Current Pharmaceutical Design - Volume 23, Issue 3, 2017

Quantum dots are semiconducting nanocrystals that exhibit extraordinary optical properties. QD have shown higher photostability compared to standard organic dye type probes. Therefore, they have been heavily explored in the biomedical field. This review will discuss the different approaches to synthesis, solubilise and functionalise QD. Their main biomedical applications in imaging and photodynamic therapy will be highlighted. Finally, QD biodistribution profile and in vivo toxicity will be discussed.

Crystalline and amorphous dispersions have been the focus of academic and industrial research due to their potential role in formulating poorly water-soluble drugs. This review looks at the progress made starting with crystalline carriers in the form of eutectics moving towards more complex crystalline mixtures. It also covers using glassy polymers to maintain the drug as amorphous exhibiting higher energy and entropy. However, the amorphous form tends to recrystallize on storage, which limits the benefits of this approach. Specific interactions between the drug and the polymer may retard this spontaneous conversion of the amorphous drug. Some studies have shown that it is possible to maintain the drug in the amorphous form for extended periods of time. For the drug and the polymer to form a stable mixture they have to be miscible on a molecular basis. Another form of solid dispersions is pharmaceutical co-crystals, for which research has focused on understanding the chemistry, crystal engineering and physico-chemical properties. USFDA has issued a guidance in April 2013 suggesting that the co-crystals as a pharmaceutical product may be a reality; but just not yet! While some of the research is still oriented towards application of these carriers, understanding the mechanism by which drug-carrier miscibility occurs is also covered. Within this context is the use of thermodynamic models such as Flory-Huggins model with some examples of studies used to predict miscibility.

Liposomes are established drug carriers for inhalation owing to their safety and ability to provide controlled drug release in the lung. These carriers can entrap a wide range of therapeutic molecules for delivery in large volumes to the peripheral airways using medical nebulizers. Pressurized metered inhalers (pMDIs), soft mist inhalers (SMIs) and dry powder inhalers (DPIs) can deliver relatively small quantities of medication to the lung when compared to medical nebulizers which can deliver large volumes using simple liposome preparation techniques. Unfortunately, the shearing provided during nebulization to convert the aqueous liposome dispersions into “respirable” aerosol droplets may exert physical stress on liposome bilayers, causing losses of the originally entrapped drug. The development of successful liposome carriers for inhalation depends on two main factors which are formulation composition and nebulizer design, with the aim of reducing the detrimental effect of shearing on liposome stability and maximizing the deposition of vesicles in the ‘deep lung’. A number of nebulizable liposome formulations have reached clinical trials. For example, Arikace® (liposomal amikacin) and Pulmaquin® (liposomal ciprofloxacin) are antibacterial formulations currently in advanced stages of development. In this review, the role of liposome formulation and inhalation device design on the suitability of liposomes for eliciting controlled drug release in the lung was evaluated. Moreover, the factors contributing to the success of Arikace® in clinical trials were appraised.

Background: Due to its unique features, the respiratory tract had received great attention as a promising non-invasive route for drug administration to achieve both local and systemic effects. Efforts spent to tailor systems able to overcome the lung defence mechanisms and biological barriers are followed in this review. Aerodynamic diameter, morphology, lung deposition and drug release profiles are the main criteria describing the selected new smart lung targeted delivery systems. Methods: Novel systems such as nanoparticles, nano-embedded-in microparticles (NEM), small microparticles (MP), large porous particles (LPP), PulmospheresTM and polymeric micelles are used to passively target different areas in the respiratory tract. The most common preparation methods are outlined in the article. Special emphasis was given to the characteristics of the polymers used to fabricate the developed systems. Efforts made to prepare systems using chitosan (CS), alginate (alg), hyaluronic acid (HA), gelatin and albumin as examples of natural polymers and poly lactic-co-glycolic acid (PLGA) and poly(#144;-caprolactone) (PCL) as synthetic polymers were compiled. Conclusion: The continuous development and work in the area of lung targeting resulted in the development of engineered smart platforms with the capability to carry small drug molecules, proteins and genes to treat a variety of local and systemic diseases.

Background: The brain is the most protected organ in the human body; its protective shield, relying on a complex system of cells, proteins and transporters, prevents potentially harmful substances from entering the brain from the bloodstream but, on the other hand, it also stops drugs administered via the systemic route. To improve the efficacy of pharmacological treatments, targeted drug delivery by means of polymer nanoparticles is a challenging but, at the same time, efficient strategy. Methods: Thanks to a highly multidisciplinary approach, several ways to overcome the brain protection have provided effective solutions to treat a large number of diseases. Important advances in polymer science, together with the development of novel techniques for nanocarrier preparation, and the discovery of novel targeting ligands and molecules, allow a fine-tuning of size, shape, chemicophysical properties and surface chemistry of functional particulate systems; it enables the improvement of the therapeutic performances for several drugs, also toward districts that are difficult to be treated, such as the brain. Conclusion: This review focuses on the great strides made from scientists and doctors in the development of polymer nano-sized drug delivery systems for brain diseases. Even though the optimal nanocarrier was not yet discovered, important advances were made to strive for safer, performant and successful systems, with the expectation to find soon better solutions to cure some still untreatable pathologies.

The pharmaceutical applications of cyclodextrins (CDs), cyclic oligosaccharides capable of including hydrophobic molecules inside their cavities, have been known for decades. Besides the solubilising and encapsulating abilities of natural and modified CDs due to the formation of inclusion complexes, there is an increasing interest in organized macrostructures based on CDs as potential drug delivery devices and gene carrier systems. The present review discusses first the case of drug carriers based on monomeric modified CDs (amphiphilic and CD core-star polymers), in which self-assembly plays a major role. Polyrotaxanes, i.e., CDs threaded onto a polymer chain, are then reviewed in relation to their pharmaceutical applications. Finally, covalently linked CDs, either by grafting or crosslinking, are analyzed, including more complex structures formed by assembling CDcontaining networks or chains. We have tried along this review to cover the most recent developments on these structures for drug delivery in a “beyond the cyclodextrin” approach. The review will be helpful, both for readers who want to be introduced into the world of these remarkable structures, or for specialists who are doing research in this field.

Three-dimensional (3D) printing is an emerging manufacturing technology for biomedical and pharmaceutical applications. Fused deposition modelling (FDM) is a low cost extrusion-based 3D printing technique that can deposit materials layer-by-layer to create solid geometries. This review article aims to provide an overview of FDM based 3D printing application in developing new drug delivery systems. The principle methodology, suitable polymers and important parameters in FDM technology and its applications in fabrication of personalised tablets and drug delivery devices are discussed in this review. FDM based 3D printing is a novel and versatile manufacturing technique for creating customised drug delivery devices that contain accurate dose of medicine( s) and provide controlled drug released profiles.

Background: The drug delivery of macromolecules such as proteins and peptides has become an important area of research and represents the fastest expanding share of the market for human medicines. The most common method for delivering macromolecules is parenterally. However parenteral administration of some therapeutic macromolecules has not been effective because of their rapid clearance from the body. As a result, most macromolecules are only therapeutically useful after multiple injections, which causes poor compliance and systemic side effects. Method: Therefore, there is a need to improve delivery of therapeutic macromolecules to enable non-invasive delivery routes, less frequent dosing through controlled-release drug delivery, and improved drug targeting to increase efficacy and reduce side effects. Result: Non-invasive administration routes such as intranasal, pulmonary, transdermal, ocular and oral delivery have been attempted intensively by formulating macromolecules into nanoparticulate carriers system such as polymeric and lipidic nanoparticles. Conclusion: This review discusses barriers to drug delivery and current formulation technologies to overcome the unfavorable properties of macromolecules via non-invasive delivery (mainly intranasal, pulmonary, transdermal oral and ocular) with a focus on nanoparticulate carrier systems. This review also provided a summary and discussion of recent data on non-invasive delivery of macromolecules using nanoparticulate formulations.

A lot of effort has been devoted to achieving active targeting for cancer therapy in order to reach the right cells. Hence, increasingly it is being realized that active-targeted nanocarriers notably reduce off-target effects, mainly because of targeted localization in tumors and active cellular uptake. In this context, by taking advantage of the overexpression of transferrin receptors on the surface of tumor cells, transferrin-conjugated nanodevices have been designed, in hope that the biomarker grafting would help to maximize the therapeutic benefit and to minimize the side effects. Notably, active targeting nanoparticles have shown improved therapeutic performances in different tumor models as compared to their passive targeting counterparts. In this review, current development of nano-based devices conjugated with transferrin for active tumor-targeting drug delivery are highlighted and discussed. The main objective of this review is to provide a summary of the vast types of nanomaterials that have been used to deliver different chemotherapeutics into tumor cells, and to ultimately evaluate the progression on the strategies for cancer therapy in view of the future research.

Background: Improvement of oral bioavailability through enhancement of dissolution for poorly soluble drugs has been a very promising approach. Recently, mesoporous silica based molecular sieves have demonstrated excellent properties to enhance the dissolution velocity of poorly water-soluble drugs. Description: Current research in this area is focused on investigating the factors influencing the drug release from these carriers, the kinetics of drug release and manufacturing approaches to scale-up production for commercial manufacture. Conclusion: This comprehensive review provides an overview of different methods adopted for synthesis of mesoporous materials, influence of processing factors on properties of these materials and drug loading methods. The drug release kinetics from mesoporous silica systems, the manufacturability and stability of these formulations are reviewed. Finally, the safety and biocompatibility issues related to these silica based materials are discussed.

Different types of injectable nanoparticles, including metallic nanoparticles, polymeric nanocarriers, dendrimers, liposomes, niosomes, and lipid nanoparticles, have been employed to load drugs for lung delivery. Nanoparticles used for lung delivery offer some benefits over conventional formulations, including increased solubility, enhanced stability, improved epithelium permeability and bioavailability, prolonged half-life, tumor targeting, and minimal side effects. In recent years, the concept of using injectable nanocarriers as vehicles for drug delivery has attracted increasing attention. This review highlights recent developments using nanomedical approaches for drug targeting to the lungs. We systematically introduce the concepts and amelioration mechanisms of the nanomedical techniques for lung cancer therapy. Passive targeting by modulating the nanoparticulate structure and the physicochemical properties is an option for efficient drug delivery to the lungs. In addition, active targeting such as antibody or peptide conjugation to nanoparticles is another efficient way to deliver the drugs to the targeted site. This review describes various nanocarriers loaded with anticancer drugs for passive or active targeting of lung malignancy. In this review, we principally focus on the nanomedical application in animal studies. The article excludes investigations limited to cell-based experiments. The review ends by anticipating future developments and trends.

Nanoemulsion has the potential to overcome several disadvantages in drug formulation. Loading poor water-soluble drugs in the appropriate nanoemulsions enhances their wettability and/or solubility. Consequently, this improves their pharmacokinetics and pharmacodynamics by different routes of administration. Associated with the optimum nanodroplets size or even combined with key components, the droplets act as a reservoir of drugs, enabling nanoemulsion to be multifunctional platform to treat diverse diseases. A number of important advantages, which comprise nanoemulsion attributes, such as efficient drug release with appropriate rate, prolonged efficacy, drug uptake control, low side effects and drug protection properties from enzymatic or oxidative processes, have been reported in last decade. The high flexibility of nanoemulsion includes also a variety of manufacturing process options and a combination of widely assorted components such as surfactants, liquid lipids or even drug-conjugates. These features provide alternatives for designing innovative nanoemulsions aiming at high-value applications. This review presents the challenges and prospects of different nanoemulsion types and its application. The drug interaction with the components of the formulation, as well as the drug mechanistic interaction with the biological environment of different routes of administration are also presented.

Amphotericin B (AmB) is the drug of choice in the treatment of invasive fungal infections and visceral leishmaniasis. Although AmB has a higher selectivity for ergosterol (present in fungi and Leishmania spp. membrane) than for cholesterol, mammalian cells are affected by AmB, mainly in its oligomeric aggregated form, resulting in side effects, especially nephrotoxicity. The development of nanotechnology-based drug delivery systems for AmB is a promising avenue since nanoparticles have the ability to target drugs to the infected cells, and their prolonged drug release profile permits longer contact between the drug and the fungi/parasite. In this review, we made an overview about nanoparticles as colloidal carriers for AmB, including polymeric-based nanoparticles, protein-based nanoparticles and solid lipid-based nanoparticles with respect to their application for the treatment of invasive fungal infections and leishmaniasis.

Background: Cyclodextrins (CDs), as one type of the novel pharmaceutical excipients, have been widely used in drug delivery and pharmaceutical industry. Over the past decades, a large amount of molecular modeling studies in CDs were reported for profound understanding of structural, dynamic and energetic features of CDs systems. Thus, this review is focused on qualitative and quantitative analysis of research outputs on molecular modeling in CDs. Methods: The original data were collected from Web of Science and analyzed by scientific knowledge mapping tools, including Citespace, Science of Science, VOSviewer, GPSvisualizer and Gephi software. Scientific knowledge mapping, as an emerging approach for literature analysis, was employed to identify the knowledge structure and capture the development of the science in a visual way. Results: The results of analysis included research outputs landscape, collaboration patterns, knowledge structure and research frontiers shift with time. China had the largest contributions to the publication number in this area, while USA dominated the high quality research outputs. International collaboration between USA and Europe was much stronger than that within Asia. J American Chemical Society, as one of the most important journals, played a pivotal role in linking different research fields. Furthermore, seven important thematic clusters were identified by the research cluster analysis with visualization tools and demonstrated from three different perspectives including: (1) the mostly-used CD molecules: β-Cyclodextrin, (2) preferred modeling tools: docking calculation and molecular dynamic, (3) hot research fields: structural properties, solubility, chiral recognition and solidstate inclusion complexes. Moreover, research frontier shift in the past three decades was traced by detecting keywords bursts with high citation. Conclusion: The current review provided us a macro-perspective and intellectual landscape to molecular modeling in CDs.