Preparation and characterization of 5-fluorouracil pH-sensitive niosome and its tumor-targeted evaluation: in vitro and in vivo

The purpose of this study was to investigate preparation, characterization and tumor-targeted effect of pH-sensitive niosomes, composed of a nonionic surfactant mixed with cholesteryl hemisuccinate (CHEMS), a derivative of cholesterol (CHOL), as a pH-sensitive molecule. CHEMS was synthesized with CHOL and succinic acid, the structure of which was analyzed by Mass spectrometry (MS) and (1)H Nuclear magnetic resonance ((1)H NMR) spectrum. Niosomes were prepared via film hydration-probe ultrasound method. Both normal niosomes and pH-sensitive niosomes showed spherical morphology under transmission electron microscope (TEM) with a average particle sizes of 172 ± 6.2 nm and 153 ± 4.7 nm, respectively. The thermotropic behavior, structure changes and interaction of 5-fluorouracil (5-Fu) with other materials were characterized by differential scanning calorimetry (DSC), and the disappearance of the melting peak of drug revealed the fact that drug was encapsulated in niosomes. Bulk-equilibrium reverse-dialysis method was chosen to investigate the behavior of drug release from normal niosomes and pH-sensitive niosomes in different pH medium, and the results showed that the noisome containing CHEMS had a pH-sensitive property. Tumor-targeted effect was proved by the fact that pH-sensitive niosomes showed a remarkable high concentration in tumor site of the mice transplanted with tumor cell.     

Preparation and characterization of pH-sensitive vesicles made of cholesteryl hemisuccinate

pH-sensitive vesicles are designed to promote efficient release of entrapped agents in response to low pH. In this study, such vesicles were prepared from cholesteryl hemisuccinate (CHEMS) in Tris-HCl buffer. Vesicles prepared by this direct hydration method had a small particle size of 74.1 nm based on intensity of Gaussian and a size of 65.8 nm based on volume of Gaussian. The mean zeta potential was about -73mV, indicating that the vesicle system was stable. Entrapment efficiency for calcein by these vesicles was measured at 37 ± 2.36%, which is higher than that by phospholipid MLVs. These calcein loaded vesicles exhibited excellent stability at pH 7.4 and underwent rapid destabilization upon acidification as showed by calcein release. However these vesicles were unstable in Fetal Bovine Serum (FBS). Optimization of formulation might improve their stability in serum.     

Preparation of novel cationic copolymer microspheres and evaluation of their function by in vitro and in vivo tests as pH-sensitive drug carrier systems

Novel pH-sensitive copolymer microspheres containing methylacrylic acid and styrene cross-linking with divinylbenzene were synthesized by free radical polymerization. The microspheres that were formed were then characterized by Fourier-Transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), size analysis, and X-ray analysis. The copolymer microspheres showed pulsatile swelling behavior whenthe pH of the media changed. The pH-sensitive microspheres were loaded with diltiazem hydrochloride (DH). The release characteristics of the free drug and the drug-loaded microspheres were studied under both simulated gastric conditions and intestinal pH conditions. The in vivo evaluation of the pulsatile preparation was subsequently carried out using beagle dogs as experimental subjects. The results demonstrated that the drug release exhibited a pulsatile character both in vitro and in vivo.     

Improved initial burst of estradiol organogel as long-term in situ drug delivery implant: formulation,in vitro and in vivo characterization

Objective: The present investigation was aimed at optimizing of estradiol (E2) loaded l-amino acid derivatives organogel formulations resulting in improved the high initial release problems and sustained release of E2.

Methods: The visco-elastic properties of blank organogels were measured by rheometer. The E2 organogel formulations were optimized using a central composite design. Also, the effect of gelator structure and composition of the gel formulations on release behavior (in vitro and in vivo) had been studied.

Results: The change of the gelator structure could affect significantly the stiffness of the implants. The release behavior of gel without N-Methyl-2-pyrrolidinone (NMP) was controlled by gel corrosion only. While the drug release of the gel with NMP was controlled by both corrosion and diffusion. The high initial release problems of the organogels were improved by optimizing the formulations. The system consisting by N-Lauroyl l-lysine methyl ester (LLM) derivative in the oil indicated the lowest initial drug release, showed a much lower blood drug level and maintained a steady state for nearly 1 month.

Conclusion: Organogels based on l-lysine methyl ester derivative were ideal carriers for long-term parenteral administration of E2.     

Preparation and in vitro/in vivo evaluation of azilsartan osmotic pump tablets based on the preformulation investigation

The objective of this study was to design and evaluate azilsartan osmotic pump tablets. Preformulation properties of azilsartan were investigated for formulation design. Azilsartan osmotic pump tablets were prepared by incorporation of drug in the core and subsequent coating with cellulose acetate and polyethylene glycol 4000 as semi-permeable membrane, then drilled an orifice at the center of one side. The influence of different cores, compositions of semipermeable membrane and orifice diameter on azilsartan release were evaluated. The formulation of core tablet was optimized by orthogonal design and the release profiles of various formulations were evaluated by similarity factor (f₂). The optimal formulation achieved to deliver azilsartan at an approximate zero-order up to 14?h. The pharmacokinetic study was performed in beagle dogs. The azilsartan osmotic pump tablets exhibited less fluctuation in blood concentration and higher bioavailability compared to immediate-release tablets. Moreover, there was a good correlation between the in vitro dissolution and in vivo absorption of the tablets. In summary, azilsartan osmotic pump tablets presented controlled release in vitro, high bioavailability in vivo and a good in vitro-in vivo correlation.     

Preliminary evaluation of the in vitro release and in vivo absorption in rabbits of the modified-release dosage forms

Objective: The suitability of the rabbit as an animal model for the primary screening and selection of the pilot scale batches during the early stages of the formulation development was studied.

Materials and methods: Three modified-release formulations of aminophylline consisted of Carbopol® 971P/HPMC K4M (F-I), and HPMC K100M (F-II) or HPMC K4M (F-III) were used. Commercial products were Aminofilin retard 350?mg tablets, Srbolek, Serbia (R-I) and Phyllocontin^® 350, tablets Purdue Frederic, Canada (R-II).

Results: Calculated release rate constants and the ?2 values between R-I/F-I (84.1) and R-II/F-III (83.4) indicated similar in vitro release while the coefficient n showed presence of different mechanisms of release from Anomalous transport, Fickian diffusion to Case-II transport. Higher T_max, was found in the rabbits, dosed with F-II (12.00?h), F-III (10.50?h), and R-II (15.00?h) formulation. The highest C_max (9.22?mg/L) was obtained with F-II, similar lower values was seen for F-I and F-III, while commercial products showed the lowest values R-I (5.58?mg/L) and R-II (4.18?mg/L). Higher AUC values were detected for all three formulations (from 115.90 to 204.06 mgh/L) in relation to commercial products (105.33 and 113.25 mgh/L).

Discussion and conclusion: The results demonstrated a good correlation of Level A (r² = 0.97) for the two formulations (F-I, F-III) and commercial product (R-I) indicates that there is a reasonable assumption that the rabbit might be use as a model for the preliminary comparison of scale up formulations in the early stages of the product development.     

Construction and in vitro/in vivo evaluation of 17-allylamino-17-demethoxygeldanamycin (17AAG)-loaded PEGylated nanostructured lipid carriers

In this study, the PEGylated nanostructured lipid carriers (PEG-NLC) were constructed for the intravenous delivery of 17-allylamino-17-demethoxygeldanamycin (17AAG). 17AAG-PEG-NLC was successfully prepared by the method of emulsion evaporation at a high temperature and solidification at a low temperature using a mixture of glycerol monostearate and PEG₂₀₀₀-stearate as solid lipids, and medium-chain triglyceride as the liquid lipid. The results revealed that the morphology of the NLC was spheroidal. The particle size, zeta potential and entrapment efficiency for 17AAG-PEG-NLC were observed as 189.4?nm, ?20.2 mV and 83.42%, respectively. X-ray diffraction analysis revealed that 17AAG existed as amorphous structures in the nanoparticles. In the in vitro release study, the 17AAG from 17AAG-PEG-NLC exhibited a biphasic release pattern with burst release initially and sustained release afterwards. In addition, 17AAG-PEG-NLC showed a significantly higher in vitro antitumor efficacy and longer retention time in vivo than 17AAG solution. These results indicated that 17AAG-PEG-NLC may offer a promising alternative to the current 17AAG formulations for the treatment of solid tumors.     

Cellulose acetate microspheres as floating depot systems to increase gastric retention of antidiabetic drug: formulation, characterization and in vitro-in vivo evaluation

Gastric emptying is a complex process that is highly variable and makes the in vivo performance of drug delivery systems uncertain. In order to avoid this variability, efforts have been made to increase the retention time of the drug delivery systems for more than 12 hours utilizing floating or hydrodynamically controlled drug delivery systems. The objective of this investigation was to develop a floating, depot-forming drug delivery system for an antidiabetic drug based on microparticulate technology to maintain constant plasma drug concentrations over a prolonged period of time for effective control of blood sugar levels. Formulations were optimized using cellulose acetate as the polymer and evaluated in vitro for physicochemical characteristics and drug release in phosphate buffered saline (pH 7.4), and evaluated in vivo in healthy male albino mice. The shape and the surface morphology of the prepared microspheres were characterized by optical microscopy and scanning electron microscopy. In vitro drug release studies were performed and drug release kinetics were calculated using the linear regression method. Effects of stirring rate during preparation and polymer concentration on the size of microspheres and drug release were observed. The prepared microspheres exhibited prolonged drug release (more than 10 hours) and remained buoyant for over 10 hours. Spherical and smooth-surfaced microspheres with encapsulation efficiency ranging from 73% to 98% were obtained. The release rate decreased and the mean particle size increased at higher polymer concentrations. Stirring speed affected the morphology of the microspheres. This investigation revealed that upon administration, the biocompatible depot-forming polymeric microspheres controlled the drug release and plasma sugar levels more efficiently than plain orally given drug. These formulations, with their reduced frequency of administration and better control over drug disposition, may provide an economic benefit to the user compared with products currently available for diabetes control.     

Formulation and optimisation of famotidine proniosomes: an in vitro and ex vivo study

The aim of the study was to develop a proniosomal system for famotidine (FAM), a potent H₂ receptor antagonist that could efficiently deliver entrapped drug over a prolonged period of time. The proniosomal system was formulated by selecting various ratios of Span 60 and cholesterol using a coacervation-phase separation method. The formulated systems were characterised for drug excipient compatibility studies by Fourier transform infrared spectroscopy (FTIR), vesicle size determination by the particle size analyser, % drug encapsulation, drug-release profiles, field emission scanning electron microscopy (FESEM) for surface morphology, X-ray diffraction (XRD) and vesicular stability at different storage conditions. By using this method, the % drug loading that resulted by the encapsulation of proniosome was found to be 78%–89%. Increase in cholesterol and surfactant concentration increases encapsulation efficiency, but further increment decreases encapsulation. In vitro drug-release studies showed prolonged release of entrapped famotidine. The highest % cumulative drug release was achieved in formulation FAM2 (96%) in 24 hours. The ex vivo data on the release of famotidine from proniosomal formulations have shown significantly increased per cent release and flux in comparison to the same dose of marketed preparation of famotidine. Stability studies were carried out in refrigerated conditions, and higher drug retention was observed. It is evident from this study that proniosomes are a promising prolonged delivery system for famotidine and have reasonably good stability characteristics.     

Hydrogel containing dexamethasone-loaded nanocapsules for cutaneous administration: preparation,characterization, and in vitro drug release study

Context: Our group previously reported the development of dexamethasone-loaded polymeric nanocapsules as an alternative for topical dermatological treatments. Objective: Our study aimed to prepare and characterize a hydrogel containing this system to improve the effectiveness of the glucocorticoid for cutaneous disorders. Methods: For the antiproliferative activity assay, a dexamethasone solution and D-NC were tested on Allium cepa root meristem model. D-NC were prepared by the interfacial deposition of preformed polymer. Hydrogels were prepared using Carbopol Ultrez® 10 NF, as polymer, and characterized according to the following characteristics: pH, drug content, spreadability, viscosity, and in vitro drug release. Results and Discussion: Nanocapsules showed mean particle size and zeta potential of 201 ± 6 and ?5.73 ± 0.42 nm, respectively. They demonstrated a lower mitotic index (4.62%) compared to free dexamethasone (8.60%). Semisolid formulations presented acidic pH values and adequate drug content (between 5.4% and 6.1% and 100% and 105%, respectively). The presence of nanocapsules in hydrogels led to a decrease in their spreadability factor. Intact nanoparticles were demonstrated by TEM as well as by dynamic light scattering (mean particle size < 300 nm). In vitro studies showed a controlled dexamethasone release from hydrogels containing the drug associated to the nanocapsules following the Higuchi's squared root model (k = 20.21 ± 2.96 mg/cm²/h^1/2) compared to the hydrogels containing the free drug (k = 26.65 ± 2.09 mg/cm²/h^1/2). Conclusion: Taking all these results together, the hydrogel containing D-NC represent a promising approach to treat antiproliferative-related dermatological disorders.     

双氯灭痛壳聚糖水凝胶微球的制备及其性能研究

在Span80与植物油形成的反相胶束体系中,通过戊二醛交联制备出壳聚糖水凝胶微球(CHM)。采用红外光谱和透射电镜等方法对CHM结构及粒子形态进行了研究。同时对CHM的溶胀度及其对模型药物双氯灭痛的体外释放行为进行了考察。结果表明,CHM具有较好的控制药物释放的作用。交联程度对微球粒径、溶胀度及药物释放性能影响较大。     

Celecoxib-cyclodextrin systems: characterization and evaluation of in vitro and in vivo advantage

Solid dispersions of Celecoxib were prepared with hydroxypropyl β cyclodextrin by various methods such as physical mixture, cogrinding, kneading, and coevaporation. The dispersions were characterized by differential scanning calorimetry (DSC), X-ray diffraction patterns, infrared spectroscopy, and nuclear magnetic resonance studies. The DSC thermograms of the dispersions indicated potential of heat-induced interaction between Celecoxib and cyclodextrin that could influence in vitro drug dissolution. The dispersions exhibited faster rates of dissolution compared to that of Celecoxib. The kneaded dispersion with the fastest in vitro dissolution rate when compressed into tablets showed a better release profile compared to the tablets of pure Celecoxib. In vivo studies revealed that the kneaded dispersion provided for quicker response and was more effective in inhibiting rat paw edema as compared to Celecoxib alone, thus confirming the advantage of improved pharmacological activity of Celecoxib when administered as a solid dispersion with cyclodextrin.     

Damar Batu as a novel matrix former for the transdermal drug delivery: in vitro evaluation

Purpose: Damar Batu (DB) is a novel film-forming biomaterial obtained from Shorea species, evaluated in this study for its potential application in transdermal drug delivery system. Methods: DB was characterized initially in terms of acid value, softening point, molecular weight (M_w), polydispersity index (M_w/M_n), and glass transition temperature (T_g). Neat, plasticized films of DB were investigated for mechanical properties. The biomaterial was further investigated as a matrix-forming agent for transdermal drug delivery system. Developed matrix-type transdermal patches were evaluated for thickness and weight uniformity, folding endurance, drug content, in vitro drug release study, and skin permeation study. Results: On the basis of in vitro drug release and in vitro skin permeation performance, formulation containing DB/Eudragit RL100 (60 : 40) was found to be better than other formulations and was selected as the optimized formulation. IR analysis of physical mixture of drug and polymer and thin layer chromatography study exhibited compatibility between drug and polymer. Conclusion: From the outcome of this study, it can be concluded that applying suitable adhesive layer and backing membrane-developed DB/ERL100, transdermal patches can be of potential therapeutic use.     

Development and in vitro/in vivo evaluation of HPMC/chitosan gel containing simvastatin loaded self-assembled nanomicelles as a potent wound healing agent

The aim of this study was to develop hydroxypropyl methyl cellulose (HPMC)/chitosan gel containing polymeric micelles loaded with simvastatin (Sim) and evaluates its wound healing properties in rats. An irregular full factorial design was employed to evaluate the effects of various formulation variables including polymer/drug ratio, hydration temperature, hydration time, and organic solvent type on the physicochemical characteristics of pluronic F127-cholesterol nanomicelles prepared using the film hydration method. Among single studied factors, solvent type had the most impact on the amount of drug loading and zeta potential. Particle size and release efficiency was more affected by hydration temperature. The optimized formulation suggested by desirability of 93.5% was prepared using 1?mg of Sim, 10?mg of copolymer, dichloromethane as the organic solvent, hydration time of 45?min and hydration temperature of 25?°C. The release of the drug from nanomicelles was found to be biphasic and showed a rapid release in the first stage followed by a sustained release for 96?h. The gel-contained nanomicelles exhibited pseudo-plastic flow and more sustained drug release profile compared to nanomicelles. In excision wound model on normal rats, the wound closure of the group treated by Sim loaded micelles-gel was superior to other groups. Taken together, Sim loaded micelles-gel may represent a novel topical formulation for wound healing.     

Sildenafil vaginal suppositories: preparation,characterization, in vitro and in vivo evaluation

Aim: The main objective was to investigate the in vitro release profile/kinetics, and in vivo plasma pharmacokinetics (PK) and organ biodistribution (BD) of the prepared sildenafil vaginal suppositories (SVS).

Methods: Suppositories containing 25?mg of sildenafil were prepared by the cream melting technique using Witepsol H-15 as a suppository base. The suppositories were characterized for weight variation, content uniformity, hardness, disintegration time and crystallinity change. The in vitro dissolution in pH 4.5, and in vivo plasma PK and organ BD of sildenafil from SVS in female Sprague Dawley rats, were also investigated.

Results: The mean weight variation, content uniformity, hardness and disintegration time of the prepared SVS were 1.127?±?0.020?g, 98.25?±?2.50%, 2.5?±?0.08?kg and 9?±?1.0?min, respectively. The release of sildenafil from the SVS was more than 90% at 30?min, with a release kinetic of Hixson--Crowell model and non-Fickian diffusion (n?=?0.464). The plasma PK study demonstrated a significantly lower C_max (～10 times) and AUC_0–24?h (～13 times) of sildenafil in plasma following intravaginal (IVG) administration of suppositories compared to oral (PO) administration of sildenafil solution. Nevertheless, the organ BD study showed a phenomenally higher C_max (～40 times) and AUC_0–24?h (～20 times) of sildenafil in uterus following IVG administration of suppositories than PO administration of sildenafil solution.

Conclusion: This study demonstrated enhanced sildenafil exposure in the uterus following IVG administration of SVS, which could be used to target the uterus for therapeutic benefits.     

Considerations in the development of an in vitro dissolution condition for lacidipine tablets: in vivo pharmacokinetic evaluation

In this study, a new discriminative dissolution condition for lacidipine tablets was developed by the established in vitro–in vivo relationship. Series of dissolution media of phosphate buffer solution (PBS) covering the pH range of 1–7.2 and pH 6.8 PBS containing different concentrations of sodium dodecyl sulfate (SDS), were prepared and used to investigate the dissolution behavior of lacidipine tablets. There was an obvious difference in the dissolution profiles of the both brands in pH 6.8 PBS medium containing 0.1% SDS. The pharmacokinetic study of the two lacidipine tablets was carried out in the healthy beagle dogs at a single dose of 4?mg. Statistical comparison of the AUC_0–24, C_max, and T_max showed a significant difference in the two brand tablets, coinciding with the dissolution performance with pH 6.8 PBS containing 0.1% SDS. The superiority of the proposed system, pH 6.8 PBS containing 0.1% SDS, could serve as a dissolution medium for lacidipine tablets, and more important it could discriminate the in vivo pharmacokinetic behavior for different brands of products. In summary, in vivo pharmacokinetic evaluation is essential to develop an appropriate in vitro dissolution condition for oral solid dosage forms of poorly soluble drugs.     

Preparation,characterization and in vitro evaluation of microemulsion of raloxifene hydrochloride

Raloxifene hydrochloride (RLX) is a selective estrogen receptor modulator which is orally used for treatment of osteoporosis and prevention of breast cancer. The drug has low aqueous solubility and bioavailability. The aim of the present study is to formulate and characterize oil-in-water microemulsion systems for oral delivery of RLX. To enhance the drug aqueous solubility, microemulsion based on sesame oil was prepared. Sesame oil and Tween 80 were selected as the drug solvent oil and surfactant, respectively. In the first and second formulations, Edible glycerin and Span 80 were applied as co-surfactant, respectively. Pseudo-ternary phase diagrams showed that the best surfactant/co-surfactant ratios in the first and second formulations were 4:1 and 9:1, respectively. The particle size of all free drug-loaded and drug loaded samples were in the range of 31.25?±?0.3?nm and 60.9?±?0.1?nm, respectively. Electrical conductivity coefficient and refractive index of all microemulsion samples confirmed the formation of oil-in-water type of microemulsion. In vitro drug release profile showed that after 24?hours, 46% and 63% of the drug released through the first formulation in 0.1% (w/v) Tween 80 in distilled water as a release medium and phosphate buffer solution (PBS) at pH?=?5.5, respectively. These values were changed to 57% and 98% for the second formulation. Results confirmed that the proposed microemulsion system containing RLX could improve and control the drug release profile in comparison to conventional dosage form.     

纳米磁性壳聚糖载药体的制备与体外释药评价

以自制Fe3O4磁性纳米为磁性靶向核,在乳液体系中制备壳聚糖／三聚磷酸钠／5-Fu磁性壳聚糖纳米载药体（TCF）,经一定比例的PHB和PEG混合外包覆,得到载药率为16．56％的磁性纳米微囊（PTCF）,通过红外光谱、x-射线粉末衍射、透射电镜和振动磁强计表征,结果显示,TCF、PTCF分别为粒径15nm和20nm均匀颗粒,25℃时的矫顽力和剩磁均趋于零,表现出超顺磁性;体外释药行为显示,PTCF无突释现象,释药速率随PHB和PEG用量可控,具备磁靶向控释药物的潜在性质。     

Formulation and in vivo evaluation of niosome-encapsulated daunorubicin hydrochloride

The central aim of this present study was to modify the reverse evaporation process, such that an enhanced entrapment, with increased storage stability and prolonged release, could be achieved, and to translate these advantages to increased therapeutic efficacy of daunorubicin hydrochloride on Dalton's ascitic lymphoma. Niosomes prepared exhibited entrapment efficiency 20% higher than theoretically possible by the reverse evaporation process. The niosomes were found to be very stable at a storage temperature of 4°C for a duration of three months. Even the drug leakage was restricted to just 10%. The in vivo studies suggested a prolonged release of 20 hr. Niosomal daunorubicin hydrochloride exhibited an enhanced anti-tumor efficacy when compared to free drug. The niosomal formulation was able to destroy the Dalton's ascitic lymphoma cells in the peritoneum within the third day of treatment, while free drug took around six days and the process was incomplete. The hematological studies also prove that the niosomal formulation was superior to free drug treatment. An enhanced mean survival time was achieved by the niosomal formulation that finally substantiates the overall efficacy of the niosomal formulation. This study suggests that the multilamellar vesicles obtained by the presently utilized reverse evaporation process resulted in vesicles that resisted the immediate lysis in the Kupffer cells, whereby a prolonged drug concentration was achieved which enhanced the cell lysis. But the major factor responsible for the quicker onset of action could be the increased permeability of the niosomes into the cell membrane and the cytoplasm of the Dalton's ascitic lymphoma cells.     

5-氟尿嘧啶载药微球的制备工艺及性能研究

以PLA为载体材料,以5-Fu为模型药物,制备5-Fu/PLA载药微球,通过正交设计优化微球制备工艺.另外,检测了载药微球的回收率、稳定性、缓释性能等物理性质.用紫外分光光度计测定药物含量,激光粒度仪分析粒径. 结果表明,载药微球的平均粒径为(133.2±32.5)nm,平均包封率为(11.3±5.0)%,缓释时间延长至80～100h,具有良好的缓释功能.