Optimization of controlled release nanoparticle formulation of verapamil hydrochloride using artificial neural networks with genetic algorithm and response surface methodology

This study was performed to optimize the formulation of polymer–lipid hybrid nanoparticles (PLN) for the delivery of an ionic water-soluble drug, verapamil hydrochloride (VRP) and to investigate the roles of formulation factors. Modeling and optimization were conducted based on a spherical central composite design. Three formulation factors, i.e., weight ratio of drug to lipid (X₁), and concentrations of Tween 80 (X₂) and Pluronic F68 (X₃), were chosen as independent variables. Drug loading efficiency (Y₁) and mean particle size (Y₂) of PLN were selected as dependent variables. The predictive performance of artificial neural networks (ANN) and the response surface methodology (RSM) were compared. As ANN was found to exhibit better recognition and generalization capability over RSM, multi-objective optimization of PLN was then conducted based upon the validated ANN models and continuous genetic algorithms (GA). The optimal PLN possess a high drug loading efficiency (92.4%, w/w) and a small mean particle size (∼100 nm). The predicted response variables matched well with the observed results. The three formulation factors exhibited different effects on the properties of PLN. ANN in coordination with continuous GA represent an effective and efficient approach to optimize the PLN formulation of VRP with desired properties.     

High throughput screening: an in silico solubility parameter approach for lipids and solvents in SLN preparations

Objective: The present paper describes an in silico solubility behavior of drug and lipids, an essential screening study in preparation of solid lipid nanoparticles (SLN).

Materials and methods: Ciprofloxacin HCl was selected as a model drug along with 11 lipids and 5 organic solvents. In silico miscibility study of drug/lipid/solvent was performed using Hansen solubility parameter approach calculated by group contribution method of Van Krevelen and Hoftyzer. Predicted solubility was validated by determining solubility of lipids in various solvent at different temperature range, while miscibility of drug in lipids was determined by apparent solubility study and partition experiment.

Results and discussion: The presence of oxygen and OH functionality increases the polarity and hydrogen bonding possibilities of the compound which has reflected the highest solubility parameter values for Geleol and Capmul MCM C8. Ethyl acetate, Geleol and Capmul MCM C8 was identified as suitable organic solvent, solid lipid and liquid lipid respectively based on a solubility parameter approach which was in agreement with the result of an apparent solubility study and partition coefficient.

Conclusion: These works demonstrate the validity of solubility parameter approach and provide a feasible predictor to the rational selection of excipients in designing SLN formulation.     

Fabrication and Evaluation of Curcumin-loaded Nanoparticles Based on Solid Lipid as a New Type of Colloidal Drug Delivery System

Curcumin has very broad spectrum of biological activities; however, photodegradation, short half-life and low bioavailability have limited its clinical application. Curcumin-loaded solid lipid nanoparticles were studied to overcome these problems. The aim of this study was to optimize the best formulation on curcumin-loaded solid lipid nanoparticles. Emulsion-evaporation and low temperature-solidification technique was applied with monostearin as lipid carriers. The single factor analysis and orthogonal design were used to optimize formulation and various parameters were investigate. By the optimisation of a single factor analysis and orthogonal test, the particles size, polydispersity index, zeta potential, encapsulation efficiency and drug loading capacity of the optimised formulation were 99.99 nm, 0.158, −19.9 mV, 97.86%, and 4.35%, respectively. The differential scanning calorimetry and X-ray diffraction analysis results demonstrated new structure was formed in nanoparticles. The release kinetics in vitro demonstrated curcumin-loaded solid lipid nanoparticles can control drug release. These studies confirmed that curcumin-loaded solid lipid nanoparticles could be prepared successfully with high drug entrapment efficiency and loading capacity. Curcumin-loaded solid lipid nanoparticles may be a promising drug delivery system to control drug release and improve bioavailability.     

The use of quantitative analysis and Hansen solubility parameter predictions for the selection of excipients for lipid nanocarriers to be loaded with water soluble and insoluble compounds

The aim of these studies was to determine the miscibility of different API with lipid excipients to predict drug loading and encapsulation properties for the production of solid lipid nanoparticles and nanostructured lipid carriers. Five API exhibiting different physicochemical characteristics, viz., clarithromycin, efavirenz, minocycline hydrochloride, mometasone furoate, and didanosine were used and six solid lipids in addition to four liquid lipids were investigated. Determination of solid and liquid lipids with the best solubilization potential for each API were performed using a traditional shake-flask method and/or a modification thereof. Hansen solubility parameters of the API and different solid and liquid lipids were estimated from their chemical structure using Hiroshi Yamamoto’s molecular breaking method of Hansen Solubility Parameters in Practice software. Experimental results were in close agreement with solubility parameter predictions for systems with ΔδT < 4.0 MPa^1/2. A combination of Hansen solubility parameters with experimental drug-lipid miscibility tests can be successfully applied to predict lipids with the best solubilizing potential for different API prior to manufacture of solid lipid nanoparticles and nanostructured lipid carriers.     

Ion pair approach of ampicillin using in vitro methods

The hydrophilic drug ampicillin (AP) was comprehensively studied in vitro with focus on an ion pair approach of AP. The influence of the counter ions in comparison with AP derivatives was studied on the water solubility, lipid partition, and transport across artificial lipid membranes as well as using an in vitro absorption model system. It was found that the water solubility of AP is pH dependent. The water solubility is markedly increased by derivatives such as bacampicillin (BAP). In contrast, the lipid partition and the transport across lipid membranes of AP were markedly enhanced by counter ions, particularly by dodecylsulfate (DS). However, ion pair formation is only in acidic solution (pH 2.5) possible. Taking this into account the same increase of the bioavailability of AP was obtained in the presence of DS as after application of BAP using the in vitro absorption model system.     

Synthesis and solution properties of deferoxamine amides

The poor membrane permeability and oral bioavailability of the iron chelating agent deferoxamine (DFO) mesylate result from the low octanol/water partition coefficient and high aqueous solubility. With the ultimate aim to improve biomembrane permeability while retaining the iron-binding ability of DFO, a series of more lipophilic amides were prepared by reacting the terminal primary amino group with fatty and aromatic acid chlorides or anhydrides. Octanol/water partition coefficients and equilibrium solubilities of these analogs in solvents, chosen to delineate physicochemical interactions, were determined as a function of temperature. Solid-state properties were evaluated by calorimetry. All DFO amide derivatives had higher melting points, indicating that derivatives formed strong intermolecular interactions in the solid phase. Formamidation of the primary amine of deferoxamine resulted in a 200-fold increase in the octanol/water partition coefficient and reduced aqueous solubility at least 2000-fold compared with the parent molecule. The partition coefficient increased and aqueous solubility decreased 2-fold with the addition of each methylene group in the homologous series of aliphatic amides. Solubilities of the derivatives in water-saturated octanol and hexane showed irregular profiles as a function of increasing aliphatic chain length that were attributed to intermolecular packing in the solid state. The temperature dependence of the partition coefficients was interpreted to indicate that interfacial transfer of the deferoxamine amides was, in part, affected by an apparent diminished ability to form energetically favorable interactions in the water-saturated organic phase.     

Study of solid lipid nanoparticles with respect to particle size distribution and drug loading

This work deals with the formulation and development of Solid Lipid Nanoparticles (SLN) using pressure homogenization technique, nimesulide being used as the model drug. Main emphasis of the work was to study the effect of individual process parameters (homogenization pressure and homogenization cycles) and formulation parameters (lipid concentration and surfactant concentration) on particle size distribution and drug loading. Particle size distribution data indicate that by optimizing the homogenization process and formulation parameters it is possible to produce SLN within a desired size range as required for carrier mediated drug targeting. Approaches to improve drug loading efficiency indicate that drug loading was higher in case of SLN prepared from glyceryl beheanate, palmitostearate and glyceryl tristearate + span 60 as compared to monoacid triglyceride (MAT) tristearate. Thermal analysis by differential scanning calorimetry of the drug loaded SLN indicates the solid nature of the lipid carrier as required for sustained drug release.     

Plackett-Burman联用Box-Behnken响应面法优化5-氨基水杨酸固体脂质纳米粒的制备及表征

目的：制备并优化5-氨基水杨酸固体脂质纳米粒（5-ASA-SLN）的处方组成及工艺参数,以提高5-氨基水杨酸（5-ASA）溶解度,并对其进行表征。方法：采用微乳法制备5-ASA-SLN,以包封率为考察指标,通过Plackett-Burman设计结合Box-Behnken响应面法优化其最佳处方组成和制备工艺参数;通过傅里叶变换红外光谱法（Fourier transform infrared spectrometer,FTIR spectrometer）、差示量热扫描法（differential scanning calorimetry,DSC）、透射电镜、激光粒度分布仪对5-ASA-SLN进行表征并验证其形成。测定5-ASA及5-ASA-SLN的饱和溶解度,并探讨其体外释药机制。结果：确定5-ASA-SLN最佳处方为：乳化剂与助乳化剂比为5.32∶1、混合乳化剂与脂质比为7.38∶1、药脂比为1∶20;优化后最佳处方的5-ASA-SLN平均包封率为90.15%,与预测值偏差为2.15%,平均粒径为（124.7±2.62）nm,分散系数为0.32±0.02,Zeta电位为（-15.0±0.8） mV,呈类球形,外观圆整。将5-ASA制备成5-ASA-SLN后其在纯化水和pH 7.8~8.0含胰酶的磷酸盐缓冲液中的溶解度分别提高了33.12倍和16.6倍,体外释药模型拟合符合Higuchi方程。结论：经优化后的5-ASA-SLN制备工艺稳定可行,显著提高了5-ASA的溶解度,且具有缓释效果。     

Distribution and unspecific protein binding of the xenoestrogens bisphenol A and daidzein

Physiological toxicokinetic (PT) models are used to simulate tissue burdens by chemicals in animals and humans. A prerequisite for a PT model is the knowledge of the chemical's distribution among tissues. This depends on the blood flow and also on the free fraction of the substance and its tissue:blood partition coefficients. In the present study we determined partition coefficients in human tissues at 37 degrees C for the two selected xenoestrogens bisphenol A (BA) and daidzein (DA), and their unspecific binding to human serum proteins. Partition coefficients were obtained by incubating blood containing BA or DA with each of the following tissues: brain, liver, kidney, muscle, fat, placenta, mammary gland, and adrenal gland. Blood samples were analysed by HPLC. For BA and DA, all partition coefficients in non-adipose tissues were similar (average values: BA 1.4, DA 1.2). However, the lipophilic properties of both compounds diverge distinctly. Fat:blood partition coefficients were 3.3 (BA) and 0.3 (DA). These values indicate that with the exception of fat both compounds are distributed almost equally among tissues. In dialysis experiments, the unspecific binding of BA and DA with human serum proteins was measured by HPLC. For BA, the total concentration of binding sites and the apparent dissociation constant were calculated as 2000 and 100 nmol/ml, respectively. Because of the limited solubility of DA, only the ratio of the bound to the free DA concentration could be determined and was found to be 7.2. These values indicate that at low concentrations only small percentages of about 5% (BA) and 12% (DA) are as unbound free fractions in plasma. Since only the unbound fraction can bind to the estrogen receptor, binding to serum proteins represents a mechanism that limits the biological response in target tissues.     

Production of solid lipid nanoparticle suspensions using supercritical fluid extraction of emulsions (SFEE) for pulmonary delivery using the AERx system

The aims of the current work included: development of a new production method for nanoparticles of water-insoluble drugs in combination with lipids, characterization of the nanoparticles and development of lipid nanosuspension formulations, and investigation of the feasibility of delivering the nanosuspensions as aerosols for inhalation using Aradigm's AERx Single Dose Platform (SDP) with micron-sized nozzles and the all mechanical AERx Essence with sub-micron-sized nozzles. The continuous SFEE method was used for particle precipitation of solid lipid nanoparticles (SLN). The method allowed for production of stable particulate aqueous suspensions of a narrow size distribution, with a volume mean diameter below 30 nm (D99% cumulative volume below 100 nm). Thus the particle size obtained was significantly smaller than previously has been achieved by other techniques. The residual solvent content in the final suspension was consistently below 20 ppm. Drug loading values between 10-20% w/w drug were obtained for model compounds ketoprofen and indomethacin in formulation with lipids such as tripalmitin, tristearin and Gelucire 50/13. It was observed that the loading capacity achieved was higher than the thermodynamic limit of the solubility of the drugs in molten lipids. Lipid nanosuspension formulations were successfully aerosolized using both of the AERx systems. As measured by both cascade impactor and laser diffraction, the aerosol fine particle fraction (FPF) was comparable to drug solution formulations typically used in these devices; i.e., greater than 90% of the aerosol mass resided in particles less than 3.5 mum aerodynamic diameter.     

Effect of inclusion complexation of decanoic acid with alpha-cyclodextrin on rectal absorption of cefmetazole sodium suppository in rabbits

Inclusion complex of decanoic acid (DA) with alpha-cyclodextrin (alpha-CyD) was prepared as an additive of cefmetazole sodium (CMZ) suppository and rectally administered to rabbits. The resulting complexation was examined by the phase solubility method, differential scanning calorimetry (DSC) and X-ray diffractometry. Plasma concentration and AUC of CMZ after rectal administration of a suppository containing DA/alpha-CyD complex to rabbits increased more significantly than those with none additive.     

双氯灭痛缓释复合骨架微丸制备工艺影响因素

目的用新辅料甲壳胺 (CS)与三聚磷酸钠 (TPP Na)发生聚合反应 ,生成复合骨架材料 ,以双氯灭痛为模型药物 ,制备缓释复合骨架微丸 ,并对其制备工艺影响因素进行考察。方法通过对反应温度、干燥条件、丸径、聚合反应时间、TPP Na的浓度、pH值、含药量、(CS)的粘度、浓度、脱乙酰度 (D .D) %等项试验 ,以释放度为检验指标确定制备工艺条件。结果所得缓释微丸外观圆整、粒子大小分布均匀 ,流动性好。反应温度干燥条件对微丸性质有影响。其他条件对微丸性质影响不大。缓释结果符合《中华人民共和国药典》规定。结论甲壳胺 三聚磷酸钠可以作为双氯灭痛缓释微丸的骨架材料。     

Phloretin and 6-ketocholestanol: membrane interactions studied by a phospholipid/polydiacetylene colorimetric assay and differential scanning calorimetry.

The aim of this study was to investigate membrane interactions of phloretin and 6-ketocholestanol using different methods. A previously reported colorimetric assay with phospholipid/polydiacetylene (PDA) vesicles was used to examine a possible interaction of phloretin and 6-ketocholestanol with this target. During this interaction the used aggregates of lipids and conjugated PDA undergo a visible and quantifiable blue to red color transition. A positive result is indicative for a reaction response with membrane lipids of a simplified bilayer structure instead of the complex bilayer system of the stratum corneum. Results of this test confirm previous proposed membrane interactions by skin diffusion studies. Additional differential scanning calorimetry studies with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) liposomes confirm a membrane interaction and indicates that phloretin and 6-ketocholestanol interact with the lipid layer and change structural parameters. They strongly decrease the lipid phase transition temperature of DMPC and DPPC liposomes by at least about 6.6 degrees C and maximally about 13.9 degrees C which refers to a higher fluidity of the membrane.     

The Effects of Solid and Liquid Lipids on the Physicochemical Properties of Nanostructured Lipid Carriers

The aim of this work was to identify from a review of current literature the effects of lipids used in the development of Nanostructured Lipid Carriers (NLCs) on the physicochemical properties of the resulting formulation. The size of the solid lipid, affected by the molecular weight and the complexity of the structure, tends to affect the particle size of the final formulation proportionally; the higher the molecular weight and the more complex the molecular structure, the bigger the particle size of the NLCs. However, there is no straight correlation between the size and the structure of the liquid lipid and the particle size. Moreover, there seems to be a correlation of the solid to liquid lipid ratio which affects the particle size; there has been a trend of increasing particle size when more solid lipid was used. Regarding the entrapment efficiency, it is highly affected by the drug and its interaction with the lipids, as its solubility in the lipids needs to be high so the drug can stay entrapped within the lipid core. There was no direct correlation between the type of lipid used or the ratio and the zeta potential, which affects the stability of the NLCs.     

Skin permeation of buprenorphine and its ester prodrugs from lipid nanoparticles: lipid emulsion,nanostructured lipid carriers and solid lipid nanoparticles

The aim of this study was to develop and characterize lipid nanoparticle systems for the transdermal delivery of buprenorphine and its prodrugs. A panel of three buprenorphine prodrugs with ester chains of various lengths was synthesized and characterized by solubility, capacity factor (log K′), partitioning between lipids and water and the ability to penetrate nude mouse skin. Colloidal systems made of squalene (lipid emulsion, LE), squalene + Precirol (nanostructured lipid carriers, NLC) and Precirol (solid lipid nanoparticles, SLN) as the lipid core material were prepared. Differential scanning calorimetry showed that the SLN had a more-ordered crystalline lattice in the inner matrix compared to the NLC. The particle size ranged from 220–300 nm, with NLC showing the smallest size. All prodrugs were highly lipophilic and chemically stable, but enzymatically unstable in skin homogenate and plasma. The in vitro permeation results exhibited a lower skin delivery of drug/prodrug with an increase in the alkyl chain length. SLN produced the highest drug/prodrug permeation, followed by the NLC and LE. A small inter-subject variation was also observed with SLN carriers. SLN with soybean phosphatidylcholine (SLN-PC) as the lipophilic emulsifier showed a higher drug/prodrug delivery across the skin compared to SLN with Myverol, a palmitinic acid monoglyceride. The in vitro permeation of the prodrugs occurred in a sustained manner for SLN-PC. The skin permeation of buprenorphine could be adjusted within a wide range by combining a prodrug strategy and lipid nanoparticles.     

Preparation and Evaluation of Quinapyramine Sulphate-Docusate Sodium Ionic Complex Loaded Lipidic Nanoparticles and Its Scale Up Using Geometric Similarity Principle

The objective of the present work is to prepare and evaluate ionically complexed Quinapyramine sulphate (QS) loaded lipid nanoparticles and its scale up using geometric similarity principle. Docusate sodium (DS), at a molar ratio of 1:2 of QS to DS, was used to prepare hydrophobic Quinapyramine sulphate-Docusate sodium (QS-DS) ionic complex. Based on the difference in total solubility parameter and polarity of QS-DS complex and different lipids, precirol was selected as a lipid for the preparation of lipidic nanoparticles. The particle size, zeta potential, and % entrapment efficiency (%EE) of QS-DS ionic complex loaded solid lipid nanoparticles (QS-DS-SLN) was found to be 250.10 ± 26.04 nm, ?27.41 ± 4.18 mV and 81.26 ± 4.67% respectively. FTIR studies confirmed the formation of QS-DS ionic complex. DSC and XRD studies revealed the amorphous nature of QS in QS-DS-SLN. The spherical shape of nanoparticles was confirmed by scanning electron microscopy. QS-DS-SLN showed sustained release of QS for up to 60 h. No significant difference was observed in particle size, zeta potential, and % entrapment efficiency of pilot-scale batch prepared by using rotational speed of 700 rpm. In conclusion, ionic complexation approach can be used to increase % EE of charged drugs into lipid nanoparticles.     

Development of nanosomes using high‐pressure homogenization for gene therapy

Objectives The aim of this project was to develop a novel lipid‐based formulation suitable for gene therapy. Methods Novel nanosize liposome (nanosome) formulations containing pDNA (plasmid DNA) were developed using high‐pressure homogenization (HPH). The effect of lipid concentration was studied at two levels: 3 mm and 20 mm . The preformed nanosomes were incubated for 18–20 h with pDNA or pDNA/protamine sulfate (PS) complex. The physical properties of the pDNA nanosomes were compared by particle size distribution and zeta‐potential measurements. Their biological properties were also compared by pDNA efficiency of encapsulation/complexation, integrity, nuclease digestion, transfection efficiency and cell cytotoxicity. Key findings pDNA nanosomes prepared with 20 mm lipid (nanosomes : pDNA : PS at a ratio of 8.6 : 1 : 2) had particle sizes of 170–422 nm (90% confidence). The zeta‐potential of the formulation was 49.2 ± 1.5 mV, and the pDNA encapsulation/complexation efficiency was ～98%. pDNA nanosomes prepared with 3 mm lipid (nanosomes : pDNA : PS at a ratio of 2.09 : 1 : 2) had particle sizes of 140–263 nm (90% confidence). The zeta‐potential of this formulation was 36.4 ± 1.2 mV, and the pDNA encapsulation/complexation efficiency was ～100%. However, a comparison of the efficiency of transfection indicated that pDNA nanosomes prepared with low‐concentration lipids (3 mm ) showed significantly higher transfection efficiency compared with the pDNA nanosomes prepared with high‐concentration lipids (20 mm ), as well as those prepared with Fugene‐6 (a commercially available transfection reagent). This particular formulation (pDNA nanosomes, 3 mm lipids) also showed significantly less cytotoxicity compared with the other pDNA nanosome formulations. Conclusions To conclude, these results indicate that condensing pDNA with PS followed by subsequent complexation with low‐concentration nanosomes generated from HPH can produce a pDNA nanosome formulation that will boost transfection efficiency, while minimizing cytotoxicity. This new technology appears to be an efficient tool for future commercial or large‐scale manufacture of DNA delivery systems for gene therapy.     

Diclofenac salts, part 6: release from lipid microspheres

The release of diclofenac (20%, w/w) was studied from lipidic solid dispersions using three different chemical forms (acid, sodium salt, and pyrrolidine ethanol salt) and two different lipid carriers (Compritol 888 ATO or Carnauba wax) either free or together with varying amounts (10%–30%, w/w) of stearic acid. Microspheres were prepared by ultrasound‐assisted atomization of the molten dispersions and analyzed by scanning electron microscopy, differential scanning calorimetry, and hot stage microscopy. The effects of different formulations on the resulting drug release profiles as a function of pH were studied and the results were discussed. The formulation of the 18 systems and the chemical form of the drug were found to strongly affect the mode of the drug release. The solubility of the chemical forms in the lipid mixture is in the following order: pyrrolidine ethanol salt ? acid > sodium salt (according to the solubility parameters), and the nature of the systems thus obtained ranges from a matrix, for mutually soluble drug/carrier pairs, to a microcapsule, for pairs wherein mutual solubility is poor. Drug release from microspheres prepared by pure lipids was primarily controlled by diffusion, whereas the release from microspheres containing stearic acid was diffusion/erosion controlled at pH 7.4. © 2011 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 100:3482–3494, 2011