Module-combinatorial design and screening of multifunctional polymers based on polyaspartic acid for DNA delivery.

It is crucial to develop non-viral gene vectors that can efficiently and safely transfect plasmid DNA into cells. Low transfection efficiency and high cytotoxicity of cationic polymers hinder their application as gene carriers. Modification of cationic polymers has emerged as an attractive strategy for efficient and safe nucleic acids delivery. In this study, a simple and rapid method is developed to synthesize a series of multifunctional polymers by utilizing biodegradable polyaspartic acid as the backbone and modifying it with three modules. This one-component polymer possesses capabilities for nucleic acid condensation, cellular uptake, and endosomal escape. Polymers containing imidazole, triazole, or pyridine group exhibited promising transfection activity. Substituted with dodecylamine or 2-hexyldecan-1-amine enhance cellular uptake and subsequent transfection. Furthermore, the influence of ionizable amine side chains on gene delivery is investigated. Two optimal polymers, combined with the avian encephalomyelitis virus (AEV) plasmid vaccine, induced robust specific antibody responses and cellular immune responses in mice and chickens. Through module-combination design and screening of polyaspartamide polymers, this study presents a paradigm for the development of gene delivery vectors.

Immuno-Enhancing Effect of Ginsenoside Rh2 Liposomes on Foot-and-Mouth Disease Vaccine.

The adjuvant is essential for vaccines because it can enhance or directly induce a strong immune response associated with vaccine antigens. Ginsenoside Rh2 (Rh2) had immunomodulatory effects but was limited by poor solubility and hemolysis. In this study, Rh2 liposomes (Rh2-L) were prepared by ethanol injection methods. The Rh2-L effectively dispersed in a double emulsion adjuvant system to form a Water-in-Oil-in-Water (W/O/W) emulsion and had no hemolysis. The physicochemical properties of the adjuvants were tested, and the immune activity and auxiliary effects indicated by the Foot-and-Mouth disease (FMDV) antigen were evaluated. Compared with the mice vaccinated with the FMD vaccine prepared with the double emulsion adjuvant alone, those with the FMD vaccine prepared with the double emulsion adjuvant containing Rh2-L had significantly higher neutralizing antibody titer and splenocyte proliferation rates and showed higher cellular and humoral immune responses. The results demonstrated that Rh2-L could further enhance the immune effect of the double emulsion adjuvant against Foot-and-Mouth Disease.

Corosolic acid-modified lipid nanoparticles as delivery carriers for DNA vaccines against avian influenza.

Cholesterol (CHOL) is essential for developing lipid nanoparticles (LNPs) for gene delivery because it enhances membrane fusion and improves the delivery efficiency of gene cargos. An attractive pDNA carrier, corosolic acid (CA)-modified lipid nanoparticles (CLNPs), was developed by replacing CHOL in LNPs to deliver pDNA at various ratios of nitrogen groups to phosphate groups (N/P). The resultant CLNPs with a higher CHOL/CA ratio exhibited similar mean particle size, zeta potential, and encapsulation efficiency to those of LNPs. In comparison with LNPs, CLNPs (CHOL:CA ratio = 2:1) achieved increased cellular uptake and enhanced transfection efficacy while maintaining low cytotoxicity. In vivo results from chicken experiments demonstrated that CLNPs encapsulating DNA vaccines against avian influenza at a N/P ratio of 3 could elicit similar-level humoral and cellular immune responses compared with those of LNPs at a higher N/P ratio, thereby suggesting the induction of desirable immune effects using less ionizable lipids. Our study provides a reference for further research on the application of CA in LNPs for gene delivery, and the development of novel delivery systems for DNA vaccines against avian influenza.

Stabilizing Effect of Soluplus on Erlotinib Metastable Crystal Form in Microparticles and Amorphous Solid Dispersions.

Microparticles (MPs) and amorphous solid dispersions (SDs) are effective methods to improve the dissolution of insoluble drugs. However, stability is a concern for these two high-energy systems, resulting from high surface area and amorphous polymorph, respectively. As an amphiphilic polymer, Soluplus (SOL) is usually used as a carrier in SDs. In this study, erlotinib microparticles (ERL MPs) and erlotinib solid dispersions (ERL SDs) were prepared with SOL by bottom-up technology and solvent evaporation. The solid-state properties of ERL MPs and ERL SDs were characterized by Differential Scanning Calorimetry (DSC), Powder X-Ray Diffraction (PXRD) and Scanning Electron Microscopy (SEM). The ERL MPs existed in a metastable crystal form A while the ERL SDs existed in an amorphous state. Fourier transform infrared spectroscopy (FT-IR) showed that there was a hydrogen bond interaction between the N-H group of ERL and the carbonyl group of SOL in ERL MPs and SDs. The dissolution profiles of ERL SDs and ERL MPs were improved significantly. ERL MPs showed better stability than ERL SDs in accelerated stability test. The discrepant stabilizing effects of polymer SOL in two systems may provide effective ideas for solubilization of insoluble drugs and the stability of drugs after recrystallization.

Predicting physical stability of solid dispersions by machine learning techniques.

Amorphous solid dispersion (SD) is an effective solubilization technique for water-insoluble drugs. However, physical stability issue of solid dispersions still heavily hindered the development of this technique. Traditional stability experiments need to be tested at least three to six months, which is time-consuming and unpredictable. In this research, a novel prediction model for physical stability of solid dispersion formulations was developed by machine learning techniques. 646 stability data points were collected and described by over 20 molecular descriptors. All data was classified into the training set (60%), validation set (20%), and testing set (20%) by the improved maximum dissimilarity algorithm (MD-FIS). Eight machine learning approaches were compared and random forest (RF) model achieved the best prediction accuracy (82.5%). Moreover, the RF models revealed the contribution of each input parameter, which provided us the theoretical guidance for solid dispersion formulations. Furthermore, the prediction model was confirmed by physical stability experiments of 17ß-estradiol (ED)-PVP solid dispersions and the molecular mechanism was investigated by molecular modeling technique. In conclusion, an intelligent model was developed for the prediction of physical stability of solid dispersions, which benefit the rational formulation design of this technique. The integrated experimental, theoretical, modeling and data-driven AI methodology is also able to be used for future formulation development of other dosage forms.

Investigating molecular interactions of high-loaded glipizide-HPMCAS microparticles by integrated experimental and modeling techniques.

Molecular interactions between drug and polymeric carriers are believed to be the key for high drug loading and better physical stability of micro-particles. However, molecular interactions between drug and polymer are still difficult to investigate using only experimental tools. In this study, high-loaded glipizide (GLP)/hydroxypropyl methylcellulose acetate succinate (HPMCAS) (1/1 w/w) micro-particles were prepared using an in situ pH-dependent solubility method. Molecular interactions within the micro-particles were investigated by integrated experimental and modeling techniques. The dissolution rate of GLP/HPMCAS micro-particles was significantly better than those of solid dispersions and physical mixtures. Scanning electron microscopy images showed that the polymer inhibited GLP recrystallization. Experimental (FTIR spectroscopy, differential scanning calorimetry, powder X-ray diffraction and nuclear magnetic resonance spectroscopy) and molecular dynamics simulation revealed that hydrogen-bonding was the key to the properties of the micro-particles. Our research developed high drug-loading GLP/HPMCAS micro-particles and investigated the interactions between drug and polymer at the molecular level. This integrated approach could be practical methodology for future formulation design.

Antisolvent Recrystallization Strategy to Screen Appropriate Carriers to Stabilize Filgotinib Amorphous Solid Dispersions.

Drugs in amorphous solid dispersions (ASDs) are highly dispersed in hydrophilic polymeric carriers, which also help to restrain recrystallization and stabilize the ASDs. In this study, microscopic observation after antisolvent recrystallization was developed as a rapid screening method to select appropriate polymers for the initial design filgotinib (FTN) ASDs. Using solvent evaporation, FTN ASDs with the polymers were prepared, and accelerated experimentation validated this screening method. Fourier-transform infrared spectroscopy, Raman scattering, and nuclear magnetic resonance revealed hydrogen-bonding formation in the drug-polymer binary system, which was critical for ASDs stabilization. A Flory-Huggins interaction parameter and water sorption isotherms were applied to evaluate the strength of the interaction between FTN and the polymers. The dissolution rate was also significantly improved by ASDs formulation, and the presence of the polymers exerted solubilization effects. These results suggested the efficacy of this screening method as a preliminary tool for polymer selection in ASDs design.

Screen for Inhibitors of Crystal Growth to Identify Desirable Carriers for Amorphous Solid Dispersions Containing Felodipine.

The solvent-shift method was used to identify appropriate polymers that inhibit the growth of felodipine crystals by monitoring particle size in supersaturated drug solutions in the presence of different polymers. We speculated that there would be an intermolecular interaction between the selected polymer (zein) and felodipine by extrapolating the inhibitory effect on crystal growth and then used the selected polymer as a carrier to prepare solid dispersions. The formulations were characterized by crystalline properties, thermodynamics of mixing, dissolution behavior, and physical stability. Powder x-ray diffraction and differential scanning calorimetry experiments indicated that amorphous solid dispersions were formed when the proportion of felodipine was < 30% (w/w). Stability tests showed that a solid dispersion with 20% felodipine remained in an amorphous state and was stable under accelerated storage conditions for 6 months. The dissolution rates of solid dispersions were significantly greater than those of the active pharmaceutical ingredient or physical mixtures. Analysis by Fourier-transform infrared spectroscopy and Raman microspectroscopy indicated the formation of intermolecular interactions between zein and felodipine. The study demonstrates the successful application of the chosen polymer as a carrier in solid dispersions and validates the concept of extrapolating the inhibitory effect on crystal growth to intermolecular interactions.

Complexes of Felodipine Nanoparticles With Zein Prepared Using a Dual Shift Technique.

To improve the dissolution of felodipine, felodipine-zein complexes were prepared using a dual shift technique, with zein as both stabilizer and carrier. The complexes were characterized by particle size, zeta potential, morphology, crystalline properties, and release behavior. The complexes could be prepared in high yield and showed good redispersibility. The mean diameters of the felodipine particles in complexes were 150-300 nm, with negative zeta potentials of -30 to -25 mV after rehydration, and the particle sizes of the complexes were in the range 10-80 µm. The size of the felodipine nanoparticles incorporated into zein increased gradually with increasing drug content. Powder X-ray diffraction and differential scanning calorimetry indicated that felodipine in the complexes was markedly less crystalline than the pure drug. Both the rate and extent of dissolution of the complexes were significantly greater than those of the active pharmaceutical ingredient or physical mixtures. Spectroscopic analyses indicated that intermolecular interactions, especially hydrophobic interactions, are the major driving forces for the formation of the felodipine nanoparticles and contribute to the stabilization effect. This study provides a promising strategy for enhancing the dissolution rate of drugs using simplified preparation processes and showcases the design of zein-based oral delivery systems for bioactive components.

Improving the physicochemical properties of bicalutamide by complex formation with bovine serum albumin.

Bicalutamide-bovine serum albumin (Bic-BSA) complexes were prepared by anti-solvent precipitation. Bovine serum albumin (BSA) was used as a stabilizer for particle growth. The physicochemical properties of Bic-BSA were analyzed by scanning electron microscopy, X-ray powder diffraction and differential scanning calorimetry. The interaction between Bic and BSA was characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, fluorescence spectroscopy and molecular docking. The particle size could be easily reduced to 1-10µm with a good lognormal distribution. The Bic-BSA complexes exhibited nonporous spherical morphology with a uniformly plicated surface. Moreover, the crystal form and thermostability of Bic were altered in the presence of BSA. Bic was found to make hydrogen bonding and hydrophobic interactions with BSA by spectroscopic studies and molecular docking. Results from the Van't Hoff equation and binding free energy calculations indicated that the improvement of physicochemical properties was the consequence of a variety of interactions in the Bic-BSA system. Bic-BSA tablets showed significantly enhanced dissolution. It was concluded that BSA plays an important role in improving the physicochemical properties of Bic due to strong multiple interactions between Bic and BSA.

The Physicochemical Investigation of 17ß-Estradiol Crystalline Prepared by In Situ pH-Dependent Solubility Technique with Polyvinylpyrrolidone.

Micro-particles of 17ß-estradiol (ED) were prepared with polyvinylpyrrolidone (PVP) by in situ pH-dependent solubility technique. Products were characterized using multiple instruments, and molecular interactions between ED and PVP were explored. Powder X-ray diffraction and thermal analysis revealed crystalline ED in the micro-particles is hemihydrated. PVP was also present in the micro-particles. Laser particle size analysis and scanning electron microscopy revealed thin slice morphology, which might have resulted from the influence of PVP. Moreover, the results of contact angle, specific surface area, and dynamic vapor sorption showed that the surface properties of products were improved. These physicochemical properties of the micro-particles resulted in an obvious improvement in dissolution rate. Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance revealed hydrogen bonding between ED and PVP. A method was established for the preparation of micro-particles through the addition of PVP during the reaction process.

Characterization of ibuprofen microparticle and improvement of the dissolution.

The objective of this study was to prepare ibuprofen (IBP) microparticles by pH-change method and enhance the dissolution rate in vitro. Tween80 and Cremophor RH40 were selected as stabilizers to change the microparticles morphology. The microparticles were evaluated by dissolution profiles and characterized by differential scanning calorimetry (DSC), powder X-ray diffraction (XRD), laser particle size analyzer, scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). IBP microparticle prepared with surfactants showed a significant increase in dissolution rate (more than three times within 10 min) and an obvious decrease in mean particle size. The morphology of microparticles was obviously changed. XRD and DSC results revealed that the crystalline state of the untreated IBP and the prepared IBP microparticles were similar. The crystallinity of microparticles produced might be lightly reduced by adding surfactants in preparation process. All results showed that it was useful to prepare high dispersion microparticle by adding surfactants in the preparation process for improving the dissolution.

A mixed solvent system for preparation of spherically agglomerated crystals of ascorbic acid.

The objective of this research was to develop a novel solvent system to prepare spherically agglomerated crystals (SAC) of ascorbic acid with improved flowability for direct compression. A spherical agglomeration method was developed by selecting the mixed solvents (n-butyl and ethyl acetate) as a poor solvent and the process was further optimized by using triangular phase diagram and particle vision measurement. Physiochemical properties of SAC were characterized and compared with original drug crystals. It showed that amount of poor solvent, ratio of solvent mixture, and drug concentration are critical for preparation of SAC with desirable properties. The solid state of SAC was same as original crystals according to DSC, XRD, and FT-IR results. There was no significant difference in solubility and dissolution rate of drug between SAC and original crystals. The flowability and packability of SAC as well as the tensile strength and elastic recovery of tablets made from SAC were all significantly improved when compared with original crystals and tablets from crystals. It is concluded that the present method was suitable to prepare SAC of ascorbic acid for direct compression.

New self-nanoemulsifying drug delivery system (SNEDDS) with amphiphilic diblock copolymer methoxy poly (ethylene glycol)-block-poly (ε-caprolactone).

The objective of the study is to prepare a new self-nanoemulsifying drug delivery system (SNEDDS) with amphiphilic diblock copolymers methoxy poly (ethylene glycol)-block-poly (ε-caprolactone) (MPEG-b-PCL) and to investigate the effect of MPEG-b-PCL on the characteristics of SNEDDS. MPEG-b-PCL was synthesized and characterized by (1)H-NMR, IR and GPC. Various ratios of MPEG-b-PCL copolymers and Tween 80 were used as emulsifier to prepare the new SNEDDS. SNEDDS with high oil and low surfactant content forms a semi-solid gel at room temperature, which could be effectively sealed in soft or hard capsules. The mean droplet size of SNEDDS-generated nanoemulsions significantly decreased after the addition of diblock polymer and increased with increase of PCL chain in MPEG-b-PCL. The drug Coenzyme Q10 (CoQ10) was chosen as the model compound in this study due to its insolubility in water. CoQ10 from SNEDDS was rapidly dissolved regardless of the fluid condition.

Characteristics of bicalutamide solid dispersions and improvement of the dissolution.

The purpose of our study was to formulate and evaluate bicalutamide (BL) solid dispersions (SD). The physicochemical properties were evaluated by differential scanning calorimetry (DSC), Fourier-Transform infrared (FT-IR) spectroscopy, Powder X-ray diffractometry (PXRD), dissolution studies, and stability studies. The dissolution studies demonstrated that the dissolution of BL from BL-SD increased with an increase in carrier content (PVP K30). X-ray assays and DSC results both confirmed the amorphous state of BL in BL-SD. Stability studies conducted after 6 months showed that BL exhibited excellent stability in the solid dispersion of PVP K30 (1:5).

HPLC determination of anethole trithione and its application to pharmacokinetics in rabbits.

To evaluate the relative bioavailability of anethole trithione (ATT) from self-microemulsifying drug delivery system (SMEDDS) and tablet, a sensitive, accurate and reliable liquid chromatography method was developed and validated to determine ATT in rabbit plasma. Chromatographic separation was performed on a Diamonsil C18 column by using a mixture of methanol-water (90:10, v/v) delivered at a flow rate of 1.0 ml/min. The wavelength was set at 348 nm and mifepristone was used as the internal standard. A linear relationship for ATT was found in the range of 0.5-32 ng/ml. The mean extraction recoveries of ATT determined over three concentrations were 84.7+/-5.8, 92.3+/-3.4 and 89.9+/-5.1%. After administration of SMEDDS and tablets to rabbits, significant differences were found in main pharmacokinetic parameters of Tmax, Cmax and AUC(0-infinity) between these two formulations, and a 2.5-fold enhancement of relative bioavailability of ATT was observed from the SMEDDS compared with tablets.

Determination of nelfinavir mesylate as bulk drug and in pharmaceutical dosage form by stability indicating HPLC.

A isocratic, selective, accurate and stability indicating HPLC method of analysis of nelfinavir mesylate both as a bulk drug and in formulations was developed and validated. A CN chromatographic column (250 mmx4.6 mm, 5 microm) was used for the separation at 40 degrees C. The mobile phase consisted of a mixture of acetonitrile (MeCN) and 25 mM monobasic ammonium phosphate (containing 25 mM triethylamine, pH 3.4 with phosphate acid) (40:60, v/v) was delivered at a flow rate of 1.0 ml/min with detection at 210 nm. The developed method was validated in terms of selectivity, linearity, limit of quantitation, precision, accuracy and solution stability. As the proposed LC method achieved satisfactory resolution between nelfinavir mesylate, its degradation products, intermediate product possibly present in nelfinavir drug substance and other impurities in the end product before refining in the final step of synthetic process, it can be employed as a stability indicating one, used for the synthetic process control and determination of nelfinavir mesylate in pharmaceutical preparations.

Quantitative determination of puerarin in dog plasma by HPLC and study on the relative bioavailability of sustained release tablets.

To evaluate the bioavailability of puerarin sustained release tablet (SR-Tab.) and Yufengningxin tablet (YU-Tab.), a liquid chromatography method was developed and validated to determine puerarin in dog plasma. Chromatographic separation was performed on Diamonsil C18 column using a mixture of methanol-acetic acid-water (25:6:69, v/v/v) delivered at a flow rate of 1.0 ml/min and detected by UV. 4-Hydroxybenzaldehyde was used as the internal standard. The linear range for puerarin was from 60 to 1800 ng/ml (r=0.9991) with a limit of quantitation of 60 ng/ml. Within-day accuracy and precision ranged from -3.0 to 2.2% and from 1.2 to 4.3%, between-day accuracy and precision ranged from -4.1 to 2.6% and from 1.3 to 5.7%, respectively. The mean extraction recoveries of puerarin determined over the three concentrations were (90.3+/-5.2)%, (95.7+/-1.4)% and (93.1+/-3.5)%. A significant difference was observed in main pharmacokinetic parameters of Tmax, Cmax and AUC0-infinity between puerarin SR-Tab. and YU-Tab. in dogs. The smoother plasma concentrations were obtained from SR-Tab. in dogs and the results were as expected.