Acute effects of liposome aerosol inhalation on pulmonary function in healthy human volunteers

Dry powder inhalers of antitubercular drugs

Despite advancements in the medical and pharmaceutical fields, tuberculosis remains a major health problem globally. Patients do not widely accept the conventional approach to treating tuberculosis (TB) due to prolonged treatment periods with multiple high doses of drugs and associated side effects. A pulmonary route is a non-invasive approach to delivering drugs, hormones, nucleic acid, steroids, proteins, and peptides directly to the lungs, improving the efficacy of the treatment and consequently decreasing the adverse effect of the treatment. This route has been successfully developed for the treatment of various respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD), tuberculosis (TB), lung cancer, and other pulmonary infections. The major approaches of inhalation delivery systems include nebulizers, metered-dose inhalers (MDIs), and dry powder inhalers (DPIs). However, dry powder inhalers (DPIs) are more advantageous due to their stability and ability to deliver a high dose of the drug to the lungs. The present review analyzes the modern therapeutic approach of inhaled dry powders, with a special focus on novel drug delivery system (NDDS) based DPIs for the treatment of TB. The article also discussed the challenges of preparing inhalable dry powder formulations for the treatment of TB. The clinical development of inhalable anti-TB drugs is also reviewed.

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.

Cationic liposomes containing antioxidants reduces pulmonary injury in experimental model of sepsis: Liposomes antioxidants reduces pulmonary damage

The intracellular redox state of alveolar cells is a determining factor for tolerance to oxidative and pro-inflammatory stresses. This study investigated the effects of intratracheal co-administration of antioxidants encapsulated in liposomes on the lungs of rats subjected to sepsis. For this, male rats subjected to sepsis induced by lipopolysaccharide from Escherichia coli or placebo operation were treated (intratracheally) with antibiotic, 0.9% saline and antioxidants encapsulated or non-encapsulated in liposomes. Experimental model of sepsis by cecal ligation and puncture (CLP) was performed in order to expose the cecum. The cecum was then gently squeezed to extrude a small amount of feces from the perforation site. As an index of oxidative damage, superoxide anions, lipid peroxidation, protein carbonyls, catalase activity, nitrates/nitrites, cell viability and mortality rate were measured. Infected animals treated with antibiotic plus antioxidants encapsulated in liposomes showed reduced levels of superoxide anion (54% or 7.650±1.263 nmol/min/mg protein), lipid peroxidation (33% or 0.117±0.041 nmol/mg protein), protein carbonyl (57% or 0.039 ± 0.022 nmol/mg protein) and mortality rate (3.3%), p value <0.001. This treatment also reduced the level of nitrite/nitrate and increased cell viability (90.7%) of alveolar macrophages. Taken togheter, theses results support that cationic liposomes containing antioxidants should be explored as coadjuvants in the treatment of pulmonary oxidative damage.

Disposition and safety of inhaled biodegradable nanomedicines: Opportunities and challenges

The inhaled delivery of nanomedicines can provide a novel, non-invasive therapeutic strategy for the more localised treatment of lung-resident diseases and potentially also enable the systemic delivery of therapeutics that are otherwise administered via injection alone. However, the clinical translation of inhalable nanomedicine is being hampered by our lack of understanding about their disposition and clearance from the lungs. This review provides a comprehensive overview of the biodegradable nanomaterials that are currently being explored as inhalable drug delivery systems and our current understanding of their disposition within, and clearance from the lungs. The safety of biodegradable nanomaterials in the lungs is discussed and latest updates are provided on the impact of inflammation on the pulmonary pharmacokinetics of inhaled nanomaterials. Overall, the review provides an in-depth and critical assessment of the lung clearance mechanisms for inhaled biodegradable nanomedicines and highlights the opportunities and challenges for their translation into the clinic.

Pulmonary drug delivery systems for tuberculosis treatment

Tuberculosis (TB) remains a major global health problem as it is the second leading cause of death from an infectious disease worldwide, after the human immunodeficiency virus (HIV). Conventional treatments fail either because of poor patient compliance to the drug regimen or due to the emergence of multidrug-resistant tuberculosis. The aim of this review is to give an update on the information available on tuberculosis, its pathogenesis and current antitubercular chemotherapies. Direct lung delivery of anti-TB drugs using pulmonary delivery systems is then reviewed since it appears as an interesting strategy to improve first and second line drugs. A particular focus is place on research performed on inhalable dry powder formulations of antitubercular drugs to target alveolar macrophages where the bacteria develop. Numerous studies show that anti-TB drugs can be incorporated into liposomes, microparticles or nanoparticles which can be delivered as dry powders to the deep lungs for instantaneous, targeted and/or controlled release. Treatments of infected animals show a significant reduction of the number of viable bacteria as well as a decrease in tissue damage. These new formulations appear as interesting alternatives to deliver directly drugs to the lungs and favor efficient TB treatment.

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.

Improving the efficacy of inhaled drugs in cystic fibrosis: challenges and emerging drug delivery strategies

Cystic fibrosis (CF) is the most common autosomal recessive disease in Caucasians associated with early death. Although the faulty gene is expressed in epithelia throughout the body, lung disease is still responsible for most of the morbidity and mortality of CF patients. As a local delivery route, pulmonary administration represents an ideal way to treat respiratory infections, excessive inflammation and other manifestations typical of CF lung disease. Nonetheless, important determinants of the clinical outcomes of inhaled drugs are the concentration/permanence at the lungs as well as the ability of the drug to overcome local extracellular and cellular barriers. This review focuses on emerging delivery strategies used for local treatment of CF pulmonary disease. After a brief description of the disease and formulation rules dictated by CF lung barriers, it describes current and future trends in inhaled drugs for CF. The most promising advanced formulations are discussed, highlighting the advantages along with the major challenges for researchers working in this field.

Hydrogels for controlled pulmonary delivery

A significant number of research articles have focused on pulmonary delivery as an alternative administration route owing to no first-pass metabolism, low protease activity, thin epithelium barrier and large surface area in the lung system. Controlled release in the pulmonary delivery system further reduces loading dose, frequency of dosing and systemic side effects, and also increases duration of action and patient compliance. Compared with other microparticles used in controlled-release pulmonary administration, hydrogels (3D polymeric matrix networks) have recently been investigated due to their swelling and mucoadhesive properties that could help bypass pulmonary delivery barriers. This review introduces controlled-release drug delivery to the lung, followed by a summary of currently available approaches for controlled-release pulmonary drug delivery. Lastly, the origin, advantages, detailed applications and concerns of hydrogels in pulmonary delivery are discussed.

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.

Current Status of Gene Therapy for Cystic Fibrosis Pulmonary Disease

Cystic fibrosis (CF) is a common lethal genetic disorder that affects all ethnic populations; however, it is most prevalent in Caucasians. Intensive basic research over the last 20 years has resulted in a wealth of information regarding the CF gene, its protein product and the mutational basis of disease. This increased understanding has lead to the development of gene therapy for the treatment of CF pulmonary disease. Delivery of the CF gene to the airway requires direct in vivo transfer using vectors encoding for normal CF transmembrane regulator (CFTR) protein. Several vectors are currently available for CF gene transfer and include both viral (adenoviruses, adeno-associated viruses) and non-viral (liposomal) systems. Initial clinical trials with each of these vectors have demonstrated that gene transfer to the CF airway is possible. The efficiency of transfer and duration of expression, however, have been limited. The effects of gene transfer on correction of the basic ion transport defects have also been highly variable and inconsistent, irrespective of the vector. Currently, the risk of severe immunological reactions is the primary factor limiting the clinical advancement of gene therapy. Both the adenoviral and liposomal vectors are associated with significant acute inflammatory reactions. The adenoviruses and adeno-associated viruses also elicit humoral immune responses that significantly reduce the efficiency of transgene expression and increase the risk of readministration. Several strategies are under investigation to improve the efficiency of gene transfer to the CF airway. These include overcoming local barriers in the lung, circumventing the immune response and improving vector internalization and/or uptake. Application of gene transfer in the child and possibly the fetus are also potential future clinical applications of gene therapy. However, despite considerable research with gene therapy, there is little evidence to suggest that a well tolerated and effective gene transfer method is imminent and aggressive use of conventional pharmacological therapies currently offer the greatest promise in the treatment of patients with CF.

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.

Therapeutic liposomal dry powder inhalation aerosols for targeted lung delivery

Therapeutic liposomal powders (i.e., lipospheres and proliposomes) for dry powder inhalation aerosol delivery, formulated with phospholipids similar to endogenous lung surfactant, offer unique opportunities in pulmonary nanomedicine while offering controlled release and enhanced stability. Many pulmonary diseases such as lung cancer, tuberculosis (TB), cystic fibrosis (CF), bacterial and fungal lung infections, asthma, and chronic obstructive pulmonary disease (COPD) could greatly benefit from this type of pulmonary nanomedicine approach that can be delivered in a targeted manner by dry powder inhalers (DPIs). These delivery systems may require smaller doses for efficacy, exhibit reduced toxicity, fewer side effects, controlled drug release over a prolonged time period, and increased formulation stability as inhaled powders. This state-of-the-art review presents these novel aspects in depth.

Liposomal Antioxidants for Protection against Oxidant-Induced Damage

Reactive oxygen species (ROS), including superoxide anion, hydrogen peroxide, and hydroxyl radical, can be formed as normal products of aerobic metabolism and can be produced at elevated rates under pathophysiological conditions. Overproduction and/or insufficient removal of ROS result in significant damage to cell structure and functions. In vitro studies showed that antioxidants, when applied directly and at relatively high concentrations to cellular systems, are effective in conferring protection against the damaging actions of ROS, but results from animal and human studies showed that several antioxidants provide only modest benefit and even possible harm. Antioxidants have yet to be rendered into reliable and safe therapies because of their poor solubility, inability to cross membrane barriers, extensive first-pass metabolism, and rapid clearance from cells. There is considerable interest towards the development of drug-delivery systems that would result in the selective delivery of antioxidants to tissues in sufficient concentrations to ameliorate oxidant-induced tissue injuries. Liposomes are biocompatible, biodegradable, and nontoxic artificial phospholipid vesicles that offer the possibility of carrying hydrophilic, hydrophobic, and amphiphilic molecules. This paper focus on the use of liposomes for the delivery of antioxidants in the prevention or treatment of pathological conditions related to oxidative stress.

Nanocarriers for pulmonary administration of peptides and therapeutic proteins

Peptides and therapeutic proteins have been the target of intense research and development in recent years by the pharmaceutical and biotechnology industry. Preferably, they are administered through the parenteral route, which is associated with reduced patient compliance. Formulations for noninvasive administration of peptides and therapeutic proteins are currently being developed. Among them, inhalation appears as a promising alternative for the administration of such products. Several formulations for pulmonary delivery are in various stages of development. Despite positive results, conventional formulations have some limitations such as reduced bioavailability and side effects. Nanocarriers may be an alternative way to overcome the problems of conventional formulations. Some nanocarrier-based formulations of peptides and therapeutic proteins are currently under development. The results obtained are promising, revealing the usefulness of these systems in the delivery of such drugs.

A characterisation study on the application of inverted lyotropic phases for subcutaneous drug release

An experimental characterisation of lipid mixtures consisting of inverted hexagonal and inverted cubic phases composed of soybean phosphatidylcholine (SPC) and glycerol dioleate (GDO) was performed. The release of five chromophores of varying lipophilicity, used as model drugs, was investigated. Two experimental setups were applied: one based on maintaining sink condition, while a constant volume release medium was employed for the other. For neither setup, no correlation between the model drug lipophilicity and the polarity of the carrier matrix was found. However, the lipid phases showed a prolonged release, spanning weeks, of the model drugs, which exhibit lipophilicity values ranging by four orders of magnitude.

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.

A gamma scintigraphy study to investigate lung deposition and clearance of inhaled amikacin-loaded liposomes in healthy male volunteers

BACKGROUND

The purpose of this study was to investigate the inhalation of a liposomal formulation of amikacin in healthy male volunteers in terms of pulmonary deposition, clearance, and safety following nebulization with a commercial jet nebulizer.

METHODS

Amikacin was encapsulated in liposomes comprised of dipalmitoyl phosphatidylcholine (DPPC) and cholesterol via a proprietary manufacturing process (20 mg/mL final amikacin concentration). The liposomes were radiolabeled with (99m)Tc using the tin chloride labeling method. A nominal dose of 120 mg of drug product was loaded into a PARI LC STAR nebulizer, aerosolized using a PARI Boy compressor where subjects inhaled for 20 min. Lung deposition was determined by gamma scintigraphy in three healthy male volunteers at the following time points (0, 1, 3, 6, 12, 24, 48, and 72 h post-administration).

RESULTS

Total lung deposition, expressed as a percentage of the emitted dose, was 32.3 +/- 3.4%. The time-dependent retention of radiolabeled liposomes was biphasic with an initial rapid reduction in counts, followed by a slower phase to 48 h. The overall mean retention at 24 and 48 h was 60.4 and 38.3% of the initial dose deposited, respectively. The observed clearance of radiolabel is consistent with clearance of amikacin following aerosol delivery to rats. There were no clinically significant changes in laboratory parameters, vital signs, or ECG. No adverse events including cough or bronchospasm were reported.

CONCLUSIONS

Inhalation of a single nominal dose of 120 mg liposomal amikacin results in prolonged retention of drug-loaded liposomes in the lungs of healthy volunteers. The treatment was well tolerated.

Nebulization of Liposomal rh-Cu/Zn–SOD with a Novel Vibrating Membrane Nebulizer

Liposomes are potential drug carriers for pulmonary drug delivery: They can be prepared from phospholipids, which are endogenous to the respiratory tract as a component of pulmonary surfactant, and at an appropriate dose liposomes do not pose a toxicological risk to this organ. Among the various categories of drug that benefit from liposomal entrapment is the anti-inflammatory enzyme superoxide dismutase, thus prolonging its biological half-life. The delivery of liposomes by nebulization is hampered by stability problems, like physical and chemical changes that may lead to chemical degradation and leakage of the encapsulated drug. Here we present data of liposomes aerosolized with a novel electronic nebulizer based on a vibrating membrane technology (PARI eFlow), which amends drawbacks like liposomes degradation and product release. The data acquisition included aerosol properties such as aerodynamic particle size, nebulization efficiency, and liposome leakage upon nebulization. In conclusion, this study shows the ability of the PARI eFlow to nebulize high amounts of liposomal recombinant human superoxide dismutase with reduced vesicle disruption tested in an enclosing experimental protocol.

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.

Ocular hypotensive effects of an intratracheally delivered liposomal delta9-tetrahydrocannabinol preparation in rats

This study investigated the effect of an intratracheal (i.t.) administration of a liposome-entrapped Delta9-tetrahydrocannabinol (LTHC) preparation on intraocular pressure (IOP) in nonanaesthetized Brown Norway rats. The ocular hypotensive effects of i.t. LTHC were compared to that of intraperitoneal (i.p.) LTHC administration. All i.t. LTHC doses >0.05 mg/kg significantly decreased IOP (P < 0.05) within 30 min of administration, and doses of i.t. LTHC >0.1 mg/kg decreased IOP within 15 min of administration. A maximal reduction in IOP of 2.32 +/- 0.27 mmHg (n = 4) was seen with 1.0 mg/kg of i.t. LTHC. In comparison, no significant IOP drop was apparent prior to 30 min with all doses (0.01-1.0 mg/kg) of i.p. LTHC tested, although a similar maximum drop in IOP (2.15 +/- 0.12 mmHg; n = 8) was obtained with 1.0 mg/kg of LTHC. The ED(50) for i.t. and i.p. LTHC was 0.08 mg/kg and 0.12 mg/kg, respectively. The IOP-lowering effects of i.p. LTHC (0.2 mg/kg) were reduced by 14% and 80% by 0.25 mg/kg (n = 6) and 2.5 mg/kg (n = 6), respectively, of the CB1R antagonist, SR141716A. In conclusion, i.t. LTHC was superior to i.p. LTHC in producing a more rapid and potent decrease in IOP. The IOP-lowering effect of LTHC was blocked by the CB1R-selective antagonist, SR141716A, suggesting that CB1Rs contribute to the ocular hypotensive effect of Delta9-tetrahydrocannabinol.

Antitubercular inhaled therapy: opportunities, progress and challenges

Pulmonary tuberculosis remains the commonest form of this disease and the development of methods for delivering antitubercular drugs directly to the lungs via the respiratory route is a rational therapeutic goal. The obvious advantages of inhaled therapy include direct drug delivery to the diseased organ, targeting to alveolar macrophages harbouring the mycobacteria, reduced risk of systemic toxicity and improved patient compliance. Research efforts have demonstrated the feasibility of various drug delivery systems employing liposomes, polymeric microparticles and nanoparticles to serve as inhalable antitubercular drug carriers. In particular, nanoparticles have emerged as a remarkably useful tool for this purpose. While some researchers have preferred dry powder inhalers, others have emphasized nebulization. Beginning with the respiratory delivery of a single antitubercular drug, it is now possible to deliver multiple drugs simultaneously with a greater therapeutic efficacy. More experience and expertise have been observed with synthetic polymers, nevertheless, the possibility of using natural polymers for inhaled therapy has yet to be explored. Several key issues such as patient education, cost of treatment, stability and large scale production of drug formulations, etc. need to be addressed before antitubercular inhaled therapy finds its way from theory to clinical reality.

Design of liposomal aerosols for improved delivery of rifampicin to alveolar macrophages

The present study was aimed at preparation, characterization, and performance evaluation of rifampicin-loaded aerosolized liposomes for their selective presentation to alveolar macrophages, that being the most dense site of tuberculosis infection. Egg phosphatidylcholine (PC)- and cholesterol (Chol)-based liposomes were modified by imparting negative charge (using dicetylphosphate, DCP) or by coating them with alveolar macrophage-specific ligands (maleylated bovine serum albumin, MBSA; and O-steroyl amylopectin, O-SAP). The prepared formulations were characterized in vitro for vesicle morphology, mean vesicle size, and percent drug entrapment. Pressurized packed systems based on preformed liposomal formulations in chlorofluorocarbon aerosol propellants were prepared. In vitro airway penetration efficiency of the liposomal aerosols was determined by percent dose reaching the base of the lung, it was recorded 1.5-1.8 times higher as compared to plain drug solution-based aerosol. Percent viability of Mycobacterium smegmatis inside macrophages (in vitro) after administration of drug (in vivo) was in the range of 7-11% in the case of ligand-anchored liposomal aerosols, while it was recorded to be 45.7 and 31.6% in case of plain drug and plain neutral liposomal aerosol (based on PC:Chol)-treated macrophages. Results suggest the preferential accumulation of MBSA- and O-SAP-coated formulations in the lung macrophages, which was further reflected in the periodically monitored in vivo tissue distribution studies. Higher lung drug concentration was recorded in case of ligand-anchored liposomal aerosols and negatively charged liposomal aerosols (based on PC:Chol:DCP) as compared to plain drug and plain liposome-based aerosols. The drug was estimated in the lung in high concentration even after 24h. The drug localization index calculated after 6h was nearly 1.4- and 3.5-fold, respectively, for both ligand-appended liposome-based systems as compared to negatively charged and plain neutral liposome-based aerosolized systems. These results suggest that the ligand-anchored liposomal aerosols are not only effective in rapid attainment of high-drug concentration in lung with high population of alveolar macrophages but also maintain the same over prolonged period of time. The significance of targeting potential of the developed systems was established.

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.

A double-blind, placebo controlled, dose ranging study to evaluate the safety and biological efficacy of the lipid-DNA complex GR213487B in the nasal epithelium of adult patients with cystic fibrosis

GTAB1001: A Double-Blind, Placebo Controlled, Dose Ranging Study to Evaluate the Safety and Biological Efficacy of the Lipid-DNA Complex GR213487B in the Nasal Epithelium of Adult Patients with Cystic Fibrosis.

OBJECTIVES

To evaluate the effectiveness of various dosages of the lipid-DNA complex GR213487B (0.4375mg and either 4.0mg or 0.0625mg) for producing CFTR gene transfer and correcting the chloride ion transport defect in the nasal epithelium of patients with cystic fibrosis. To assess the safety and tolerability of the lipid-DNA complex GR213487B when applied to the nasal epithelium of patients with cystic fibrosis.

DESIGN

Single-center, double-blind, placebo controlled, dose ranging study.

DURATION

Pre-treatment evaluations will be performed during two outpatient study visits (ie. between Day -7 to -3 and at Day -2). Patients will be admitted to the Clinical Research Unit (CRU) at the University of North Carolina at Chapel Hill on Day -1 for additional pre-treatment evaluations performed the day prior to administration of double-blind treatment (ie. gene transfer) on Treatment Day 0. Patients will remain in the CRU for 7 days (Day -1 to Day 6) and will be discharged on Day 6. Patients will subsequently be followed on an outpatient basis but will return for another assessment between Days 9-11, and may also return to the CRU for two optional study visits on Days 14 and 21. All patients will return to the CRU on an out-patient basis for follow-up evaluations on Day 28 +/- 3.

SETTING

Patients will receive in-patient treatment in the CRU at the University of North Carolina at Chapel Hill and will remain in the CRU for 7 days.

PATIENTS

A target enrollment of 12 evaluable patients is planned. STUDY TREATMENTS: Patients who meet all entry criteria will complete pre-treatment assessments, which will take place between Day -7 to Day -1, and will serve as a baseline for specific evaluations and to ensure clinical stability. Patients will return on Day -1 for admission to the CRU the day prior to gene transfer. Each nostril of the patients will be randomly assigned in a double blind manner to receive either GR213487B liquid nasal spray or the lipid alone (ie. control administered as liposome), by topical application directed at the inferior turbinate. The first four patients will receive an initial dosage of GR213487B containing 0.4375 mg of DNA. The decision to proceed to administer a higher dose (ie. 4.0mg DNA) or a lower dose (ie. 0.0625mg DNA) in the subsequent eight patients will be determined by the Principal Investigator in association with an FDA officer serving as an independent Clinical Ombudsman, according to the study plan (see Section 5.5 and Appendix 3-Dosing Flow Chart).

MEASUREMENTS

Efficacy Evaluations The primary variables to determine the efficacy of transgene expression will be: * Evidence of vector derived CFTR (cystic fibrosis transmembrane conductance regulator) mRNA, as measured by reverse transcriptase polymerase chain reaction (RT-PCR) in nasal epithelial cells obtained from nasal scrapes on Day 3 and, nasal biopsies on Day 5, if sufficient tissue is available. * Correction of chloride ion transport across the nasal epithelium as measured by the transepithelial electrical potential difference (TEPD). The baseline TEPD will initially be measured, and again subsequently following perfusion of: --zero chloride perfusion containing amiloride (to induce chloride secretion) --zero chloride perfusion containing amiloride and isoproterenol (to increase cAMP-mediated chloride secretion) Secondary measures to determine the efficacy of gene transfer will be: * Evidence of delivery of plasmid DNA in the nasal lavage (Day 1-5, Day 9-11 and Day 28) * Evidence of vector derived CFTR mRNA from nasal scrapes performed after the nasal biopsy (ie. Day 9-11 and/or Day 28) * Percentage of cells from nasal biopsies expressing vector derived CFTR mRNA as measured by in situ hybridization * Evidence of vector derived CFTR

Ex vivo liposome-mediated gene transfer to lung isografts

OBJECTIVE

Gene therapy is a promising strategy to modify ischemia-reperfusion injury and rejection after transplantation. We evaluated variables that may affect ex vivo gene transfer to rat lung isografts.

METHODS

Left lungs were harvested and perfused via the pulmonary vein with chloramphenicol acetyltransferase complementary deoxyribonucleic acid complexed with cationic liposomes. Several variables were examined: (1) Influence of temperature: In group I (n = 4), grafts were stored for 4 hours at 23 degrees C and transplanted. Chloramphenicol acetyltransferase activity was assessed on postoperative day 2. In groups II and III (n = 4), grafts were stored at 10 degrees and 4 degrees C, respectively. Arterial oxygen tension and inflammatory infiltrate were also determined. (2) Influence of storage time: Grafts were preserved at 10 degrees C for 1, 2, 3, 4 (n = 4), and 10 hours (n = 5). chloramphenicol acetyltransferase activity was assessed on postoperative day 2. (3) Rapidity and duration of transgene expression: Grafts were preserved at 10 degrees C for 1 hour and then transplanted. Chloramphenicol acetyltransferase activity was assessed 2, 4, 6, 12, and 24 hours and 2, 7, 14, 21, and 28 days after implantation.

RESULTS

Chloramphenicol acetyltransferase expression was apparently less in lungs transfected at 4 degrees C than in those transfected at 10 degrees and 23 degrees C. Storage for 1 hour at 10 degrees C was sufficient to yield significant expression. Increasing the exposure time to 10 hours did not increase toxicity. There were no differences in arterial oxygen tension between transfected and nontransfected lungs. Chloramphenicol acetyltransferase expression was detected for at least 28 days.

CONCLUSION

Ex vivo liposome-mediated transfection of lung isografts can be achieved after a short time of cold storage, with minimal toxicity.

Liposome-mediated gene transfer to lung isografts

OBJECTIVES

Our objective were to determine the feasibility, efficacy, and safety of in vivo and ex vivo liposome-mediated gene transfer to lung isografts.

METHODS

Fischer rats were divided into three main groups: (1) Nontransplant setting: Liposome-chloramphenicol acetyl transferase cDNA was intravenously injected, and lungs were harvested at different time points: 2, 6, 12, and 24 hours; 2, 5, 8, and 21 days (n = 3). Chloramphenicol acetyl transferase activity was determined in lungs, hearts, livers, and kidneys. The distribution and type of transfected cells were evaluated by in situ hybridization. Lung toxicity was assessed by arterial oxygen tension, histology, and tumor necrosis factor-alpha levels. (2) In vivo graft transfection: Left lungs were transplanted 6 hours, 4 hours, and 15 minutes after intravenous injection and were assessed for chloramphenicol acetyl transferase activity and arterial oxygen tension on postoperative day 2. (3) Ex vivo graft transfection: Grafts were infused ex vivo with either 660 micrograms (n = 3) or 330 micrograms (n = 3) of DNA complexed to liposomes and stored at 10 degrees C for 4 hours. Chloramphenicol acetyl transferase activity was assessed 44 hours after transplantation.

RESULTS

Transgene expression was detected in endothelial cells, macrophages, and interstitial cells. Chloramphenicol acetyl transferase activity was present as early as 2 hours, increased significantly between 6 hours and 8 days, and then decreased to minimal levels by 21 days. Chloramphenicol acetyl transferase activity was greatest in donor lungs and hearts and minimal in livers and kidneys. Arterial oxygen tension was normal in treated animals. Inflammation was minimal, and tumor necrosis factor-alpha levels increased only sevenfold in treated animals.

CONCLUSION

In vivo and ex vivo liposome-mediated gene transfer to lung isografts allows significant transgene expression with minimal effects on graft function.

Effects of cationic liposome-DNA complexes on pulmonary surfactant function in vitro and in vivo

Cationic liposome-DNA complexes are being evaluated as potential gene therapy agents for the lung. Cations have strong effects on the biophysical functions of lung surfactant. Therefore, we assessed whether cationic liposomes [composed of N-(1-(2,3-dioleyloxy) propyl)-N,N,N-trimethyl-ammonium chloride and dioleylphosphatidylethanolamine] with or without DNA affect behavior of four types of surfactant in vitro. Experiments were carried out using a modified Wilhelmy surface balance. The ability of surfactants that contain protein and anionic lipids to lower surface tension was inhibited in the presence of cationic liposomes. Inactivation was less when DNA was preincubated with cationic liposomes. Surfactant that contained neither protein nor anionic lipids was not inactivated. Mechanical properties of the lung were studied to assess in vivo surfactant function after intratracheal instillation of a cationic liposome-DNA complex into adult rats. Pressure-volume deflation curves were shifted by 18% compared with those from normal (untreated) animals, but this effect was transient and not different from that observed in animals who received a similar volume of saline. These findings indicate that cationic liposomes alone may have deleterious effects on behavior of some surfactants possibly by disrupting charge interactions between negatively charged phospholipids and surfactant proteins. When DNA is added to liposomes before exposure to surfactants, the adverse charge interactions may be obviated by charge neutralization of liposomes by DNA.

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

STUDY OBJECTIVE

To test the tolerance and safety of single doses of beclomethasone dipropionate (Bec)-dilauroylphosphatidylcholine (DLPC) liposome aerosol in volunteers.

DESIGN

Single-dose inhalations of liposome preparations of Bec-DLPC and DLPC alone were administered for 15 min from a jet nebulizer (Puritan-Bennett, modified twin jet; mass median aerodynamic diameter of 1.6 microns) under close clinical and laboratory surveillance. Two dose levels (0.5 mg Bec/12.5 mg DLPC per milliliter, and 1.0 mg Bec and 25 mg DLPC per milliliter in the reservoirs, respectively) were administered. The Bec doses were selected to approximate the dosages of this glucocorticoid used with metered-dose inhalers (MDIs). First, four volunteers were exposed to an initial low dose; the mean (+/-SD) inhaled doses were 0.56 +/- 0.07 mg of Bec and/or 14.0 +/- 1.8 mg of DLPC. Subsequently, a second group of six volunteers was exposed to a higher dose; the mean (+/-SD) inhaled doses were 1.29 +/- 0.14 mg of Bec and/or 34.6 +/- 6.8 mg of DLPC.

SETTING

Outpatient and inpatient.

PATIENTS

Normal male (n = 6) and female (n = 4) adult volunteers.

INTERVENTIONS

Inhalation of Bec-DLPC and DLPC liposome aerosols in a single-dose tolerance study involving 10 normal volunteers.

MEASUREMENTS AND RESULTS

Spirometry, clinical observations, clinical chemistry, and hematology were monitored. No adverse clinical or laboratory events were observed.

CONCLUSIONS

Bec-DLPC liposome aqueous aerosol was well tolerated in doses equivalent to those currently administered by MDIs and dry powder inhalers for treatment of asthma.

Efficacy of prophylactic aerosol amphotericin B lipid complex in a rat model of pulmonary aspergillosis

Invasive pulmonary aspergillosis remains an important cause of morbidity and mortality among transplant recipients and patients receiving cancer chemotherapy. The lipid-associated formulation of amphotericin B (AmB), AmB lipid complex (ABLC), was evaluated for its prophylactic efficacy when it was administered as an aerosol in a rat model of pulmonary aspergillosis. Aerosol ABLC (aero-ABLC), in doses from 0.4 to 1.6 mg/kg of body weight given 2 days before infection, significantly delayed mortality compared to the mortality of rats given placebo (P < 0.001). At day 10 postinfection, 50% of rats in the 0.4-mg/kg group and 75% of rats in the 1.6-mg/kg group were alive, while all control animals had died. In a second trial aero-ABLC was more effective than an equivalent dose of aerosol AmB (aero-AmB) in prolonging survival, with 100% survival at day 14 postinfection in the ABLC group, compared to 62.5% survival in the AmB group. Mean concentrations of AmB in lungs were 3.7 times higher at day 1 (P < 0.002) and almost six times higher at day 7 (P < 0.001) after treatment with aero-ABLC than after treatment with a similar dose of aero-AmB. We conclude that aero-ABLC provided higher and more prolonged levels of the parent compound in the lungs than aero-AmB and was more effective in delaying mortality from aspergillosis in this model.

Receptor ligand-facilitated gene transfer: enhancement of liposome-mediated gene transfer and expression by transferrin

A high-efficiency, nonviral gene transfer protocol employing cationic liposome plus a receptor ligand is described. The delivery of the beta-galactosidase (beta-Gal) gene (pCMVlacZ) by lipofectin plus transferrin can achieve 98-100% transfection of HeLa cells as compared to 3-4% by lipofectin alone. A dose-dependent gene transfer was observed between 1 and 16 micrograms transferrin, and maximal transfection efficiency was obtained at > or = 16 micrograms transferrin. The expression of beta-Gal activity in 100% transfected cells decreased progressively with each passage and returned to the baseline value after six passages, indicating that the DNA delivered was only transiently expressed. The amount of DNA delivered to the cells by lipofectin plus transferrin was approximately two times that obtained by lipofectin, which in turn was two times that by transferrin or without lipofectin and transferrin. In addition, DNA can form complexes with lipofectin and transferrin. These results suggest that transferrin enhances gene transfer and expression in the presence of lipofectin by further facilitating the entry of DNA into the cells through the lipofectin-DNA-transferrin complex. The enhancement of liposome-mediated gene transfer efficiency and expression by transferrin varies with different cationic liposomes. The four different liposomes examined show the following relative transfection efficiency: transfectin > lipofectACE > > DC-cholesterol > > lipofectAMINE.

PC:PS liposomes induce a recruitment of neutrophils and the release of TNF alpha in the lungs of mice sensitized with Saccharopolyspora rectivirgula

The aim of this study was to verify the effect of nasally instilled liposomes (L) or dexamethasone-containing L (Ldexa) on normal or inflamed lung tissue. Three groups of mice were studied. Group I was given saline instillations for 3 weeks prior to the instillation with liposomes. In groups II and III lung inflammation was induced by repeated instillations of Saccharopolyspora rectivirgula before the instillation of liposomes (group II) or liposomes containing dexamethasone (group III). Animals from all groups were killed at regular time intervals for up to 48 h after the instillation of liposomes. The total cell count in bronchoalveolar lavage fluid did not differ significantly between groups I and II. However, in group III it decreased rapidly from 6.2 to 2.8 x 10(5) cells mL-1 within 2 h. Differential counts did not change in group I, but in group II a transient neutrophilia was observed 180 min after the instillation of liposomes. In group III, the instillation of dexamethasone-containing liposomes depleted all neutrophils and lymphocytes after 4 h. No TNF alpha was found in samples of lavage fluid from any of the groups at time 0. In group I, liposomes induced the production of 0.03 ng mL-1 of TNF alpha in the 1 h sample only. In group II, TNF alpha peaked to 1 ng mL-1 at 1 h and had decreased to 0.35 ng mL-1 by 3 h. In group III, TNF alpha peaked at 1 h, but only reached a level of 0.1 ng mL-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Gene therapy for cystic fibrosis

Following the cloning of the cystic fibrosis (CF) gene, in vitro studies rapidly established the feasibility of gene therapy for this disease. Unlike ex vivo approaches that have been utilized for other genetic diseases such as adenosine deaminase deficiency, gene therapy for CF will likely require direct in vivo delivery of gene transfer vectors to the airways of patients with CF. Hence, major research efforts have been directed at the development of efficient gene transfer vectors that are safe for use in human subjects. Several vectors have now emerged from the laboratory for evaluation in clinical safety and efficacy trials in the United States and in the United Kingdom. Adenovirus-mediated gene transfer has been utilized for initial clinical safety and efficacy trials in the United States, while liposome-mediated gene transfer has been chosen for initial clinical safety and efficacy trials in the United Kingdom. The rationale and laboratory studies are reviewed leading to initial clinical safety and efficacy trials. Also reviewed are the currently available vectors for potential use in clinical studies, their advantages and disadvantages, and the promises and pitfalls of current gene therapy efforts for CF in the United States focusing on adenovirus vectors in current clinical trials.