Formulation and evaluation of novel reverse microemulsions containing salmon calcitonin in hydrofluoroalkane propellants

Lecithin Reverse Micelle System is Promising in Constructing Carrier Particles for Protein Drugs Encapsulated Pressurized Metered‐Dose Inhalers

Protein drugs contained within pressurized metered dose inhalers (pMDIs) show immense potential for fundamental research and industrial applications, owing to their high bioavailability, convenient administration, and cost‐effectiveness. To deliver protein drugs efficiently, researchers have reached a consensus on the use of carrier particles. However, the main obstacle impeding the commercial availability of pMDI carrier particles is their low stability. This instability is primarily attributed to particle aggregation caused by the Ostwald ripening phenomenon and chemical degradation by water sensitivity of protein drugs. This study proposes the utilization of lecithin, a carrier material possessing an amphiphilic structure, to overcome this bottleneck. By constructing lecithin‐based reverse micelle systems with protein drugs encapsulated within the high‐polarity microdomain, this work anticipates an improvement in the stability of carrier particles within pMDIs. Specifically, the formation of crystalline phases in the reverse micelle systems can control carrier particle size through crystalline self‐limiting effect, preventing particle aggregation. Additionally, the low‐polarity microdomain of the carrier serves as a hydrophobic barrier, shielding protein drugs from water and preventing chemical degradation. Consequently, this work believes that the lecithin‐based reverse micelle system holds significant potential in providing new theoretical insights and experimental support for the advancement of pMDIs containing protein drugs.

A Pilot Study Exploiting the Industrialization Potential of Solid Lipid Nanoparticle-Based Metered-Dose Inhalers

BACKGROUND

Delivery of inhalable nanoparticles through metered-dose inhalers (MDI) is a promising approach to treat lung disease such as asthma and chronic obstructive pulmonary disease. Nanocoating of the inhalable nanoparticles helps in stability and cellular uptake enhancement but complicates the production process. Thus, it is meaningful to accelerate the translation process of MDI encapsulating inhalable nanoparticles with nanocoating structure.

METHODS

In this study, solid lipid nanoparticles (SLN) are selected as a model inhalable nanoparticle system. An established reverse microemulsion strategy was utilized to explore the industrialization potential of SLN-based MDI. Three categories of nanocoating with the functions of stabilization (by Poloxamer 188, encoded as SLN(0)), cellular uptake enhancement (by cetyltrimethylammonium bromide, encoded as SLN(+)), and targetability (by hyaluronic acid, encoded as SLN(-)) were constructed upon SLN, whose particle size distribution and zeta-potential were characterized. Subsequently, SLN were loaded into MDI, and evaluated for the processing reliability, physicochemical nature, formulation stability, and biocompatibility.

RESULTS

The results elucidated that three types of SLN-based MDI were successfully fabricated with good reproducibility and stability. Regarding safety, SLN(0) and SLN(-) showed negligible cytotoxicity on cellular level.

CONCLUSIONS

This work serves as a pilot study for the scale-up of SLN-based MDI, and could be useful for the future development of inhalable nanoparticles.

Nanotechnology as a tool to overcome macromolecules delivery issues

Nanocarriers can deliver drugs to specific organs or cells, potentially bridging the gap between a drug's function and its interaction with biological systems such as human physiology. The untapped potential of nanotechnology stems from its ability to manipulate materials, allowing control over physical and chemical properties and overcoming drug-related problems, e.g., poor solubility or poor bioavailability. For example, most protein drugs are administered parenterally, each with challenges and peculiarities. Some problems faced by bioengineered macromolecule drugs leading to poor bioavailability are short biological half-life, large size and high molecular weight, low permeability through biological membranes, and structural instability. Nanotechnology emerges as a promising strategy to overcome these problems. Nevertheless, the delivery system should be carefully chosen considering loading efficiency, physicochemical properties, production conditions, toxicity, and regulations. Moving from the bench to the bedside is still one of the major bottlenecks in nanomedicine, and toxicological issues are the greatest challenges to overcome. This review provides an overview of biotech drug delivery approaches, associated nanotechnology novelty, toxicological issues, and regulations.

Tadalafil Nanoemulsion Mists for Treatment of Pediatric Pulmonary Hypertension via Nebulization

Oral tadalafil (TD) proved promising in treating pediatric pulmonary arterial hypertension (PAH). However, to ensure higher efficacy and reduce the systemic side effects, targeted delivery to the lungs through nebulization was proposed as an alternative approach. This poorly soluble drug was previously dissolved in nanoemulsions (NEs). However, the formulations could not resist aqueous dilution, which precluded its dilution with saline for nebulization. Thus, the current study aimed to modify the previous systems into dilutable TD-NEs and assess their suitability for a pulmonary application. In this regard, screening of various excipients was conducted to optimize the former systems; different formulations were selected and characterized in terms of physicochemical properties, nebulization performance, stability following sterilization, and biocompatibility. Results showed that the optimal system comprised of Capmul-MCM-EP:Labrafac-lipophile (1:1) (w/w) as oil, Labrasol:Poloxamer-407 (2:1) (w/w) as surfactant mixture (S_mix) and water. The optimum formulation P2_TD resisted aqueous dilution, exhibited reasonable drug loading (2.45 mg/mL) and globule size (25.04 nm), acceptable pH and viscosity for pulmonary administration, and could be aerosolized using a jet nebulizer. Moreover, P2_TD demonstrated stability following sterilization and a favorable safety profile confirmed by both in-vitro and in-vivo toxicity studies. These favorable findings make P2_TD promising for the treatment of pediatric PAH.

Low Drug Loading Hampers the Clinical Translation of Peptide Drugs-Containing Metered-Dose Inhalers

Peptide-based drugs have attracted extensive attention from the medical and pharmaceutical industry because of their relatively high safety and efficacy. However, most of the peptide drugs approved are administrated by injection, which can easily cause poor patient compliance. In this circumstance, pulmonary administration as an alternative to injection administration can not only avoid the above issue but also accelerate the absorption rate of peptide drugs and improve bioavailability. Among the pulmonary delivery systems available on the market, metered-dose inhalers (MDIs) have emerged as appealing candidates for pulmonary delivery systems with clinical translational value, owing to their many merits, including portable, easy-to-operate, and cost-effective properties. Nevertheless, the industrialization of peptide drugs-containing MDIs encounters a bottleneck of low drug loading, owing to the incompatibility between the propellant and the peptide drugs, which cannot be effectively overcome by the current carrier particle encapsulation strategy. Herein, we put forward the following strategies: (1) To screen amphiphilic materials with high surface activity and strong interaction with peptide drugs; (2) To construct a chemical connection between peptide drugs and amphiphilic substances; (3) To optimize the cosolvent for dispersing peptide drugs. We suppose these strategies have the potential to defeat the bottleneck problem and provide a new idea for the industrialization of peptide drugs-containing MDIs.

Enhancing Stability of Exenatide-Containing Pressurized Metered-Dose Inhaler Via Reverse Microemulsion System

The dispersibility and stability issues of peptide drugs during preparation and storage hinder the widespread adoption of pressurized metered-dose inhaler (pMDI). This study aimed to develop a reverse microemulsion (RM) of exenatide (EXE) pMDI through a liquid-based bottom-up method, thus to overcome the stability issue of peptide drugs encountered in traditional top-down methods, such as milling down and high-pressure homogenization. In this study, Pluronic® L64 (L64) was chosen as a surfactant to prepare the EXE-RM pMDI formulations with the assistance of ethanol. The results showed RM possessed a particle size of 123.80 ± 2.91 nm with 0.121 ± 0.024 PdI and a satisfied fine-particle fraction of 41.30 ± 3.73% measured by a next-generation impactor. In addition, the dispersion stability of RM pMDI was maintained after storage at 4 °C for 50 days. The secondary structure of EXE was maintained during the preparation process. Moreover, the results indicated that L64 was compatible with cells and could improve the penetration of EXE through cell monolayers. Through the liquid-based bottom-up method, EXE-RM pMDI was successfully prepared and exhibited favorable stability and aerodynamic performance. This study offers a preparation strategy to enhance the stability of peptides in pMDIs.

Supramolecular nanoparticles of calcitonin and dipeptide for long-term controlled release

Salmon calcitonin (sCT) is a therapeutic polypeptide drug widely used to treat bone diseases such as osteoporosis (more than 200 million patients all over the world). The half-life of sCT is very short (~1h), thus various delivery systems have been developed for sCT in order to avoid frequent injections. However, most delivery systems use polymeric materials, which may limit their applications in clinic formulations due to the biocompatibility issue. We observed that a very simple dipeptide (Asp-Phe, DF) was co-assembled with sCT into supramolecular nanoparticles. These nanoparticles can significantly prolong the acting time of sCT to beyond one month after just a single subcutaneous injection. The assembling and releasing mechanisms were thoroughly investigated by both in vitro and in vivo methods, as well as by molecular dynamics simulations. This work provides an alternative strategy of designing protein/peptide drug delivery systems with long-lasting therapeutic effects.

Anhydrous reverse micelle nanoparticles: new strategy to overcome sedimentation instability of peptide-containing pressurized metered-dose inhalers

The objective of this study was to develop a novel anhydrous reverse micelle nanoparticles (ARM-NPs) system to overcome the sedimentation instability of peptide-containing pressurized metered-dose inhalers (pMDIs). A bottom-up method was utilized to fabricate ARM-NPs. Tertiary butyl alcohol (TBA)/water system, freeze-drying and lipid inversion method were successively used to produce the ARM-NPs for pMDI. Various characteristics of ARM-NPs were investigated including particle size, morphology, secondary structure of the peptide drug, aerosolization properties and storage stability. As revealed by the results, ARM-NPs with spherical shape possessed 147.7 ± 2.0 nm of particle size with 0.152 ± 0.021 PdI. The ARM-NPs for pMDI had satisfactory fine particle fraction (FPF) value of 46.99 ± 1.33%, while the secondary structure of the peptide drug was unchanged. Stability tests showed no pronounced sedimentation instability for over 12 weeks at 4–6 °C. Furthermore, a hypothesis was raised to explain the formation mechanism of ARM-NPs, which was verified by the differential scanning calorimetry analysis. The lecithin employed in the reverse micelle vesicles could serve as a steric barrier between peptide drugs and bulk propellant, which prevented the instability of peptide drugs in hydrophobic environment. Homogenous particle size could avoid Ostwald ripening phenomenon of particles in pMDIs. It was concluded that the ARM-NPs for pMDI could successfully overcome sedimentation instability by the steric barrier effect and homogeneous particle size.

Development of a liquid formulation of poorly water-soluble isosteviol sodium using the co-solvent technology

An intravenously injectable liquid formulation of the poorly water-soluble isosteviol sodium (ISVNa) that has a great clinical potential for cardiovascular diseases was developed using the co-solvent technology. The pH and composition of the co-solvent were optimized to obtain a stable liquid formulation (termed as STVNa) based on saline at pH 10.0 containing 25% (v/v) of ethanol and 20% (v/v) of propylene glycol. STVNa was physicochemically stable upon storage for more than 3 months under various conditions. In vitro studies showed that STVNa did not induce hemolytic effects up to 9.1% (v/v) after 3 h of incubation and it was cytocompatible up to 50 μg/mL in H2C9 cells. Furthermore, STVNa showed acceptable safety and pharmacokinetic parameters comparable with those of ISVNa in saline (dissolved at 60 °C) upon i.v. injection in Wistar rats. Overall, the results demonstrated that STVNa is a promising formulation of ISVNa for clinical translation.

Effects of Temperature and Humidity on Laser Diffraction Measurements to Jet Nebulizer and Comparison with NGI

Laser diffraction (LD) and next generation impactor (NGI) are commonly used for the evaluation of inhaled drug formulations. In this study, the effect of temperature and humidity on the assessment of the nebulizer particle size distribution (PSD) by LD was investigated, and the consistency between NGI and LD measurements was evaluated. There was an increase in particle size with higher temperature or lower humidity. The particle population with a diameter less than 1 μm was significant at a temperature of 5°C or at relative humidity >90%; however, the same particle population became undetectable when temperature increased to 39°C or at relative humidity of 30-45%. The results of the NGI and LD measurements of aerosol generated from three types of jet nebulizers were compared. A poor correlation between the NGI and LD measurements was observed for PARI LC (2.2 μm) (R (2) = 0.893) and PARI LC (2.9 μm) (R (2) = 0.878), while a relatively good correlation (R (2) = 0.977) was observed for the largest particle size nebulizer (PARI TIA (8.6 μm)). We conclude that the ambient environment and the nebulizer have significant impacts on the performance and consistency between these instruments. These factors should be controlled in the evaluation of inhaled aerosol drug formulations when these instruments are used individually or in combination.

Topical drug delivery systems: a patent review

INTRODUCTION

Topical administration is the favored route for local delivery of therapeutic agents due to its convenience and affordability. The specific challenge of designing a therapeutic system is to achieve an optimal concentration of a certain drug at its site of action for an appropriate duration.

AREAS COVERED

This review summarizes innovations from the past 3 years (2012-2015) in the field of topical drug delivery for the treatment of local infections of the vagina, nose, eye and skin. The review also throws some light on the anatomy and physiology of these organs and their various defensive barriers which affect the delivery of drugs administered topically.

EXPERT OPINION

Topical administration has been gaining attention over the last few years. However, conventional topical drug delivery systems suffer from drawbacks such as poor retention and low bioavailability. The successful formulation of topical delivery products requires the careful manipulation of defensive barriers and selection of a soluble drug carrier. Extensive research is required to develop newer topical drug delivery systems aiming either to improve the efficacy or to reduce side effects compared to current patented systems.

Targeting REDV peptide functionalized polycationic gene carrier for enhancing the transfection and migration capability of human endothelial cells

Targeting gene engineering should be considered as an effective method for promoting endothelialization of vascular grafts. Herein, we developed a targeting REDV peptide functionalized polycationic gene carrier for carrying the pEGFP-ZNF580 plasmid with the aim of enhancing the transfection and migration capability of human endothelial cells. This polycationic gene carrier with the REDV peptide (mPEG-P(LA-co-CL)-PEI-REDV) was prepared by the conjugation of the Cys-Arg-Glu-Asp-Val-Trp (CREDVW) peptide with the amphiphilic block copolymer methoxy poly(ethylene glycol) ether-poly(l-lactide-co-ε-caprolactone)-poly(ethyleneimine) (mPEG-P(LA-co-CL)-PEI). mPEG-P(LA-co-CL)-PEI nanoparticles (NP) and mPEG-P(LA-co-CL)-PEI-REDV nanoparticles (REDV-NP) were formed by the self-assembly of the corresponding polycationic polymers, and then their pEGFP-ZNF580 complexes were prepared via the electrostatic interaction with pEGFP-ZNF580 plasmids, respectively. Gel electrophoresis results show that the targeted REDV-NPs could compress pEGFP-ZNF580 plasmids into stable complexes and protect the plasmids against desoxyribonuclease degradation. MTT assay indicates that these targeted REDV-NP/pEGFP-ZNF580 complexes exhibit better cyto-compatibility than the non-targeted NP/pEGFP-ZNF580 complexes and the control PEI 1800 Da/pEGFP-ZNF580 complexes. In vitro transfection experiments and western blot analysis of EA.hy926 endothelial cells show that the pEGFP-ZNF580 plasmid expression and the relative protein level transfected by targeted REDV-NP/pEGFP-ZNF580 complexes are roughly consistent with that transfected by PEI 25 kDa/pEGFP-ZNF580 complexes. More importantly, the scratch wound assay results demonstrate that the migration capability of EA.hy926 cells has been improved significantly by the expression of the pEGFP-ZNF580 plasmid. Our results indicate that the polycationic polymer with functional REDV peptides can be a potential candidate as a pEGFP-ZNF580 plasmid delivery carrier and may be used in the endothelialization of vascular grafts.