Sustained-release diclofenac potassium-loaded solid lipid microparticle based on solidified reverse micellar solution: in vitro and in vivo evaluation

Objective: To formulate sustained-release diclofenac potassium-loaded solid lipid microparticles (SLMs) based on solidified reverse micellar solution (SRMS) and to evaluate the in vitro and in vivo properties.

Methods: SRMS consisting of mixtures of Phospholipon® 90H and Softisan® 154 were used to formulate diclofenac potassium-loaded SLMs. Characterization based on the particle size and morphology, stability and encapsulation efficiency (EE%) were carried out on the SLMs. In vitro release was carried out in simulated intestinal fluid (pH 7.5). Anti-inflammatory and ulcerogenic properties were studied using rats.

Results: Maximum EE% of 95%, 94% and 93% were obtained for SLMs formulated with SRMS 1:1, 2:1 and 1:2, respectively. In vitro release showed about 85–90% drug release at 13?h. Diclofenac potassium-loaded SLMs showed good anti-inflammatory and gastro-protective properties.

Conclusion: Diclofenac potassium-loaded SLMs based on SRMS could be used orally or parenterally under controlled conditions, for once daily administration.     

Preparation of novel solid lipid microparticles loaded with gentamicin and its evaluation in vitro and in vivo

Objective: To formulate and evaluate solid-reversed-micellar-solution (SRMS)-based solid lipid microparticles (SLMs) for intramuscular administration of gentamicin.

Methods: SRMS formulated with Phospholipon® 90G and Softisan® 154 were used to prepare gentamicin-loaded SLMs. Characterizations based on size and morphology, stability and encapsulation efficiency (EE%) were carried out on the SLMs. In vitro release of gentamicin from the SLMs was performed in phosphate buffer while in vivo release studies were conducted in rats.

Results: Maximum EE% of 90.0, 91.6 and 83.0% were obtained for SLMs formed with SRMS 1:1, 1:2 and 2:1, respectively. Stable, spherical and smooth SLMs of size range 9.80?±?1.46?µm to 33.30?±?6.42?µm were produced. The release of gentamicin in phosphate buffer varied widely with the lipid contents. Moreover, significant (p?<?0.05) amount of gentamicin was released in vivo from the SLMs.

Conclusion: SRMS-based SLMs would likely offer a reliable means of delivering gentamicin intramuscularly.     

Solid lipid microparticles: An approach for improving oral bioavailability of aspirin

The objectives of the work were to develop a lipid based delivery system for aspirin and to evaluate its physicochemical and pharmacodynamic properties. Aspirin-loaded solid lipid microparticles (SLMs) were formulated by hot homogenization and analysed for their encapsulation efficiency (EE%), in vitro release, particle size, anti-inflammatory and ulcer inhibition properties. Particle size ranged from 33.10 ± 5.85 to 43.50 ± 7.27 µm for batches A1 to A3 SLMs loaded with 1, 3 and 5% aspirin and containing Poloxamer 407, while batches B1, B2 and B3 formulated with Soluplus as surfactant had particle size range of 31.10 ± 1.46 to 45.60 ± 2.92 µm. Batches A1 and B1 containing 1% of aspirin had the highest EE of 70 and 72% respectively. Maximum in vitro release of 95.1 and 93.2% were obtained at 8 h from batches A1 and B1 respectively. SLMs exhibited about 77.8% oedema inhibition, while the reference had 66.7% and ulcer inhibition range of 25–75%. Aspirin-loaded SLMs exhibited good properties and could be used orally twice daily for the treatment of inflammation.     

Formulation of novel sustained release rifampicin-loaded solid lipid microparticles based on structured lipid matrices from Moringa oleifera

Abstract

Objectives: To formulate sustained release rifampicin-loaded solid lipid microparticles (SLMs) using structured lipid matrices based on Moringa oil (MO) and Phospholipon 90G (P90G).

Methods: Rifampicin-loaded and unloaded SLMs were formulated by melt homogenization and characterized in terms of particle morphology and size, percentage drug content (PDC), pH stability, stability in simulated gastric fluid (SGF, pH 1.2), minimum inhibitory concentration (MIC) and in vitro release. In vivo release was studied in Wistar rats.

Results: Rifampicin-loaded SLMs had particle size range of 32.50?±?2.10 to 34.0?±?8.40?μm, highest PDC of 87.6% and showed stable pH. SLMs had good sustained release properties with about 77.1% release at 12?h in phosphate buffer (pH 6.8) and 80.3% drug release at 12?h in simulated intestinal fluid (SIF, pH 7.4). SLMs exhibited 48.51% degradation of rifampicin in SGF at 3?h, while rifampicin pure sample had 95.5% degradation. Formulations exhibited MIC range of 0.781 to 1.562, 31.25 to 62.5 and 6.25 to 12.5?μg/ml against Salmonella typhi, Escherichia coli, and Bacillus subtilis respectively and had higher in vivo absorption than the reference rifampicin (p?<?0.05).

Conclusion: Rifampicin-loaded SLMs could be used once daily for the treatment tuberculosis.     

Formulation and evaluation of novel solid lipid microparticles as a sustained release system for the delivery of metformin hydrochloride

Abstract

The low encapsulation efficiency of conventional solid lipid microparticles (SLMs) especially for hydrophilic drugs has remained a challenge to drug formulation experts. This work seeks to address the issue of inefficient delivery of metformin hydrochloride (MTH), a potent hydrophilic oral antihyperglycemic agent, using novel SLMs based on solidified reverse micellar solutions (SRMS) prepared by melt-emulsification using a lipid derived from Capra hircus and Phospholipon® 90H. Characterization based on size, morphology, zeta potential, polydispersity index, encapsulation efficiency (EE%), loading capacity (LC) and time-resolved stability were carried out on the SLMs. The in vitro release of MTH from the SLMs was performed in phosphate buffer (pH 7.4) while the in vivo antidiabetic properties were investigated in alloxan-induced diabetic rats. Stable, spherical and smooth SLMs were obtained. Loading of MTH into the SLMs had no effect on the surface charge of the particles. The SLMs with 1.0%w/w PEG 4000 resulted in significantly (p?<?0.05) higher EE% while those with 2.0%w/w gave the least. The LC values ranged from 20.3 to 29.1 and 14.6 to 24.1 for SLMs containing 500?mg and 250?mg of MTH, respectively. The in vitro release studies revealed significant release of MTH from the SLMs whereas the in vivo antidiabetic studies indicated that novel SLMs containing 500?mg of MTH gave significantly (p?<?0.05) higher glucose reduction than glucophage®. This research has shown that SLMs based on SRMS offer a new and better approach of delivering MTH, thus encouraging further development of this formulation.     

Formulation in vitro and in vivo evaluation of SRMS-based heterolipid-templated homolipid delivery system for diclofenac sodium

The sole objective of this work was to design successful dosage oral forms of diclofenac sodium (DiNa)-loaded solid lipid microparticles (SLM) based on solidified reverse micellar solution (SRMS). Hot homogenization technique was employed to prepare DicNa SLM using a mixture goat fat and Phospholipon® 90?G as lipid matrix and Tween®-80 as mobile surfactant. Characterization based on percentage yield, morphology, particle size, zeta potential, percentage encapsulation, pH and stability of SLMs were investigated. Anti-inflammatory, gastrointestinal tract (GIT) sparing effect and pharmacokinetics were carried out in rat model after oral administration. Results showed that the SLMs were spherical and smooth. The optimized formulation (SLM-4) had particle size of 79.40?±?0.31?µm, polydispersity index of 0.633?±?0.190, zeta potential of ?63.20?±?0.12?mV and encapsulation efficiency of 91.2?±?0.1% with good stability after 8?months of storage. The DicNa SLM had sustained release effect with good anti-inflammatory activity. Higher and prolonged plasma DicNa concentration was shown by the SLM-4 compared to pure drug and a conventional sample. These studies demonstrate that DicNa-loaded SLM based on SRMS could be a promising oral formulation for enhanced bioavailability, pharmacologic activity and gastrointestinal sparing effect of the NSAID, DicNa.     

Evaluation of solid lipid microparticles produced by spray congealing for topical application of econazole nitrate

Objectives The aims of this study were to evaluate the suitability of the spray congealing technique to produce solid lipid microparticles (SLMs) for topical administration and to study the skin permeation of a drug from SLMs compared with solid lipid nanoparticles (SLNs). Methods Econazole nitrate was used as model drug and Precirol ATO 5 as the lipidic carrier. SLMs and SLNs were both prepared at 5: 1, 10: 1 and 12.5: 1 lipid: drug weight ratios and characterised in terms of particle size, morphology, encapsulation efficiency and chemical analysis of the particle surface. SLMs and SLNs were also incorporated into HPMC K 100M hydrogels for ex‐vivo drug permeation tests using porcine epidermis. Key findings SLMs had particle sizes of 18–45 μm, while SLNs showed a mean diameter of 130–270 nm. The encapsulation efficiency was 80–100%. Permeation profiles of econazole nitrate were influenced by both particle size (significant difference until 9 h) and the amount of lipid. Conclusions The results confirm the usefulness of SLNs as carriers for topical administration and suggest the potential of SLMs for the delivery of drugs to the skin.     

Formulation,in vitro and in vivo evaluation of halofantrine-loaded solid lipid microparticles

Abstract

Context: Formulation, characterization, in vitro and in vivo evaluation of halofantrine-loaded solid lipid microparticles (SLMs).

Objective: The objective of the study was to formulate and evaluate halofantrine-loaded SLMs.

Materials and methods: Formulations of halofantrine-loaded SLMs were prepared by hot homogenization and thereafter lyophilized and characterized using particle size, pH stability, loading capacity (LC) and encapsulation efficiency (EE). In vitro release of halofantrine (Hf) from the optimized SLMs was performed in SIF and SGF. In vivo study using Peter’s Four day suppressive protocol in mice and the mice thereafter subjected to histological studies in kidney and liver.

Results: Results obtained indicated that EE of 76.32% and 61.43% were obtained for the SLMs containing 7% and 3% of Hf respectively. The SLMs loaded with 3% of Hf had the highest yield of 73.33%. Time-dependent pH stability analysis showed little variations in pH ranging from 3.49?±?0.04 to 4.03?±?0.05.

Discussion: The SLMs showed pH-dependent release profile; in SIF (43.5% of the drug for each of H₂ and H₃) compared with SGF (13 and 18% for H₂ and H₃ respectively) after 8?h. The optimized SLMs formulation and Halfan® produced a percentage reduction in parasitemia of 72.96% and 85.71% respectively. The histological studies revealed that the SLMs formulations have no harmful effects on the kidney and liver.

Conclusion: SLMs formulations might be an alternative for patients with parasitemia as there were no harmful effects on vital organs of the mice.     

Co-Spray-Dried Urea Cross-Linked Hyaluronic Acid and Sodium Ascorbyl Phosphate as Novel Inhalable Dry Powder Formulation

The pathogenesis and progression of several lung disorders is propagated by inflammatory and oxidative processes, which can be controlled by adjunctive inhaled therapies. The present study aimed to develop an inhalable dry powder formulation consisting of co-spray-dried urea-crosslinked hyaluronic acid and sodium ascorbyl phosphate (SD HA-CL–SAP), a novel combination which was recently shown to possess anti-inflammatory, antioxidant, and wound healing properties. Native HA and SAP were co-spray dried (SD HA–SAP) and evaluated as control formulation. Yield (Y%) and encapsulation efficiency (EE%) were 67.0 ± 4.8% and 75.5 ± 7.2% for SD HA–SAP, 70.0 ± 1.5% and 66.5 ± 5.7% for SD HA-CL–SAP, respectively. Both formulations were shown to be suitable for lung delivery in terms of morphology, particle size (median volumetric diameter ～ 3.4 μm), physical and thermal stability, in vitro aerosol performance - respirable fraction: 30.5 ± 0.7% for SD HA–SAP and 35.3 ± 0.3% for SD HA-CL–SAP. SAP release was investigated using Franz cells and air-interface Calu-3 cell model (>90% of SAP transported within 4 h). The innovative SD HA-CL–SAP formulation holds potential as inhalable dry powder for the treatment of inflammatory lung disorders.     

Brain targeted solid lipid nanoparticles for brain ischemia: preparation and in vitro characterization

This study aims at formulating solid lipid nanoparticles (SLNs) of Vinpocetine (VIN) to be used as a brain targeted sustained drug-delivery system. VIN is a derivative of vincamine alkaloid, used for chronic cerebral vascular ischemia. However, it suffers from low bioavailability and short half-life. Its oral bioavailability is recorded to be between 7 and 55%. Its elimination half-life is 1–2?h so it would be a good candidate for a sustained drug-delivery system. VIN SLNs were prepared using modified high shear homogenization followed by ultrasonication technique. The effect of incorporating different lipids at different concentrations of various surfactants was investigated. The VIN SLNs were characterized by entrapment efficiency percent (EE%), particle size distribution, zeta-potential, and cumulative released percent after 96?h. The EE% ranged between 83.34% ± 0.95–94.56% ± 0.11 due to the lipophilic character of VIN. The mean particle size measured ranged from 123 nm–464?nm. The cumulative released percent after 96?h ranged from 23.55% to 75.67% showing a controlled release profile. Formula (F32) composed of 5% glyceryl monostearate (GMS) and stabilized by 2% surfactant mixture [Tween 80, Pluronic F 68 (1:1)] was the most appropriate formula for brain delivery having EE% of 89.09% ± 1.49, zero-order release kinetics with cumulative released percent of 72.12% after 96?h, zeta-potential of –11.3?±?0.97 mV. It showed a unimodal size distribution with particle size ≈90?nm and polydispersity index of 0.121. The formula of choice in this study exhibited a zero-order sustained release profile and met the requirement for a brain targeted SLN so it could be a promising formula to deliver VIN to the brain.     

Nanostructured Lipid Carriers for Oral Delivery of a Corticosteroid: Role of Formulation on Biopharmaceutical Performance

Corticosteroids are potent anti-inflammatory and immunosuppressive drugs widely used world-wide for treatment of diverse conditions. However, their use is restricted by their poor bioavailability and high risk-benefit ratio. Therefore, the aim of this study was to develop nanostructred lipid carriers (NLC) of prednisolone acetate (PA) to improve the drug's therapeutic outcome by altering its pharmacokinetic profile and/or allow preferential targeting to inflammatory tissues. PA-loaded NLCs were formulated by solvent injection method using Compritol (solid lipid), oleic acid (liquid lipid) and Tween 80 or Pluronic F68 (surfactant). Formulation conditions, such as liquid lipid concentration, total lipids, drug:lipid ratio and surfactant type were optimized based on particle size (PS), polydispersity index (PDI), and encapsulation efficiency (EE%) results. Optimized formulation was further characterized for its surface morphology, thermal properties, storage stability and anti-inflammatory activity in an animal acute inflammation model. Selected NLCs displayed PS of 170.7 nm, EE% of 67.4%, sustained release over 72 h and good stability for 30 days at refrigeration conditions. PA NLCs displayed superior anti-inflammatory activity of 83.9 ± 4.46% compared to PA suspension (40.5 ± 7.03%) and drug-free NLCs (54.7 ± 6.12%). The current work delineates the potential of NLCs for distinctly improved biopharmaceutical performance of PA.     

Solid lipid micro-dispersions (SLMs) based on PEGylated solidified reverse micellar solutions (SRMS): a novel carrier system for gentamicin

Abstract

The purpose of this study was to formulate and evaluate novel PEGylated solidified reverse micellar solutions (SRMS)-based solid lipid microparticles (SLMs) for improved delivery of gentamicin. Lipid matrix (SRMS) [consisting of 15% w/w Phospholipon® 90G (P90G) in 35% w/w dika wax (Irvingia gabonensis) was formulated and characterized by differential scanning calorimetry (DSC). SLMs were formulated by melt-emulsification using the SRMS, PEG 4000 and gentamicin (1.0, 2.0, 3.0% w/w), and their physicochemical as well as pharmacokinetic parameters determined. In vitro permeation of gentamicin from the SLMs through artificial membrane (0.22?μm pore size) was carried out using Franz’s cell and phosphate-buffered saline (PBS, pH 7.4) as acceptor medium, while bioevaluation was performed using clinical isolates of Pseudomonas aeruginosa and Staphylococcus aureus. Stable and irregularly-shaped gentamicin-loaded SLMs of size range 34.49?±?2.56 to 53.52?±?3.09?µm were obtained. The SLMs showed sustained drug permeation and exhibited time-dependent and capacity-limited bioactivity. Overall, SLMs containing 2% w/w SRMS, 3% w/w gentamicin and PEG 4000 entrapped the highest amount of drug, gave highest IZD against the test organisms and highest permeation flux (5.239?μg/cm².min) and permeation coefficient (1.781?×?10^?6?cm/min) within 420?min, while pure gentamicin gave the least. Preliminary in vivo pharmacokinetic studies also showed an AUC-₂₄ of 1507?µg/h/ml for the optimized formulation, while that of oral drug solution was 678?µg/h/ml. This showed a 2.2-fold increase in the systemic bioavailability of gentamicin from the optimized formulation. PEGylated SRMS-based SLMs prepared with heterolipid from Irvingia gabonensis would likely offer a reliable delivery system for gentamicin.     

新型可降解聚酯材料地西泮缓释微球的研制

目的　优化制备工艺,用新型的生物可降解材料聚羟基丁酸酯—羟基戊酸酯共聚物（PHBV）与D,L-聚乳酸（PLA）共混物为基材制备以地西泮（diazepam,DZP）为模型药物的缓释微球（MS）。方法　用正交设计优化微球制备工艺,用扫描电镜（SEM）观察微球表面形态。对微球粒径及其分布、体外释药、稳定性及在动物体内药动学进行了测定。结果　微球平均粒径为(20.45±4.50) μm,粒径在15.5～35.2 μm占总数88%以上。载药量为(16.95±0.80)%,包封率为(69.68±1.13)%;体外释药方程为Q=2.7027t+13.50(γ=0.9827),动物体内实验表明,微球的血药浓度-时间曲线下面积AUC是溶液对照组的2.35倍,平均驻留时间MRT是对照组的3.62倍。微球在冰箱4℃与室温（20～25℃）条件下性质稳定。结论　微球制备工艺稳定,与DZP针剂相比,具有明显缓释作用。     

Fabrication of long-acting insulin formulation based on poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanoparticles: preparation,optimization, characterization,and in vitro evaluation

The purpose of this research was the fabrication, statistical optimization, and in vitro characterization of insulin-loaded poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) nanoparticles (INS-PHBV-NPs). Nanopar-ticles were successfully developed by double emulsification solvent evaporation method. The NPs were characterized for particle size, entrapment efficiency (EE%), and polydispersity index (PDI). The NPs also were characterized by scanning electron microscopy (SEM), Fourier transformed infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and circular dichroism (CD). The optimum conditions were found to be 1.6% polyvinyl alcohol (PVA), 0.9% of PHBV, and 15?mg/ml of insulin with the aid of the Box–Behnken experimental design results. The optimized NPs showed spherical shape with particle size of 250.21?±?11.37?nm, PDI of 0.12?±?0.01, and with EE% of 90.12?±?2.10%. In vitro drug release pattern followed Korsmeyer–Peppas model and exhibited an initial burst release of 19% with extended drug release of 63.2% from optimized NPs within 27?d. In conclusion, these results suggest that INS-PHBV-NPs could be a promising candidate for designing an injectable sustained release formulation for insulin.     

THE MEASUREMENT OF GLOMERULAR BLOOD FLOW IN THE RAT KIDNEY: INFLUENCE OF MICROSPHERE SIZE

1. Radioactively labelled microspheres were used to determine glomerular blood flow in glomerular populations with distinct vascular characteristics. Two batches of microspheres (15 ± 5.0 μm diameter and 7.0–10 μm diameter) were utilized. 2. The results show that the larger microspheres overestimate the superficial glomerular blood flow (414 ± 61 nl/min, mean ± s.e.m.) and underestimate the deep glomerular blood flow (98 ± 10 nl/min), when compared with the data obtained with 7.0–10 μm diameter microspheres (317 ± 30 nl/min and 209 ± 23 nl/min, respectively). 3. The rheological artefact associated with the use of larger microspheres is confirmed by finding an uneven size distribution of microspheres lodged in the glomeruli. In each of three experiments, the mean diameter of 200 microspheres lodged in the superficial glomeruli (16.43 ± 0.27 μm, 15.87 ± 0.23/mi and 16.58 ± 0.27 Jim) was significantly greater than that found in the deep glomeruli (15.36 ± 0.15μm, 15.25 ± 0.21 μm and 15.73 ± 0.24μm; P<0.01, <0.05 and < 0.01, respectively). No such difference was detected when the 7.0–10 μm spheres were used. 4. Glomerular blood flow can be measured at all depths of the rat's cortex and the demonstrated rheological artefact associated with use of the larger spheres is circumvented with the use of 7.0–10 μm microspheres.     

Flixotide™‐pressurized metered‐dose inhalers loaded with [18F]fluticasone propionate particles for drug deposition studies in humans with PET–formulation and analysis

Fluticasone propionate (FP) is a potent anti‐inflammatory synthetic steroid, used for the treatment of asthma. Flixotide? is a formulated pressurized metered‐dose inhaler (pMDI) that contains small‐micronized FP particles in a blend of CFC propellants. Our objective was to develop a radiotracer method for accurately measuring the regional deposition of FP within the human lung using positron emission tomography (PET), which would be of important clinical interest. Flixotide? pMDIs were used to prepare [¹⁸F]FP pMDIs labeled isotopically with the positron emitter, fluorine‐18 (t_1/2=109.7 min). FP particles from Flixotide? pMDIs were mixed with [¹⁸F]FP formulated into a pMDI and sonicated at room temperature. The drug delivery of [¹⁸F]FP pMDI (250 μg of FP per actuation dose) was assessed for particle size distribution and dose uniformity. The distributions of FP and [¹⁸F]FP across particle size in such preparations were measured with an Andersen cascade impactor. This procedure was shown to provide an emitted dose from a [¹⁸F]FP pMDI of 246±19 μg/per metered dose. The particle size distribution as measured by mass median aerodynamic diameter (MMAD) (The mass median aerodynamic diameter (MMAD) and the geometric standard deviation (GSD) for each distribution were calculated. MMAD is defined as the aerodynamic diameter around which the mass of particles is equally distributed and the GSD is a measure of the dispersion of these particle diameters around the MMAD) from a commercial Flixotide? pMDI was 2.6±0.2 μm and agreed well with that from an [¹⁸F]FP pMDI (2.8±0.1 μm). The MMAD and geometric standard deviation (GSD) of newly formulated [¹⁸F]FP pMDIs were unaffected by the formulation procedure. [¹⁸F]FP was distributed with good uniformity with respect to the mass of FP for particles greater than 0.43 μm. Hence, the radiolabeled pMDI is a suitable source of radiotracer for the regional measurement of lung deposition for inhaled FP in human subjects with PET. Copyright © 2003 John Wiley & Sons, Ltd.     

Novel multifunctional platforms for potential treatment of cutaneous wounds: Development and in vitro characterization

An original formulative/manufacturing approach for the development of a multi-composite wound dressing able to control the release of a water soluble API (lidocaine HCl) for several days was evaluated. The prepared multi-composite wound dressing is a microstructured spongy matrix, which embeds solid lipid microparticles (SLMs). The matrices were obtained by freeze drying of polyelectrolyte complexes made up two biopolymers: three different chitosan to alginate weight ratios (1:1, 3:1 and 1:3) were studied. The drug-loaded matrices were investigated as regards water uptake ability, swelling, drug loading, morphology and release profiles. SLMs were prepared at two different drug loadings (5% and 25%, w/w) by the spray congealing technology and were then incorporated in the spongy matrices. The characterization of the SLMs evidenced their spherical shape, mean dimensions lower than 20 μm, controlled release and the modification of the drug crystalline state. Comparing the release profiles of the SLMs-loaded sponges, the matrices with 1:3 chitosan/alginate ratio displayed a sustained release profile with the lower burst effect. Then hyaluronan and cysteine were embedded into the matrix to enhance the wound healing properties of the dressing. The final multi-composite platform was able to promote the growth of fibroblasts maintaining its prolonged release characteristic.     

Preparation and Characterization of Docetaxel-PLGA Nanoparticles Coated with Folic Acid-chitosan Conjugate for Cancer Treatment

The conjugation of chitosan (CS) and folic acid (FA) was prepared and used to coat PLGA nanoparticles (NPs) that are loaded with Docetaxel (DTX) to target cancer cells that have lower pH and overexpression of folate receptors in comparison to normal cells. Three formulations had been prepared to reach the highest loading capacity (LC%) and encapsulation efficiency (EE%) and to study the effect of the amount of FA-CS on the drug release. The sizes, charges, homogeneity, surface morphology, LC% and EE% of the NPs were determined. The NPs were characterized using FTIR and XRD. In vitro release profiles of DTX from PLGA NPs, at pH 5.5 and 7.4 were determined. Finally, in vitro cytotoxicity assay on three cancer cell lines (RPMI 2650, Calu-3, and A549) was studied. The sizes of the three formulations ranged between 250.3±1.7 and 356.3±17.7. All prepared formulations showed acceptable monodispersity with highly positive charges. The EE% was above 85% and the LC% ranged between 6-35%. The in vitro release of DTX show an inverse relation to the amounts of FA-CS used and the pH of the dissolution medium. Coated PLGA NPs showed a significant difference in RPMI 2650, Calu-3, and A549 cell viability in comparison to free DTX. The NPs components were safe and non-toxic to human cells. In conclusion, coating PLGA NPs with FA-CS may be used as a good carrier for chemotherapeutic agents that selectively target carcinogenic tissues.     

pH敏感的肿瘤靶向聚合物胶束的体外性质

目的 制备肿瘤微环境敏感、具有肿瘤细胞靶向能力和穿膜能力的融合肽FQSIYPpIKRRRRRRRRHHHHC (FRH)修饰的聚合物胶束,并对其体外性质进行初步考察.方法 采用FRH修饰N-(2-羟丙基)-甲基丙烯酰胺(HPMA)聚合物-β-谷甾醇(β-SITO),形成HPMA聚合物胶束(FRH-M),考察其理化性质、肿瘤细胞的摄取和抑制肿瘤细胞生长的效果.结果 透射电镜显示:胶束为均匀的类球形.FRH-M胶束粒径约为55 nm,阿霉素载药量8.3％.该胶束在pH7.4条件下,Zeta电位为-3.01±0.05 mV,在pH6.4条件下,电荷翻转为5.27-0.32 mV.FRH-M的药物释放速度随释放介质的pH降低而加快.FRH-M的细胞摄取较未经修饰胶束的P-M提升了1.9倍;且在pH6.4条件下的细胞摄取明显高于pH7.4的,FRH-M的IC50值为1.40 ±0.41 μg·mL-1,明显低于未经配体修饰的胶束(5.08±0.33 μg· mL-1).结论 经FRH多肽修饰的聚合物胶束具有良好的肿瘤微环境响应能力,且有更好的细胞摄取能力和体外抗肿瘤活性,极具发展前景.     

Synthesis and in vitro studies of cross-linked hydrogel nanoparticles containing amoxicillin

In this paper, we report the synthesis and characterization of a novel cross-linked N-isopropylacrylamide-acrylic acid-hydroxyethyl methacrylate [P (NIPASM-AA-HEM)] hydrogel nanoparticles (NPs) containing amoxicillin. The aim of present study was to investigate whether these hydrogel NPs have the potential to be used in antibiotic delivery to stomach for treatment of Helicobacter pylori. Amoxicillin-loaded hydrogel NPs were prepared using cross-linked P (NIPASM-AA-HEM) as mucoadhesive polymer for the potential use of treating gastric and duodenal ulcers. Aiming at predicting the in vivo behavior of the amoxicillin-loaded NPs, the physicochemical properties in terms of entrapment efficiency (EE%), mean diameter, and morphology of NPs was evaluated. The dependence of the EE% of the drug on the organic to aqueous phase ratio was also studied. The profile of amoxicillin release from P (NIPASM-AA-HEM) NPs system was studied under various conditions. In all these experiments, amoxicillin release in the free form was studied by ultraviolet (UV) spectrophotometric analysis. Experimental results showed that at pH 7.4, drug release rises when polymer concentration in the formulation increases; in human plasma on the contrary, drug release is reduced as concentration of the polymer in the formulation rises. In vitro amoxicillin release rate was also higher in pH 1 than that in pH 7.4. About 88.5% of amoxicillin entrapped in the NPs was released in 4 h in the pH 1.0 medium, whereas in phosphate buffer at pH 7.4 no more than 45% was released after 4 h incubation at 37 °C. Amoxicillin concentration in rat's gastric tissue was determined. The results of in vivo studies showed that the hydrogel NPs enhance drug concentration at topical site than powder amoxicillin. Thus, amoxicillin-loaded hydrogel NPs may provide therapeutic concentration at a much lower dose that may reduce the adverse effects of amoxicillin in high doses.