The measurement of beclomethasone dipropionate entrapment in liposomes: a comparison of a microscope and an HPLC method

The purpose of this study was to examine the methodologies that may be used to estimate the maximum incorporation (<5 mole% drug) of beclomethasone dipropionate (BDP) in dipalmitoylphosphatidylcholine (DPPC) multilamellar liposomes. Two approaches are described. First, differential interference contrast (DIC) microscopy and cross-polarisation microscopy have been used to measure the concentration at which BDP crystals become apparent in BDP-containing liposome preparations, thereby allowing a semi-quantitative but simple estimation of entrapment. An alternative method is described whereby the unentrapped solid drug is separated from the liposomes via suspension in D2O, followed by centrifugation and HPLC analysis. The method resulted in an estimate of 1.5-2 mole% BDP, while the HPLC method yielded a value of 2.52 mole% BDP.     

An in vitro investigation into the effect of glycosaminoglycans on the skin partitioning and deposition of NSAIDs

Beclomethasone dipropionate (BDP) liposomes were prepared from various lipids, dilauroyl phosphatidylcholine (DLPC), dimyristoyl phosphatidylcholine (DMPC), dipalmitoyl phosphatidylcholine (DPPC), and hydrogenated soybean phosphatidylcholine (Epikuron 200 SH). A lipid with a low transition temperature (T(m)) (DLPC) incorporated a higher amount of BDP than lipid with a high T(m). The nebulisation of rehydrated freeze-dried BDP liposomes was carried out using a Pari LC Plus nebuliser and the generated aerosol characterised by an Andersen Cascade Impactor operated at 28.3 l/min. The rehydrated BDP-DLPC liposomes showed a higher output (78.3%) and a higher fine particle fraction (FPF) (75.0%) and smaller mass median aerodynamic diameter (MMAD) (3.31 microm) than the other rehydrated liposome preparations. Liposomes containing lipid with a high T(m) (DPPC and Epikuron) underwent aggregation during nebulisation. This was shown by the large increase in size of the DPPC liposomes from 15.78 to 47.51 microm and the Epikuron liposomes from 5.84 to 46.70 microm.     

卡铂前体脂质体的制备及安全性的初步评价

目的：制备卡铂前体脂质体,并对用药安全性进行初步评价.方法：采用薄膜挤压法制备卡铂脂质体,加入冻干支持剂冷冻干燥后得到卡铂前体脂质体.对豚鼠全身用药的过敏性、家兔全身用药的血管刺激性以及溶血性进行考察.结果：制备所得的卡铂前体脂质体水合后的包封率为72.0%,载药量为24.0%,平均粒径为125.1 nm.卡铂前体脂质体不引起豚鼠过敏反应,不引起家兔溶血和红细胞凝集反应,静脉注射对家兔血管无刺激性.结论：制备所得的卡铂前体脂质体有较高的包封率和载药量,水合后粒径均匀,形态圆整,且具有较好的用药安全性.     

Oral beclometasone dipropionate in the treatment of extensive and left-sided active ulcerative colitis: a multicentre randomised study

AIM: To explore the efficacy and safety of the topically acting steroid beclometasone dipropionate (BDP) in an oral controlled release formulation in the treatment of extensive or left-sided ulcerative colitis. METHODS: In a multicentre, randomised, parallel-group, single-blind study, patients with active mild to moderate ulcerative colitis were randomised to a 4-week treatment with BDP 5 mg/day o.d. vs. 5-ASA 0.8 g t.d.s. The primary efficacy variable was the decrease of Disease Activity Index (DAI) (clinical symptoms and endoscopic appearance of mucosa). Safety was evaluated by monitoring adverse events, vital signs, haematochemical parameters and adrenal function. RESULTS: One hundred and seventy-seven patients were enrolled and randomly treated with BDP (n = 90) or 5-ASA (n = 87). Mean DAI score decreased in both treatments groups (P < 0.0001 vs. baseline for both groups). Clinical remission was achieved in 63.0% of patients in the BDP group vs. 62.5% in the 5-ASA group. A significant DAI score improvement (P < 0.05) in favour of BDP was observed in patients with extensive disease. Both treatments were well tolerated. Mean plasma cortisol levels were significantly reduced vs. baseline in BDP recipients, but without signs of pituitary-adrenal function depletion. CONCLUSION: Oral BDP gave an overall treatment result in patients with active ulcerative colitis without signs of systemic side-effects.     

Poly(l-lactic acid) microspheres for pulmonary drug delivery: release kinetics and aerosolization studies

We have previously developed poly(l-lactic acid) (PLA) microspheres containing nedocromil sodium and beclomethasone dipropionate (BDP) for aerosolisation to the respiratory tract (El-Baseir, M.M., Phipps, M.A., Kellaway, I.W., Preparation and subsequent degradation of poly(l-lactic acid) microspheres suitable for aerosolisation: a physico-chemical study. Int. J. Pharm. 151 (1997) 145–153). In this study we have investigated the in vitro release kinetics of these two drugs from PLA microspheres and the deposition of the microspheres in an in vitro lung model (Andersen cascade impactor) following aerosolisation from a dry powder inhaler (Spinhaler^®). The in vitro kinetics of drug release revealed a controlled release of nedocromil sodium over 8 days with a burst effect (27–60%, w/w) which varied with the particle size of the microspheres. For BDP entrapped in PLA microspheres, controlled release of BDP occurred over 6 days. BDP release was determined by measuring the shift in the phase transition temperature of dimyristoylphosphatidylcholine (DMPC) liposomes induced by partitioning of the steroid into the lipid bilayers. The residual poly(vinyl alcohol) used as an emulsifier in the production of the microspheres was < 7% (w/w). The in vitro deposition of the microspheres (1.00 ± 0.21 μm) containing BDP from a Spinhaler^® to a cascade impactor at a flow rate of 60 l/min, resulted in 20% of the emitted dose deposited on stages corresponding to particles < 3 μm and approximately 42% < 5 μm.     

槲皮素前体脂质体的质量考察

目的制备液体型槲皮素前体脂质体,并对制剂质量进行考察。方法采用一种新型前体脂质体制备方法制备液体型槲皮素前体脂质体,将脂质体膜材和药物等以一定比例溶于分散介质中,形成一种无水的澄明溶液。考察其水合后粒子形态、粒径、电位、包封率及自组装速度等理化性质,并评价其体外释药性质。结果槲皮素前体脂质体遇水即可快速自组装成纳米级含药脂质体混悬液,水合后形态多为类球形,平均粒径为228.7nm,Zeta电位为21.2 mV,包封率可达90%以上,体外释药符合Higuchi方程。结论槲皮素口服前体脂质体制备工艺简单可行,包封率高,具有一定的缓释效果。     

The interaction of the penetration enhancer DDAIP with a phospholipid model membrane

Differential scanning calorimetry (DSC) was used to investigate the mechanism of action of a proprietary skin penetration enhancer, dodecyl-2-(N,N-dimethylamino)propionate (DDAIP) in dipalmitoylphosphatidylcholine (DPPC) liposomes. Furthermore, the effect of enhancer concentration on lipid thermotropic transitions was investigated. With increasing concentrations of DDAIP (from 5 to 50 mol%), the main transition peak shifted to lower temperatures and became more broad. The pretransition peak also shifted to lower temperatures with increasing concentrations of DDAIP and disappeared completely above an enhancer concentration of 20 mol%. Main transition and pretransition enthalpies of reaction decreased with increasing DDAIP concentration, indicating that enhancer treatment destabilized both rippled gel and liquid crystal phases within the bilayer. At and above a DDAIP concentration of 33.3 mol%, an additional transition was evident, indicating the presence of two phases of enhancer-lipid complex. Results suggest that DDAIP enhances drug transport by interacting with the polar region of the phospholipid bilayer and also by increasing the motional freedom of lipid hydrocarbon chains.     

Mixed micelle proliposomes for preparation of liposomes containing amphotericin B, in-vitro and ex-vivo studies

The aim of this work was to produce a form of injectable liposomes containing amphotericin B derived from mixed micelle proliposomes. Mixed micelles were derived from a mixture of lecithin/sodium cholate in aqueous media. The solubility of amphotericin B in proliposomes was studied as a function of lipid composition (total lipid concentration, molar ratio of lecithin/sodium cholate), and the dispersion media (pH, ionic strength, presence or absence of human serum albumin), and the temperature. The data show that micelle-->liposome transformation occurs during the dilution of proliposomes containing amphotericin B. These transformations could be followed via transmission electron microscopy (TEM). Data related to dilution of proliposomes as well, show that under no circumstance there occurs any precipitation that might be assigned to the decreased solubility of amphotericin B. These indicate that the incorporated drug also participates during the transformation of the proliposomes into liposomes. It is thus concluded that mixed micelle proliposomes are prime candidates for the production of a form of injectable amphotericin B in liposomes.     

High Sensitivity Differential Scanning Calorimetry Study of DNA-Cationic Liposome Complexes

PURPOSE: To investigate plasmid DNA interactions with liposomes prepared from dimyristoylglyceroethylphosphocholine (EDMPC) and DOPE using high sensitivity differential scanning calorimetry (HSDSC). MATERIALS AND METHODS: Large unilamellar liposomes of EDMPC with DOPE (mol ratio 0-50%) were prepared. Plasmid DNA was added to give a final DNA/lipid (-/+) charge ratio of 0.5. Samples were placed into an HSDSC and cooled to 3 degrees C, held isothermally for 30 min and then the temperature was ramped to 120 degrees C at a rate of 1 degree C/min. RESULTS: On heating EDMPC liposomes, the main phase transition occurred at 21.2 degrees C, with a low temperature shoulder on the endothermic peak. At low DOPE concentrations the main phase transition temperatures and enthalpies of transition were lower than for pure EDMPC, with a peak corresponding to a pure EDMPC phase occurring at DOPE concentrations of 12-17 mol%. At 50 mol%, no main transition endotherm was observed. DNA solution produced two endothermic peaks with numerous 'satellite' peaks indicating thermal denaturation. DNA binding to EDMPC changed the shape of the thermogram, indicating alteration in lipid packing within the bilayer. DNA induced demixing in the bilayers of DOPE-containing liposomes. CONCLUSION: HSDSC provided information for characterizing liposome formulations and DNA interactions with such vesicles.     

水飞蓟素前体脂质体的制备和大鼠药代动力学的研究水飞蓟素前体脂质体的制备和大鼠药代动力学的研究

目的为了提高水飞蓟素的口服生物利用度，研制水飞蓟素前体脂质体并对其理化性质进行考察；研究水飞蓟素前体脂质体的大鼠体内生物利用度。方法采用薄膜载体沉积法制备水飞蓟素前体脂质体，通过研究水合后脂质体的包封率、粒径、稳定性来考察其理化性质；将水飞蓟素前体脂质体在体外进行水合，再给予大鼠灌胃，用RP-HPLC法测定不同时间血浆中总的和游离的水飞蓟素的浓度，通过3P97程序计算药代动力学参数。结果用该法制得的前体脂质体包封率可达90%以上，平均粒径为238.8 nm，稳定性较好；药代动力学研究表明水飞蓟素脂质体在体内吸收较快，生物利用度较高。结论采用薄膜载体沉积法制备水飞蓟素前体脂质体，制备工艺简单，易于工业化生产；将水飞蓟素制备成前体脂质体提高了水飞蓟素的生物利用度。     

Liposome encapsulation improves efficacy of betamethasone dipropionate in atopic eczema but not in psoriasis vulgaris

Summary The effect of a liposomal preparation of betamethasone dipropionate (0.039%, BDP) has been compared to that of a commercial propylene glycol-gel containing 0.064% BDP in a double-blind, randomized, paired trial lasting 14 d in 10 patients with atopic eczema and 10 patients with psoriasis vulgaris.In eczema, the liposome preparation tended to reduce erythema and scaling more than the conventional gel, the difference in the latter parameter being significant on Day 7. There was greater improvement of psoriasis on the side treated with the reference gel.Hence, liposome encapsulation of BDP may increase the antiinflammatory action but not the antiproliferative effect. Since inhibition of mitotic activity is linked to the atrophogenicity of topical corticosteroids, the results suggest that liposome encapsulation may improve the benefit-risk ratio in eczema.     

Conformational stability of human interferon-gamma on association with and dissociation from liposomes

The integrity of a therapeutic protein has to be safeguarded when formulated in delivery systems such as liposomes. In this study, we investigated the conformational stability of recombinant human interferon gamma (hIFNgamma) on association with and after dissociation from liposomal bilayers using circular dichroism (CD) and steady-state fluorescence spectroscopy as well as time-resolved fluorescence methodology. We used hIFNgamma adsorption to and desorption from empty liposomes as a model for hIFNgamma-containing liposomes prepared via the film hydration method. CD studies indicated that no changes in the secondary and tertiary protein structure occur during and after interaction of hIFNgamma with the liposomes. Steady-state fluorescence emission spectra of untreated and liposome-desorbed hIFNgamma revealed that the environment of the sole Trp residue was not affected by the adsorption/desorption process. The Trp-36 residue remained fully quenchable by acrylamide after desorption of hIFNgamma from the liposomes. Time-resolved fluorescence studies were conducted to probe the local environment and the mobility of Trp-36 before, during, and after interaction of hIFNgamma with the liposomal membrane. Differences in rotational correlation time between free and liposomal hIFNgamma were attributed to immobilization of the protein on adsorption to the liposome bilayer. Disparities were detected between the average lifetimes of liposome-adsorbed hIFNgamma and hIFNgamma-liposomes, indicating that subtle changes in the Trp-36 environment took place during preparation of the liposomes via the film hydration method compared with the adsorption of hIFNgamma to the liposome surface. The results of this study indicate that association of hIFNgamma with negatively charged liposomes results in minimal changes in the secondary and tertiary structure of the protein. We conclude that all techniques used point to a full retention or restoration of the protein conformation after desorption from the liposomes.     

Oral beclometasone dipropionate in the treatment of active ulcerative colitis: a double-blind placebo-controlled study

AIM: To evaluate efficacy and safety of oral beclometasone dipropionate (BDP) when added to 5-ASA in the treatment of patients with active ulcerative colitis. METHODS: In a 4-week, placebo-controlled, double-blind study, patients with extensive or left-sided mild to moderate active ulcerative colitis were randomized to receive oral 5-ASA (3.2 g/day) plus BDP (5 mg/day) or placebo. Clinical, endoscopic and histologic features, and haematochemical parameters were recorded at baseline and at the end of the study. RESULTS: One hundred and nineteen patients were enrolled and randomly treated with BDP plus 5-ASA (n = 58) or placebo plus 5-ASA (n = 61). Both treatment groups showed a statistically significant decrease of disease activity index (DAI) and histology score at the end of treatment (P = 0.001, each). DAI score was lower in the BDP group than in the placebo group (P = 0.014), with more patients in clinical remission in the BDP group (58.6% vs. 34.4%, P = 0.008). Serum cortisol levels significantly decreased in BDP group vs. baseline (P = 0.002), but without signs of pituitary-adrenal function depletion. A low incidence of adverse events was observed in both groups. CONCLUSIONS: Oral BDP in combination with oral 5-ASA is significantly more effective than 5-ASA alone in the treatment of patients with extensive or left-sided active ulcerative colitis.     

反相高效液相色谱法测定鬼臼毒素和丙酸倍氯米松的含量

目的 :建立反相高效液相色谱法测定鬼臼毒素和丙酸倍氯米松含量的方法。方法 :采用SB -C18 为固定相的色谱柱 ,甲醇 -水(70∶30)为流动相 ,流速为0 8ml/min ,紫外检测波长为262nm ,柱温为25℃ ,用外标两点法定量。结果 :该方法下鬼臼毒素标准曲线为Y=0 3594X +0 2667 ,r=0 9999(n=5) ,线性范围为5～350μg/ml,回收率98 03 %～99 60 % (n=5) ;丙酸倍氯米松标准曲线为Y=1 462X—0 08 ,r=0 9999(n=5) ,线性范围为3～40μg/ml ,回收率为98 82 %～101 70 % (n=5) ;鬼臼毒素和丙酸倍氯米松的日内RSD分别为0 86 %和1 63 % (n=5) ,日间RSD分别为1 94 %和2 02 % (n=10)。结论 :该方法准确可靠、重现性好 ,能满足制剂质量标准的要求     

Formulation Development and in vitro Characterization of Proliposomes for Topical Delivery of Aceclofenac

Non-steroidal antiinflammatory drugs are routinely prescribed for the patients with rheumatic disease and such patients are at increased risk of serious gastrointestinal complications, when non-steroidal antiinflammatory drugs administered by oral route. The aim of the present study was to develop and characterized a vesicular drug carrier system (proliposome) for topical delivery of aceclofenac to overcome the problems related with oral route. Aceclofenac proliposome were prepared by the film-deposition on carriers method and characterized for size and surface morphology, drug content in both proliposomes and liposomal system, percent yield, in vitro drug release studies and drug permeation studies. The prepared system was also characterized for drug-excipients interaction by Fourier transform infrared spectrophotometer and stability studies. The size and surface morphology were studied using optical microscopy, scanning electron microscopy and transmission electron microscopy. A spherical shape of reconstituted aceclofenac liposome with an average vesicular size of about 500 nm was observed in photomicrographs. The maximum entrapment efficiency of reconstituted liposomes was 80.31% whereas the drug content in proliposomes was found to be more than 90%. In vitro release of drug was significantly retarded indicating sustained release of aceclofenac from proliposomes. Stability study was performed at various temperatures indicating that aceclofenac proliposomes are stable at lower temperature.     

Beclometasone dipropionate/formoterol: in an HFA-propelled pressurised metered-dose inhaler

A hydrofluoroalkane (HFA)-propelled pressurised metered-dose inhaler (pMDI) has been developed (using Modulite technology) for a new fixed combination of beclometasone dipropionate/formoterol fumarate (BDP/formoterol) 100 microg/6 microg. Each actuation of the BDP/formoterol HFA pMDI 100 microg/6 microg delivers 86.4 microg of BDP and 5 microg of formoterol. BDP/formoterol HFA pMDI was associated with significantly higher morning peak expiratory flow (PEF) values than BDP administered alone via a chlorofluorocarbon (CFC) pMDI (including when BDP was administered at a higher dosage) in well designed trials in adults with mild to moderate or moderate to severe asthma. In terms of morning PEF values, BDP/formoterol HFA pMDI was noninferior to BDP plus formoterol administered via separate inhalers in well designed trials in adults with moderate to severe asthma. BDP/formoterol HFA pMDI was noninferior to fixed-combination budesonide/formoterol (the daily dosage of BDP was half that of budesonide) in terms of lung function, asthma symptoms and use of rescue medications in adults with moderate to severe asthma. BDP/formoterol HFA pMDI was also noninferior to, and had a faster onset of bronchodilation than, fixed-combination fluticasone propionate/salmeterol. BDP/formoterol 200 microg/12 microg per day or 400 microg/24 microg per day administered by the HFA pMDI was generally well tolerated. Moreover, a single high dose of BDP/formoterol (1000 microg/60 microg) was generally well tolerated in patients with asthma.     

Chitosan‐coated antifungal formulations for nebulisation

Objectives The aim of this study was to produce and characterise amphotericin B (AmB) containing chitosan‐coated liposomes, and to determine their delivery from an air‐jet nebuliser. Methods Soya phosphatidylcholine : AmB (100 : 1) multilamellar vesicles were generated by dispersing ethanol‐based proliposomes with 0.9% sodium chloride or different concentrations of chitosan chloride. These liposomes were compared with vesicles produced by the film hydration method and micelles. AmB loading, particle size, zeta potential and antifungal activity were determined for formulations, which were delivered into a two‐stage impinger using a jet nebuliser. Key findings AmB incorporation was highest for liposomes produced from proliposomes and was greatest (approximately 80% loading) in chitosan‐coated formulations. Following nebulisation, approximately 60% of the AmB was deposited in the lower stage of the two‐stage impinger for liposomal formulations, for which the mean liposome size was reduced. Although AmB loading in deoxycholate micellar formulations was high (99%), a smaller dose of AmB was delivered to the lower stage of the two‐stage impinger compared to chitosan‐coated liposomes generated from proliposomes. Chitosan‐coated and uncoated liposomes loaded with AmB had antifungal activities against Candida albicans and C. tropicalis similar to AmB deoxycholate micelles, with a minimum inhibitory concentration of 0.5 µg/ml. Conclusions This study has demonstrated that chitosan‐coated liposomes, prepared by an ethanol‐based proliposome method, are a promising carrier system for the delivery of AmB using an air‐jet nebuliser, having a high drug‐loading that is likely to be effectively delivered to the peripheral airways for the treatment of pulmonary fungal infections.     

载基因纳米阳离子脂质体前体制剂的制备及性质研究

目的:制备稳定的载反义寡核苷酸的阳离子脂质体前体制剂。方法:以磷脂-二油酰磷脂酰乙醇胺(dioleoylphophatidylethanolamine,DOPE)-十八胺-胆固醇为类脂成分,采用薄膜超声-挤压制备空白阳离子脂质体,吸附-冷冻干燥法制备载反义寡核苷酸阳离子脂质体前体。激光粒度仪测定冷冻干燥前后脂质体Zeta电位及粒径,透射电镜观察其形态,葡聚糖凝胶柱分离未包封的反义寡核苷酸,紫外法测定冻干前后的载药率。结果:海藻糖与甘露醇及甘氨酸为较好的冻干保护剂,制得的阳离子脂质体前体带正电荷,规则球形,大小较均匀,海藻糖作为保护剂复溶前后平均粒径为175和320 nm左右,复融前后Zeta电位值在+32和+40 mV左右,脂质体的载药率复溶前后分别为87.6%与83.21%。结论:海藻糖作为冻干保护剂,薄膜超声挤压法与冷冻干燥法结合,可成功制备反义寡核苷酸阳离子脂质体前体制剂,稳定性大大改善。     

Pharmacokinetic and pharmacodynamic properties of inhaled beclometasone dipropionate delivered via hydrofluoroalkane-containing devices

Inhaled corticosteroids have a key role in the treatment of asthma and chronic obstructive pulmonary disease. In recent times, beclometasone dipropionate has been reformulated in pressurised metered dose inhalers (pMDIs), using hydrofluoroalkanes (HFAs) as a propellant. Extensive toxicological testing has shown that HFA-propellants are well tolerated. Among the reformulated beclometasone dipropionate-containing pMDIs, only the characteristics of the two Qvar formulations have been thoroughly explored. Compared to the reference beclometasone dipropionate formulation, the mass median aerodynamic diameter of the Qvar formulations are substantially smaller (1.1 vs 4.0 microm), whereas that of Modulite averages 2.6 microm. Scintigraphic and pharmacokinetic studies indicate a higher lung deposition for both the Qvar and the Beclazone formulations, compared with reference beclometasone dipropionate formulation. Since the 2- to 3-fold increase in pulmonary deposition results in a 2.6- to 3-fold difference in relative efficacy for Qvar, half the dose of the reference beclometasone dipropionate formulation has been currently recommended in adult patients with asthma, a recommendation that is supported by a large number of clinical trials. Conversely, the design of the studies conducted to compare the efficacy of Qvar with fluticasone propionate and budesonide does not allow establishing their equivalence on a milligram per milligram basis. Good studies on the bioequivalence between the reference beclometasone dipropionate formulation and the Modulite or Beclazone formulations are not available.     

Interleukin-2-Containing Liposomes: Interaction of Interleukin-2 with Liposomal Bilayers and Preliminary Studies on Application in Cancer Vaccines

Interleukin-2 (IL-2) incorporation in liposomes was studied under different conditions. Information was obtained on the mechanism of interaction of glycosylated recombinant IL-2 with liposomal bilayers. This information was utilized to formulate liposomes with high levels of incorporated IL-2. Multilamellar vesicles were prepared by hydration of a lipid film with an IL-2 solution. The incorporation efficiency, measured with a bioassay after forced release of IL-2 from the vesicles, was strongly dependent on the charge of the liposomes and the pH and ionic strength of the hydration medium. Negatively charged liposomes composed of phosphatidylcholine/ phosphatidylglycerol (9:1) and prepared with IL-2 dissolved in 10 mM NaAc/270 mM glycerol, 0.1% BSA, pH 5, showed the highest incorporation efficiency (81%) among the investigated preparations. This type of liposome was selected for further study. Electrostatics play a crucial role in the process of IL-2 association with this type of liposome. Initial studies concerning induction of protective tumor immunity by immunization with reconstituted membranes with mu-ramyl tripeptide phosphatidylethanolamine indicate that coinjection of IL-2-containing liposomes provided a significant enhancement of the immune response.