Daniela Traini

Recent advances in curcumin nanoformulation for cancer therapy

Introduction: Natural compounds are emerging as effective agents for the treatment of malignant diseases. Curcumin (diferuloylmethane), the active constituent of turmeric extract, has gained significant interest as a plant-based compound with anti-cancer properties. Curcumin is physiologically very well tolerated, with negligible systemic toxicity observed even after high oral doses administration. Despite curcumin’s superior properties as an anti-cancer agent its applications are limited due to its low solubility and physico-chemical stability, rapid systemic clearance and low cellular uptake. Areas covered: This review focuses on the development of curcumin nano-particle formulation to improve its therapeutic index through enhanced cellular uptake, localization to targeted areas and improved bioavailability. The feasibility of nano-formulation in delivering curcumin and the limitations and challenges in designing and administrating the nano-sized curcumin particles are also covered in this review. Expert opinion: Nanotechnology is a promising tool to enhance efficacy and delivery of drugs. In this context, formulation of curcumin as nano-sized particles could reduce the required therapeutic dosages and subsequently reduced its cell toxicity. These nanoparticles are capable to provide local delivery of curcumin targeted to specific areas and thereby preventing systemic clearance. In addition, using specific coating, better pharmacokinetic and internalization of nano-curcumin could be achieved. However, the potential toxicity of nano-carriers for curcumin delivery is an important issue, which should be taken into account in curcumin nano-formulation.

The Influence of Lactose Pseudopolymorphic Form on Salbutamol Sulfate-Lactose Interactions in DPI Formulations

A series of 63- to 90-μm sieve-fractioned lactose pseudopolymorphs were investigated in terms of carrier functionality for dry powder inhaler (DPI) formulations. Stable α-anhydrous, α-monohydrate, and β-anhydrous were chosen as model pseudopolymorphs. In addition, the β-anhydrous was further purified to remove residual α-monohydrate content (β-treated). The carriers were investigated in terms of morphology, particle size, crystallinity, and surface energy using inverse gas chromatography. Furthermore, the lactose samples carrier performance was evaluated by studying the aerosolization efficiency of the model drug, micronized salbutamol sulfate, from drug–carrier blends using a next generation impactor (NGI). In general, the aerosol performance of drug from carrier followed the rank order α-monohydrate > β-anhydrous > β-treated > α-anhydrous. Significant difference in carrier size was observed, specifically with relation to the amount of fines (where a rank order of β-treated > β-anhydrous > α-monohydrate > α-anhydrous. No direct relationship between fine content and particle morphology was observed. In comparison, an inverse relationship between surface energy and aerosolization efficiency was found, where a plot of fine particle fraction (aerodynamic diameter < 4.46 μm) against total surface energy resulted in R2 = .977. Such observations are most likely due to increased particle carrier adhesion and reduced drug liberation during the aerosolization process, indicating surface chemistry (in this case due to the existence of different pseudopolymorphs) to play a dominating role in DPI systems.

Time- and passage-dependent characteristics of a Calu-3 respiratory epithelial cell model

Background: Although standard protocols for the study of drug delivery in the upper airways using the sub-bronchial epithelial cell line Calu-3 model, particularly that of the air-liquid interface configuration, are readily available, the model remains un-validated with respect to culture conditions, barrier integrity, mucous secretion, and transporter function. With respect to the latter, the significance of functional P-glycoprotein (P-gp) activity in Calu-3 cells has recently been questioned, despite previous reports demonstrating a significant contribution by the same transporter in limiting drug uptake across the pulmonary epithelium. Therefore, the aim of this study was the standardization of this model as a tool for drug discovery. Methods: Calu-3 cells were grown using air-interfaced condition (AIC) on polyester cell culture supports. Monolayers were evaluated for transepithelial electrical resistance (TEER), permeability to the paracellular marker fluorescein sodium (flu-Na), surface P-gp expression, and functionality. Mucous secretion was also identified by alcian blue staining. Results: TEER and permeability values obtained for Calu-3 monolayers were shown to plateau between day 5 and day 21 in culture with values reaching 474 ± 44 ωcm2 and 2.33 ± 0.36 × 10–7 cm/s, respectively, irrespective of the passage number examined. 32.7 ± 1.49% of Calu-3 cells cultured under these conditions detected positive for cell surface P-gp expression from day 7 onwards. Functional cell surface expression was established by rhodamine 123 drug extrusion assays. Conclusion: This study establishes a clear dependence on culture time and passage number for optimal barrier integrity, mucous secretion, and cell-surface P-gp expression and function in Calu-3 cells. Furthermore it provides initial guidelines for the optimization of this model for high throughput screening applications.

Co-spray-dried mannitol-ciprofloxacin dry powder inhaler formulation for cystic fibrosis and chronic obstructive pulmonary disease.

The aim of this study was to assess the potential of delivering a combination therapy, containing mannitol (a sugar alcohol with osmotic characteristics), and ciprofloxacin hydrochloride (an antibacterial fluoroquinolone), as a dry powder inhaler (DPI) formulation for inhalation. Single and combination powders were produced by spray drying ciprofloxacin and mannitol, from aqueous solution, at different ratios and under controlled conditions, as to obtain similar particle size distributions. Each formulation was characterised using laser diffraction, scanning electron microscopy, differential scanning calorimetry, dynamic vapour sorption, X-ray powder diffraction, and colloidal force microscopy. The in vitro aerosol performance of each formulation was studied using an Aerolizer DPI device and a multi-stage liquid impinger (analysed using high performance liquid chromatography). In addition, a disk diffusion test was performed to assess the in vitro antimicrobial activity of each formulation and starting materials. All formulations had similar particle size distributions, however, the morphology, thermal properties and moisture sorption was dependent on the relative percentages of each component. In general, the combination formulation containing 50% (w/w) mannitol appeared to have the best aerosol performance, good stability and lowest particle cohesion (as measured by colloid probe microscopy). Furthermore, of the formulations tested, mannitol did not appear to alter the effectiveness of the ciprofloxacin antimicrobial activity to Staphylococcus aureus, Pseudomonas aeruginosa and Streptococcus pyogenes. The combination of co-spray-dried mannitol and ciprofloxacin from a DPI is an attractive approach to promote mucous clearance in the respiratory tract while simultaneously treating local chronic infection, such as chronic obstructive pulmonary disease and cystic fibrosis.

Micro-particle corrugation, adhesion and inhalation aerosol efficiency.

Atomic force microscopy (AFM) was used to evaluate the particle adhesion and surface morphology of engineered particles for dry powder inhaler (DPI) respiratory therapy to gain a greater understanding of interparticle forces and the aerosolisation process. A series of spherical model drug particles of bovine serum albumin (BSA) was prepared with different degrees of surface corrugation. The particles were evaluated in terms of particle size (laser diffraction) and microscopic morphology (scanning electron microscopy). Conventional tapping mode AFM was used to evaluate the nanoscopic morphology and derive specific roughness parameters, while AFM colloid probe microscopy was used to directly measure the interaction of functionalised probes. The physical characterisation and AFM measurements were evaluated in terms of in vitro aerosolisation performance, using a conventional Rotahaler((R)) DPI and multistage liquid impinger. A direct relationship between the root mean square roughness, particle adhesion and in vitro aerosol performance (measured as fine particle fraction, FPF) was observed suggesting that as the degree of corrugation increased, particle adhesion was reduced which, resulted in a concomitant increase in FPF. This study demonstrates that AFM may be used to predict the aerosolisation performance micron sized particles for inhalation based on their morphological properties.

The nanoscale in pulmonary delivery. Part 1: deposition, fate, toxicology and effects

This two-part review explores the nanoscale in inhalation delivery. The first part covers the deposition, fate, toxicity and effects of nanoparticles delivered via inhalation. The second part analyses the potential of major inhalation delivery routes. Efficient particle deposition in the lung can be achieved with nanoparticles (50 – 100 nm). However, this particle range has hardly been exploited in a medical setting. Thus, formulation scientists have a rare opportunity to develop new concepts in inhalation delivery. The delivery of nanoparticles raises concern over increased toxicity, but also opens up the possibility for enhanced therapeutic effects and reduced dosage. Toxicity data available so far concerns mainly non-therapeutic molecules, and it remains a moot point as to whether these apply to drug molecules.

Preparation and characterisation of controlled release co-spray dried drug-polymer microparticles for inhalation 2: evaluation of in vitro release profiling methodologies for controlled release respiratory aerosols.

Three in vitro methodologies were evaluated as models for the analysis of drug release from controlled release (CR) microparticulates for inhalation. USP Apparatus 2 (dissolution model), USP Apparatus 4 (flow through model) and a modified Franz cell (diffusion model), were investigated using identical sink volumes and temperatures (1000 ml and 37 degrees C). Microparticulates containing DSCG and different percentages of PVA (0%, 30%, 50%, 70% and 90%) were used as model CR formulations. Evaluation of the release profiles of DSCG from the modified PVA formulations, suggested that all data fitted a Weibull distribution model with R2 > or =0.942. Statistical analysis of the t(d) (time for 63.2% drug release) indicated that all methodologies could distinguish between microparticles that did or did not contain PVA (Students t-test, p<0.05). However, only the diffusion model could differentiate between samples containing different PVA percentages. Similar results were observed when analysing the data using similarity and difference factors. Furthermore, analysis of the release kinetic profiles for all samples suggested the data fitted the Higuchi diffusion model (R2 > or =0.862 for the diffusion methodology data set). Due to the relatively low water content in the respiratory tract and the lack of differentiation between formulations for USP Apparatus 2 and 4, it is concluded that the diffusion model is more applicable for the evaluation of CR inhalation medicines.

Delivery of antibiotics to the respiratory tract: an update

The use of inhaled medications for the treatment of pulmonary diseases has become an increasingly popular drug delivery route over the past few decades. This delivery route allows for a drug to be delivered directly to the site of the disease, with a lower dose than more conventional oral or intravenous delivery methods, with reduced systemic absorption and consequently reduced risk of adverse effects. For asthma this delivery route has become the ‘golden standard’ of therapy. It is not unexpected therefore, that there has been great interest in the prospect of using inhaled antibiotics for the treatment of both chronic and recurrent respiratory infections. Since the early 1980s, several investigations have demonstrated that antibiotics could be delivered safely by means of inhalation, using nebulisers as their delivery systems. Lately, antibiotics delivery via inhalation have seen a ‘revival’ in interest and most of these studies have focused on delivering antibiotics to the lungs by means of a dry powder format. This review focuses on recent advances in antibiotic inhalation therapy.

A novel dry powder inhalable formulation incorporating three first-line anti-tubercular antibiotics

Treatment for tuberculosis (TB) using the standard oral antibiotic regimen is effective but inefficient, requiring high drug dosing and lengthy treatment times. Three concurrent first-line antibiotics recommended by the World Health Organization (WHO) guidelines are pyrazinamide, rifampicin and isoniazid. Combining these antibiotics in a novel formulation for dry powder inhalation (DPI) may facilitate rapid and efficient resolution of local and systemic infection. However, spray-dried individually, these antibiotics were found to be physically unstable. A solution of the three antibiotics, at the WHO-recommended ratio, was spray-dried. The collected powder was assessed by a series of in vitro methods to investigate aerosol performance, particle physico-chemical characteristics and dissolution profile. Particles obtained were spherical with a surface composed primarily of rifampicin, as identified by TOF-SIMS. A mass median aerodynamic diameter of 3.5 ± 0.1 μm and fine particle fraction (<5 μm) of 45 ± 3% indicated excellent aerosol performance. The combination powder was differentiated by the presence of rifampicin dihydrate and the delta polymorph of pyrazinamide. Quantitative analysis indicated individual particles contained the three antibiotics at the expected proportions (400:150:75 w/w). This excipient-free triple antibiotic DPI formulation could be used as a significant enhanced treatment for TB.

Liposomal nanoparticles control the uptake of ciprofloxacin across respiratory epithelia.

ABSTRACTPurposeLiposomal ciprofloxacin nanoparticles were developed to overcome the rapid clearance of antibiotics from the lungs. The formulation was evaluated for its release profile using an air interface Calu-3 cell model and further characterised for aerosol performance and antimicrobial activity.MethodsLiposomal and free ciprofloxacin formulations were nebulised directly onto Calu-3 bronchial epithelial cells placed in an in vitro twin-stage impinger (TSI) to assess the kinetics of release. The aerosol performance of both the liposomal and free ciprofloxacin formulation was characterised using the next generation impactor. Minimum inhibitory and bactericidal concentrations (MICs and MBCs) were determined and compared between formulations to evaluate the antibacterial activity.ResultsThe liposomal formulation successfully controlled the release of ciprofloxacin in the cell model and showed enhanced antibacterial activity against Pseudomonas aeruginosa. In addition, the formulation displayed a respirable aerosol fraction of 70.5 ± 2.03% of the emitted dose.ConclusionResults indicate that the in vitro TSI air interface Calu-3 model is capable of evaluating the fate of nebulised liposomal nanoparticle formulations and support the potential for inhaled liposomal ciprofloxacin to provide a promising treatment for respiratory infections.