Artemether-Loaded Zein Nanoparticles: An Innovative Intravenous Dosage Form for the Management of Severe Malaria.

Artemether, an artemisinin derivative, is used in the management of life-threatening severe malaria. This study aimed to develop an intravenous dosage form of artemether using nanotechnology. Artemether-loaded zein nanoparticles were prepared by modified antisolvent precipitation using sodium caseinate as a stabilizer. Subsequently, the physicochemical properties of the nanoparticles were characterized; the in vitro hemolytic property was examined with red blood cells, while the pharmacokinetic profile was evaluated in Sprague-Dawley rats after intravenous administration. The artemether-loaded zein nanoparticles were found to display good encapsulation efficiency, excellent physical stability and offer an in vitro extended-release property. Interestingly, encapsulation of artemether into zein nanoparticles substantially suppressed hemolysis, a common clinical phenomenon occurring after artemisinin-based antimalarial therapy. Upon intravenous administration, artemether-loaded zein nanoparticles extended the mean residence time of artemether by ~80% in comparison to the free artemether formulation (82.9 ± 15.2 versus 45.6 ± 16.4 min, p < 0.01), suggesting that the nanoparticles may prolong the therapeutic duration and reduce the dosing frequency in a clinical setting. In conclusion, intravenous delivery of artemether by artemether-loaded zein nanoparticles appears to be a promising therapeutic option for severe malaria.

Preparation of quercetin nanorod/microcrystalline cellulose formulation via fluid bed coating crystallization for dissolution enhancement.

This study reports a novel quercetin nanorod/microcrystalline cellulose (MCC) formulation prepared by fluid bed coating crystallization technique. The process comprises fluidized bed spray coating of quercetin acetone solution onto MCC particles, solvent evaporation and crystallization of quercetin nanorods on MCC surface. Depending on the quercetin solution concentration, quercetin nanorods with 100-300 nm in diameter and 1-3 µm in length were obtained. Owing to the small particle size and large surface area, a higher dissolution rate was achieved for quercetin nanorods in contrast to the raw quercetin, which therefore led to higher antioxidant activities. In addition, the obtained quercetin nanorod/MCC formulation exhibited a good storage stability within 12 months. The developed quercetin nanorod/MCC formulation could be used for further pharmaceutical dosage or food supplements processing.

Preparation and characterization of quercetin/dietary fiber nanoformulations.

Quercetin is well known for its beneficial health effects on the human body. However, the slow dissolution rate leading to poor bioavailability constitutes a barrier to being further developed for nutritional products. In this work, quercetin was co-precipitated with dietary fibers into a fast-dissolving nanoformulation via antisolvent precipitation, followed by spray drying. With the help of cellulose fiber, resistant starch or resistant maltodextrin, a high dissolution rate and good storage stability was achieved for quercetin nanoformulations. In addition, nanoformulations exhibited higher level of antioxidant activities in contrast to raw quercetin. The developed quercetin/dietary fiber nanoformulations could be used as supplements or functional ingredients for food development.

Hot-melt extrusion microencapsulation of quercetin for taste-masking.

Besides its poor dissolution rate, the bitterness of quercetin also poses a challenge for further development. Using carnauba wax, shellac or zein as the shell-forming excipient, this work aimed to microencapsulate quercetin by hot-melt extrusion for taste-masking. In comparison with non-encapsulated quercetin, the microencapsulated powders exhibited significantly reduced dissolution in the simulated salivary pH 6.8 medium indicative of their potentially good taste-masking efficiency in the order of zein > carnauba wax > shellac. In vitro bitterness analysis by electronic tongue confirmed the good taste-masking efficiency of the microencapsulated powders. In vitro digestion results showed that carnauba wax and shellac-microencapsulated powders presented comparable dissolution rate with the pure quercetin in pH 1.0 (gastric) and 6.8 (intestine) medium; while zein-microencapsulated powders exhibited a remarkably slower dissolution rate. Crystallinity of quercetin was slightly reduced after microencapsulation while its chemical structure remained unchanged. Hot-melt extrusion microencapsulation could thus be an attractive technique to produce taste-masked bioactive powders.

Nanostructured material formulated acrylic bone cements with enhanced drug release.

To improve antibiotic properties, poly(methyl methacrylate) (PMMA)-based bone cements are formulated with antibiotic and nanostructured materials, such as hydroxyapatite (HAP) nanorods, carbon nanotubes (CNT) and mesoporous silica nanoparticles (MSN) as drug carriers. For nonporous HAP nanorods, the release of gentamicin (GTMC) is not obviously improved when the content of HAP is below 10%; while the high content of HAP shows detrimental to mechanical properties although the release of GTMC can be substantially increased. As a comparison, low content of hollow nanostructured CNT and MSN can enhance drug delivery efficiency. The presence of 5.3% of CNT in formulation can facilitate the release of more than 75% of GTMC in 80 days, however, its mechanical strength is seriously impaired. Among nanostructured drug carriers, antibiotic/MSN formulation can effectively improve drug delivery and exhibit well preserved mechanical properties. The hollow nanostructured materials are believed to build up nano-networks for antibiotic to diffuse from the bone cement matrix to surface and achieve sustained drug release. Based on MSN drug carrier in formulated bone cement, a binary delivery system is also investigated to release GTMC together with other antibiotics.

Clay as a matrix former for spray drying of drug nanosuspensions.

Utilization of sugars (e.g. lactose, sucrose) as matrix formers for spray drying of drug nanosuspensions is associated with two drawbacks: (1) sugars are incapable of preventing agglomeration of drug nanoparticles (NPs) in the suspension state; and (2) the spray-dried sugars are usually amorphous and hygroscopic. This work aimed to apply a clay, montmorillonite (MMT) as an alternative matrix former for spray drying of drug nanosuspensions with fenofibrate (feno) as a model compound. Drug nanosuspensions were synthesized by liquid antisolvent precipitation with different amount of MMT followed by spray drying. It is found that MMT is able to reduce the agglomeration of drug nanoparticles in the suspension state, as observed from the gradual alleviation of the clogging with the increased clay during the spray drying. The spray-dried feno NPs/MMT powders exhibited a much lower moisture sorption than spray-dried feno NPs/lactose powders as evidenced by the dynamic vapor sorption (DVS) analysis. The dissolution within 5 min for the spray-dried feno NPs/MMT powders at drug:MMT weight ratio of 1:3 was 81.4 ± 1.8% and the total dissolution within 60 min was 93.4 ± 0.9%. Our results demonstrate that MMT is a useful matrix former for preservation of the high dissolution rate of nanosized drug particles after drying.

Scalable ionic gelation synthesis of chitosan nanoparticles for drug delivery in static mixers.

The purpose of this study is to synthesize chitosan (CS) nanoparticles (NPs) by ionic gelation with tripolyphosphate (TPP) as crossslinker in static mixers. The proposed static mixing technique showed good control over the ionic gelation process and 152-376 nm CS NPs were achieved in a continuous and scalable mode. Increasing the flow rates of CS:TPP solution streams, decreasing the CS concentration or reducing the CS:TPP solution volume ratio led to the smaller particles. Sylicylic acid (SA) was used as a model drug and successfully loaded into the CS NPs during the fabrication process. Our work demonstrates that ionic gelation-static mixing is a robust platform for continuous and large scale production of CS NPs for drug delivery.

Applications of mesoporous materials as excipients for innovative drug delivery and formulation.

Due to uniquely ordered nanoporous structure and high surface area as well as large pore volume, mesoporous materials have exhibited excellent performance in both controlled drug delivery with sustained release profiles and formulation of poorly aqueoussoluble drugs with enhanced bioavailability. Compared with other bulk excipients, mesoporous materials could achieve a higher loading of active ingredients and a tunable drug release profile, as the high surface density of surface hydroxyl groups offered versatility to be functionalized. With drug molecules stored in nano sized channels, the pore openings could be modified using functional polymers or nano-valves performing as stimuli-responsive release devices and the drug release could be triggered by environmental changes or other external effects. In particular, mesoporous silica nanoparticles (MSN) have attracted much attention for application in functional target drug delivery to the cancer cell. The smart nano-vehicles for drug delivery have showed obvious improvements in the therapeutic efficacy for tumor suppression as compared with conventional sustained release systems, although further progress is still needed for eventual clinical applications. Alternatively, unmodified mesoporous silica also exhibited feasible application for direct formulation of poorly water-soluble drugs to enhance dissolution rate, solubility and thus increase the bioavailability after administration. In summary, mesoporous materials offer great versatility that can be used both for on-demand oral and local drug delivery, and scientists are making great efforts to design and fabricate innovative drug delivery systems based on mesoporous drug carriers.

Solid lipid nanoparticles: continuous and potential large-scale nanoprecipitation production in static mixers.

This work aimed at developing continuous and scalable nanoprecipitation synthesis of solid lipid nanoparticles (SLN) by mixing lipids acetonic solution with water using static mixers. The developed platform exhibited good control over the nanoprecipitation process and enabled the production of SLN below 200 nm at a throughput of 37.5-150 g/h (for 25 mg/ml lipid solution at a flow rate of 25-100 ml/min). Among the several process parameters investigated, the lipid concentration played primary role in influencing the size of the SLN and higher lipid concentration resulted in relatively larger particles. Fenofibrate, a model drug, has been successfully loaded into the SLN. Our work demonstrates the potential of applying static mixing-nanoprecipitation for continuous and large scale production of SLN.

Controlled antisolvent precipitation of spironolactone nanoparticles by impingement mixing.

Continuous antisolvent precipitation of spironolactone nanoparticles were performed by impingement mixing in this work. In the range of Reynolds numbers (Re) 2108-6325 for the antisolvent water stream and 1771-5313 for the solvent stream, i.e. acetonic drug solution, 302-360 nm drug nanoparticles were achieved. Increasing drug concentration from 25 to 50 and 100 mg/ml led to a significant size increase from 279.0±2.6 to 302.7±4.9 and 446.0±17.3 nm, respectively. "Two-step crystallization" was first observed for spironolactone in the water/acetone system: the drug was precipitated initially as spherical cluster, which rearranged into ordered cuboidal nanocrystals finally. The nanoformulation showed faster dissolution rate in comparison with the raw drug. By combining the impingement mixing and an on-line spray drying, a fully continuous process may be developed for mass-production of dried drug nanoparticles.

Continuous and scalable process for water-redispersible nanoformulation of poorly aqueous soluble APIs by antisolvent precipitation and spray-drying.

This work investigates the technical feasibility of formulating water-redispersible nanocrystals of a poorly aqueous soluble drug by a continuous and scalable route. By coupling antisolvent precipitation with immediate spray-drying, fenofibrate nanoparticles were precipitated and formulated into a dry powder form containing lactose or mannitol as redispersant, hydroxylpropyl methyl cellulose (HPMC) and sodium dodecyl sulfate (SDS) as stabilizers. Field emission scanning electron microscopy (FESEM) and dynamic laser light scattering (DLLS) showed that nanosized fenofibrate were observed both upon precipitation and after the formulated powder was reconstituted in water. Analyses with powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) showed that the formulated drug remained predominantly in the crystalline state. USP dissolution testing in 0.1N HCl solution with 0.5% (w/w) Tween-80 showed that the nanocrystals could be readily redispersed upon reconstitution and exhibited significantly a higher dissolution rate with 84.2% drug dissolved in 5 min as compared to the conventional spray-dried formulation (31.7%) and the physical mixture (9.7%) using micronized fenofibrate. The results suggest the potential of combining static mixing and spray drying for large-scale continuous production of pharmaceutical nanoformulations.

A continuous and highly effective static mixing process for antisolvent precipitation of nanoparticles of poorly water-soluble drugs.

Rapid and homogeneous mixing of the solvent and antisolvent is critical to achieve submicron drug particles by antisolvent precipitation technique. This work aims to develop a continuous and highly effective static mixing process for antisolvent precipitation of nanoparticles of poorly water-soluble drugs with spironolactone as a model drug. Continuous antisolvent production of drug nanoparticles was carried out with a SMV DN25 static mixer comprising 6-18 mixing elements. The total flow rate ranged from 1.0 to 3.0 L/min while the flow rate ratio of solvent to antisolvent was maintained at 1:9. It is found that only 6 mixing elements were sufficient to precipitate the particles in the submicron range. Increasing the number of elements would further reduce the precipitated particle size. Increasing flow rate from 1.0 to 3.0 L/min did not further reduce the particle size, while higher drug concentrations led to particle size increase. XRD and SEM results demonstrated that the freshly precipitated drug nanoparticles are in the amorphous state, which would, in presence of the mixture of solvent and antisolvent, change to crystalline form in short time. The lyophilized spironolactone nanoparticles with lactose as lyoprotectant possessed good redispersibility and showed 6.6 and 3.3 times faster dissolution rate than that of lyophilized raw drug formulation in 5 and 10 min, respectively. The developed static mixing process exhibits high potential for continuous and large-scale antisolvent precipitation of submicron drug particles.

Stabilized amorphous state of ibuprofen by co-spray drying with mesoporous SBA-15 to enhance dissolution properties.

A novel formulation process via co-spray drying ibuprofen (IBU) with mesoporous SBA-15 submicron particles exhibited excellence in production of stable amorphous IBU with significantly enhanced dissolution rate. With drug loading of IBU/SBA-15 ratio being 50:50 (w/w) or below, most drug molecules were entrapped inside the straight mesoporous channels via the co-spray drying and the morphology of SBA-15 submicron particles remained unchanged. IBU confined inside the mesoporous structure was in the amorphous state shown by PXRD and DSC measurements. The amorphous state of IBU in the solid dispersion showed remarkable stability when subject to stress test condition of 40 degrees C/75% RH in open pans for 12 months. The uniform pore walls were believed to prevent the re-crystallization of the homogeneously dispersed drug molecules inside the mesoporous channels with confined nanospace. The dissolution rate of IBU from the co-spray-dried solid dispersion was significantly enhanced to achieve a rapid release. Even after the accelerated stability test, the rapid drug release property was well preserved.

DNA stretching in the nucleosome facilitates alkylation by an intercalating antitumour agent.

DNA stretching in the nucleosome core can cause dramatic structural distortions, which may influence compaction and factor recognition in chromatin. We find that the base pair unstacking arising from stretching-induced extreme minor groove kinking near the nucleosome centre creates a hot spot for intercalation and alkylation by a novel anticancer compound. This may have far reaching implications for how chromatin structure can influence binding of intercalator species and indicates potential for the development of site selective DNA-binding agents that target unique conformational features of the nucleosome.

Preparation and characterization of spironolactone nanoparticles by antisolvent precipitation.

Due to low aqueous solubility and slow dissolution rate, spironolactone, a synthetic steroid diuretic, has a low and variable oral bioavailability. Nanoparticles were thus prepared by antisolvent precipitation in this work for accelerating dissolution of this kind of poorly water-soluble drugs. Effects of surfactant type/concentration and feed drug concentration on the precipitated particle size were evaluated. It was found that introduction of spironolactone solution in N-methyl-2-pyrrolidone (NMP) to the antisolvent water can produce the particles in the submicron range with hydroxypropyl methylcellulose (HPMC) as the stabilizer. The particle size decreased with the increase of HPMC concentration from 0 to 0.125% (w/v), further increase of which did not affect the size significantly. Increasing feed drug concentration from 10 to 100 mg/ml resulted in the particle size decrease. In comparison with raw drug, the chemical structure of nanosized spironolactone was not changed but the crystallinity was reduced. Dissolution of spironolactone nanoparticles in 0.1M HCl was 2.59 times faster than raw drugs in 60 min.

Solubilization and preformulation of poorly water soluble and hydrolysis susceptible N-epoxymethyl-1,8-naphthalimide (ENA) compound.

N-Epoxymethyl-1,8-naphthalimide (ENA) is a novel antiproliferative drug candidate with potent anticancer and antifungal activity. It has an aqueous solubility of 0.0116mg/mL and also exhibits hydrolytic instability with a first-order hydrolysis rate of 0.051 h(-1). The present preformulation study aimed to characterize the physicochemical properties of ENA and develop an early injectable solution formulation for preclinical studies. To minimize hydrolysis, ENA is proposed to be formulated as either lyophilized powders or nonaqueous solutions followed by solubilization/reconstitution prior to administration. ENA solubilization was investigated in both aqueous media (by cosolvency, micellization and complexation) and nonaqueous solutions (mixture of Cremophor EL and ethanol). It is found that none of the solubilization techniques in aqueous media could increase ENA solubility to a desired level of several hundreds microg/mL at pharmaceutically acceptable excipient concentrations (< or =10%). In contrast, a combination of 70% Cremophor EL and 30% ethanol (v/v) proved effective in solubilizing ENA at 4 mg/mL, which exhibited good physical and chemical stability on storage at both 4 degrees C and room temperature over 4 months. No precipitation was observed upon 5-20 times dilution by the saline; in addition, less than 5% of ENA was hydrolyzed in 4h for the saline-diluted aqueous solutions. This nonaqueous ENA formulation is thus proposed for further preclinical studies, which can be reconstituted, prior to administration, by the 5-20 times infusion fluids (saline, 5% dextrose, etc.) to the desired drug dosing concentration at the acceptable excipient level. The approach used in this work could serve as a useful reference in formulating nonpolar drugs with hydrolytic instability.

d-alpha-Tocopheryl polyethylene glycol 1000 succinate (TPGS) modified poly(l-lactide) (PLLA) films for localized delivery of paclitaxel.

d-alpha-Tocopheryl polyethylene glycol 1000 succinate (TPGS) was used as a novel additive to the poly(l-lactide) (PLLA) films for local drug delivery with paclitaxel as a prototype therapeutic agent. Paclitaxel-loaded PLLA/TPGS films were prepared by the solvent casting technique with dichloromethane as the solvent. Effects of TPGS component on the films' physicomechanical properties and the drug release profile were investigated. It was found by field emission scanning microscopy (FESEM) that a biphasic honeycomb surface was formed for the PLLA/TPGS films, while the PLLA film exhibited a smooth and homogeneous surface. There was no significant effect of the drug loading on the morphological structure of the PLLA/TPGS films. Differential scanning calorimetry (DSC) demonstrated that the PLLA/TPGS films was a phase-separated system. Tensile testing showed that the flexibility of the PLLA/TPGS films was much higher than that of the PLLA film. The elongation at break for the PLLA/TPGS film of 5%, 10% and 15% TPGS content was 6.8, 8.9 and 19.4 times of that for the PLLA film, respectively. In vitro drug release studies found that incorporation of TPGS considerably facilitated paclitaxel release.

Poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles prepared by high pressure homogenization for paclitaxel chemotherapy.

High pressure homogenization was employed in the current work to prepare poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles (NPs) for controlled release of paclitaxel. The prepared drug-loaded PLGA NPs were found of spherical shape with a size of 200-300 nm. The drug encapsulation efficiency ranged from 34.8+/-1.6 to 62.6+/-7.9% depending on the homogenization pressure and cycles. Paclitaxel was released from the nanoparticles in a biphasic profile with a fast release rate in the first 3 days followed by a slow first-order release. A higher or comparable cytotoxicity against glioma C6 cells was found for the drug formulated in the PLGA NPs in comparison with the free drug Taxol. Confocal laser scanning microscopy (CLSM) evidenced internalization of the fluorescent coumarin 6-loaded PLGA NPs by the C6 cells. The freeze-dried nanoparticles were found to possess excellent water redispersability. The high pressure homogenization could be applied for large industrial scale production of nanoparticles for drug delivery.

In vitro and in vivo evaluation of methoxy polyethylene glycol-polylactide (MPEG-PLA) nanoparticles for small-molecule drug chemotherapy.

Methoxy polyethylene glycol-polylactide (MPEG-PLA) nanoparticles (NPs) were prepared by the nanoprecipitation method with particle size of 140+/-21nm in diameter and drug encapsulation efficiency of 87.6+/-3.1%. In vitro cytotoxicity of the drug formulated in the NPs was investigated with MCF-7 cancer cells in close comparison with that of Taxol((R)). The in vitro cytotoxicity with MCF-7 cells showed that the NP formulation could be 33.3, 10.7, 7.7 times more effective than Taxol((R)) after 24, 48, 72h culture at the same drug concentration of 1microg/ml. Confocal laser scanning microscopy (CLSM) visualized cellular internalization of the coumarin 6-loaded MPEG-PLA NPs. The in vitro results were further confirmed by the in vivo pharmacokinetic analysis with SD rats. The total area-under-the-curve (AUC(0-infinity)), which determines the therapeutic effects of a dose, was found to be 29,600+/-1,690ng-h/ml for the NP formulation, which is 3.09 times of 9,570+/-1,480ng-h/l for Taxol((R)) with 10mg/kg dose i.v. injection. The half-life (t(1/2)) of the drug formulated in the NPs was found to be 18.80+/-3.14h, which is 2.75 times of 6.84+/-1.39h for Taxol((R)). The distribution volume at steady state for the drug loaded in the NPs was 7.21+/-2.17l/kg, which was 2.93 times of 2.46+/-1.41l/kg for Taxol((R)). Our proof-of-concept in vitro and in vivo valuation shows that our MPEG-PLA NP formulation could have great advantages versus the original drug in small-molecule drug chemotherapy as well as in various applications in nanomedicine.

Nanoparticles of poly(D,L-lactide)/methoxy poly(ethylene glycol)-poly(D,L-lactide) blends for controlled release of paclitaxel.

Paclitaxel is one of the best antineoplastic drugs found in nature in the past decades, which has excellent therapeutic effects against a wide spectrum of cancers. Because of its high hydrophobicity, Cremophor EL has to be used as adjuvant in its clinical dosage form (Taxol), which has been found to cause serious side effects. Nanoparticles of biodegradable polymers may provide an ideal solution. In this research, paclitaxel-loaded nanoparticles of poly(D,L-lactide)/methoxy poly(ethylene glycol)-polylactide (PLA/MPEG-PLA) blends of various blend ratio 100/0, 75/25, 50/50, 25/75, and 0/100 were formulated by the nanoprecipitation method for controlled release of paclitaxel. It was found that increasing the proportion of MPEG-PLA component in the blend from 0 to 100% resulted in a progressive decrease of the particle size from 230.6+/-11.1 nm to 74.8+/-14.0 nm. The zeta potential of the drug-loaded nanoparticles was increased accordingly from -19.60+/-1.13 mV to a nearly neutral, that is, -0.33+/-0.28 mV, which indicates the gradual enrichment of PEG segments on the particle surface. The findings were further confirmed by X-Ray Photoelectron Spectroscopy (XPS) analysis. Differential scanning calorimetry (DSC) analysis showed that the glass transition temperature of PLA was significantly decreased from 58.7 to 52.1 degrees C with an increase of MPEG-PLA proportion from 0 to 75%, suggesting the miscibility of PLA and MPEG-PLA. The pure PLA nanoparticles (100/0) exhibited the slowest drug-release rate with 37.3% encapsulated drug released from the nanoparticles for 14 days while the MPEG-PLA nanoparticles (0/100) achieved the fastest drug release with 95.9% drug release in the same period.