theophylline processed using a 3-fluid nozzle spray drier. Spray drying from the solutions resulted in co-amorphous (i) and partially amorphous powders (iii), whereas spray drying of the nanosuspensions resulted in crystalline products (ii and iv). Even though budesonide was amorphous in (i) and (iii), it failed to exhibit any dissolution advantage over the unprocessed budesonide. In contrast, the dissolution of budesonide from its nanocrystalline formulations, i.e., (ii) and (iv), was significantly higher compared to a physical mixture or unprocessed budesonide. Furthermore, the spray-dried powders obtained from the 2-fluid nozzle spray drier, i.e., (i) and (ii), exhibited co-deposition of budesonide and theophylline at the same weight ratio in the aerodynamic assessment using the New Generation Impactor. In contrast, the depositions of budesonide and theophylline deviated from the starting weight ratio in the aerodynamic assessment of spray-dried powders obtained from the 3-fluid nozzle spray drier, i.e., (iii) and (iv). Based on these results, the powders spray-dried from the suspension by using the 2-fluid nozzle spray drier, i.e., (ii), offered the best formulation properties given the physically stable crystalline solid-state properties and the co-deposition profile.

Multifunctional Glycoconjugate Assisted Nanocrystalline Drug Delivery for Tumor Targeting and Permeabilization of Lysosomal-Mitochondrial Membrane.

Nanotechnology has emerged as the most successful strategy for targeting drug payloads to tumors with the potential to overcome the problems of low concentration at the target site, nonspecific distribution, and untoward toxicities. Here, we synthesized a novel polymeric conjugate comprising chondroitin sulfate A and polyethylene glycol using carbodiimide chemistry. We further employed this glycoconjugate possessing the propensity to provide stability, stealth effects, and tumor targeting via CD44 receptors, all in one, to develop a nanocrystalline system of docetaxel (DTX@CSA-NCs) with size < 200 nm, negative zeta potential, and 98% drug content. Taking advantage of the enhanced permeability and retention effect coupled with receptor mediated endocytosis, the DTX@CSA-NCs cross the peripheral tumor barrier and penetrate deeper into the cells of tumor mass. In MDA-MB-231 cells, this enhanced cellular uptake was observed to exhibit a higher degree of cytotoxicity and arrest in the G2 phase in a time dependent fashion. Acting via a mitochondrial-lysosomotropic pathway, DTX@CSA-NCs disrupted the membrane potential and integrity and outperformed the clinically used formulation. Upon intravenous administration, the DTX@CSA-NCs showed better pharmacokinetic profile and excellent 4T1 induced tumor inhibition with significantly less off target toxicity. Thus, this glycoconjugate stabilized nanocrystalline formulation has the potential to take nano-oncology a step forward.

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.

Development of surface stabilized candesartan cilexetil nanocrystals with enhanced dissolution rate, permeation rate across CaCo-2, and oral bioavailability.

Candesartan cilexetil (CC), an ester prodrug of candesartan, is BCS class II drug with extremely low aqueous solubility limiting its oral bioavailability. The present research aimed to develop a nanocrystalline formulation of CC with improved saturation solubility in gastrointestinal fluids and thereby, exhibiting enhanced oral bioavailability. CC nanocrystals were prepared using a low energy antisolvent precipitation methodology. A combination of hydroxypropyl methylcellulose (HPMC) and Pluronic® F 127 (50:50 w/w) was found to be optimum for the preparation of CC nanocrystals. The particle size, polydispersity index (PDI), and zeta potential of optimized formulation was found to be 159 ± 8.1nm, 0.177 ± 0.043, and -23.7 ± 1.02mV, respectively. Optimized formulation was found to possess irregular, plate-like morphology as evaluated by scanning electron microscopy and crystalline as evaluated by differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD). A significant increase in saturation solubility and dissolution rate of the optimized nanosuspension was observed at all the tested pH conditions. Optimized CC nanocrystals exhibited a storage stability of more than 3months when stored under cold and room temperature conditions. In vitro Caco-2 permeability further revealed that CC nanocrystals exhibited nearly 4-fold increase in permeation rate compared to the free CC. In vivo oral bioavailability studies of optimized CC nanocrystals in murine model revealed 3.8-fold increase in the oral bioavailability and twice the C max as compared with the free CC when administered orally. In conclusion, this study has established a crystalline nanosuspension formulation of CC with improved oral bioavailability in murine model. Graphical Abstract Antisolvent precipitation methodology for the preparation of Candesartan Cilexetil nanocrystals for enhanced solubility and oral bioavailability.

In Vitro and In Vivo Performance of Different Sized Spray-Dried Crystalline Itraconazole

The objectives of the present study were to formulate and optimize different sized liquid and solid nanocrystalline formulations and evaluate their in vitro and in vivo performance to determine the effect of particle size on the oral bioavailability of solid nanocrystalline formulations. Nanotechnology is a promising approach to solve the problem of poor oral bioavailability of Biopharmaceutical Classification System class II/IV compounds. However, the highly exposed surface area of nanocrystals and hence their high Gibb's free energy poses a great challenge to nanocrystalline suspension stabilization. In this study, stabilization was achieved by preparing spray-dried nanocrystalline powders. A design of experiment approach was utilized to optimize the nanocrystalline suspensions/powders. On the basis of drug solubility studies, polyvinylpyrrolidone 40 KDa and sodium lauryl sulfate were selected for wet milling processing. Mannitol was chosen as the auxiliary excipient for spray-drying processing. In vitro dissolution utilizing a United States Pharmacopeia (USP) apparatus II showed superior release profiles for both liquid and nanocrystalline powder formulations compared with coarse-sized and unmilled formulations. Significantly, the oral bioavailability of nanocrystalline formulations with particle size of 280 nm was more than 20 times that of the unmilled formulation, whereas the nanocrystalline formulation with particle size of 750 nm showed only a 2.8 times increase in bioavailability compared with the unmilled formulation.

Nano-amorphous spray dried powder to improve oral bioavailability of itraconazole.

The objective of this study was to formulate nano-amorphous spray-dried powders of itraconazole to enhance its oral bioavailability. A combination approach of solvent-antisolvent precipitation followed by spray drying was used. DoE studies were utilized to understand the critical processing parameters: antisolvent-to-solvent ratio, drug concentration and stabilizer concentration. Particle size was the critical quality attribute. Spray drying of the nano-precipitated formulation was performed with several auxiliary excipients to obtain nano-sized amorphous powder formulations. PLM, DSC and PXRD were utilized to characterize the spray-dried powders. In vitro dissolution and in vivo bioavailability studies of the nano-amorphous powders were performed. The particle size of the nano-formulations was dependent on the drug concentration. The smallest size precipitates were obtained with low drug concentration. All high molecular weight auxiliary excipients and mannitol containing formulations were unstable and crystallized during spray drying. Formulations containing disaccharides were amorphous and non-aggregating. In vitro dissolution testing and in vivo studies showed the superior performance of nano-amorphous formulations compared to melt-quench amorphous and crystalline itraconazole formulations. This study shows superior oral bioavailability of nano-amorphous powders compared to macro-amorphous powders. The nano-amorphous formulation showed similar bioavailability to the nano-crystalline formulation but with a faster absorption profile.

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.

Formulation parameters of crystalline nanosuspensions on spray drying processing: A DoE approach

Nanocrystalline suspensions offer a promising approach to improve dissolution of BCS class II/IV compounds. Spray drying was utilized as a downstream process to improve the physical and chemical stability of dried nanocrystals. The effect of nanocrystalline suspension formulation variables on spray-drying processing was investigated. Naproxen and indomethacin nanocrystalline formulations were formulated with either Dowfax 2A1 (small molecule) or HPMC E15 (high molecular weight polymer) and spray drying was performed. A DoE approach was utilized to understand the effect of critical formulation variables, i.e. type of stabilizer, type of drug, ratio of drug-to-stabilizer and drug concentration. The powders were analyzed for particle size, moisture content, powder X-ray diffraction and dissolution. A dialysis sac adapter for USP apparatus II was developed which provided good discrimination between aggregated and non-aggregated formulations. Nanocrystal aggregation was dependent on the drug-to-stabilizer ratio. The glass transition temperature and the charge effect played a dominant role on spray-dried powder yield. Those formulations with low drug-to-excipient ratios were less aggregating and showed faster dissolution compared to those formulations with high drug-to-excipient ratios. All stable (less aggregated) formulations were subjected to accelerated storage stability testing. The Flory-Huggins interaction parameter (between drug and excipients) correlated with the spray-dried nanocrystal formulations stability.

In vitro/in vivo characterization of nanocrystalline formulation of tranilast with improved dissolution and hepatoprotective properties

The present study was undertaken to develop a nanocrystalline formulation of tranilast (NC/TL), an acidic anti-inflammatory agent, with the aim of improving its biopharmaceutical and hepatoprotective properties. NC/TL was prepared by wet-mill technology, and its physicochemical properties were characterized in terms of morphology, crystallinity, particle size distribution, stability and dissolution. Even after the storage of NC/TL for 8weeks under accelerated conditions, there were no significant transitions in the crystalline form, crystallinity and particle size distribution of wet-milled TL. The nanosized TL particles could be immediately dispersed when the NC/TL was introduced into aqueous medium, and the NC/TL exhibited significant improvement in the dissolution behavior even under acidic conditions, compared with crystalline TL and a physical mixture of TL and polymer (PM/TL). The hepatoprotective effects of orally dosed TL formulations were evaluated in a carbon tetrachloride (CCl4)-treated rat model of acute liver injury. In a rat model of acute liver injury, repeated treatment with NC/TL (2mgTL/kg) every 12h led to marked attenuation of hepatic damage as evidenced by decreases in alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and total reactive oxygen species levels. However, PM/TL was found to be less effective, and the difference in efficacy between NC/TL and PM/TL should be attributable to the highly enhanced dissolution behavior of NC/TL. Strategic application of NC formulation technology might be an efficacious approach for enhancing the therapeutic potential of TL to treat liver dysfunction.

Development of a Nanocrystalline Paclitaxel Formulation for Hipec Treatment

To develop a nanocrystalline paclitaxel formulation with a high paclitaxel-to-stabilizer ratio which can be used for hyperthermic intraperitoneal chemotherapy (HIPEC). Paclitaxel (PTX) nanocrystals were prepared via wet milling using Pluronic F127(®) as stabilizer. The suitability of paclitaxel nanosuspensions for HIPEC treatment was evaluated by analyzing the cytotoxicity of both stabilizer and formulation, and by determining the maximum tolerated dose (MTD) and bioavailability. The effect on tumor growth was evaluated by magnetic resonance imaging (MRI) at day 7 and 14 after HIPEC treatment in rats with peritoneal carcinomatosis of ovarian origin. Monodisperse nanosuspensions (±400nm) were developed using Pluronic F127(®) as single additive. The cytotoxicity and MTD of this nanocrystalline formulation was similar compared to Taxol(®), while its bioavailability was higher. MRI data after HIPEC treatment with a PTX nanocrystalline suspension showed a significant reduction of tumor volume compared to the non-treated group. Although no significant differences on tumor volume were observed between Taxol(®) and the nanosuspension, the rats treated with the nanosuspension recovered faster following the HIPEC procedure. Nanosuspensions with a high paclitaxel-to-stabilizer ratio are of interest for the treatment of peritoneal carcinomatosis of ovarian origin via HIPEC.

A Formulation Strategy for Gamma Secretase Inhibitor ELND006, a BCS Class II Compound: Development of a Nanosuspension Formulation with Improved Oral Bioavailability and Reduced Food Effects in Dogs

ELND006 is a novel gamma secretase inhibitor previously under investigation for the oral treatment of Alzheimer's disease. ELND006 shows poor solubility and has moderate to high permeability, suggesting it is a Biopharmaceutics Classification System Class II compound. The poor absolute oral bioavailability of the compound in fasted dogs (F ∼11%) is attributed to poor aqueous solubility. In addition, inhibiting amyloid precursor protein but not Notch cleavage is an important goal for gamma secretase inhibitors; therefore, significant variation in bioavailability resulting from food consumption is a potential liability for this class of compounds. The objective of the present study was to determine if an ELND006 nanocrystalline formulation would offer improved and predictable pharmacokinetics. ELND006 was formulated as a nanosuspension with a mean particle size of less than 200 nm, which was stable in particle size and crystallinity for over 1 year. In addition, ELND006 nanosuspension exhibited rapid dissolution in comparison with reference active pharmaceutical ingredient (API). The in vivo performance of the ELND006 nanosuspension was tested in fed and fasted beagle dogs and compared with a gelatin capsule containing reference API. The results show that nanosizing ELND006 profoundly improved the oral bioavailability and virtually eliminated variation resulting from food intake.