Systemic delivery of biotherapeutics through the lung: opportunities and challenges for improved lung absorption

N,N,N-Trimethyl chitosan as a permeation enhancer for inhalation drug delivery: Interaction with a model pulmonary surfactant

N,N,N-Trimethyl chitosan (TMC), a biocompatible and biodegradable derivative of chitosan, is currently used as a permeation enhancer to increase the translocation of drugs to the bloodstream in the lungs. This article discusses the effect of TMC on a mimetic pulmonary surfactant, Curosurf®, a low-viscosity lipid formulation administered to preterm infants with acute respiratory distress syndrome. Curosurf® exhibits a strong interaction with TMC, resulting in the formation of aggregates at electrostatic charge stoichiometry. At nanoscale, Curosurf® undergoes a profound reorganization of its lipid vesicles in terms of size and lamellarity. The initial micron-sized vesicles (average size 4.8 μm) give way to a froth-like network of unilamellar vesicles about 300 nm in size. Under such conditions, neutralization of the cationic charges by pulmonary surfactant may inhibit TMC permeation enhancer capacity, especially as electrostatic charge complexation is found at low TMC content. The permeation properties of pulmonary surfactant-neutralized TMC should then be evaluated for its applicability as a permeation enhancer for inhalation in the alveolar region.

Performance of Cell-Penetrating Peptides Anchored to Polysaccharide Platforms Applied via Various Mucosal Routes as an Absorption Enhancer

We have been investigating the potential of cell-penetrating peptides anchored to polymeric platforms as a novel absorption enhancer which delivers biologics into systemic circulation via mucosal routes. Our previous mouse experiments demonstrated that hyaluronic acid modified with l-octaarginine, a typical cell-penetrating peptide, via a tetraglycine spacer significantly enhanced the mucosal absorption of protein drugs applied into the nasal cavities, irrespective of the molecular weights (M_w) of the drugs. The present study evaluated the performance of tetraglycine-l-octaarginine-linked hyaluronic acid applied via various mucosal routes. Somatropin (M_w: ca. 22.1 kDa) was moderately absorbed from the lung mucosa, and the mean absolute bioavailability (BA) reached 19% under enhancer-free conditions; nevertheless, its BA under intranasal administration was approximately 1% or less. Its BA significantly elevated to 46% on average through intrapulmonary coadministration with tetraglycine-l-octaarginine-linked hyaluronic acid. When the administration site was replaced with the oral cavities, an extreme reduction in somatropin absorption was observed with a mean BA of 0.056% under enhancer-free conditions. Intraoral coadministration with tetraglycine-l-octaarginine-linked hyaluronic acid resulted in a 6.3-fold elevation of somatropin absorption with statistical significance. A similar enhancement was observed under intrarectal administration with a further reduction in BA. On the other hand, the hyaluronic acid derivative did not exhibit the absorption-enhancing ability under intragastric administration, probably due to the lack of stabilization effects against enzyme-susceptible biologics. The results indicated that the intrapulmonary route was suitable for maximizing the mucosal absorption of biologics, and that there was a likelihood of the intraoral route with user convenience. When somatropin was substituted with fluorescein isothiocyanate-conjugated dextran with an average M_w range of 4-70 kDa, similar phenomena were observed under intrapulmonary and intranasal administration. BA decreased with an increase in the M_w of dextran; however, the ratio of BA under enhancer-present conditions to that under enhancer-free conditions was consistently around 3, indicating that the performance of the hyaluronic acid derivative was M_w-independent, irrespective of the administration route.

Physiologically-based pharmacokinetic model for pulmonary disposition of protein therapeutics in humans

Lung related disorders like COPD and Asthma, as well as various infectious diseases, form a major therapeutic area which would benefit from a predictive and adaptable mathematical model for describing pulmonary disposition of biological modalities. In this study we fill that gap by extending the cross-species two-pore physiologically-based pharmacokinetic (PBPK) platform with more detailed respiratory tract that includes the airways and alveolar space with epithelial lining fluid. We parameterize the paracellular and FcRn-facilitated exchange pathways between the epithelial lining fluid and lung interstitial space by building a mechanistic model for the exchange between the two. The optimized two-pore PBPK model described pulmonary exposure of several systemically dosed mAbs for which data is available and is also in agreement with the observed levels of endogenous IgG and albumin. The proposed framework can be used to assess pharmacokinetics of new lung-targeting biologic therapies and guide their dosing to achieve desired exposure at the pulmonary site-of-action.

Turning genome-wide association study findings into opportunities for drug repositioning

Drug development is a very costly and lengthy process, while repositioned or repurposed drugs could be brought into clinical practice within a shorter time-frame and at a much reduced cost. Numerous computational approaches to drug repositioning have been developed, but methods utilizing genome-wide association studies (GWASs) data are less explored.

The past decade has observed a massive growth in the amount of data from GWAS; the rich information contained in GWAS has great potential to guide drug repositioning or discovery. While multiple tools are available for finding the most relevant genes from GWAS hits, searching for top susceptibility genes is only one way to guide repositioning, which has its own limitations.

Here we provide a comprehensive review of different computational approaches that employ GWAS data to guide drug repositioning. These methods include selecting top candidate genes from GWAS as drug targets, deducing drug candidates based on drug-drug and disease-disease similarities, searching for reversed expression profiles between drugs and diseases, pathway-based methods as well as approaches based on analysis of biological networks. Each method is illustrated with examples, and their respective strengths and limitations are discussed. We also discussed several areas for future research.

In Vivo Pulmonary Delivery and Magnetic-Targeting of Dry Powder Nano-in-Microparticles

This brief communication evaluates the cytotoxicity and targeting capability of a dry powder chemotherapeutic. Nano-in-microparticles (NIMs) are a dry powder drug delivery vehicle containing superparamagnetic iron oxide nanoparticles (SPIONs) and either doxorubicin (w/w solids) or fluorescent nanospheres (w/v during formulation; as a drug surrogate) in a lactose matrix. In vitro cytotoxicity was evaluated in A549 adenocarcinoma cells using MTS and LDH assays to assess viability and toxicity after 48 h of NIMs exposure. In vivo magnetic-field-dependent targeting of inhaled NIMs was evaluated in a healthy mouse model. Mice were endotracheally administered fluorescently labeled NIMs either as a dry powder or a liquid aerosol in the presence of an external magnet placed over the left lung. Quantification of fluorescence and iron showed a significant increase in both fluorescence intensity and iron content to the left magnetized lung. In comparison, we observed decreased targeting of fluorescent nanospheres to the left lung from an aerosolized liquid suspension, due to the dissociation of SPIONs and nanoparticles during pulmonary administration. We conclude that dry powder NIMs maintain the therapeutic cytotoxicity of doxorubicin and can be better targeted to specific regions of the lung in the presence of a magnetic field, compared to a liquid suspension.

Stability and efficacy of synthetic cationic antimicrobial peptides nebulized using high frequency acoustic waves

Surface acoustic wave (SAW), a nanometer amplitude electroelastic wave generated and propagated on low-loss piezoelectric substrates (such as LiNbO3), is an extremely efficient solid-fluid energy transfer mechanism. The present study explores the use of SAW nebulization as a solution for effective pulmonary peptide delivery. In vitro deposition characteristics of the nebulized peptides were determined using a Next Generation Cascade Impactor. 70% of the peptide-laden aerosols generated were within a size distribution favorable for deep lung distribution. The integrity of the nebulized peptides was found to be retained, as shown via mass spectrometry. The anti-mycobacterial activity of the nebulized peptides was found to be uncompromised compared with their non-nebulized counterparts, as demonstrated by the minimum inhibition concentration and the colony forming inhibition activity. The peptide concentration and volume recoveries for the SAW nebulizer were significantly higher than 90% and found to be insensitive to variation in the peptide sequences. These results demonstrate the potential of the SAW nebulization platform as an effective delivery system of therapeutic peptides through the respiratory tract to the deep lung.

How perifosine affects liposome-encapsulated drug delivery across a cell barrier

BACKGROUND

The development of efficient drug delivery systems to transport therapeutics across barrier-forming cells remains a challenge. Recently it was shown that liposomes containing perifosine, a synthetic analog of lysophosphatidylcholine, efficiently deliver liposome encapsulated content across barrier-forming cells.

METHODS

To elucidate the mechanism of the delivery, fluorescent and spin labeled analog of perifosine were synthesized and their transport from liposomes to the barrier-forming MDKC cells was measured.

RESULTS & CONCLUSION

Perifosine analogs are rapidly transported from liposomes into cell membranes. The total amount of perifosine accumulated in plasma membranes seems to be the most important factor in efficient transepithelial transport of liposome-encapsulated substances. Lysolipid-containing liposomal formulations seem to be promising candidates as drug delivery systems in general.

Pulmonary delivery of anorectic oxyntomodulin in rats: food intake suppression, reduced body weight gain and pharmacokinetics

Background: Oxyntomodulin (OXM1–37) is an anorectic gut-secreting peptide with a promise to treat obesity, but its needle-free delivery has yet to be successful. Results: Pulmonary delivery of OXM1–37, but not its C-terminal octapeptides, caused dose-related, transient 4–6 h food intake suppression in rats. At 0.5 mg/kg, its 30–38% food intake suppression led to 46% reduction in body weight gain by day 8. Its lung absorption was fast, elevating the systemic level rapidly, yet the bioavailability was low at 13%. In the brain, twofold neuronal c-fos activation was seen in the hypothalamus arcuate nucleus and brainstem area postrema. Conclusion: Pulmonary delivery is a promising needle-free systemic delivery option for OXM1–37 to treat obesity, as enabling effective lung absorption and brain interaction.

Long-term delivery of protein therapeutics

INTRODUCTION

Proteins are effective biotherapeutics with applications in diverse ailments. Despite being specific and potent, their full clinical potential has not yet been realized. This can be attributed to short half-lives, complex structures, poor in vivo stability, low permeability, frequent parenteral administrations and poor adherence to treatment in chronic diseases. A sustained release system, providing controlled release of proteins, may overcome many of these limitations.

AREAS COVERED

This review focuses on recent development in approaches, especially polymer-based formulations, which can provide therapeutic levels of proteins over extended periods. Advances in particulate, gel-based formulations and novel approaches for extended protein delivery are discussed. Emphasis is placed on dosage form, method of preparation, mechanism of release and stability of biotherapeutics.

EXPERT OPINION

Substantial advancements have been made in the field of extended protein delivery via various polymer-based formulations over last decade despite the unique delivery-related challenges posed by protein biologics. A number of injectable sustained-release formulations have reached market. However, therapeutic application of proteins is still hampered by delivery-related issues. A large number of protein molecules are under clinical trials, and hence, there is an urgent need to develop new methods to deliver these highly potent biologics.

Emerging aerosol drug delivery strategies: from bench to clinic

Patients with tracheostomies, those requiring mechanical ventilation, and those too small or compromised for conventional devices, are realizing the benefits of increasingly sophisticated aerosol delivery systems. New medicines and novel aerosol formulations, have enhanced our ability to treat lung disease, and are opening the doors for therapy to treat diseases like diabetes, pulmonary hypertension, and cancer. Progress in the aerosol delivery of drugs has been spurred by the significant benefits, including ease of use, patient comfort, greater selectivity of effect, and the potential to decrease side effects.

Inhalable PEGylated Phospholipid Nanocarriers and PEGylated Therapeutics for Respiratory Delivery as Aerosolized Colloidal Dispersions and Dry Powder Inhalers

Nanomedicine is making groundbreaking achievements in drug delivery. The versatility of nanoparticles has given rise to its use in respiratory delivery that includes inhalation aerosol delivery by the nasal route and the pulmonary route. Due to the unique features of the respiratory route, research in exploring the respiratory route for delivery of poorly absorbed and systemically unstable drugs has been increasing. The respiratory route has been successfully used for the delivery of macromolecules like proteins, peptides, and vaccines, and continues to be examined for use with small molecules, DNA, siRNA, and gene therapy. Phospholipid nanocarriers are an attractive drug delivery system for inhalation aerosol delivery in particular. Protecting these phospholipid nanocarriers from pulmonary immune system attack by surface modification by polyethylene glycol (PEG)ylation, enhancing mucopenetration by PEGylation, and sustaining drug release for controlled drug delivery are some of the advantages of PEGylated liposomal and proliposomal inhalation aerosol delivery. This review discusses the advantages of using PEGylated phospholipid nanocarriers and PEGylated therapeutics for respiratory delivery through the nasal and pulmonary routes as inhalation aerosols.