Pulmonary delivery of beclomethasone liposome aerosol in volunteers. Tolerance and safety

Inhaled lipid nanocarriers for pulmonary delivery of glucocorticoids: previous strategies, recent advances and key factors description

In view of the strong anti-inflammatory activity of glucocorticoids (GC) they are used in the treatment of almost all inflammatory lung diseases. In particular, inhaled GC (IGC) allow high drug concentrations to be deposited in the lung and may reduce the incidence of adverse effects associated with systemic administration. However, rapid absorption through the highly absorbent surface of the lung epithelium may limit the success of localized therapy. Therefore, inhalation of GC incorporated into nanocarriers is a possible approach to overcome this drawback. In particular, lipid nanocarriers, which showed high pulmonary biocompatibility and are well known in the pharmaceutical industry, have the best prospects for pulmonary delivery of GC by inhalation. This review provides an overview of the pre-clinical applications of inhaled GC-lipid nanocarriers based on several key factors that will determine the efficiency of local pulmonary GC delivery: 1) stability to nebulization, 2) deposition profile in the lungs, 3) mucociliary clearance, 4) selective accumulation in target cells, 5) residence time in the lung and systemic absorption and 6) biocompatibility. Finally, novel preclinical pulmonary models for inflammatory lung diseases are also discussed.

Nanoapproaches to Modifying Epigenetics of Epithelial Mesenchymal Transition for Treatment of Pulmonary Fibrosis

Idiopathic Pulmonary Fibrosis (IPF) is a chronically progressive interstitial lung that affects over 3 M people worldwide and rising in incidence. With a median survival of 2-3 years, IPF is consequently associated with high morbidity, mortality, and healthcare burden. Although two antifibrotic therapies, pirfenidone and nintedanib, are approved for human use, these agents reduce the rate of decline of pulmonary function but are not curative and do not reverse established fibrosis. In this review, we discuss the prevailing epithelial injury hypothesis, wherein pathogenic airway epithelial cell-state changes known as Epithelial Mesenchymal Transition (EMT) promotes the expansion of myofibroblast populations. Myofibroblasts are principal components of extracellular matrix production that result in airspace loss and mortality. We review the epigenetic transition driving EMT, a process produced by changes in histone acetylation regulating mesenchymal gene expression programs. This mechanistic work has focused on the central role of bromodomain-containing protein 4 in mediating EMT and myofibroblast transition and initial preclinical work has provided evidence of efficacy. As nanomedicine presents a promising approach to enhancing the efficacy of such anti-IPF agents, we then focus on the state of nanomedicine formulations for inhalable delivery in the treatment of pulmonary diseases, including liposomes, polymeric nanoparticles (NPs), inorganic NPs, and exosomes. These nanoscale agents potentially provide unique properties to existing pulmonary therapeutics, including controlled release, reduced systemic toxicity, and combination delivery. NP-based approaches for pulmonary delivery thus offer substantial promise to modify epigenetic regulators of EMT and advance treatments for IPF.

Lipid-based carriers for pulmonary products: preclinical development and case studies in humans

A number of lipid-based technologies have been applied to pharmaceuticals to modify their drug release characteristics, and additionally, to improve the drug loading for poorly soluble drugs. These technologies, including solid-state lipid microparticles, many of which are porous in nature, liposomes, solid lipid nanoparticles and nanostructured lipid carriers, are increasingly being developed for inhalation applications. This article provides a review of the rationale for the use of these technologies in the pulmonary delivery of drugs, and summarizes the manufacturing processes and their limitations, the in vitro and in vivo performance of these systems, the safety of these lipid-based systems in the lung, and their promise for commercialization.

Newer glucocorticosteroids and corticosteroid resistance reversal in asthma

Inflammation is the hallmark of asthma. Glucocorticosteroids inhibit this inflammation and are the mainstay of therapy in asthma, however, they suffer from their own drawbacks. They possess high potency but their continued use has a negative influence on health. Hence, quest for a steroid with good potency but without the undesirable effects is ongoing. Besides, steroid resistance is a problem in a substantial proportion of severe asthmatics. Deeper insight into the molecular mechanism of this refractoriness has led to the successful trial of certain drugs to overcome this problem. This review attempts to discuss some of the patents related to improved glucocorticoids and those agents that have the potential to restore steroid sensitivity in severe asthmatics.

Liposomal corticosteroids for the treatment of inflammatory disorders and cancer

Glucocorticoids (GC) are known for their potent immunosuppressive and anti-inflammatory properties. As a consequence, they have been extensively used for the treatment of many different diseases. Prolonged and/or high-dose GC therapy, however, generally comes with severe side effects, resulting not only from their very diverse mechanism(s) of action, but also from their relatively poor biodistribution. Drug delivery systems, and in particular liposomes, have been extensively used to enhance the biodistribution and the target site accumulation of GC, and to thereby improve the balance between their efficacy and their toxicity. Many different types of liposomes have been employed, and both local and systemic treatments have been evaluated. We here summarize the progress made in the use of liposomal GC formulations for the treatment of asthma, rheumatoid arthritis, multiple sclerosis and cancer, and we show that the targeted delivery of GC to pathological sites holds significant clinical potential.

Liposomal formulations for inhalation

No marketed inhaled products currently use sustained release formulations such as liposomes to enhance drug disposition in the lung, but that may soon change. This review focuses on the interaction between liposomal formulations and the inhalation technology used to deliver them as aerosols. There have been a number of dated reviews evaluating nebulization of liposomes. While the information they shared is still accurate, this paper incorporates data from more recent publications to review the factors that affect aerosol performance. Recent reviews have comprehensively covered the development of dry powder liposomes for aerosolization and only the key aspects of those technologies will be summarized. There are now at least two inhaled liposomal products in late-stage clinical development: ARIKACE® (Insmed, NJ, USA), a liposomal amikacin, and Pulmaquin™ (Aradigm Corp., CA, USA), a liposomal ciprofloxacin, both of which treat a variety of patient populations with lung infections. This review also highlights the safety of inhaled liposomes and summarizes the clinical experience with liposomal formulations for pulmonary application.

Surfactants: their critical role in enhancing drug delivery to the lungs

For local lung conditions and diseases, pulmonary drug delivery has been widely used for more than 50 years now. A more recent trend involves the pulmonary route as a systemic drug-delivery target. Advantages such as avoidance of the gastrointestinal environment, different enzyme content compared with the intestine, and avoidance of first-pass metabolism make the lung an alternative route for the systemic delivery of actives. However, the lung offers barriers to absorption such as a surfactant layer, epithelial surface lining fluid, epithelial monolayer, interstitium and basement membrane, and capillary endothelium. Many delivery strategies have been developed in order to overcome these limitations. The use of surfactants is one of these approaches and their role in enhancing pulmonary drug delivery is reviewed in this article. A systematic review of the literature relating to the effect of surfactants on formulations for pulmonary delivery was conducted. Specifically, research reporting enhancement of in vivo performance was focused on. The effect of the addition of surfactants such as phospholipids, bile salts, non-ionic, fatty acids, and liposomes as phospholipid-containing carriers on the enhancement of therapeutic outcomes of drugs for pulmonary delivery was compiled. The main use attributed to surfactants in pulmonary drug delivery is as absorption enhancers by mechanisms of action not yet fully understood. Furthermore, surfactants have been used to improve the delivery of inhaled drugs in various additional strategies discussed herein.

Lipid-based carriers: manufacturing and applications for pulmonary route

INTRODUCTION

Recent advances in aerosol therapy have sparked considerable interest in the development of novel drug delivery systems for pulmonary route. Development of colloidal carriers as pharmaceutical drug delivery systems has spurred an exponential growth; the encapsulation of bioactive molecules into relatively inert and non-toxic carriers for in vivo delivery constitutes a promising approach for improving their therapeutic index while reducing the side effects. Extraordinary success has been made toward improving efficacy by developing lipid-based carriers (LBCs); among classical examples are liposomes and solid lipid nanoparticles (SLNs).

AREAS COVERED

The authors review lipid-based colloidal carriers - liposomes and SLNs - as pulmonary drug delivery systems. Conventional methods of liposome preparation and recently developed systems are discussed. Special attention is given to SLNs and their main manufacturing techniques. Finally, a summary of recent scientific publications and important results in the field of pulmonary lipidic carriers are presented. Some practical considerations regarding the toxicological concerns of such systems are briefly cited.

EXPERT OPINION

Despite several scientific investigations, numerous advantages and encouraging results, LBCs for pulmonary route have attained only few great achievements as many challenges still remain. Problems limiting the use of such system seem to be the complexity of the respiratory tract as well as the lack of toxicity assessment risks of colloidal carriers.

Alternatives to conventional suspensions for pulmonary drug delivery by nebulisers: a review

This review discusses the reports of alternative dosage forms to suspension formulations of hydrophobic drugs for nebulisers. Suspensions for nebulisers, although widely used over recent years, have several limitations which have led to pharmaceutical researchers looking for alternative, better performing preparations. Particular attention has been directed towards the use of nanoparticles as carriers of hydrophobic active ingredients. Several nanoformulations have been prepared and compared in vitro and/or in vivo with the corresponding microsuspension formulation. It is also clear that future studies in this field should address the parallel important aspects of safety and economical aspects of nanoparticualte formulations.

Ethanol injection method for hydrophilic and lipophilic drug-loaded liposome preparation

In this article, a hydrophobic (beclomethasone dipropionate; BDP) and a hydrophilic (cytarabine; Ara-C) drugs have been encapsulated in liposomes in order to be administered via the pulmonary route. For this aim, a liposome preparation method, which is easy to scale up, the ethanol injection method, has been selected. The effects of critical process and formulation parameters have been investigated. The drug-loaded liposomes were prepared and characterized in terms of size, zeta potential, encapsulation efficiency, release study, cell uptake, and aerodynamic behavior. Small multilamellar vesicles, with sizes ranging from about 80 to 170 nm, were successfully obtained. Results indicated a significant influence of phospholipid and cholesterol amounts on liposome size and encapsulation efficiency. The higher encapsulation efficiencies were about 100% for the hydrophobic drug (BDP) and about 16% for the hydrophilic one (Ara-C). The in vitro release study showed a prolonged release profile for BDP, in contrast with Ara-C, which was released more rapidly. The cell-uptake test revealed that fluorescent liposomes have been well internalized into the cytoplasm of SW-1573 human lung carcinoma cells, confirming the possibility to use liposomes for lung cell targeting. Nebulized Ara-C and BDP liposomes presented aerodynamic diameters compatible with deep lung deposition. In conclusion, the elaborated liposomes seem to be promising carriers for both Ara-C and BDP pulmonary delivery.

Development of liposomal salbutamol sulfate dry powder inhaler formulation

The purpose of our study was to develop a formulation of liposomal salbutamol sulfate (SBS) dry powder inhaler (DPI) for the treatment of asthma. Liposomes of high encapsulation efficiency (more than 80%) were prepared by a vesicular phospholipid gel (VPG) technique. SBS VPG liposomes were subjected to lyophilization using different kinds of cryoprotectants in various mass ratios. Coarse lactose (63-106 microm) in different mass ratios was used as a carrier. Magnesium stearate (0.5%) was added as a lubricator. The dry liposomal powders were then crushed by ball milling and sieved through a 400-mesh sieve to control the mean particle size at about 10 microm. The effects of different kinds of cryoprotectants and the amount of lactose carrier on the fine particle fraction (FPF) of SBS were investigated. The results showed that the developed formulation of liposomal dry powder inhaler was obtained using lactose as a cryoprotectant with a mass ratio of lyophilized powder to carrier lactose at 1 : 5; 0.5% magnesium stearate was used as a lubricator. The value of FPF for SBS was 41.51+/-2.22% for this formulation. Sustained release of SBS from the VPG liposomes was found in the in vitro release study. The study results offer the promising possibility of localized pulmonary liposomal SBS delivery in the anhydrous state.

Formulation and in vitro evaluation of highly dispersive insulin dry powder formulations for lung administration

The aim of this work was to develop highly dispersible and dry formulations of insulin for use in dry powder inhalers (DPIs) using high-pressure homogenisation (HPH) and spray-drying. Several formulations were evaluated, including formulations spray-dried without excipients and formulations coated with lipids. A physiological lipid composition based on a mixture of cholesterol and phospholipids was used to form the coating film around micronised drug particles. The production technique and excipients were chosen in order to limit the degradation of the active ingredient. The resulting powders exhibited a size and shape suitable for the deep lung deposition of drugs, and good aerodynamic features were obtained for the different formulations tested, with fine particle fractions between 46% and 63% vs. 11% for raw insulin powder. The presence of a lipid coating of up to 30% (w/w) did not significantly affect the aerodynamic behaviour, and the coated formulations also exhibited a decreased residual moisture content of between 2.3% and 3.7% vs. 4.8% for raw insulin, which should improve the long-term stability of the protein formulations. No degradation of the insulin molecule occurred during the HPH/spray-drying process, as it was shown using an HPLC method (insulin content between 98.4% and 100.5%), and the content in high molecular weight proteins, assessed using a gel filtration method, stayed below 0.4%.

Monitoring safety of liposomes containing rifampicin on respiratory cell lines and in vitro efficacy against Mycobacterium bovis in alveolar macrophages

Rifampicin-encapsulated liposome suspensions were prepared by a chloroform-film method and converted to dry powders by freeze-drying with mannitol as a cryoprotectant. The liposome suspension had multilamellar nanovesicles with 50% rifampicin encapsulation. The liposome dry powder comprised particles with a mass median aerodynamic diameter of 3.4 mum, with 60% present as a fine particle fraction. Rifampicin-encapsulated liposomes were evidently nontoxic to respiratory associated cells, including bronchial epithelial cells, small airway epithelial and alveolar macrophages (AMs). Furthermore, the liposomes did not activate AMs to produce interleukin-1 beta, tumor necrosis factor-alpha, and nitric oxide at a level that would cascade to other inflammatory effects. The minimum inhibitory concentrations against Mycobacterium bovis was 0.2 and 0.8 microM for liposomes containing rifampicin and free rifampicin, respectively. The less negatively charged reconstituted liposome displayed the greatest activity against intracellular growth of M. bovis.

Effect of betamethasone phosphate loaded polymeric nanoparticles on a murine asthma model

Although inhaled steroids are the treatment of first choice to control asthma, administration of systemic steroids is required for treatment of asthmatic exacerbation and intractable asthma. To improve efficacy and reduce side effects, we examine the effects of betamethasone disodium phosphate (BP) encapsulated in biocompatible, biodegradable blended nanoparticles (stealth nanosteroids) on a murine model of asthma. These stealth nanosteroids were found to accumulate at the site of airway inflammation and exhibit anti-inflammatory activity. Significant decreases in BALF eosinophil number were maintained for 7 days with a single injection of nanosteroids containing 40 microg BP. Airway responsiveness was also attenuated by the injection of stealth nanosteroids. A single injection of 40 microg of free BP and 8 microg of free BP once daily for 5 days did not show any significant effects. We conclude that stealth nanosteroids achieve prolonged and higher benefits at the site of airway inflammation compared to free steroids.

Enhanced anti-inflammation of inhaled dexamethasone palmitate using mannosylated liposomes in an endotoxin-induced lung inflammation model

Inhalation of bacterial endotoxin induces pulmonary inflammation by activation of nuclear factor kappaB (NFkappaB), production of cytokines and chemokines, and neutrophil activation. Although glucocorticoids are the drugs of choice, administration of free drugs results in adverse effects as a result of a lack of selectivity for the inflammatory effector cells. Because alveolar macrophages play a key role in the inflammatory response in the lung, selective targeting of glucocorticoids to alveolar macrophages offers efficacious pharmacological intervention with minimal side effects. We have demonstrated previously the selective targeting of mannosylated liposomes to alveolar macrophages via mannose receptor-mediated endocytosis after intratracheal administration. In this study, the anti-inflammatory effects of dexamethasone palmitate incorporated in mannosylated liposomes (DPML) at 0.5 mg/kg via intratracheal administration were investigated in lipopolysaccharide-induced lung inflammation in rats. DPML significantly inhibited tumor necrosis factor alpha, interleukin-1beta, and cytokine-induced neutrophil chemoattractant-1 levels, suppressed neutrophil infiltration and myeloperoxidase activity, and inhibited NFkappaB and p38 mitogen-activated protein kinase activation in the lung. These results prove the value of inhaled mannosylated liposomes as powerful targeting systems for the delivery of anti-inflammatory drugs to alveolar macrophages to improve their efficacy against lung inflammation.

Disease guided optimization of the respiratory delivery of microparticulate formulations

BACKGROUND

Inhalation of microparticulate dosage forms can be effectively used in the treatment of respiratory and systemic diseases.

OBJECTIVE

Disease states investigated for treatment by inhalation of microparticles were reviewed along with the drugs' pharmacological, pharmacokinetic and physical chemical properties to identify the advantages of microparticulate inhalation formulations and to identify areas for further improvement.

METHODS

Microbial infections of the lung, asthma, diabetes, lung transplantation and lung cancer were examined, with a focus on those systems intended to provide a sustained release.

CONCLUSION

In developing microparticulate formulations for inhalation in the lung, there is a need to understand the pharmacology of the drug as the key to revealing the optimal concentration time profile, the disease state, and the pharmacokinetic properties of the pure drug as determined by IV administration and inhalation. Finally, in vitro release studies will allow better identification of the best dosing strategy to be used in efficacy and safety studies.

Synthesis, physicochemical properties and in vitro cytotoxicity of nicotinic acid ester prodrugs intended for pulmonary delivery using perfluorooctyl bromide as vehicle

This study explores perfluorooctyl bromide (PFOB) as a potential vehicle for the pulmonary delivery of a series of prodrugs of nicotinic acid using cell culture studies. The prodrugs investigated have PFOB-water (logK(p)=0.78 to >2.2), perfluoromethylcyclohexane-toluene (logK(p)=-2.62 to 0.13) and octanol-water (logK(p)=0.90-10.2) partition coefficients spanning several orders of magnitude. In confluent NCI-H358 human lung cancer cells, the toxicity of prodrugs administered in culture medium or PFOB depends on the medium of administration, with EC20's above 8 mM and 2.5 mM for culture medium and PFOB, respectively. Short-chain nicotinates administered both in PFOB and medium increase cellular NAD/NADP levels at 1mM nicotinate concentrations. Long-chain nicotinates, which could not be administered in medium due to their poor aqueous solubility, increased NAD/NADP levels if administered in PFOB at concentrations > or =10 mM. These findings suggest that even highly lipophilic prodrugs can partition out of the PFOB phase into cells, where nicotinic acid is released and converted to NAD. Thus, PFOB may be a novel and biocompatible vehicle for the delivery of lipophilic prodrugs of nicotinic acid and other drugs directly to the lung of laboratory animals and humans.

Iloprost-Containing Liposomes for Aerosol Application in Pulmonary Arterial Hypertension: Formulation Aspects and Stability

PURPOSE

Pulmonary arterial hypertension (PAH) is a severe and progressive disease. The prostacyclin analogue iloprost is effective against PAH, but requires six to nine inhalations per day. The feasibility of liposomes to provide a sustained release formulation to reduce inhalation frequency is evaluated from a technological point of view.

METHODS

Liposomal formulations consisting of di-palmitoyl-phosphatidyl-choline (DPPC), cholesterol (CH) and polyethyleneglycol-di-palmitoyl-phosphatidyl-ethanolamine (DPPE-PEG) were prepared. Their physico-chemical properties were investigated using dynamic light scattering, atomic force microscopy and differential scanning calorimetry. Stability of liposomes during aerosolization using three different nebulizers (air-jet, ultrasonic and vibrating mesh) was investigated with respect to drug loading and liposome size, pre- and post-nebulization.

RESULTS

The phospholipid composition affected the diameters of liposomes only slightly in the range of 200-400 nm. The highest iloprost loading (12 microg/ml) and sufficient liposome stability (70% drug encapsulation post-nebulization) was observed for the DPPC/CH (70:30 molar ratio) liposomes. The formulation's stability was confirmed by the relatively high phase transition temperature (53 degrees C) and unchanged particle sizes. The incorporation of DPPE-PEG in the liposomes (DPPC/CH/DPPE-PEG, 50:45:5 molar ratio) resulted in decreased stability (20-50% drug encapsulation post-nebulization) and a phase transition temperature of 35 degrees C. The vibrating mesh nebulizer offered a number of significant advantages over the other nebulizers, including the production of small aerosol droplets, high output, and the lowest deleterious physical influence upon all investigated liposomes.

CONCLUSION

Iloprost-loaded liposomes containing DPPC and CH components yield formulations which are well suited to aerosolization by the vibrating mesh nebulizer. The investigation of sustained release effects for the treatment of PAH in ex vivo and in vivo models is under way.

Comparative pharmacology, bioavailability, pharmacokinetics, and pharmacodynamics of inhaled glucocorticosteroids

A comparison of the pharmacodynamics and pharmacokinetics of inhaled corticosteroids is necessary for their assessment. A good knowledge of these two aspects allows the optimization of efficacy and safety.The currently available inhaled corticosteroids already show some of the desired PK/PD parameters. The local adverse effects are decreased as soon as the inhaled corticosteroid is administered as an inactive prodrug or shows a bet-ter lung deposition. HFA-MDI beclomethasone dipropionate (BDP) and ciclesonide are two agents that illustrate this. Low oral bioavailability, rapid systemic clearance, and high plasma protein binding can minimize systemic adverse effects. Mometasone furoate, ciclesonide, and fluticasone propionate possess those characteristics. The pulmonary efficacy is maximized by high lung deposition and long pulmonary residence times. This effect can be achieved by slow dissolution in the lungs, as is the case for fluticasone propionate or lipid conjugation and has been shown for budesonide and ciclesonide. Furthermore, the lung deposition depends on the inhalation device, the particle size, and the inhalation technique. Therefore,improvement in the design of MDIs, DPIs, and nebulizers, and the development of more effective drug particles will lead to an optimized pulmonary targeting. Much progress has been made in the treatment of asthma. The available inhaled corticosteroids show a high safety profile and a good pulmonary selectivity. Development of newer compounds showed that improvement is possible as the result of a complete understanding of the PK/PD concepts. However,the introduction of further improved formulations with a better efficacy/safety profile will be difficult and protracted because the existing drugs are already highly efficient.

Liposomes in the treatment of inflammatory disorders

This review focuses on the therapeutic utility of liposomes in the treatment of inflammatory disorders, and aims to offer the reader an overview of the in vivo results obtained with liposomally encapsulated anti-inflammatory and immune suppressive drugs. The past 30 years has clearly indicated the added value of liposomes in the search for solutions for the delivery problems encountered. However, only a few liposomal anti-inflammatory therapeutics have entered the clinic. Reasons for the hurdles existing in the translation of promising preclinical findings to clinical studies are discussed.

Displacement of fibrinogen from the air/aqueous interface by dilauroylphosphatidylcholine lipid

Fibrinogen (FB) and other serum proteins leak into the aqueous alveolar lining layer due to lung injuries. The adsorption of these serum proteins at the air/aqueous interface can produce higher surface tensions than the pulmonary lipids, and acute respiratory distress syndrome (ARDS) can ensue. By having a molecular adsorption mechanism, as compared to a particulate adsorption mechanism of other longer chain lipids, dilauroylphosphatidylcholine (DLPC) lipid can expel FB from the air/aqueous interface at 25 degrees C, in water or in phosphate-buffered saline, as proven by tensiometry (also at 37 degrees C), ellipsometry, and infrared reflection-absorption spectroscopy. Moreover, before FB is displaced by DLPC at the interface, there is a substantial initial enhancement in the FB adsorption, consistent with some interaction or binding of DLPC with FB to produce a more hydrophobic protein surface. After the FB molecules have been displaced by DLPC, or when DLPC has already adsorbed at the interface, FB molecules are less favored to adsorb near the DLPC monolayer with the lecithin headgroups facing toward them. The results have implications for possible uses of DLPC lipid in potential lung surfactant formulations in treating patients with ARDS.

A preliminary pharmacokinetic study of liposomal leuprolide dry powder inhaler: a technical note

The developed liposomal DPI of LEU (LLEUn-DPI) demonstrated approximately 50% bioavailability compared with SC route. The studies justify the role of the pulmonary route as a promising alternative to the presently available SC route. The components of liposomal vesicles may be suitably changed to achieve higher bioavailability. Pulmonary delivery of LEU is expected to help in improving patient compliance, self-administration and avoiding the complications related to injection procedure. The developed LEU-DPI may be employed for both male and female contraception and treatment of prostate cancer in men and early puberty in children. In women it may be used for ovarian, endometrial, pancreas, and breast cancer; endometriosis; Uterine Leiomyoma; and anemia due to uterine fibroid tumors. However, the role of LEU-DPI in clinical practice can only be justified only after in vivo studies on 2 species of animals followed by extensive clinical trials.

The use of sterically stabilized liposomes to treat asthma

Asthma is characterized by airway hyperresponsiveness, chronic inflammation, and airway remodeling, which may lead to progressive, irreversible lung damage. Liposomes have been used for the delivery of aerosolized asthma medications into the lungs. This method could facilitate sustained action of steroids while using only a fraction of the dosage and a less frequent dosing interval than conventional therapy. We describe the evaluation of the effect of budesonide encapsulated in sterically stabilized liposomes on lung inflammation and airway hyperreactivity in a mouse model of asthma. We outline the determination of markers implicated in the progression of asthma, including histopathology, eosinophil peroxidase activity in bronchoalveolar lavage, and airway hyperresponsiveness to methacholine. Weekly administration of budesonide in sterically stabilized liposomes results in a significant reduction in the total lung inflammation score, peripheral blood eosinophil counts, and the total serum IgE level, similar to that obtained with daily budesonide. Airway hyperresponsiveness to methacholine challenge decreases significantly in the group treated with weekly budesonide in sterically stabilized liposomes, while it does not decrease in the daily budesonide group.

Liposomal methylprednisolone differentially regulates the expression of TNF and IL-10 in human alveolar macrophages

Glucocorticoids (GC) are frequently used for therapy of various inflammatory lung diseases by either systemic or inhalative application. Because the oral application often has various side effects and because the inhalative application is not as potent, new formulations of GCs are required. We evaluated the effect of a liposomal (Lip) formulation of methylprednisolone (MP) on the expression of lipopolysaccharide (LPS)-induced proinflammatory tumor necrosis factor (TNF) and antiinflammatory interleukin-10 (IL-10) in human alveolar macrophages (AM). AM were obtained from bronchoalveolar lavage fluids of patients with various inflammatory lung diseases and precultured 20 h+/-MP, either liposomal or free, and then stimulated with LPS. Cells were harvested for analysis of mRNA levels by real-time reverse transcriptase polymerase chain reaction (RT-PCR); supernatants were used to measure protein concentrations by ELISA. We confirm the suppression of LPS-induced TNF production by an average of factor 7 at the mRNA level and factor 3 at the protein level. On the other hand, we detected a strong increase of the IL-10 production by MP. At the mRNA level, liposomal MP alone led to an 18-fold increase, and the LPS-induced IL-10 mRNA was enhanced by factor 2. At the protein level, MP alone had no effect, but LPS-induced IL-10 was increased by factor 2.5. Our data show that liposomal MP can consistently induce IL-10 and reduce TNF when macrophages are exposed for a prolonged period of time. In all respects, liposomal MP had similar activities as free MP, but liposomes were selectively taken up by monocytes and macrophages and not by lymphocytes in blood and in the lung. This suggests that liposomal glucocorticoids when applied locally in the lung may act efficiently but with less side effects.

Alternative administration of camptothecin analogues

In order to improve the therapeutic index of camptothecin (CPT) analogues, alternative administration of CPT analogues is being evaluated. Topotecan, irinotecan, rubitecan, lurtotecan and 9-aminocamptothecin have been administered orally with response rates equivalent to that seen after intravenous administration, where applicable. Oral availability and administration of some of the newer CPT analogues, including diflomotecan (BN80915) and grimatecan (ST1481), have also shown promising results. Aerosolisation of liposomal 9-nitrocamptothecin has been studied in patients with advanced malignancies involving the lung, demonstrating systemic antitumour activity. Intrathecal administration of topotecan has been studied in children with refractory neoplastic meningitis. It is well tolerated and associated with some antitumour activity. Intraperitoneal administration of topotecan as consolidation therapy in patients with ovarian cancer has shown promising results. Transdermal administration of rubitecan has been studied in mice. So far, no CPT has been approved for an alternative route of administration.

Expulsion of bovine serum albumin from the air/water interface by a sparingly soluble lecithin lipid

Dynamic surface tensiometry, ellipsometry, and infrared reflection-absorption spectroscopy (IRRAS) were used to study the dynamic adsorption and surface tensions of dilauroylphosphatidylcholine (DLPC) in the presence of bovine serum albumin (BSA). Results show that the equilibrium adsorbed layers consist mostly of DLPC, which can produce dynamic surface tensions (1 mN/m) as low as the more successful lung surfactant replacement formulations. When the aqueous surface expands and contracts sinusoidally, BSA can coadsorb and lead to slightly higher dynamic surface tensions than when DLPC is alone. Similar results were obtained with BSA and sodium myristate [McClellan and Franses, Colloids Surf. B 30 (2003) 1]. Expulsion of the BSA in the layer by DLPC can take from 5 to 15 min, depending on relative concentrations and history of solute addition. This is shown by tensiometry measurements on mixtures, and also by injecting aqueous DLPC underneath adsorbed BSA layers and probing the surface layer with ellipsometry and IRRAS. Albumin layers from buffer solutions aged up to 30 h can be expelled by DLPC. In pure water, there is an initial enhancement in protein adsorption after the DLPC is injected. This can be explained by the hypothesis that DLPC molecules bind with BSA molecules to form a hydrophobic lipoprotein complex, which is more hydrophobic than the protein itself. Since DLPC produces lower surface energy than BSA and--being slightly soluble--adsorbs to the surface by a molecular mechanism, it fulfills the thermodynamic and dynamic requirements for expelling the BSA from the surface. The results have implications for minimizing lung surfactant inhibition by serum proteins, as it occurs in the cases of adult or acute respiratory distress syndrome.

Dynamic adsorption and surface tension of aqueous dilauroylphosphatidylcholine dispersions under physiological conditions

The dynamic surface tension and equilibrium adsorption behavior of DLPC dispersions in phosphate buffer saline at 37 and 25 degrees C was studied with tensiometry, infrared reflection--absorption spectroscopy (IRRAS), and ellipsometry. The results are compared with those in water (Pinazo et al. Langmuir 2002, 18, 8888). Even though the pH and salinity have no apparent effect on the equilibrium surface tension and the surface pressure--area isotherm, they affect the dynamic surface tension by decreasing the adsorption rate and increasing the dynamic tension minima at a pulsating area of 20 or 80 cycles per minute. Moreover, IRRAS and ellipsometry results show that the adsorbed layers and the spread monolayers have larger area per molecule, or looser packing, in buffer than in water. A new hypothesis is proposed to elucidate the effect of pH/salinity on this zwitterionic surfactant: there is some specific interaction or binding between the ions from the buffer saline with the polar headgroups of DLPC. This interaction induces stronger intermolecular repulsions of the surfactant layer in buffer than that in water, despite the expected electrostatic screening effect, and causes higher dynamic surface tensions. The results have implications in designing lung surfactant replacement formulations.

Efficacy of liposomal budesonide in experimental asthma

BACKGROUND

Inhaled corticosteroids, such as budesonide, attenuate the inflammatory response in asthma. However, patient noncompliance and side effects of available inhaled corticosteroids limit their use. Liposomes are currently used in medicine to deliver a variety of drugs.

OBJECTIVE

The objective of our study was to determine whether weekly therapy with budesonide encapsulated in sterically stabilized (stealth) liposomes would be comparable to daily budesonide therapy in reducing allergic inflammation.

METHODS

Ovalbumin-sensitized C57/Black 6 mice received aerosolized (1) budesonide encapsulated in stealth or conventional liposomes, administered weekly, (2) budesonide (without liposomes), administered either daily or weekly, or (3) empty stealth liposomes, administered weekly. All treatment groups were compared with sensitized untreated or unsensitized mice. Histopathologic examination of the lung tissues and measurements of eosinophil peroxidase activity, peripheral blood eosinophil counts, and total serum IgE levels were done weekly for 4 weeks.

RESULTS

Weekly therapy with budesonide encapsulated in stealth liposomes was as effective as daily budesonide therapy in decreasing lung inflammation and lowering eosinophil peroxidase activity, peripheral blood eosinophils, and total serum IgE levels. In none of the other groups was there a significant decrease in the inflammatory parameters evaluated.

CONCLUSION

We conclude that weekly therapy with budesonide encapsulated in stealth liposomes is as effective as daily budesonide in reducing markers of lung inflammation in experimental asthma. This novel strategy offers an effective alternative to standard daily budesonide therapy in asthma and has the potential to reduce toxicity and improve compliance.

No impairment of peripheral deposition in novel asthmatics treated with an MDI corticosteroid with spacer

Pulmonary distribution and lung functions were evaluated during a 4-month inhaled corticosteroid treatment period in 10 steroid-naïve novel asthmatics with normal or slightly reduced lung functions. Patients were given a total daily dose of 1000 microg of beclomethasone dipropionate aerosol twice a day via a pressured metered dose inhaler with a large-volume chamber device (Volumatic, GlaxoSmith Kline, U.K.). Gamma lung scintigraphy and lung function tests were performed before and after 2 months and 4 months. Inhaled 99mTc-labelled beclomethasone dipropionate liposomes were used to assess lung deposition patterns during inhaled steroid therapy. Serum eosinophil cationic protein (ECP) concentration was used as a surrogate marker of asthmatic inflammation. Following beclomethasone treatment, all lung functions were enhanced, but only FVC values showed significant improvement. The FEV1/FVC ratio remained slightly reduced in spite of inhaled corticosteroid therapy. However, the association between changes in improved FVC values and reduced ECP levels proved to be statistically significant. In lung scintigraphy, no evidence of changes in pulmonary deposition patterns were seen during the follow-up period. We conclude that inhaled corticosteroid therapy can lead to improvements in lung functions and surrogate markers of airway inflammation in novel asthma without affecting the peripheral deposition pattern of aerosols.

Reverse water-in-fluorocarbon emulsions for use in pressurized metered-dose inhalers containing hydrofluoroalkane propellants

Pulmonary administration of drugs has demonstrated numerous advantages in the treatment of pulmonary diseases due to direct targeting to the respiratory tract. It enables avoiding the first pass effect, reduces the amount of drugs administered, targets drugs to specific sites and reduces their side effects. Reverse water-in-fluorocarbon (FC) emulsions are potential drug delivery systems for pulmonary administration using pressurized metered-dose inhalers (pMDI). The external phase of these emulsions consists of perfluorooctyl bromide (PFOB, perflubron), whereas their internal phase contains the drugs solubilized or dispersed in water. These emulsions are stabilized by a perfluoroalkylated dimorpholinophosphate (F8H11DMP), i.e. a fluorinated surfactant. This study demonstrates the possibility of delivering a reverse fluorocarbon emulsion via the pulmonary route using a CFC-free pMDI. Two hydrofluoroalkanes (HFAs) (Solkane(R) 134a and Solkane(R) 227) were used as propellants, and various solution (or emulsion)/propellant ratios (1/3, 1/2, 2/3, 1/1, 3/2, 3/1 v/v) were investigated. The insolubility of water (with or without the fluorinated surfactant F8H11DMP) in both HFA 227 and HFA 134a was demonstrated. PFOB and the reverse emulsion were totally soluble or dispersible in all proportions in both propellants. This study demonstrated also that the reverse FC emulsion can be successfully used to deliver caffeine in a homogeneous and reproducible way. The mean diameter of the emulsion water droplets in the pressured canister was investigated immediately after packaging and after 1 week of storage at room temperature. Best results were obtained with emulsion/propellant ratios comprised between 2/3 and 3/2, and with HFA 227 as propellant.

Eradication of osteosarcoma lung metastasis using intranasal gemcitabine

We sought to determine whether gemcitabine, a new pyrimidine antimetabolite, could inhibit the growth of human osteosarcoma cells (OS) in vitro and in vivo. Four human OS cell lines (MG-63, TE-85, SAOS-2 and SAOS-LM7) were used to assess the activity of the drug in vitro. Gemcitabine caused growth inhibition and cell death in all four cell lines as measured using the MTT and colony-forming assays (IC(50) = 6.5 nM-9 microM and 7-14 nM, respectively). Using our newly developed human SAOS-LM7 OS lung metastasis mouse model, we assessed the in vivo activity of gemcitabine given i.p. and intranasally (i.n.). Mice were treated twice weekly for 3 weeks and then once weekly for 3 weeks using either i.p. or i.n. gemcitabine starting 4 weeks after tumor cell injection. The i.p. injection, at 120 mg/kg, resulted in a decrease in lung weights and the size of the nodules. However, no significant reduction in the number of metastatic nodules was seen (control median: >200 versus gemcitabine median: 150, p = 0.084). In contrast, the number of lung metastases was significantly decreased in mice that received i.n. gemcitabine at 15 (median: 1; range: 0-115, p<0.005) and 12 mg/kg (median: 41; range: 7-163, p = 0.005) when compared with control mice (median: >200). Intranasal therapy is a non-invasive method of drug delivery and has the advantage of targeting the lung, resulting in a higher drug concentration in the tumor area. In our study, i.n. instillation of gemcitabine inhibited the growth of lung metastases at an 8- to 10-fold lower dose than that used i.p. and appeared to be more effective in eradicating OS lung nodules. Because the lung is the most common site of OS metastasis, our data suggest that i.n. gemcitabine may be a novel therapeutic approach in the treatment of OS lung metastases.

Lectin-functionalized liposomes for pulmonary drug delivery: effect of nebulization on stability and bioadhesion

The generation of respirable aerosols of a functionalized colloidal carrier has been investigated in this study. Lectin-functionalized liposomes, which proved to show improved cell association (using A549 cell line and primary human alveolar cells) even in the presence of a commercial lung surfactant preparation, have been developed. The stability of non-functionalized liposomes during nebulization using a jet nebulizer (Pari II provocation nebulizer, operated using an air flow of 30 l/min) was firstly investigated, and the experimental and formulation conditions were optimized and applied for the preparation of lectin-functionalized liposomes. The incorporation of cholesterol enhanced the stability of the liposomes during nebulization (from 15-20% leakage of a hydrophilic marker to 8% upon cholesterol incorporation) and upon incubation with lung surfactant preparation. Nebulization of the functionalized liposomes did not significantly influence their physical stability. Their enhanced cell binding capability (compared to non-functionalized liposomes) was also maintained. A drop in cell association compared to fresh functionalized liposomes was detected after nebulization, nevertheless, the binding was still significantly higher than that of the non-functionalized liposomes. The deposition of the liposomal preparation in lung periphery, proved by the deposition of the liposomal preparation on the lower stages of an ASTRA type cascade impinger and a mean median aerodynamic diameter (MMAD) of 2.85 microm, makes it a potential candidate as a macromolecule-drug carrier for local and/or systemic administration.

Rationale for the choice of an aerosol delivery system

The choice of an aerosol delivery system depends on numerous factors such as the drug itself, the characteristics of the aerosol generator, the patient and his or her disease, the physician, and the clinical setting, notably an emergency situation or not. Some rules always apply: an ultrasonic nebulizer should not be used to aerosolize a drug suspension; whenever possible, the same type of aerosol generator should be used for all inhaled medications received by a given patient; for outpatients, education is a major factor to ensure treatment efficacy. When the deposition of the aerosolized drug is aimed at the terminal respiratory units, nebulizers that generate micronic aerosols should be chosen. When the deposition of the aerosolized drug is aimed at the conducting airways, the metered dose inhaler (MDI) is the first choice. However, the MDI is often ill-used, notably in children and elderly people. Therefore, other inhalation devices have been developed: spacers, dry-powder inhalers, breath-actuated MDIs and, more recently, piezo-electric devices. They have been shown to increase lung deposition of drugs in poor coordinators but they all have limitations, which may affect their clinical efficacy. These limitations include the cumbersome dimensions of spacers, the dependency of lung deposition of dry powders on the inspiratory flow rate, the need for reformulation of breath-actuated or not MDIs with CFC-free gases. Nebulization of drugs should be considered only when no portable device is available for the considered drug, or in case of failure of other forms of aerosol administration.

Alternative administration of camptothecin analogues

The binding of camptothecin (CPT) to the DNA-topoisomerase complex is reversible, but it needs to be maintained for maximal inhibitory activity. It is also dependent on the chemical structure of CPT. The lactone form is thought to be necessary for the activity. In human serum, the equilibrium between lactone and carboxylate is in favor of the latter. For these reasons, alternative administration of CPT analogues is being evaluated. The ideal compound would remain in lactone form and would expose the host for long periods of time to its effects. Oral administration of irinotecan (CPT-11) and topotecan (TPT) is discussed by other investigators. We studied oral rubitecan and reported a low lactone to total drug area under the plasma concentration-time curve (AUCP) ratio (14.7%), with low plasma concentration over time despite repeated administrations and the presence of an enterohepatic cycle. Aerosolization of a liposomal formulation of rubitecan is currently under study. Six patients have been treated once a day for 5 days every 3 weeks. The dose was 6.7 micrograms/kg/day. Plasma levels are dose for dose higher than those after oral administration, but the ratio of lactone versus total drug is low. No toxicity was observed. The study will continue with increasing doses and lengths of administration. Intrathecal administration of topotecan has been studied in a phase I trial in children. Doses of 0.4 mg are tolerated without toxicity, and clinical responses have been seen in patients with refractory meningial carcinomatosis. Phase II studies are planned. Intraperitoneal (i.p.) administration of topotecan has been studied in a phase I trial as a 24-hour infusion in 5% dextrose at pH 3.5 every 21 days. Dose-limiting toxicity is 4 mg/m2. Toxic effects are neutropenia, anemia, emesis, fever, and pain. Five of 10 patients with ascites had symptomatic relief. Pharmacokinetic analysis demonstrates a second-order kinetics with elimination half-lives of 0.49 and 2.7 hours. The peritoneal to plasma AUC ratio was 31.2. Intramuscular, transdermal, and subcutaneous administrations have been extensively studied in the mouse.

Nebulizer-compatible liquid formulations for aerosol pulmonary delivery of hydrophobic drugs: glucocorticoids and cyclosporine

This review discusses pulmonary delivery of glucocorticoids and cyclosporine in pharmaceutically acceptable organic solvents and liposomes, as well as in micellar solutions and microemulsions, by means of liquid aerosols generated by nebulizers. The review points out the importance of a variety of parameters for successful treatment of immunologically mediated lung diseases by inhalation of drug containing aerosols with particular references to physico-chemical properties of formulations, aerosol parameters, pharmacokinetics, and lung deposition in experimental animals and humans. The prospects for the use of these types of formulations for clinical treatment of asthma, lung transplant rejection processes and other lung diseases are summarized.

Stabilization of aerosolized IFN-gamma by liposomes

Aerosolized IFN-gamma is very unstable. We have improved the stability of IFN-gamma in the jet nebulizer by adding small liposomes. Aerosolized IFN-gamma was recovered in PBS solution by bubbling and its concentration was determined. After nebulization for 30 min, aerosolized IFN-gamma was detected only 0.4+/-0.2% of the initial amount in the PBS solution and 3.1+/-0.7% in the reservoir. On the other hand, the addition of small liposomes (HSPC/DSPG=10/1 (molar ratio), 45+/-24 nm) in the nebulizer increased the stability of IFN-gamma, 27.2+/-4.7% of the initial amount in the PBS solution and 25.7+/-12.6% in the reservoir. The present study also examined the effects of composition and concentration of liposomes on the stabilization of aerosolized IFN-gamma. Liposome prepared from distearoyl phosphatidylcholine (DSPC) or hydrogenated soy phosphatidylcholine (HSPC) was very effective for stabilization of aerosolized IFN-gamma (DSPC/DPPG=10/1, HSPC/DSPG=10/1). HSPC/DSPG liposome was efficient at the concentration higher than 12.5 micromols/ml for the stabilization of 5x10(5) JRU/ml of IFN-gamma. In considering the mechanism of this stabilization, the results of gel filtration chromatography suggest that IFN-gamma is inactivated by polymerization or aggregation in nebulization, while the inactivation is suppressed by liposomes due to their adsorption to IFN-gamma.

Pulmonary distribution and clearance of two beclomethasone liposome formulations in healthy volunteers

The pulmonary distribution and clearance of 99mTc-labelled beclomethasone dipropionate (Bec) dilauroylphosphatidylcholine (DLPC) and dipalmitoylphosphatidylcholine (DPPC) liposomes were compared in 11 healthy volunteers using gamma scintigraphy. As delivered by using the Aerotech jet nebulizer both liposome aerosols had a suitable droplet size (mass median aerodynamic diameter 1.3 microm) allowing deep pulmonary deposition. However, in the total drug output during the inhalation there was a relatively large difference between DLPC and DPPC of 11.4 and 3.1 microg, respectively. In a gamma camera study no significant differences existed in the central/peripheral lung deposition between the DLPC and DPPC formulations. Progressive clearance of both Tc-labelled Bec liposomes was seen: 24 h after inhalation, 79% of the originally deposited radioactivity of DLPC liposomes and 83% of that of DPPC liposomes remained in the lungs. Thus there was slightly slower clearance of inhaled liposomes using DPPC instead of DLPC. We conclude that both liposome formulations are suitable for nebulization, although aerosol clouds were more efficiently made from the DLPC liposome suspension. Our results support the view that liposome encapsulation of a drug can offer sustained release and drug action in the lower airways.

Regional lung deposition and clearance of 99mTc-labeled beclomethasone-DLPC liposomes in mild and severe asthma

OBJECTIVE

To compare the distribution and clearance of inhaled beclomethasone dipropionate (Bec)-dilauroylphosphatidylcholine (DLPC) liposomes in patients with mild and severe asthma.

DESIGN

A 99mTc-labeled Bec-DLPC suspension was delivered via a nebulizer (Aerotech II). Immediately after inhalation, anterior and posterior views of the lungs and an anterior view of the oropharynx were measured by a large field gamma camera with the patient in a supine position. To evaluate the mucociliary clearance of the inhaled liposomes, anterior and posterior lung scans were repeated 1, 2, 4, and 24 h after the aerosol delivery.

PATIENTS

Ten patients with mild asthma (FEV1 >80% of the predicted) and 10 patients with severe asthma (FEV1 <60% of the predicted) were included in an open, parallel group study.

RESULTS

Clearance is more rapid among patients with severe asthma (p<0.0001). At the 4-h measurement, a mean of 82% (SD, 5.9) of the total pulmonary dose was detected in the lungs of patients with mild asthma while in those with severe asthma the figure was 69% (SD, 10.9). The ratio between central and peripheral deposition was significantly higher for patients with severe asthma than for those having a mild form of the disease; 1.07 (SD, 0.29) and 0.76 (SD, 0.07), respectively (p=0.008).

CONCLUSIONS

Inhaled Bec-DLPC liposomes were deposited more centrally in the lower airways of patients with severe asthma than those having a milder form of the disease. The clearance of Bec-DLPC liposomes is strikingly slow in both groups of asthmatic patients. However, due to the more peripheral penetration of inhaled liposomes in patients with mild asthma, the clearance rate in this group was slower than in those with severe asthma.