Antimicrobial Peptides: A New Hope in Biomedical and Pharmaceutical Fields.

Antibiotics are essential drugs used to treat pathogenic bacteria, but their prolonged use contributes to the development and spread of drug-resistant microorganisms. Antibiotic resistance is a serious challenge and has led to the need for new alternative molecules less prone to bacterial resistance. Antimicrobial peptides (AMPs) have aroused great interest as potential next-generation antibiotics, since they are bioactive small proteins, naturally produced by all living organisms, and representing the first line of defense against fungi, viruses and bacteria. AMPs are commonly classified according to their sources, which are represented by microorganisms, plants and animals, as well as to their secondary structure, their biosynthesis and their mechanism of action. They find application in different fields such as agriculture, food industry and medicine, on which we focused our attention in this review. Particularly, we examined AMP potential applicability in wound healing, skin infections and metabolic syndrome, considering their ability to act as potential Angiotensin-Converting Enzyme I and pancreatic lipase inhibitory peptides as well as antioxidant peptides. Moreover, we argued about the pharmacokinetic and pharmacodynamic approaches to develop new antibiotics, the drug development strategies and the formulation approaches which need to be taken into account in developing clinically suitable AMP applications.

Flurbiprofen sodium microparticles and soft pellets for nose-to-brain delivery: Serum and brain levels in rats after nasal insufflation.

Neuroinflammation in Alzheimer's disease (AD) revamped the role of a preventive therapeutic action of non steroidal anti-inflammatory drugs; flurbiprofen could delay AD onset, provided its access to brain is enhanced and systemic exposure limited. Nasal administration could enable direct drug access to central nervous system (CNS) via nose-to-brain transport. Here, we investigated the insufflation, deposition, dissolution, transmucosal permeation, and in vivo transport to rat brain of flurbiprofen from nasal powders combined in an active device. Flurbiprofen sodium spray-dried microparticles as such, or soft pellets obtained by agglomeration of drug microparticles with excipients, were intranasally administered to rats by the pre-metered insufflator device. Blood and brain were collected to measure flurbiprofen levels. Excipient presence in soft pellets lowered the metered drug dose to insufflate. Nevertheless, efficiency of powder delivery by the device, measured as emitted fraction, was superior with soft pellets than microparticles, due to their coarse size. Both nasal powders resulted into rapid flurbiprofen absorption. Absolute bioavailability was 33% and 58% for microparticles and pellets, respectively. Compared to intravenous flurbiprofen, the microparticles were more efficient than soft pellets at enhancing direct drug transport to CNS. Direct Transport Percentage index evidenced that more than 60% of the intranasal dose reached the brain via direct nose-to-brain transport for both powders. Moreover, remarkable drug concentrations were measured in the olfactory bulb after microparticle delivery. Bulb connection with the entorhinal cortex, from where AD initiates, makes flurbiprofen sodium administration as nasal powder worth of further investigation in an animal model of neuroinflammation.

In vitro evaluation of regional nasal drug delivery using multiple anatomical nasal replicas of adult human subjects and two nasal sprays.

Quantifying drug delivery to the site of action using locally-acting nasal suspension sprays is a challenging but important step toward understanding bioequivalence (BE) between test and reference products. The main objective of this study was to investigate the in vitro deposition pattern of two common but different locally-acting nasal suspension sprays using multiple nasal cavities. Twenty anatomically accurate nasal replicas were developed from high-resolution sinonasal computed tomography scans of adults with healthy nasal airways. The airways were segmented into two regions of anterior and posterior to the internal nasal valve. Both sides of the septum were considered separately; hence, 40 nasal cavities were studied. The positioning of the spray nozzle in all 40 cavities was characterized by the head angle, coronal angle, and the insertion depth. Despite using a controlled protocol to minimize the anterior losses, a wide range of variability in posterior drug delivery was observed. The observed intersubject variability using this in vitro method may have important implications for understanding BE of locally-acting nasal suspension sprays.

Anti-inflammatory flurbiprofen nasal powders for nose-to-brain delivery in Alzheimer's disease.

Neuroinflammation occurs in the early stages of Alzheimer's disease (AD). Thus, anti-inflammatory drugs in this asymptomatic initial phase could slow down AD progression, provided they enter the brain. Direct nose-to-brain drug transport occurs along olfactory or trigeminal nerves, bypassing the blood-brain barrier. Nasal administration may enable the drug to access the brain. Here, flurbiprofen powders for nose-to-brain drug transport in early AD-related neuroinflammation were studied. Their target product profile contemplates drug powder deposition in the nasal cavity, prompt dissolution in the mucosal fluid and attainment of saturation concentration to maximise diffusion in the tissue. Aiming to increase drug disposition into brain, poorly soluble flurbiprofen requires the construction of nasal powder microparticles actively deposited in nose for prompt drug release. Two groups of powders were formulated, composed of flurbiprofen acid or flurbiprofen sodium salt. Two spray dryer apparatuses, differing for spray and drying mechanisms, and particle collection, were applied to impact on the characteristics of the microparticulate powders. Flurbiprofen sodium nasal powders disclosed prompt dissolution and fast ex vivo transport across rabbit nasal mucosa, superior to the acid form, in particular when the powder was prepared using the Nano B-90 spray dryer at the lowest drying air temperature.

Chemicals from textiles to skin: an in vitro permeation study of benzothiazole.

Despite the possible impact on human health, few studies have been conducted to assess the penetration and accumulation of contaminants in the skin after a prolonged contact with textile materials. In previous studies, we have shown that benzothiazole and its derivatives, as well as other potentially hazardous chemicals, often are present as textile contaminants in clothes available on the retail market. Since benzothiazole is a common contaminant in clothes, these can be a possible route for human chemical exposure, both systemic and onto the skin. To investigate this potential exposure, Franz-type and flow-through cells were used for the permeation studies together with a Strat-M® artificial membranes. Experiments were performed using solutions of benzothiazole, as well as contaminated textile samples in the donor chamber. Benzothiazole was demonstrated to penetrate through, as well as being accumulated in the membrane mimicking the skin. After 24 h, up to 62% of benzothiazole was found in the acceptor cell, while up to 37% was found absorbed in the skin mimicking membrane. It also was shown that there was release and permeation from contaminated fabrics. The results indicate that benzothiazole can be released from textile materials, penetrate through the skin, and further enter the human body. This will possibly also apply to other chemical contaminants in textiles, and the results of this study indicate that the presence of these textile contaminants entails potential health risks. A rough risk assessment was made for clothing textiles according to Environmental Protection Agency (EPA) and European regulations for carcinogenic and non-carcinogenic compounds, using literature data for benzothiazole.

Opportunity and challenges of nasal powders: Drug formulation and delivery.

In the field of nasal drug delivery, among the preparations defined by the European Pharmacopoeia, nasal powders facilitate the formulation of poorly water-soluble active compounds. They often display a simple composition in excipients (if any), allow for the administration of larger drug doses and enhance drug diffusion and absorption across the mucosa, improving bioavailability compared to nasal liquids. Despite the positive features, however, nasal products in this form still struggle to enter the market: the few available on the market are Onzetra Xsail® (sumatriptan) for migraine relief and, for the treatment of rhinitis, Rhinocort® Turbuhaler® (budesonide), Teijin Rhinocort® (beclomethasone dipropionate) and Erizas® (dexamethasone cipecilate). Hence, this review tries to understand why nasal powder formulations are still less common than liquid ones by analyzing whether this depends on the lack of (i) real evidence of superior therapeutic benefit of powders, (ii) therapeutic and/or commercial interest, (iii) efficient manufacturing methods or (iv) availability of suitable and affordable delivery devices. To this purpose, the reader's attention will be guided through nasal powder formulation strategies and manufacturing techniques, eventually giving up-to-date evidences of therapeutic efficacy in vivo. Advancements in the technology of insufflation devices will also be provided as nasal drug products are typical drug-device combinations.

Clarithromycin and N-acetylcysteine co-spray-dried powders for pulmonary drug delivery: A focus on drug solubility.

Cystic fibrosis (CF) lungs are usually susceptible to Pseudomonas aeruginosa colonization and this bacterium is resistant to immune system clearance and drug control. Particularly, the biofilm mode of growth protects several microorganisms from host defenses and antibacterial drugs, mainly due to a delayed penetration of the drug through the biofilm matrix. Biofilm, together with lung mucus viscosity and tenacity, reduces, therefore, the effectiveness of conventional antibiotic therapy in CF. The aim of this research was to design and develop a stable, portable, easy to use dry powder inhaler (DPI) for CF patients, able to release directly to the lung an association of macrolide antibiotics (clarithromycin) and a mucolytic agent (N-Acetyl-Cysteine). Its effectiveness is based on the counteracting of the characteristics of P. aeruginosa infections in CF (lung bacterial adhesion to lung epithelium, biofilm formation and mucus viscosity) and the ability to let the antimicrobial drug exert their pharmacological action. A solution of these two drugs, without any excipients, was spray-dried to obtain respirable microparticles, characterized by aerodynamic diameters suitable for inhalation (<5.0µm). The morphology evaluation evidenced particles shape dependent on water content in the spray drying feeds, with wrinkled particles more evident with higher water content. Moreover, thanks to the presence of N-acetylcysteine which can interact with clarithromycin dimethyl-amino group, a consistent enhancement of drug solubility was obtained, compared to raw material and to the drug sprayed alone. The mucolytic agent added in the DPI may improve the macrolide diffusion into the mucus, enabling its action.

Aerodynamic properties, solubility and in vitro antibacterial efficacy of dry powders prepared by spray drying: Clarithromycin versus its hydrochloride salt.

Antibiotic therapy for a direct administration to the lung in cystic fibrosis patients has to provide suitable availability, possibly in the lower respiratory tract, characterized by the presence of thick secretions. One of the crucial steps in the therapeutic management of the respiratory disease could be the drug solubilization directly in this site of action. The aim of the study was to prepare respirable powders of clarithromycin, while improving drug aqueous solubility. With this aim, several batches of micronized particles were prepared by spray drying different feed solutions, varying the solvent composition (water/isopropyl alcohol ratio), the drug concentration and pH of the liquid feeds. Particle size distribution of raw materials and engineered particles was determined using a light-scattering laser granulometer while particle morphology was assessed by scanning electron microscopy. The in vitro deposition of the micronized clarithromycin powders was evaluated by means of a Single-Stage Glass Impinger using the RS01 model7 by Plastiape® as device for the aerosolization. Solubility measurements of raw and spray-dried (SD) drug were carried out at 37°C in phosphate buffer (0.05M, pH 6.8). Results indicate that morphology and aerodynamic properties of SD particles were strongly influenced by organic solvent concentration and pH of the liquid feeds processed, both modifying drug solubility. Spherical particles and crystals were obtained at higher pH and lower organic solvent content, while wrinkled particles with very interesting aerodynamic properties and higher drug solubility were obtained at lower pH values. Thanks to a fine tuning of the process parameters and liquid feed composition, we produced SD powders with good aerodynamic properties, without using any excipients. Furthermore, SD powders of clarithromycin hydrochloric salt showed higher activity against Pseudomonas aeruginosa growth, compared to clarithromycin raw material.

Rheological Properties of Cystic Fibrosis Bronchial Secretion and in Vitro Drug Permeation Study: The Effect of Sodium Bicarbonate.

BACKGROUND: Cystic fibrosis (CF) is characterized by a thick, sticky mucus responsible for both airway obstruction and resistance to drug diffusion, reducing the effectiveness of drug delivery to the lung. Studies of drug-mucus interaction may be a crucial step in therapeutic management of CF. In the present research, the effect of a saline solution of sodium bicarbonate (100 mM) on sputum viscosity and the permeation properties of ketoprofen lysinate (Klys) from a previously developed dry powder inhaler were evaluated. METHODS: Rheological measurements were performed using an ARES rotational rheometer (Rheometrics, Inc.) with a parallel plate geometry. The gel fraction, separated from the liquid phase of various sputum samples from CF patients was loaded onto the plate. The elastic (G') and the viscous (G") moduli, tan δ (ratio of G" to G') and η* (complex viscosity) were evaluated as frequency-dependent parameters. Drug permeation across CF sputum from dry powders was studied by means of Franz-type vertical diffusion cells. The experiments were conducted on untreated sputum and on sputum treated with bicarbonate. RESULTS: Rheological studies showed that the elastic modulus (G') was always greater than the viscous modulus (G") and the viscosity decreased with increasing frequency, as for pseudo-plastic fluids. Bicarbonate caused a downward shift of both the elastic and viscous moduli, with a reduction in complex viscosity. As to drug permeation, the untreated sputum slowed down drug dissolution and permeation compared to buffer permeability (control). Permeation studies across CF sputum treated with bicarbonate showed higher Klys dissolution/permeation than untreated sputum. CONCLUSIONS: The interesting results confirm the previously reported bicarbonate. effectiveness in CF; this weak base seems to act by decreasing high viscosity of the CF bronchial secretion and, potentially, resulting in better mucus clearance and in fighting pulmonary infections.