Albumin Microspheres Research Articles

Formulation and in vitro characterization of spray-dried antisense oligonucleotide to NF-κB encapsulated albumin microspheres

Formulation and in vitro characterization of spray-dried antisense oligonucleotide to NF-κB encapsulated albumin microspheres

A methodology for quantitation and characterization of oligonucleotides in albumin microspheres

A fluorescence assay was developed to quantify oligonucleotides (ODNs) encapsulated in bovine serum albumin (BSA) microspheres using antisense to Nuclear Factor-kappaB (NF-kappaB) as a model ODN and employing Oligreen as the fluorescent dye. Methodologies were optimized for the suspension of the microspheres as well as release of the encapsulated ODN using protease digestion. This was followed by the detection and quantitation of the ODN using the Oligreen dye. The Oligreen fluorescence assay gave a concentration-dependent fluorescent interaction with the ODN. Further characterization of the ODN with respect to their structural integrity in non-irradiated and gamma-irradiated antisense encapsulated in BSA microspheres was performed using HPLC, infrared spectroscopy and polyacrylamide gel electrophoresis. Results showed no structural modification of antisense in the BSA microspheres as determined by HPLC retention times for the pure antisense and microsphere-encapsulated ODN. The migration pattern of the antisense in polyacrylamide gels confirmed the absence of significant alterations as a result of the encapsulation process or due to gamma-irradiation. The infrared spectra of non-irradiated and gamma-irradiated antisense to NF-kappaB microspheres also displayed peaks characteristic of the functional groups. The fluorescence assay could also detect NF-kappaB antisense in the serum of rats administered with encapsulated antisense by oral and intravenous routes. This methodology should be valuable for the analysis of BSA-encapsulated antisense ODN and for pharmacokinetic studies during antisense therapy.

Preparation and evaluation of biodegradable microspheres of methotrexate

The objective of the present study is to prepare sustained-release methotrexate microspheres of bovine serum albumin in different ratios by the emulsion cross-linking method. The prepared microspheres were subjected to various physicochemical evaluation and in vitro release studies. The drug release from microspheres of 1:6 ratio is the most constant and prolonged drug release is diffusion followed by erosion. The characteristics of the prepared microspheres are conducive to the formulation of the sustained release drug delivery system.

Labelling of albumin microspheres with <SUP align=right>188</SUP>Re: a possible agent for radiotherapy

Regional administration of labelled particles by intra-arterial infusion is an effective method for endoradiotherapy of tumours. The goal of the study was to develop an efficient method for radiolabelling of biodegradable human serum albumin microspheres with the beta emitter 188Re. The influence of different factors, as the reagents concentration, temperature, time, etc., on reaction yield was studied. Under optimised conditions, after 60 min reaction time, at 95°C, the reaction yield was more than 95%. Labelled microspheres were found to be stable in vitro; 43 h after labelling, 87% of 188Re was bound to the microspheres.

Formulation and evaluation of albumin microspheres and its enteric coating using a spray-dryer

This study optimized and evaluated the conditions for surface coating of microspheres using a spray-dryer. Four formulations of Bromophenol blue (BPB)-loaded albumin microspheres were prepared using a spray-dryer, cross-linked at different concentrations and time periods. One of the optimized formulations with the desired characteristics was selected for enteric coating with Eudragit L100-55®. The procedure involved suspending BPB microspheres in polymer solution and spray-drying it. Four enteric coated formulations were prepared with different concentrations of microspheres in suspension (0.25 and 0.5%w/v) and polymer concentrations (0.25 and 0.5%w/v). Change in the mean particle size after coating was determined using a Laser Particle Counter. The surface coating technique employed did not significantly increase the particle size. Enteric coating efficiency was determined in simulated gastric fluid. Compared to the uncoated microspheres the cumulative amount of drug released from coated microspheres was significantly lower for 3 h, implying efficient surface coating.

Inhibitory effects of 5-fluorouracil magnetic albumin microsphere on human pancreatic carcinoma

Objective To investigate the inhibiting effects of 5-fluorouracil magnetic albumin microsphere (5-FU-MAMS) in combination with constant external magnetic fields on human pancreat-ic carcinoma in vitro and in vivo. Methods The human pancreatic carcinoma PC-3 cells were cultured and an experimental model was established in nude mice to investigate the inhibiting effects. Results In vitro study showed that 5-FU-MAMS in combination with constant external magnetic fields could significantly inhibit the growth of PC-3 ceils as compared with other agents (P＜0.05). The in vivo study revealed that 5-FU-MAMS could be well localized in the tumor tissue and markedly inhibit the growth of tumor. The inhibitory rate of tumor size was 90.47% and that of tumor weight 88. 16%.There were significant differences as compared with other groups (P＜0.05). Conclusion Under con-stant external magnetic fields, 5-FU-MAMS can achieve satisfactory results for targeted therapy of pancreatic carcinoma. Key words: Pancreatic neoplasms; 5-FU-MAMS; Targeted therapy

Evaluation of albumin microspheres as oral delivery system for Mycobacterium tuberculosis vaccines

Mucosal immunization has been suggested to be the best option for preventing Mycobacterium tuberculosis infection. The purpose of this study was to develop albumin microspheres containing Mycobacterium tuberculosis antigens and to determine if oral administration of the microspheres can induce antigen-specific mucosal and systemic immune responses. Albumin microspheres containing Mycobacterium tuberculosis dead cells and cell lysate were prepared. The physico-chemical characteristics of the formulations were determined and the microspheres were administered to animal models to evaluate the induction of immune responses to the antigens. The results showed that the particle sizes, zeta potential and dissolution pattern of the microspheres were ideal for oral delivery of vaccines. In vivo studies showed high production of antigen-specific antibody production in serum, nasal, salivary and faecal samples. From the results of the study, it can be concluded that oral administration of Mycobacterium tuberculosis microspheres was successful in inducing antigen-specific systemic and mucosal immune responses.

Treatment of adjuvant arthritis using microencapsulated antisense NF-κB oligonucleotides

Antisense oligonucleotides are promising new therapeutic agents used to selectively inhibit target genes such as Nuclear Factor Kappa B (NF-κB), an important transcription factor in the pathogenesis of inflammatory disease. The purpose of the present study was to evaluate microencapsulated antisense oligonucleotides specific to NF-κB for in vitro efficacy and treatment of adjuvant-induced arthritis in rats. Oligonucleotide-loaded albumin microspheres were prepared and characterized in terms of size, zeta potential, morphology and release pattern. This study reports significant NF-κB inhibition in vitro after treatment with microencapsulated antisense oligonucleotides. Furthermore, microencapsulated antisense NF-κB oligonucleotides were found to inhibit paw inflammation associated with rat adjuvant-induced arthritis in a dose-dependent manner. Taken together, the results presented in this work described albumin microspheres to be effective delivery vehicles for antisense NF-κB oligonucleotides and a potential treatment for inflammatory diseases.

Microwave-assisted Preparation of Magnetic Albumin Microspheres

A new microwave-assisted method was used to prepare magnetic Fe3 O4 particles and magnetic bovine albumin microspheres. The microwave method produced smaller particles and is faster than traditional methods. The optimum conditions to prepare the Fe3O4 particles were three minutes at pH 13 and 80°C. Magnetic microspheres containing albumin were synthesized based on heating times and temperatures to form microspheres with different properties. For example, heating for 4min, at 160°C, yielded smaller sized microspheres (30 μm). Confirmed by XRD, SEM, and FT-IR that iron oxide particles were encapsulated in biocompatible proteins, The thermal stability of the microspheres were determined by DSC and TG. The magnetic properties were determined by UV—VIS spectraphotometry and a Guoy magnetic balance. This microwave process could become a preferred method for the synthesis of magnetized protein microspheres.

Efficacy of alternative dosing regimens of poly-aggregated amphotericin B

A new poly-aggregated form of amphotericin B was formulated as a non-microencapsulated form (P-AMB) or incorporated in albumin microspheres (MP-AMB) and compared with the conventional amphotericin B formulation (D-AMB). Mice were infected with Candida albicans and treated with two different intermittent dose regimens of the different amphotericin B formulations. Efficacy and toxicity were studied by the determination of survival rate, kidney colony-forming units counts, biochemical parameters and amphotericin B concentrations in plasma and organs. All the treatments significantly ( P < 0.05) increased the survival rate in relation to the untreated group, although non-statistically significant differences ( P > 0.05) were found between formulations and dosing regimens. All the treatments produced kidney toxicity, expressed by high urea levels. Kidney toxicity was especially significant for mice treated with the D-AMB formulation where unilateral kidney atrophy was observed in most of the mice, whereas most of the mice treated with P-AMB conserved both kidneys with a normal size and appearance. At 45 days post infection, variable distribution of amphotericin B in the body was obtained depending on the amphotericin B formulation. In conclusion, non-daily dosing regimens of P-AMB, which is less toxic than D-AMB, could be used as an alternative to the conventional D-AMB formulation to treat experimental candidiasis.

In vivo distribution and therapeutic efficacy of a novel amphotericin B poly-aggregated formulation

The purpose of this investigation is the study of toxicity, in vivo distribution and therapeutic activity against candidiasis of poly-aggregated amphotericin B, in two different formulations: not microencapsulated (P-AMB) or incorporated in albumin microspheres (MP-AMB). The therapeutic efficacy and toxicity of amphotericin B formulations was studied in an immunocompetent murine model of systemic candidiasis. A pharmacokinetic study was also performed to measure the plasma, kidney, liver and spleen amphotericin B concentrations after administration of the three formulations to mice. The acute toxicity of P-AMB in mice is lower than that of the conventional amphotericin B reference formulation (D-AMB). The 50% lethal doses were increased at least eight times. Intravenous bolus administration of doses up to 40 mg/kg of body weight of poly-aggregated amphotericin B, either P-AMB or MP-AMB, did not produce acute symptoms of toxicity. Interestingly, in the pharmacokinetic study, significant (P < 0.05) lower plasma and kidney amphotericin B concentrations and higher liver and spleen amphotericin B concentrations were achieved after poly-aggregated amphotericin B formulation (P-AMB and MP-AMB) administration in relation to the reference formulation (D-AMB). At high amphotericin B doses, no significant differences in efficacy (P > 0.05) were observed among the formulations (D-AMB, P-AMB and MP-AMB). Although the efficacy in the candidiasis treatment was decreased as a consequence of amphotericin B aggregation, it can be compensated by the possibility of increasing the doses with lower nephrotoxicity. Moreover, due to its lower toxicity while maintaining its effectiveness, the poly-aggregated formulations (P-AMB and MP-AMB) have a better therapeutic index than the conventional formulation (D-AMB).

Albumin microspheres as an ocular delivery system for pilocarpine nitrate

Pilocarpine nitrate loaded egg albumin microspheres were prepared by thermal denaturation process in the size range of 1-12 μm. A series of batches were prepared to study factors, which may affect the size and entrapment efficiency of drug in microspheres and optimized the process. Drug loaded microspheres so obtained were evaluated for their size, entrapment efficiency, release rate and biological response. Electron photomicrographs were taken (8000X) to study the morphological characteristics of microspheres. The entrapment and encapsulation of pilocarpine after process optimization was found to be 82.63% and 62.5% respectively. In vitro dissolution rate studies revealed that the release of drug from the microspheres followed spherical matrix mechanism. Biological response of microspheric suspension was measured by reduction in intraocular pressure in albino rabbit eyes and compared with marketed eye drops. Various pharmacokinetic parameters viz. onset of action, duration of action, Tmax and AUC were studied. A measurable difference was found in the mean miotic response, duration and AUC of pilocarpine nitrate microspheric suspension.

Yttrium-86-labelled human serum albumin microspheres: relation of surface structure with in vivo stability

Radiolabelled particles are an attractive tool in the therapy of malignancies of the liver. We consider particles manufactured from denatured human serum albumin (HSA) as useful carriers of therapeutic radionuclides. Covalent attachment of suitable chelators onto the surface of the spheres promises an easy access to radiolabelled HSA microspheres. We synthesized 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid (DOTA) bearing smooth, medium-rough and rough surfaced HSA microspheres (mean diameter: 25 microm). In vitro stability of 86 Y-labelled particles was determined after incubation in human plasma and in a DTPA challenge experiment. In vivo stability of 86 Y DOTA-HSA microspheres was determined after single intravenous application in rats. Subsequently, the particles were completely trapped in the lung microvasculature. Thus, the lung serves in our experiments as target organ. DOTA-HSA microspheres were 86 Y labelled in reproducible high yields (>95%). No differences between smooth and rough surfaced spheres were found for both DOTA coupling and 86 Y labelling. Labelled microspheres showed high in vitro stability in human plasma and in DTPA solution with only 8+/-1% and 2+/-0% loss of radioactivity from the surface, respectively, 48 h postinjection (pi). The three batches (smooth, medium-rough and rough surfaced microspheres) differed considerably in their radioactivity recovery in the lungs of rats 48 h pi. Smooth particles showed the highest in vivo stability of the radiolabel on the surface of the spheres, presumably because of slower proteolytic degradation. We found that for the preparation of HSA-derived microspheres for radiotherapeutic application, smooth surfaced spheres are superior to rough spheres due to their higher in vivo stability of the radionuclide fixation.

Pingyangmycin loaded bovine serum albumin microspheres for chemoembolization therapy— in vitro and in vivo studies

Chemoembolization based on microspheres have been emerged as a novel and promising way for interventional therapy, however, the exact effect and probable mechanism have not been revealed. The purpose of our study was to evaluate the potential of Pingyangmycin loaded bovine serum albumin microspheres (PYM-BSA-MSs) for chemoembolization therapy both in vitro and in vivo. The effect of PYM-BSA-MSs on cell growth curves and changes of cell morphology and activities measured by MTT assay were carried out in human umbilical vein endothelial ECV-304 cells. The in vivo occlusion effect was evaluated in 24 healthy rabbits. Macroscopic examinations and Hematoxylin-Eosin (H-E) staining of cross-section of rabbits’ central auricular arteries were employed to observe the apparent and histological changes of arterioles. The results show that the PYM-BSA-MSs could inhibit the proliferation and induce the apoptosis of ECV-304 cells in a time-dependent manner. In vivo studies demonstrated that 21 days after artery embolization with the PYM-BSA-MSs, neointimal thickening of arterioles and significant hyperplasia of endothelial cells could be detected, but without completely interruption of blood flow. Compared with plain PYM aqueous solution or BSA-MSs oily suspension, PYM-BSA-MSs showed excellent potential as an alternative to interventional embolization materials.

Preparation of 5-fluorouracil magnetic albumin microspheres and its inhibitive action on human pancreatic carcinoma cells

目的 研究5-氟尿嘧啶磁性白蛋白微球(5-fluorouracil magnetic albumin microspheres,5-FU-MAMS)的制备及其联合恒定外磁场体外对人胰腺癌PC-3细胞的生长抑制作用.方法 乳化热固化技术制备5-FU-MAMS并检测其理化性质,MTT比色分析法观察5-FU-MAMS联合恒定磁场体外对人胰腺癌细胞的抑制作用.结果 5-FU-MAMS平均粒径为200～1000 nm,呈球形,磁响应性良好,载药量为每毫克微球含5-FU 50μg;单纯磁场组和各种浓度的空白MAMS对肿瘤生长无影响;相应药物浓度的5-FU-MAMS与5-FU抑制率(inhibition ratio,IR)相似,差异无统计学意义(P＞0.05);相应药物浓度的5-FU-MAMS联合恒定外磁场与单纯的5-FU-MAMS和游离5-FU相比,IR明显提高,差异有统计学意义(P＜0.05).结论 MAMS可作为安全的药物载体;5-FU-MAMS制备方法和剂型的改变不影响5-FU的抗癌活性;联合恒定外磁场5-FU-MAMS的肿瘤细胞抑制效应显著增强。

In vitro effect of new formulations of amphotericin B on amastigote and promastigote forms of Leishmania infantum

The in vitro antileishmanial activities of various new amphotericin B (AMB) formulations were investigated, including microspheres of hydrophilic albumin with three AMB aggregation forms (monomeric, dimeric and multiaggregate) and the polymers of polylactic-co-glycolic acid, Resomer RG502 and RG503 with the multiaggregate AMB form. This in vitro study was performed on the extracellular promastigote form and the intracellular amastigote form of a canine strain of Leishmania infantum (UCM 20) using the infected J774 murine macrophage-like cell line. Albumin-encapsulated forms did not show any toxicity for murine cells and had lower median effective concentration (EC 50) values (ca. 0.003 μg/mL) for L. infantum amastigotes than free formulations (0.03 μg/mL). In addition, the aggregation state of AMB had a notable effect on the antileishmanial activity of the drug. Results obtained in vitro point towards interest in monomeric AMB encapsulated in microspheres in the chemotherapeutic control of leishmaniasis.

Application of nanosized Fe3O4 in anticancer drug carriers with target-orientation and sustained-release properties

The purpose of this study was to prepare human serum albumin (HSA) microspheres with Fe3O4 magnetic nanoparticles for tumor target therapy. Fe3O4 was obtained by liquid-phase coprecipitation; HSA-coated magnetic particles were attained by solidification at high temperature. The result was that nanosized Fe3O4 is a cubic crystal by XRD and the average size is 18.7 nm; the average size of HSA-coated magnetic particles is 341 nm. Fe3O4 magnetic nanoparticles coated with HSA can be used for targeted-drug carriers with target-orientation and sustained-release properties.

Formulation and evaluation of ketorolac tromethamine-loaded albumin microspheres for potential intramuscular administration

The objective of this work was to prepare and evaluate ketorolac tromethamine-loaded albumin microspheres using a factorial design. Albumin microspheres were prepared by emulsion cross-linking method. Selected formulations were characterized for their entrapment efficiency, particle size, surface morphology, and release behavior. Analysis of variance (ANOVA) for entrapment efficiency indicated that entrapment efficiency is best fitted to a response surface linear model. From the statistical analysis it was observed that as the drug:polymer (D:P) ratio and volume of glutaraldehyde increased, there was a significant increase in the encapsulation efficiency. Scanning electron microscopy of the microspheres revealed a spherical, nonporous and uniform appearance, with a smooth surface. Based on the entrapment efficiency and physical appearance, 9 formulations were selected for release study. The maximum particle size observed was below 40 microm. The release pattern was biphasic, characterized by an initial burst effect followed by a slow release. All selected microspheres, except those having less polymer proportion (D:P ratio is 1:1), exhibited a prolonged release for almost 24 hours. On comparing r (2) values for Higuchi and Peppas kinetic models, different batches of microspheres showed Fickian, non-Fickian, and diffusion kinetics. The release mechanism was regulated by D:P ratio and amount of cross-linking agent. From the experimental data obtained with respect to particle size and extent of drug release, it could be concluded that the prepared microspheres are useful for once-a-day intramuscular administration of ketorolac tromethamine.

Preparation and characterization of Pingyangmycin-loaded bovine serum albumin microspheres for embolization therapy

Bovine serum albumin microspheres (BSA-MSs) containing Pingyangmycin hydrochloride (PYM) were prepared for the interventional embolization by an emulsification-crosslinking method. The average diameter of the MSs was 83.6 μm with 80% ranging from 35 to 200 μm. The MSs showed a rather high entrapment efficiency (EE%) of 87.6 ± 5.7% and the drug loading efficacy (DL%) was 20.2 ± 1.3%. The drug release behaviors were evaluated both in vitro and in vivo, using UV-spectroscopy and HPLC, respectively. The in vitro results showed a significantly delayed release of drug for 10 days. The central auricular artery of rabbit was chosen as an embolization sites to study the in vivo drug release and the pharmacokinetics of the MSs compared with PYM injections. Experiments performed by artery perfusion and embolization in rabbits central auricular artery revealed that the PYM loaded BSA-MSs (PYM-BSA-MSs) could obviously prolong in vivo drug release, extend the mean residence time (MRT) and had equal bioavailability compared with plain PYM injections. These results demonstrated that by embolization of the central auricular artery with PYM-BSA-MSs, the local drug concentration could maintain at a relative high level for a longer time, thus achieve the aim of tumor targeting therapy. PYM-BSA-MSs are excellent potential alternatives of interventional embolization materials for the treatment of maxillofacial region tumors.

Preparation, characterization, and optimization of pancreas-targeted 5-Fu loaded magnetic bovine serum albumin microspheres

The magnetic bovine serum albumin (BSA) microspheres (MS) were prepared by emulsification/solidification method. In this experiment, two kinds of magnetic MS, e.g. BSA MS and PEG-incorporated BSA microspheres (PMS) were prepared. The obtained MS were characterized by Malvern laser particle sizer and scanning electron microscopy (SEM). The obtained MS were spherical and about 1.3 μm in size. The magnetic responsivity and in vitro release behavior of these MS were studied in detail. The in vivo distribution and targeting delivery of 5-fluorouracil (5-Fu) magnetic MS after artery administration were studied in rat. The results showed that PMS could efficiently delivery 5-Fu to the targeted site compared with BSA MS without PEG MS and free drug.