Polyelectrolyte-based solid dispersions for enhanced dissolution and pH-Independent controlled release of sildenafil citrate.

The aim of this study was to design a novel matrix tablet with enhanced dissolution and pH-independent controlled release of sildenafil citrate (SIL), a drug with pH-dependent solubility, by using solid dispersions (SDs) and polyelectrostatic interactions. SIL-loaded SDs were prepared using various polymeric carriers such as poloxamer 188, poloxamer 407, Soluplus®, polyvinylpyrrolidone (PVP) K 12, and PVP K 17 by the solvent evaporation method. Among these polymers, Soluplus® was found to be the most effective in SDs for enhancing the drug dissolution over 6 h in pH 6.8 intestinal fluid. SIL was well dispersed in Soluplus®-based SDs in an amorphous form. When the Soluplus®-based SDs were added in the tablet containing positively charged chitosan and negatively charged Eudragit® L100, the drug release rate was further modulated in a controlled manner. The charge density of the tablet was higher at pH 6.8 than at pH 1.2 due to the polyelectrostatic interaction between chitosan and Eudragit® L100. This interaction could provide a pH-independent controlled release of SIL. Our study demonstrates that a combinatory approach of Soluplus®-based SDs and polyelectrostatic interactions can improve the dissolution and pH-independent release performance of SIL. This approach could be a promising pharmaceutical strategy to design a matrix tablet of poorly water-soluble drugs for the enhanced bioavailability.

Development of Polyvinyl Alcohol/Polyethylene Glycol Copolymer-based Orodispersible Films Loaded with Entecavir: Formulation and In vitro Characterization.

PURPOSE: The aim of the study is to prepare entecavir (ETV)-loaded orodispersible films (ODFs) using polyvinyl alcohol (PVA)/polyethylene glycol (PEG) graft copolymer (Kollicoat® IR) as a film-forming agent, and further to evaluate the dissolution rate, mechanical and physicochemical properties of films. METHODS: ETV-ODFs were prepared by a solvent casting method. The amount of film-forming agent, plasticizer, and disintegrating agent was optimized in terms of the appearance, thickness, disintegration time and mechanical properties of ODFs. The compatibility between the drug and each excipient was conducted under high temperature (60 °C), high humidity (RH 92.5%), and strong light (4500 Lx) for 10 days. The dissolution study of optimal ODFs compared with the original commercial tablet (Baraclude®) was performed using a paddle method in pH 1.0, pH 4.5, pH 6.8, and pH 7.4 media at 37 °C. The morphology of ODFs was observed via scanning electron microscopy (SEM). The mechanical properties such as tensile strength (TS), elastic modulus (EM), and percentage elongation (E%) of ODFs were evaluated using the universal testing machine. The physicochemical properties of ODFs investigated using X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FT-IR). RESULTS: The related substances were less than 0.5% under high temperature, high humidity, and strong light for 10 days when ETV was mixed with excipients. The optimal formulation of ODFs was set as the quality ratio of Kollicoat® IR, glycerol, sodium alginate (ALG-Na): TiO2: MCC+CMC-Na: ETV was 60:9:12:1:1:1. The drug-loaded ODFs were white and translucent with excellent stripping property. The thickness, disintegration time, EM, TS, and E% were 103.33±7.02 µm, 25.31±1.95 s, 25.34±8.69 Mpa, 2.14±0.26 Mpa, and 65.45±19.41 %, respectively. The cumulative drug release from ODFs was more than 90% in four different media at 10 min. The SEM showed that the drug was highly dispersible in ODFs, and the XRD, DSC, and FT-IR results showed that there occurred some interactions between the drug and excipients. CONCLUSION: In conclusion, the developed ETV-loaded ODFs showed relatively short disintegration time, rapid drug dissolution, and excellent mechanical properties. This might be an alternative to conventional ETV Tablets for the treatment of chronic hepatitis B.

Rizatriptan-Loaded Oral Fast Dissolving Films: Design and Characterizations.

Rizatriptan (RZT) is an efficient anti-migraine drug which belongs to the class of selective 5 HT (1B/1D) serotonin receptor agonists. Nevertheless, RZT elicits several adverse effects and RZT nasal sprays have a limited half-life, requiring repeated doses that could cause patient noncompliance or harm to the nasopharynx and cilia. The current research aimed to develop orally disintegrating films (ODFs) of RZT employing maltodextrin (MTX) and pullulan (PUL) as film-forming polymers, as well as propylene glycol (PG) as a plasticizer. The ODFs were prepared by solvent casting method (SCM). The technique was optimized using Box-Behnken design (BBD), contemplating the ratios of PUL: MTX and different levels of PG (%) as factor variables. The influence of these factors was systematically analyzed on the selected dependent variables, including film thickness, disintegration time (D-time), folding endurance (FE), tensile strength (TS), percent elongation (%E), moisture content (%), and water uptake (%). In addition, the surface morphology, solid state analysis, drug content uniformity (%), drug release (%), and pH of the RZT-ODFs were also studied. The results demonstrated a satisfactory stable RZT-ODFs formulation that exhibited surface homogeneity and amorphous RZT in films with no discernible interactions between the model drug and polymeric materials. The optimized film showed a rapid D-time of 16 s and remarkable mechanical features. The in vitro dissolution kinetics showed that 100% RZT was released from optimized film compared to 61% RZT released from conventional RZT formulation in the initial 5 min. An animal pharmacokinetic (PK) investigation revealed that RZT-ODFs had a shorter time to achieve peak plasma concentration (Tmax), a higher maximum plasma concentration (Cmax), and area under the curve (AUC0-t) than traditional oral mini capsules. These findings proposed a progressive approach for developing anti-migraine drugs that could be useful in reducing the complications of dysphagia in geriatric and pediatric sufferers.

Design and evaluation of in vivo bioavailability in beagle dogs of bilayer tablet consisting of immediate release nanosuspension and sustained release layers of rebamipide.

The purpose of this study was to develop a once-daily, bilayer matrix tablet with immediate (IR) and sustained release (SR) layers of poorly water-soluble and absorption site dependent rebamipide (RBM) to substitute three times a day IR tablet. Owing to the pH-dependent poor water solubility of RBM in low pH condition, salt-caged nanosuspensions (NSPs) consisting of RBM and poloxamer 407 (POX 407) or poloxamer 188 (POX 188) were prepared using an acid-base neutralization method to increase the dissolution rate, which was subsequently applied to the immediate-release (IR) layer. Polyethylene oxide (PEO) with different molecular weights (PEO 100,000 and PEO 5,000,000) and hydroxypropyl methylcellulose 4000 (HPMC 4000) were then investigated as SR agents to incorporate into the SR layer with pure RBM via wet granulation method. The dissolution profile of the optimized bilayer tablet having 50% IR and 50% SR layer of 300 mg RBM showed that the IR layer could rapidly disintegrate in pH 1.2 buffer solution within 2 h, reaching 50% of drug release from the tablet, followed by an extended drug release from the SR layer in pH 6.8 buffer over 24 h. An in vivo pharmacokinetic study was carried out in beagle dogs to compare the optimal formulation (300 mg RBM bilayer tablet) and the commercial tablet (Mucosta® 100 mg) as a reference. Unexpectedly, despite enhanced dissolution rate in a controlled manner, a designed bilayer tablet had no dose- and dosage form dependent in vivo bioavailability in beagle dogs as compared with IR 100 mg RBM reference tablet. It was evident that solubility in low pH condition, gastric residence time and absorption site of RBM should be carefully considered for designing specific SR or gastroretentive dosage form to improve therapeutic outcomes.

Electrostatic molecular effect of differently charged surfactants on the solubilization capacity and physicochemical properties of salt-caged nanosuspensions containing pH-dependent and poorly water-soluble rebamipide.

In this study, the electrostatic molecular effect of differently charged surfactants on the solubilization capacity and physicochemical properties of salt-caged nanosuspensions (NSPs) containing poorly water-soluble drug was investigated. Anionic rebamipide (RBM) was chosen as a model drug because of its poor water solubility in low pH condition and ionizable acidic forms. Negatively charged sodium lauryl sulfate (SLS) and positively charged cetyltrimethylammonium bromide (CTAB) were selected as surfactants for the preparation of NSPs or in the dissolution medium. Salt-caged NSPs surrounded by NaCl were prepared by the HCl-NaOH neutralization method in the presence of poloxamer 407. Interestingly, the addition of positively charged CTAB in the preparation process or the dissolution media could interfere with the solubilization capacity of salt-caged NSPs containing a negatively charged drug via intermolecular electrostatic attraction. In the presence of positively charged CTAB, the salt-caged NSP was disordered in structure via electrostatic attractive interaction with partially ionizable anionic RBM resulting in changes in the physicochemical properties of the salt-caged NSP such as low drug content, increased particle size, decreased dissolution rate, and the formation of water-insoluble precipitates with rough and irregular crystals. This inhibitory effect of CTAB on the dissolution rate of pure RBM and the salt-caged NSP in pH 6.8 intestinal fluid was pronounced in a concentration-dependent manner mainly owing to the formation of precipitates, so-called poorly soluble complexes. When the salt-caged NSP (F1) was dissolved in DW containing CTAB, the dissolution rate decreased more significantly, dissolving less than 20% within 2 h. Depending on the surfactant charges, the charge density and the initial potential were varied during the dissolution of NSPs in deionized water (DW). In contrast, the negatively charged SLS did not significantly change the physicochemical properties of the salt-caged NSP. For example, the dissolution rate of the salt-caged NSP containing SLS in DW or pH 1.2 gastric fluid remained over 90% for 2 h. Surfactants for the formulation or dissolution media should be chosen carefully because of their effect on the physicochemical properties and solubilization capacity of salt-caged NSPs containing poorly water-soluble and ionizable drugs via electrostatic molecular interactions.

Combretastatin A4-loaded Poly (Lactic-co-glycolic Acid)/Soybean Lecithin Nanoparticles with Enhanced Drug Dissolution Rate and Antiproliferation Activity.

OBJECTIVE: This study aimed to prepare combretastatin A4 (CA4)-loaded nanoparticles (CA4 NPs) using poly(lactic-co-glycolic acid) (PLGA) and soybean lecithin (Lipoid S100) as carriers, and further evaluate the physicochemical properties and cytotoxicities of CA4 NPs against cancer cells. METHODS: CA4 NPs were prepared using a solvent evaporation technique. The effects of formulations on CA4 NPs were investigated in terms of particle size, zeta potential, encapsulation efficacy, and drug loading. The physicochemical properties of CA4 NPs were characterized using transmission electron microscopy, X-ray powder diffraction, differential scanning calorimetry, and Fourier transform infrared spectra. The drug release from CA4NPs was performed using a dialysis method. In addition, the cytotoxicity of CA4NPs against human alveolar basal epithelial (A549) cells was also evaluated. RESULTS: CA4 NPs prepared with a low organic/water phase ratio (1:20) and high drug/PLGA mass ratio (1:2.5) exhibited a uniform hydrodynamic particle size of 142 nm, the zeta potential of -1.66 mV, and encapsulation efficacy and drug loading of 92.1% and 28.3%, respectively. CA4 NPs showed a significantly higher release rate than pure CA4 in pH 7.4 phosphate-buffered solution with 0.5% Tween 80. It was found that the drug molecules could change from the crystal state to an amorphous form when loaded into the PLGA/Lipoid S100 matrix, and some molecular interactions could also occur between the drug and PLGA. Importantly, CA4 NPs showed a remarkably higher antiproliferation activity against A549 cancer cells compared to pure CA4. CONCLUSION: These results suggested the promising potential of PLGA/Lipoid S100 nanoparticles as the drug delivery system of CA4 for effective cancer therapy.

Formulation Optimization and In Vitro Characterization of Granisetronloaded Polylactic-co-glycolic Acid Microspheres Prepared by a Dropping-in-liquid Emulsification Technique.

PURPOSE: Traditional dosage forms of granisetron (GRN) decrease patient compliance associated with repeated drug administration because of the short half-life of the drug. METHODS: In this study, novel GRN-loaded Polylactic-co-glycolic Acid (PLGA) sustained-release microspheres were prepared for the first time via a dropping-in-liquid emulsification technique. The effects of various factors, such as pH of the outer phase, Tween 80, Polyvinyl Alcohol (PVA) concentrations, and hardening process, on the Encapsulation Efficiency (EE), Drug Loading (DL), and particle size of microspheres were extensively studied. The physicochemical properties, including drug release, surface morphology, crystallinity, thermal changes, and molecular interactions, were also studied. RESULTS: GRN has a pH-dependent solubility and it exhibits a remarkably high solubility under acidic condition. The EE of the alkaline medium (pH 8) was higher than that of the acidic medium (pH 4.0). EE and DL decreased in the presence of Tween 80 in the outer phase, whereas EE significantly increased during hardening. The particle size of microspheres was not affected by PVA and Tween 80 concentrations, but it was influenced by PVA volume and hardening. X-ray diffraction and differential scanning calorimetry results showed that the physical state of the drug changed from a crystalline form to an amorphous form, thereby confirming that the drug was encapsulated into the PLGA matrix. Fourier transform-infrared spectroscopy confirmed that some molecular interactions occurred between the drug and the polymer. GRN-loaded PLGA microspheres showed sustained release profiles of over 90% on week 3. CONCLUSION: GRN-loaded PLGA microspheres with sustained-release were successfully prepared, and they exhibited a relatively high EE without Tween 80 as an emulsifier and with the hardening process.

Enhanced nuclear gene delivery via integrating and streamlining intracellular pathway.

The essential challenge of gene therapy is to develop safe and efficient vectors that escort genes to target sites. However, due to the cumbersome workflow of gene transfection into cells, successive gene loss occurs. This leads to considerable reductions in nuclear gene uptake, eventually causing low gene expression. Herein, we designed a gene vector named CA3S2 (C: N,N'-cystamine-bis-acrylamide [CBA], A: agmatine dihydrochloride [Agm], S: 4-(2-aminoethyl) benzenesulfonamide [ABS]) with excellent gene transfection ability. This vector can promote gene delivery to the nucleus via enhanced endoplasmic reticulum (ER) targeting through integrating and streamlining of the complex intracellular pathway. Briefly, ABS endowed CA3S2/DNA nanoparticles with not only a natural ER-targeting tendency attributed to the caveolae-mediated pathway but also direct receptor-binding capacity on the ER surface. Agm enabled CA3S2 to enhance lysosomal escape and nuclear uptake ability. The gene delivery efficiency of CA3S2 was significantly better than that of polyethyleneimine 25K (PEI 25K). Therefore, CA3S2 is a promising gene carrier, and the ER-targeting strategy involving intracellular pathway integration and streamlining has potential for gene therapy.

Collagenase IV and clusterin-modified polycaprolactone-polyethylene glycol nanoparticles for penetrating dense tumor tissues.

Purpose: Novel collagenase IV (ColIV) and clusterin (CLU)-modified polycaprolactone-polyethylene glycol (PCL-PEG) nanoparticles that load doxorubicin (DOX) were designed and fully evaluated in vitro and in vivo. Methods: PCL-PEG-ColIV was synthesized by linking PCL-PEG and ColIV through a carbodiimide method. DOX-loaded nanoparticles (DOX-PCL-PEG-ColIV) were self-assembly prepared, followed by noncovalently adsorbing CLU on the DOX-PCL-PEG-ColIV surface to obtain DOX-PCL-PEG-ColIV /CLU nanoparticles, which can penetrate through the tumor extracellular matrix (ECM) and inhibit phagocytosis by macrophage. The physicochemical properties of nanoparticles were characterized. The cellular uptake and antiphagocytosis ability of nanoparticles in MCF-7 tumor cells and RAW264.7 cells were investigated. The penetration ability of nanoparticles was individually evaluated in the two-dimensional (2D) and three-dimensional (3D) ECM models. The tissue distribution and antitumor effect of nanoparticles were evaluated in MCF-7 cell-bearing nude mice. Results: Compared with DOX-PCL-PEG-COOH nanoparticles, DOX-PCL-PEG-ColIV/CLU nanoparticles could effectively overcome the phagocytosis by RAW264.7 and showed excellent cellular uptake in MCF-7 cells. In addition, they showed remarkable penetration ability through the 2D and 3D ECM models. DOX-PCL-PEG-ColIV/CLU nanoparticles significantly reduced the drug distribution in the liver and spleen and enhanced the drug accumulation in tumor tissue compared with DOX-PCL-PEG-COOH or DOX-PCL-PEG-ColIV nanoparticles. DOX-PCL-PEG-ColIV/CLU nanoparticles showed remarkable antitumor effect but did not cause severe pathological damages in the main tissues, including the heart, liver, spleen, lung, and kidney. Conclusion: Novel ColIV and CLU-modified PCL-PEG nanoparticles showed excellent cellular uptake, ECM penetration, antiphagocytosis, and antitumor effects both in vitro and in vivo.

Fatty acid chain length impacts nanonizing capacity of albumin-fatty acid nanomicelles: Enhanced physicochemical property and cellular delivery of poorly water-soluble drug.

This study aimed to design the ideal nanonizing vehicle for poorly water-soluble model curcumin (CCM) using fattigation-platform nanotechnology, and to investigate the effects of fatty acid salts chain length on nanonizing CCM and its efficient delivery to different cancer cells. HSA-fatty acid conjugates were synthesized by EDC/NHS coupling. Fattigation-platform nanomicelles (NMs), prepared by film hydration, exhibited uniform and spherical morphology, although, each NM varied in particle size, zeta potential, and critical micelle concentration according to the types of fatty acid. Preliminary solubility studies of albumin conjugates with 5 types of fatty acid salts of different chain lengths revealed that C14 exhibited the highest solubilization of CCM. CCM-loaded HSA-C14 NMs demonstrated the highest drug content (5.35 ± 0.48%) and loading efficiency (95.93 ± 1.87%) compared to other NMs. It exhibited enhanced drug release rate and reduced micelle size in biorelevant dissolution medium. Interestingly, this solubilization approach was well applied in poorly water-soluble docetaxel trihydrate (DTX). Preliminary solubility results of DTX was also corresponded to the stable nanonization phenomenon in biorelevant dissolution medium. Compared to the CCM EtOH solution, HSA-C14 NMs showed higher internalization in cancer cell lines A549 and MCF-7, and consequently, exhibited significantly increased cytotoxicity against both cell lines. Therefore, this study provides a new solubilization approach for poorly water-soluble drugs using fatty acid salts of different chain lengths and their micellar formations via nanonization, which could be a promising tool for targeted cancer therapy using poorly water-soluble drugs.

Combinatory interpretation of protein corona and shear stress for active cancer targeting of bioorthogonally clickable gelatin-oleic nanoparticles.

Nanoparticle-protein interactions under conditions mimicking physiology determine how nanoparticles (NPs) will behave inside blood vessels and, therefore, the overall outcome of the drug-delivery system. Here, for the first time, we explore the effects of bio-mimicking shear stress and protein corona conditions on novel active targeting of clickable fattigation nanoparticles (NPs) for cancer therapy. Active targeting dibenzocyclooctyne-functionalized biocompatible gelatin-oleic NPs (GON-DBCOs) via a bioorthogonal click reaction were prepared by the desolvation method for delivery of docetaxel (DTX) to lung and breast cancer models. The effect of shear stress (5 dyne/cm2) and human serum albumin (HSA) protein corona on the cellular behavior of NPs was explored under a dynamic microfluidic system in lung (A549) and breast (MCF-7) cancer cell lines. The developed drug-loaded NPs had a particle size of 300 nm, a narrow size distribution, positive zeta potential, high encapsulation efficacy (72.4%), and spherical morphology. The particle size of the protein corona-coated NPs increased to 341 nm with a negative zeta potential. The inhibitory dose (IC50) increased approximately 3- and 42-fold in A549 and MCF-7 cells, respectively, under dynamic microfluidic conditions compared to static conditions. Cellular uptake was significantly decreased in the presence of shear stress and a protein corona, compared with static conditions, in both lung (A549, **p < 0.01) and breast (MCF-7, *p < 0.05) cancer cell lines. Clathrin-and energy-dependent pathways were found to be involved in the cellular uptake of NPs. This study could serve as a vital tool for the evaluation of NPs under aggressive bio-mimicking conditions comprising shear stress and a protein corona to predict the in vivo performance of NPs and support the preclinical and clinical translation of NP drug delivery systems.

Investigation of Crystallization and Salt Formation of Poorly Water-Soluble Telmisartan for Enhanced Solubility.

The crystal changes and salt formation of poorly water-soluble telmisartan (TEL) in various solvents were investigated for enhanced solubility, stability and crystallinity. Polymorphic behaviors of TEL were characterized by dispersing in distilled water, acetone, acetonitrile, DMSO, or ethanol using Method I: without heat and then dried under vacuum at room temperature; and Method II: with heat below boiling temperature, cooled at 5 °C, and then dried under vacuum at 40 °C. For salt formation (Method III), the following four powdered mixtures were prepared by dispersing in solution of hydrochloric acid (HCl) (pH 1.2), TEL/HCl; in simulated gastric fluid (pH 1.2 buffer), TEL/simulated gastric fluid (SGF); in intestinal fluid (pH 6.8 buffer), TEL/simulated intestinal fluid (SIF); or in NaOH (pH 6.8), TEL/NaOH, respectively, and then dried under a vacuum at room temperature. The structures of powdered mixtures were then studied using a field emission scanning electron microscope (FESEM), differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), FTIR, ¹H nuclear magnetic resonance (¹H-NMR), and LC⁻MS. The solubility of TEL in powdered forms was performed in pH 6.8, pH 1.2, and distilled water. No polymorphic behaviors of TEL were observed in various solvents as characterized by FESEM, DSC, PXRD, and FTIR. However, the structural changes of powdered mixtures obtained from Method III were observed due to the formation of salt form. Moreover, the solubility of salt form (TEL/HCl) was highly increased as compared with pure TEL. There were no significant changes of TEL/HCl compared with TEL in the content assay, PXRD, DSC, and FTIR during stressed storage conditions at 40 °C/75% relative humidity (RH) for 4 weeks under the closed package condition. Therefore, the present study suggests the new approach for the enhanced stability and solubility of a poorly water-soluble drug via salt form.

Enhanced Lysosomal Escape of pH-Responsive Polyethylenimine-Betaine Functionalized Carbon Nanotube for the Codelivery of Survivin Small Interfering RNA and Doxorubicin.

The combination of gene therapy and chemotherapy has recently received considerable attention for cancer treatment. However, low transfection efficiency and poor endosomal escape of genes from nanocarriers strongly limit the success of the clinical use of small interfering RNA (siRNA). In this study, a novel pH-responsive, surface-modified single-walled carbon nanotube (SWCNT) was designed for the codelivery of doxorubicin (DOX) and survivin siRNA. Polyethylenimine (PEI) was covalently conjugated with betaine, and the resulting PEI-betaine (PB) was further synthesized with the oxidized SWCNT to form SWCNT-PB (SPB), which exhibits an excellent pH-responsive lysosomal escape of siRNA. SPB was modified with the targeting and penetrating peptide BR2 (SPBB), thereby achieving considerably higher uptake of siRNA than SWCNT-PEI (SP) or SPB. Furthermore, SPBB-siRNA presented substantially lower survivin expression and higher apoptotic index than Lipofectamine 2000. DOX and survivin siRNA were adsorbed onto SPB to form DOX-SPBB-siRNA, and siRNA/DOX was released into the cytoplasm and nuclei of adenocarcinomic human alveolar basal epithelial (A549) cells without lysosomal retention. Compared with SPBB-siRNA or DOX-SPBB treatment alone, DOX-SPBB-siRNA significantly reduced tumor volume in A549 cell-bearing nude mice, demonstrating the synergistic effects of DOX and survivin siRNA. Pathological analysis also indicated the potential therapeutic effects of DOX-SPBB-siRNA on tumors without distinct damages to normal tissues. In conclusion, the novel functionalized SWCNT loaded with DOX and survivin siRNA was successfully synthesized, and the nanocomplex exhibited effective antitumor effects both in vitro and in vivo, thereby providing an alternative strategy for the codelivery of antitumor drugs and genes.

Design and evaluation of clickable gelatin-oleic nanoparticles using fattigation-platform for cancer therapy.

The principles of bioorthogonal click chemistry and metabolic glycoengineering were applied to produce targeted anti-cancer drug delivery via fattigation-platform-based gelatin-oleic nanoparticles. A sialic acid precursor (Ac4ManNAz) was introduced to the cell surface. Gelatin and oleic acid were conjugated by 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride/N-hydroxysuccinimide (EDC/NHS) chemistry with the subsequent covalent attachment of dibenzocyclooctyne (DBCO) in a click reaction on the cell surface. The physicochemical properties, drug release, in vitro cytotoxicity, and cellular uptake of DBCO-conjugated gelatin oleic nanoparticles (GON-DBCO; particle size, ∼240 nm; zeta potential, 6 mV) were evaluated. Doxorubicin (DOX) was used as a model drug and compared with the reference product, Caelyx®. A549 and MCF-7 cell lines were used for the in vitro studies. GON-DBCO showed high DOX loading and encapsulation efficiencies. In A549 cells, the IC50 value for GON-DBCO-DOX (1.29 µg/ml) was six times lower than that of Caelyx® (10.54 µg/ml); in MCF-7 cells, the IC50 values were 1.78 µg/ml and 2.84 µg/ml, respectively. Confocal microscopy confirmed the click reaction between GON-DBCO and Ac4ManNAz on the cell surface. Flow cytometry data revealed that the intracellular uptake of GON-DBCO-DOX was approximately two times greater than that of GON-DOX and Caelyx®. Thus, the newly designed GON-DBCO-DOX provided a safe and efficient drug delivery system to actively target the anticancer agents.

Effective deactivation of A549 tumor cells in vitro and in vivo by RGD-decorated chitosan-functionalized single-walled carbon nanotube loading docetaxel.

This study aims to construct and evaluate RGD-decorated chitosan (CS)-functionalized pH-responsive single-walled carbon nanotube (SWCNT) carriers using docetaxel (DTX) as a model anticancer drug. DTX was loaded onto SWCNT via π-π stacking interaction (SWCNT-DTX), followed by the non-covalent conjugation of RGD-decorated CS to SWCNT-DTX to prepare RGD-CS-SWCNT-DTX. The RGD-CS-SWCNT-DTX showed significantly higher drug release than the pure drug, giving higher release rate at pH 5.0 (68%) than pH 7.4 (49%). The RGD-CS-SWCNT-DTX could significantly inhibit the growth of A549 tumor cells in vitro, and the uptake amount of A549 cells was obviously higher than that of MCF-7 cells. Meanwhile, the cellular uptake of RGD-CS-SWCNT-DTX was higher than that of CS-SWCNT-DTX in A549 cells, mainly through clathrin and caveolae-mediated endocytosis. The RGD-CS-SWCNT-DTX significantly inhibited tumor growth of A549 cell-bearing nude mice through active tumor-targeting ability. Furthermore, no pathological changes were found in tissues and organs. The result demonstrated that RGD-CS-SWCNT-DTX displayed high drug loading, pH-responsive drug release, remarkable antitumor effect in vitro and in vivo, and also good safety to animal body.

Design of fixed dose combination and physicochemical characterization of enteric-coated bilayer tablet with circadian rhythmic variations containing telmisartan and pravastatin sodium.

The aim of this study was to investigate a fixed dose combination (FDC) of telmisartan (TEL) and pravastatin sodium (PRA) in enteric-coated bilayer tablets, which was designed for once-daily bedtime dose in order to match circadian rhythmic variations of hypertension and cholesterol synthesis and optimize the patient friendly dosing treatment. Due to the poor aqueous solubility of TEL, ternary solid dispersions (SD) consisting of TEL, polyethylene glycol 6000 (PEG 6000) and magnesium oxide (MgO) were designed to enhance its dissolution rate in intestinal fluid. MgO was added as an effective alkalizer to maintain the high microenvironmental pH of the saturated solution in the immediate vicinity of TEL particles because TEL is known to be ionizable but poorly soluble in intestinal fluid. In contrast, PRA is known to be very unstable in low pH conditions. In the SD system, TEL was present in an amorphous structure and formed an intermolecular hydrogen bonding with MgO, giving complete drug release without precipitation in intestinal fluid. In addition, the amount of hydrophilic carrier (PEG 6000) was also a factor. In the design of tablet formulation, the diluents and superdisintegrants could play a key role in release profiles. Then, to fulfill the unmet needs of the two model drugs and match circadian rhythmic variations of hypertension and cholesterol synthesis, enteric-coated bilayer tablet consisting of TEL SD and PRA was finally prepared using Acryl-EZE® as an enteric coating material. Prior to enteric coating, a seal coating layer (Opadry®, 2% weight gains) was firstly introduced to separate the core bilayer tablet from the acidic enteric coating polymers to avoid premature degradation. Dissolution profiles of finished tablets revealed that enteric-coated bilayer tablets with 6% weight gains remained intact in acidic media (pH 1.0) for 2h and then released drugs completely within 45min after switching to the intestinal media (pH 6.8). It was observed that enteric-coated bilayer tablets were stable during 3 month under the accelerated condition of 40°C/75% RH. The delayed drug release and bedtime dosage regimen using enteric-coated bilayer tablet containing TEL and PRA, matching the circadian rhythms of hypertension and hyperlipidemia can provide therapeutic benefits for elderly patients in terms of maximizing the therapeutic effects.

Gastrointestinal stability, physicochemical characterization and oral bioavailability of chitosan or its derivative-modified solid lipid nanoparticles loading docetaxel.

OBJECTIVE: The purpose of this study was to prepare the positively charged chitosan (CS)- or hydroxypropyl trimethyl ammonium chloride chitosan (HACC)-modified solid lipid nanoparticles (SLNs) loading docetaxel (DTX), and to evaluate their properties in vitro and in vivo. METHODS: The DTX-loaded SLNs (DTX-SLNs) were prepared through an emulsion solvent evaporation method and further modified with CS or HACC (CS-DTX-SLNs or HACC-DTX-SLNs) via noncovalent interactions. The gastrointestinal (GI) stability, dissolution rate, physicochemical properties and cytotoxicities of SLNs were investigated. In addition, the GI mucosa irritation and oral bioavailability of SLNs were also evaluated in rats. RESULTS: The HACC-DTX-SLNs were highly stable in simulated gastric and intestinal fluids (SGF and SIF). By contrast, the CS-DTX-SLNs were less stable in SIF than in SGF. The drug dissolution remarkably increased when DTX was incorporated into the SLNs, which may be attributed to the change in the crystallinity of DTX and some molecular interactions that occurred between DTX and the carriers. The SLNs showed low toxicity in Caco-2 cells and no GI mucosa irritations were observed in rats. A 2.45-fold increase in the area under the curve of DTX was found in the HACC-DTX-SLN group compared with the DTX group after the modified SLNs were orally administered to rats. However, the oral absorption of DTX-SLN or CS-DTX-SLN group showed no significant difference compared with that of DTX group. CONCLUSIONS: The positively charged HACC-DTX-SLNs with a stable particle size could provide the enhanced oral bioavailability of DTX in rats.

In-Vitro Characterization and Oral Bioavailability of Organic Solvent-free Solid Dispersions Containing Telmisartan.

Poorly water-soluble drugs often suffer from limited or irreproducible clinical response due to their low solubility and dissolution rate. In this study, organic solvent-free solid dispersions (OSF-SDs) containing telmisartan (TEL) were prepared using polyvinylpyrrolidone K30 (PVP K30) and polyethylene glycol 6000 (PEG 6000) as hydrophilic polymers, sodium hydroxide (NaOH) as an alkalizer, and poloxamer 188 as a surfactant by a lyophilization method. In-vitro dissolution rate and physicochemical properties of the OSF-SDs were characterized using the USP I basket method, differential scanning calorimetry (DSC), X-ray diffractometry (XRD) and fourier transform-infrared (FT-IR) spectroscopy. In addition, the oral bioavailability of OSF-SDs in rats was evaluated by using TEL bulk powder as a reference. The dissolution rates of the OSF-SDs were significantly enhanced as compared to TEL bulk powder. The results from DSC, XRD showed that TEL was molecularly dispersed in the OSF-SDs as an amorphous form. The FT-IR results suggested that intermolecular hydrogen bonding had formed between TEL and its carriers. The OSF-SDs exhibited significantly higher AUC0-24 h and Cmax, but similar Tmax as compared to the reference. This study demonstrated that OSF-SDs can be a promising method to enhance the dissolution rate and oral bioavailability of TEL.

Positively Charged Surface-Modified Solid Lipid Nanoparticles Promote the Intestinal Transport of Docetaxel through Multifunctional Mechanisms in Rats.

Solid lipid nanoparticles (SLNs) are one of the most promising nanocarriers to increase the oral absorption of drugs with poor solubility and low permeability. However, the absorption mechanism of SLNs remains incomplete and thus requires further careful consideration. In this study, positively charged chitosan (CS) modified SLNs or hydroxypropyl trimethylammonium chloride chitosan (HACC) modified SLNs were designed and their absorption mechanisms were fully clarified to improve the oral absorption of docetaxel (DTX). The HACC-DTX-SLNs showed the highest cellular uptake in Caco-2 cell monolayer; the transport efficacy in the follicle-associated epithelium cell monolayer was higher than that in the Caco-2 cell monolayer. The CS- or HACC-modified SLNs could reversibly regulate the transepithelial electrical resistance and the expressions of tight junction (TJ) associated proteins, such as claudin-1, occludin, and zonula occludens-1. The uptake of HACC-DTX-SLNs through Peyer's patches was higher than that of the normal tissue of the small intestine in rats. The enhanced absorption mechanisms of HACC-DTX-SLNs were mainly related to the caveola-mediated endocytosis, M cell phagocytosis, and reversible TJ opening.

Effect of biomimetic shear stress on intracellular uptake and cell-killing efficiency of doxorubicin in a free and liposomal formulation.

Shear stress could be considered in the context of cellular uptake and cell-killing efficiency. Thus, mimicking the dynamic characteristics of in vivo environment is important in targeted drug delivery. We investigated the intracellular uptake and cell-killing efficiency of doxorubicin (DOX) in a free and liposomal form (Doxil(®)) under biomimetic shear stress to mimic in vivo environment. In this dynamic environment, cells demonstrated significantly higher fluorescence intensity than that of the static environment, and fluorescence microscopy images indicated increased intracellular uptake of DOX in the presence of fluidic shear stress. In cells treated with free DOX and liposomal Doxil(®), cell-killing efficiency was affected by shear stress. Taken together, shear stress, affecting drug uptake and cell-killing efficiency, is important in intracellular drug targeting.