Pulmonary delivery of amikacin liposomes and acute liposome toxicity in the sheep

Spray-Dried Proliposome Microparticles for High-Performance Aerosol Delivery Using a Monodose Powder Inhaler

Proliposome formulations containing salbutamol sulphate (SS) were developed using spray drying, and the effects of carrier type (lactose monohydrate (LMH) or mannitol) and lipid to carrier ratio were evaluated. The lipid phase comprised soy phosphatidylcholine (SPC) and cholesterol (1:1), and the ratios of lipid to carrier were 1:2, 1:4, 1:6, 1:8 or 1:10 w/w. X-ray powder diffraction (XRPD) revealed an interaction between the components of the proliposome particles, and scanning electron microscopy (SEM) showed that mannitol-based proliposomes were uniformly sized and spherical, whilst LMH-based proliposomes were irregular and relatively large. Using a two-stage impinger (TSI), fine particle fraction (FPF) values of the proliposomes were higher for mannitol-based formulations, reaching 52.6%, which was attributed to the better flow properties when mannitol was used as carrier. Following hydration of proliposomes, transmission electron microscopy (TEM) demonstrated that vesicles generated from mannitol-based formulations were oligolamellar, whilst LMH-based proliposomes generated 'worm-like' structures and vesicle clusters. Vesicle size decreased upon increasing carrier to lipid ratio, and the zeta potential values were negative. Drug entrapment efficiency (EE) was higher for liposomes generated from LMH-based proliposomes, reaching 37.76% when 1:2 lipid to carrier ratio was used. The in vitro drug release profile was similar for both carriers when 1:6 lipid to carrier ratio was used. This study showed that spray drying can produce inhalable proliposome microparticles that can generate liposomes upon contact with an aqueous phase, and the FPF of proliposomes and the EE offered by liposomes were formulation-dependent.

Pulmonary Deposition and Elimination of Liposomal Amikacin for Inhalation and Effect on Macrophage Function after Administration in Rats

Pulmonary nontuberculous mycobacterial (PNTM) infections represent a treatment challenge. Liposomal amikacin for inhalation (LAI) is a novel formulation currently in development for the treatment of PNTM infections. The pulmonary deposition and elimination of LAI and its effect on macrophage function were evaluated in a series of preclinical studies in healthy rats. The pulmonary deposition of LAI was evaluated in female rats (n = 76) treated with LAI by nebulizer at 10 mg/kg of body weight per day or 90 mg/kg per day for 27 days, followed by dosing of dually labeled LAI (LAI with a lipid label plus an amikacin label) on day 28 with subsequent lung histological and amikacin analyses. In a separate study for assessment of alveolar macrophage function, rats (n = 180) received daily treatment with LAI at 90 mg/kg per day or 1.5% saline over three 30-day treatment periods followed by 30-day recovery periods; phagocytic and Saccharomyces cerevisiae (yeast) killing capabilities and inflammatory mediator release were assessed at the end of each period. LAI demonstrated equal dose-dependent deposition across all lung lobes and regions. Lipid and amikacin labels showed diffuse extracellular colocalization, followed by macrophage uptake and gradual amikacin elimination. Macrophages demonstrated accumulation of amikacin during treatment periods and nearly complete elimination during recovery periods. No evidence of an inflammatory response was seen. No differences in microsphere uptake or yeast killing were seen between LAI-treated and control macrophages. Neither LAI-treated nor control macrophages demonstrated constitutive inflammatory mediator release; however, both showed normal mediator release on lipopolysaccharide stimulation. LAI is readily taken up by macrophages in healthy rats without compromising macrophage function.

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.

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.

A novel continuous powder aerosolizer (CPA) for inhalative administration of highly concentrated recombinant surfactant protein-C (rSP-C) surfactant to preterm neonates

BACKGROUND

In pulmonary medicine, aerosolization of substances for continuous inhalation is confined to different classes of nebulizers with their inherent limitations. Among the unmet medical needs is the lack of an aerosolized surfactant preparation for inhalation by preterm neonates, to avoid the risks associated with endotracheal intubation and surfactant bolus instillation. In the present report, we describe a high-concentration continuous powder aerosolization system developed for delivery of inhalable surfactant to preterm neonates.

METHODS

The developed device uses a technique that allows efficient aerosolization of dry surfactant powder, generating a surfactant aerosol of high concentration. In a subsequent humidification step, the heated aerosol particles are covered with a surface layer of water. The wet surfactant aerosol is then delivered to the patient interface (e.g., nasal prongs) through a tube.

RESULTS

The performance characteristics of the system are given as mass concentration, dose rate, and size distribution of the generated aerosol. Continuous aerosol flows of about 0.84 L/min can be generated from dry recombinant surfactant protein-C surfactant, with concentrations of up to 12 g/m(3) and median particle sizes of the humidified particles in the range of 3 to 3.5 μm at the patient interface. The system has been successfully used in preclinical studies.

CONCLUSION

The device with its continuous high-concentration delivery is promising for noninvasive delivery of surfactant aerosol to neonates and has the potential for becoming a versatile disperser platform closing the gap between continuously operating nebulizers and discontinuously operating dry powder inhaler devices.

Targeted drug delivery of Rifampicin to the lungs: formulation, characterization, and stability studies of preformed aerosolized liposome and in situ formed aerosolized liposome

PURPOSE

This study aimed at the preparation and characterization of preformed and in situ formed liposomes for sustained delivery to the lungs.

METHODS

Two different liposome formulations were prepared and subjected to characterization of physical parameters and drug release profile (% cumulative drug release and % drug retained). Formulations were then subjected to accelerated stability studies as per ICH guidelines.

RESULTS

In situ formed liposome showed better sustained release profile than the preformed liposome as it released sufficient amount of drug while retaining considerable amount of drug. Upon subjection to accelerated conditions for 60 days, preformed liposome lost the objective of being controlled release formulation.

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.