Effect of surfactant on 5-aminolevulinic acid uptake and PpIX generation in human cholangiocarcinoma cell

Photodynamic therapy (PDT) is a palliative therapy and has been used to cure cholangiocarcinoma (CC), which has a poor prognosis and limited available curative therapy. PDT was shown to improve the median survival time of advanced-stage patients. Recently, 5-aminolevulinic acid (ALA) has been used as a pro-photosensitizer, which can be transferred to intercellular protoporphyrin IX (PpIX), which is a strong photosensitizer, via the heme pathway. The main limitation of using ALA in PDT is the hydrophilic properties of ALA, which results in low cellular uptake. In this study, non-ionic surfactants, pluronic F68 (PF68) and Tween 80 (TW80), were used to address this limitation. The human CC cell line, HuCC-T1, was cotreated with ALA and different concentrations of surfactants for 4 h. The effect of surfactants was evaluated by monitoring the uptake of ALA, the fluorescence intensity of PpIX, and the cell survival rate after suitable light irradiation. Cotreatment with the surfactant resulted in an increased intracellular ALA level, PpIX formation, and phototoxicity.     

A Rheological Method to Evaluate the Physical Stability of Highly Viscous Pharmaceutical Oil-in-Water Emulsions

Purpose The aim of this study was to develop a rheological method to evaluate the stability of highly viscous pharmaceutical emulsions. Thereby, the time devoted to the storage tests could be reduced and manufacturers could save time in optimizing their formulations and manufacturing techniques for topical pharmaceutical forms. The influence of the type of oil and the type of emulsifier on the microstructure of the emulsions was also studied.Materials and Methods The samples were stored at 25 and at 50°C for 6 months and analysed every month using rheological as well as microscopic techniques. The size and the organization of the droplets within the emulsion were determined by freeze-fracture electron microscopy and optical contrast phase microscopy.Results A decrease in the rheological parameters was observed for the OC emulsions (“Tween/Span” emulsions made with olive oil) and the “Montanov” emulsions. The rheological measurements showed that the structure of the OC emulsions and that of the emulsions made with the Montanov 82 emulsifier become more brittle when submitted to a shear force. The micrographs obtained by freeze-fracture electron microscopy showed that for OC only the oil droplets arrange in a network structure. Storage tests at 50°C confirmed the rheological assumptions on the stability of emulsions.Conclusion The study of the effect of shearing on the emulsions allowed quick discrimination between the emulsions according to their stabilities. The rheological tool gave information on the structure of the emulsions and on the aging process.     

Development and characterization of micellar systems for application as insect repellents

N,N-diethyl-meta-toluamide (DEET) is a widely used insect repellent due to its high efficacy. In this work, micellar systems based on poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) triblock copolymer were developed and studied for the purpose of controlling the release and cutaneous permeation of DEET, using concentrated solutions of the copolymer Pluronic F127 to form thermoreversible gels. The formulations presented thermoreversible gelation above 5 °C and altered rheological behavior at 15 and 25 °C. The presence of the drug drastically changed the sol–gel transition temperatures. The micrographs suggest that DEET induced the formation of anisotropic structures, and Maltese Crosses were observed. The formulation containing 10 wt% DEET and 15 wt% Pluronic F127 presented sustained drug release for up to 7 h. DEET release profile followed the Higuchi kinetics model. There was a reduction of approximately 35% in the amount of DEET absorbed through the skin after 6 h. About 62% of DEET from the formulation consisting of Pluronic F127 and DEET remain retained on the skin. The anisotropic structure may constitute a barrier to diffusion and thereby controlling the drug release effectively. These tests suggest that the tested samples exhibit safety profile greater than some commercially available products.     

Novel approach for delivery of insulin loaded poly(lactide-co-glycolide) nanoparticles using a combination of stabilizers

Insulin stability during microencapsulation and subsequent release is essential for retaining its biological activity. The successful delivery of insulin relies on the proper selection of stabilizers in addition to other parameters. Attempts were made to address the problem with a few combination of stabilizers for maintaining the integrity of insulin during formulation and delivery. Insulin loaded nanoparticles with different stabilizers such as pluronic F68, trehalose, and sodium bicarbonate were prepared by the double emulsion evaporation method using two different copolymer ratios of poly(DL-lactide-co-glycolide) (50:50 and 85:15). The presence of stabilizers in the nanoparticles resulted in an increase in the particle size but a reduction of encapsulation efficiency. Insulin release rate was comparatively higher for the batches containing stabilizers when compared with controls for both the copolymer ratios. Also the presence of stabilizers resulted in sustained release of insulin resulting in prolonged reduction of blood glucose levels in streptozotocin induced diabetic rats. From the in vitro and in vivo studies, we concluded that a combination of stabilizers results in beneficial effects without compromising the advantages of delivery systems.     

Pluronic F127-g-poly(acrylic acid) copolymers as in situ gelling vehicle for ophthalmic drug delivery system

To prolong the precorneal resident time and improve ocular bioavailability of the drug, Pluronic F127-g-poly(acrylic acid) copolymers were studied as in situ gelling vehicle for ophthalmic drug delivery system. The rheological properties and in vitro drug release of Pluronic-g-PAA copolymer gels were investigated. The rheogram and in vitro drug release studies indicated that the drug release rates decreased as acrylic acid/Pluronic molar ratio and copolymer solution concentration increased. But the drug concentration had no obvious effect on drug release. The release rates of the drug from such copolymer gels were mainly dependent on the gel dissolution. In vivo resident experiments showed the drug resident time and the total resident amount in rabbit's conjunctiveal sac increased by 5.0 and 2.6 folds for in situ gel, compared with eye drops. The decreased loss angle at body temperature and prolonged precorneal resident time also indicated that the copolymer gels had bioadhesive properties. These in vivo experimental results, along with the rheological properties and in vitro drug release studies, demonstrated that in situ gels containing Pluronic-g-PAA copolymer may significantly prolong the drug resident time and thus improve bioavailability. Pluronic-g-PAA copolymer can be a promising in situ gelling vehicle for ophthalmic drug delivery system.     

Preparation and preliminary bioevaluation studies of 68Ga‐NOTA‐rituximab fragments as radioimmunoscintigraphic agents for non‐Hodgkin lymphoma

Rituximab is used for the treatment of non‐Hodgkin lymphoma (NHL). This study focuses on development of ⁶⁸Ga‐labeled rituximab fragments, (⁶⁸Ga‐NOTA‐F (ab′)‐rituximab and ⁶⁸Ga‐NOTA‐F (ab′)₂‐rituximab, as PET‐imaging agents for NHL. Rituximab was digested with immobilized pepsin and papain to yield F (ab′)₂ and Fab fragments respectively that were characterized by size exclusion HPLC (SE‐HPLC) and SDS‐PAGE. They were conjugated with p‐SCN‐Bn‐NOTA, labeled with ⁶⁸Ga and characterized by SE‐HPLC. Intact rituximab was labeled with gallium‐68 for comparison. Specificity of ⁶⁸Ga‐labeled immunoconjugates was ascertained by immunoreactivity and cell binding studies in Raji cells, while biodistribution studies were performed in normal Swiss mice. Gradient SDS‐PAGE under nonreducing condition showed molecular weights of F (ab′)₂‐rituximab and F (ab′)‐rituximab as approximately 100 and 40 Kd, respectively. Radiochemical purity (RCP) of ⁶⁸Ga‐NOTA‐F (ab′)₂‐rituximab and ⁶⁸Ga‐NOTA‐F (ab′)‐rituximab were 98.2 ± 0.5% and 98.8 ± 0.2% respectively with retention times of 17.1 ± 0.1 min and 19.3 ± 0.1 min in SE‐HPLC. ⁶⁸Ga‐labeled rituximab fragments were stable in saline and serum up to 2‐hour post preparation and exhibited specificity to CD20 antigen. Immunoreactivity of ⁶⁸Ga‐labeled immunoconjugates was greater than 80%. Clearance of the fragmented radioimmunoconjugates was predominantly through renal route. Preliminary results from this study demonstrate the potential of ⁶⁸Ga‐ NOTA‐F (ab′)₂‐rituximab and ⁶⁸Ga‐NOTA‐F (ab′)‐rituximab as PET imaging agents for NHL.     

Preparation and evaluation of icariside II-loaded binary mixed micelles using Solutol HS15 and Pluronic F127 as carriers

An effective anti-cancer drug, icariside II (IS), has been used to treat a variety of cancers in vitro. However, its poor aqueous solubility and permeability lead to low oral bioavailability. The aim of this work was to use Solutol®HS15 and Pluronic F127 as surfactants to develop novel mixed micelles to enhance the oral bioavailability of IS by improving permeability and inhibiting efflux. The IS-loaded mixed micelles were prepared using the method of ethanol thin-film hydration. The physicochemical properties, dissolution property, oral bioavailability of the male SD rats, permeability and efflux of Caco-2 transport models, and gastrointestinal safety of the mixed micelles were evaluated. The optimized IS-loaded mixed micelles showed that at 4:1 ratio of Solutol®HS15 and Pluronic F127, the particle size was 12.88?nm with an acceptable polydispersity index of 0.172. Entrapment efficiency (94.6%) and drug loading (9.7%) contributed to the high solubility (11.7?mg/mL in water) of IS, which increased about 900-fold. The SF-IS mixed micelle release profile showed a better sustained release property than that of IS. In Caco-2 cell monolayer models, the efflux ratio dramatically decreased by 83.5%, and the relative bioavailability of the mixed micelles (AUC_0–∞) compared with that of IS (AUC_0–∞) was 317%, indicating potential for clinical application. In addition, a gastrointestinal safety assay also provided reliable clinical evidence for the safe use of this micelle.     

铂类抗癌药物奥沙利铂原料药的稳定性研究

目的考察铂类抗癌药物奥沙利铂原料药的稳定性。方法分别在强光(4 500 lx±500 lx)照射10 d、高温(60℃)存放10 d、高湿(25℃,相对湿度90%±5%)存放10 d、加速试验(40℃±2℃,相对湿度75%±5%)6个月、长期试验(25℃±2℃,相对湿度60%±10%)12个月后,考察奥沙利铂原料药的性状、鉴别以及溶液的外观、pH、比旋度、有关物质、杂质D、干燥失重和含量变化。结果经光照试验、高湿试验、高温试验、加速试验和长期试验后,奥沙利铂原料药的各项指标均符合质量标准要求。结论奥沙利铂原料药稳定性较好。     

内水相添加氯化钠对W/O/W型复乳性质的影响

目的探讨在内水相中添加氯化钠(NaCl)对W/O/W型复乳性质的影响。方法在前期试验优选出较佳W/O/W复乳处方的基础上,以1 g/L NaCl水溶液代替处方中的纯化水作为内水相,采用二步乳化法制备复乳,从显微结构、粒径分布、稳定性等方面比较复乳性质的变化。结果在内水相中添加NaCl(1 g/L)时,复乳主要为B型结构,外观较圆整,液滴大小较均匀,且乳滴不易聚集成一团,大部分粒子粒径在20～40μm之间,稳定性良好。结论在内水相中添加NaCl(1 g/L),有助于优化W/O/W型复乳物理化学性质,提高其稳定性。     

天然甘蓝色素作为酒精饮品添加剂的稳定性研究

甘蓝色素是很好的水溶性色素,尝试研究其作为酒精饮料着色剂使用的稳定性,并观察了其与NaCl、蔗糖、琼脂、环糊精同时作为酒精饮品添加剂使用时的色泽变化。结果表明,该色素在酒精溶液中有较好的稳定性,NaCl、蔗糖对其有增色作用,琼脂、环糊精对其基本上没有影响。     

Physical Chemical Properties of Alpha Styryl Carbinol Antifungal Agents

Pharmaceutical Research -     

以酸型槐糖脂为表面活性剂的新型依托泊苷纳米乳注射剂的制备及其稳定性考察

本试验使用生物表面活性剂酸型槐糖脂(ASL)替代Tween-80为表面活性剂制备了一种新型依托泊苷纳米乳注射剂(ENE),并通过比较含ASL或Tween-80纳米乳的理化性质及稳定性,考察用ASL替代Tween-80的可行性。采用高压均质法制备纳米乳注射剂,所得ASL-ENE和Tween-ENE的粒径为(206.7±0.1)和(204.6±0.2)nm,ζ电位为(-38.4±0.2)和(-45.1±0.1)mV,包封率为(96.40±0.45)%和(97.07±0.09)%。并且,考察了初乳pH值和灭菌方式对纳米乳质量的影响。结果表明,高压均质前将初乳调至pH 5.55,所得ASL-ENE在80℃下的药物半衰期为32.84 h,121℃高压蒸汽灭菌20min前后的粒径及ζ电位均无明显变化。4℃保存3个月的稳定性试验和溶血试验结果显示,ASL-ENE的物理稳定性优于Tween-ENE,且未发生溶血现象。上述结果说明用生物表面活性剂ASL替代常用化学表面活性剂Tween-80制备依托泊苷纳米乳是可行的。     

Drying-Induced Variations in Physico-Chemical Properties of Amorphous Pharmaceuticals and Their Impact on Stability II: Stability of a Vaccine

Objectives To investigate the impact of drying method on the storage stability of dried vaccine formulations. Materials and Methods A sucrose-based formulation of a live attenuated virus vaccine of a parainfluenza strain, with and without surfactant, was dried from by different methods; freeze drying, spray drying and foam drying. Dried powders were characterized by differential scanning calorimetry, specific surface area (SSA) analysis and by electron spectroscopy for chemical analysis (ESCA) to evaluate vaccine surface coverage in the dried formulations. Dried formulations were subjected to storage stability studies at 4, 25 and 37°C. The vaccine was assayed initially and at different time points to measure virus-cell infectivity, and the degradation rate constant of the vaccine in different dried preparations was determined. Results SSA was highest with the spray dried preparation without surfactant (∼ 2.8 m²/g) and lowest in the foam dried preparations (with or without surfactant) (∼ 0.1 m²/g). Vaccine surface coverage was estimated based on ESCA measurements of nitrogen content. It was predicted to be highest in the spray dried preparation without surfactant and lowest in the foam with surfactant. Stability studies conducted at 25°C and 37°C showed that the vaccine was most stable in the foam dried preparation with surfactant and least stable in spray dried preparations without surfactant and in all freeze dried preparations regardless of the presence of surfactant. Addition of surfactant did lower the SSA and vaccine surface coverage in freeze dried preparations but still did not improve storage stability. Conclusions In drying methods that did not involve a freezing step, good storage stability of Medi 534 vaccine in the dried form was found with low SSA and low vaccine surface accumulation, both of which integrate into low fraction of vaccine at the surface. Ice appears to be a major destabilizing influence.     

Enhancing the Dissolution Stability of Hard Gelatin Capsules Using Activated Carbon as a Packaging Component

Hard gelatin capsule (HGC) shells are widely used to encapsulate drugs for oral delivery but are vulnerable to gelatin cross-linking, which can lead to slower and more variable in vitro dissolution rates. Adding proteolytic enzymes to the dissolution medium can attenuate these problems, but this complicates dissolution testing and is only permitted by some regulatory authorities. Here, we expand the scope of our previous work to demonstrate that canisters containing activated carbon (AC) or polymeric films embedded with AC particles can be used as packaging components to attenuate gelatin cross-linking and improve the dissolution stability of hard gelatin-encapsulated products under accelerated International Council for Harmonisation conditions. We packaged acetaminophen and diphenhydramine HCl HGCs with or without AC canisters in induction-sealed high-density polyethylene bottles and with or without AC films in stoppered glass vials and stored these samples at 50°C/75% relative humidity through 3 months and at 40°C/75% relative humidity for 6 months. Samples packaged with AC canisters or AC films dissolved more rapidly than samples packaged without AC when differences were observed. These results demonstrate that different sources and formats of AC can enhance the dissolution stability of HGCs packaged in bottles and other potential packaging systems such as blister cards.     

Physicochemical Properties of Salts of p-Aminosalicylic Acid. I. Correlation of Crystal Structure and Hydrate Stability

The potassium (K), sodium (NA), calcium (CA), and magnesium (MG) salts of p-aminosalicylic acid were obtained, and their thermal behavior was characterized by means of differential scanning calorimetry (DSC) and thermogravimetric analysis (TG). Their crystal and molecular structures were determined by single-crystal X-ray diffraction after powder patterns had shown them to be nonisomorphous. Different degrees of hydration were observed for the solid salts, and an assessment of hydrate stability to dehydration was made from thermogravimetric studies. The onset temperature of dehydration (T _t) of each salt varied within the series and exhibited correlation with X-ray determined structure. The observed onset of dehydration of MG and CA was higher than that of NA and is consistent with stronger ion-dipole interactions for the divalent salts. Crystallographic determination of the bond lengths between the metal ion and the water oxygens were 2.4 and 2.9 for NA, between 2.0 and 2.1 for MG, and 2.4 for CA. The open nature and presence of a channel feature in the structure of the sodium salt may have facilitated escape of water molecules from the crystal. Particle presentation (e.g., size, crystallinity) was also shown to affect dehydration behavior.     

Stability of total parenteral nutrition supplied as ‘all-in-one’ for children with chemotherapy-linked hyperhydration

The maximal allowable concentrations of calcium and phosphate in total parenteral nutrition mixtures for children from one compartment were investigated. Children treated with both chemotherapy and total parenteral nutrition are supplied with high amounts of electrolytes (besides normal nutritive needs) in a restricted volume. Such nutritive mixtures are suspected of precipitation and disintegration of the lipid emulsion by (polyvalent) electrolytes, such as calcium and phosphate. Calcium (range 1.5–150 mmol/l total parenteral nutrition) and phosphate (range 21–300 mmol/l) were added to a test total parenteral nutrition mixture. After storage (24 and 48 h) at both 22°C and 37°C the mixtures were observed by microscopy for the presence of precipitates. The stability of the fat emulsion was visually assessed and the particle size distribution was measured by flow cytometry. The examined total parenteral nutrition mixtures (pH 5.4–5.7) were stable during 48 h at 37°C if the calcium concentration is below 16 mmol/l, the phosphate concentration is below 52 mmol/l and the product of both concentrations is below 250 mmol²/l².     

Use of Surfactants as Plasticizers in Preparing Solid Dispersions of Poorly Soluble API: Stability Testing of Selected Solid Dispersions

Purpose The purpose of the study is to evaluate the effect of surfactant-plasticizers on the physical stability of amorphous drug in polymer matrices formed by hot melt extrusion.Method Solid dispersions of a poorly soluble drug were prepared using PVP-K30, Plasdone-S630, and HPMC-E5 as the polymeric carriers and surfactants as plasticizers. The solid dispersions were produced by hot melt extrusion at temperatures 10°C above and below the glass transition temperature (Tg) of the carrier polymers using a 16 mm-Haake Extruder. The surfactants tested in this study included Tween-80 and Docusate Sodium. The particle size of the extrudate was reduced to have mean of 100–200 micron. The physical stability of the solid dispersions produced was monitored at 30°C/60% for six-months and at 60°C/85% for two-months in open HDPE bottles. Modulated differential scanning calorimetry, polarized light microscopy, powder X-ray diffraction and dissolution testing was performed to assess the physical stability of solid dispersions upon stress testing.Results The dispersions containing HPMC-E5 were observed especially to be susceptible to physical instability under an accelerated stress conditions (60°C/85%RH) of the solid dispersion. About 6% conversion of amorphous drug to crystalline form was observed. Consequently, the system exhibits similar degree of re-crystallization upon addition of the surfactant. However, under 30°C/60%RH condition, the otherwise amorphous Drug-HPMC-E5 system has been destabilized by the addition of the surfactant. This effect is much more reduced in the extruded solid dispersions where polymeric carriers such as Plasdone S-603 and PVP-K30 (in addition to surfactants) are present. Furthermore, the drug release from the solid dispersions was unaffected at the stress conditions reported above.Conclusions Possible reasons for the enhanced stability of the dispersions are due to the surfactants ability to lower the viscosity of the melt, increase the API solubility and homogeneity in the carrier polymer. In contrast, while it is possible for the surfactants to destabilize the system by lowering the Tg and increasing the water uptake, the study confirms that this effect is minimal. By and large, the surfactants appear to be promising plasticizers to produce solid dispersions by hot melt extrusion, in so doing improving dissolution rate without compromising the physical stability of the systems.     

Pharmaceutical Properties of Loracarbef: The Remarkable Solution Stability of an Oral 1-Carba-l-dethiacephalosporin Antibiotic

Loracarbef is an oral 1-carba-l-dethiacephalosporin antibiotic structurally related to cefaclor. Like many -lactam antibiotics, loracar-bef exists in several hydrated crystalline forms. The pH–solubility profile curve for loracarbef monohydrate is U-shaped, resembling those for other zwitterionic cephalosporins. Loracarbef was found to be much more stable in solution than cefaclor. For example, in pH 7.4 phosphate buffer, loracarbef was unexpectedly found to be 130–150 times more stable than cefaclor and 10–12 times more stable than cephalexin, depending on the phosphate concentration. The pH-stability profile is U-shaped, similar to that of other zwitterionic cephalosporins, and shows maximum stability at the isoelectric point. At any given pH, loracarbef is more stable in solution than any other therapeutically useful cephalosporin. Acetate, borate, citrate, and especially phosphate buffers have catalytic effects on the rate of loracarbef hydrolysis.     

Developability Assessment of Physicochemical Properties and Stability Profiles of HIV-1 BG505 SOSIP.664 and BG505 SOSIP.v4.1-GT1.1 gp140 Envelope Glycoprotein Trimers as Candidate Vaccine Antigens

The induction of broadly neutralizing antibodies (bNAbs) is a major goal in the development of an effective vaccine against HIV-1. A soluble, trimeric, germline (gI) bNAb-targeting variant of the HIV-1 envelope glycoprotein (termed BG505 SOSIP.v4.1-GT1.1 gp140, abbreviated to GT1.1) has recently been developed. Here, we have compared this new immunogen with the parental trimer from which it was derived, BG505 SOSIP.664 gp140. We used a comprehensive suite of biochemical and biophysical methods to determine physicochemical similarities and differences between the 2 trimers, and thereby assessed whether additional formulation development efforts were needed for the GT1.1 vaccine candidate. The overall higher order structure and oligomeric states of the 2 vaccine antigens were quite similar, as were their thermal, chemical, and colloidal stability profiles, as evaluated during accelerated stability studies. Overall, we conclude that the primary sequence changes made to create the gl bNAb-targeting GT1.1 trimer did not detrimentally affect its physicochemical properties or stability profiles from a pharmaceutical perspective. This developability assessment of the BG505 GT1.1 vaccine antigen supports using the formulation and storage conditions previously identified for the parental SOSIP.664 trimer and enables the development of GT1.1 for phase I clinical studies.